MT 1 Flashcards
what is included in the central nervous system
brain and spinal cord
what is included in the peripheral nervous system
nerves, including cranial nerves
what is trepanning/trepanation?
It is an ancient surgical procedure involving the removal of a section of the skull to treat medical conditions or relieve pressure. it involves drilling a hole into the skull
how far back does evidence of trepanation date?
It dates back to the Neolithic period, before 2000 BC
What might have been the reasons for performing trepanation in ancient times?
Possible reasons include treating head injuries, epilepsy, mental illness, or as part of spiritual or ritualistic practices.
who is responsible for the origins of neurology
considered the father of neurology, thomas willis pioneered research in the field of the nervous system
what did willis discover
the circle of willis – the ring of arteries at the base of the brain that connects the brain’s blood supply systems
what is phrenology
the study of the shape and size of the cranium as a supposed indication of character and mental abilities
what were the four main principles of phrenology?
- the brain is the organ of the mind
- the mind is split into faculties, each controlling a different part of your personality, and each localized to a different organ of the brain.
- the size of the organ is representative of the energy of the faculty.
- these bumps are apparent on the skull and so by feeling the head and noting size differences, you can obtain information on the subjects personality.
who pioneered localization of function
paul broca
define localization of function
specific areas within the brain are responsible for particular functions
who was patient tan (aka Louis Victor Leborgne)
- aged 30
- lost ability to speak - only said “Tan” with expressive hand gestures and varying pitch and inflection
- appeared to grasp what asked
- biopsy of brain revealed large lesion in frontal area—specifically, in posterior inferior frontal gyrus
- helped realize speech function is localized
who was Cécile Mugnier-Vogt
- She specialized in neurology and brain research
- conducted extensive cytoarchitectonic studies of the brain, identifying and characterizing distinct regions in the neocortex by both functional and structural criteria
- worked a lot with neurodegeneration of the basal ganglia
- pathoclisis – some neurons are more suscepticle to disease than others
who was Augusta Dejerine-Klumpke
- found Klumpke paralysis, a type of paralysis involving the lower brachial plexus (a network of nerves that originates in the spinal cord and extends to the arms and hands)
- the “claw hand” where the forearm is supinated, the wrist extended and the fingers flexed
who was marion diamond
- conducted the first scientific analysis of Albert Einstein’s brain, contributing to the understanding of the roles of glial cells.
- contributed to advancements in neuroplasticity
what was one pro of phrenology
Though mainly flawed - phrenology did lead to the
idea that certain brain areas have certain functions -
an idea supported by Paul Broca (Localization of
Function)
what can be seen in an mri from the sagittal plane
right vs left half
what can be seen in an mri from the transverse plane
top vs bottom half
what can be seen in an mri from the coronal plane
front vs back half
name the lobes
- frontal
- parietal
- temporal
- occipital
(insula)
what splits the parietal and frontal lobe
central sulcus
what splits the frontal and temporal lobe
lateral sulcus (sylvian fissure)
how can the frontal lobe be split up
- superior frontal gyrus
- middle frontal gyrus
- inferior frontal gyrus
- precentral gyrus**
1.2 slide 20
how can the parietal lobe be split up
- postcentral gyrus**
- supramarginal gyrus
- angular gyrus
- posterior parietal cortex
1.2 slide 20
how can the temporal lobe be split up
- superior temporal gyrus
- middle temporal gyrus
- inferior temporal gyrus
1.2 slide 20
what makes up the limbic system
- amygdala
- hippocampus
- thalamus
- hypothalamus
- cingulate gyrus
- basal ganglia
posterior vs anterior comissure
anterior – front of the brain
posterior – back of the brain
what separates parietal lobe from occipital lobe
parieto-occipital sulcus
what are the three branches of the trigeminal nerve
maxillary, manibular, and opthalmic branch
% neuron to % mass in the cerebral cortex
19% neurons to 82% mass
**more mass per neuron
% neuron to % mass in the cerebellum
80% neurons to 10% mass
**more neurons per mass
% neuron to % mass in the rest of the brain (diencephalon and brainstem)
1% neurons to 8% mass
**more mass per neuron but smaller overall
importance of santiago ramón y cajal
proposed the neuron doctrine
what is the neuron doctrine
The concept that the nervous system is made up of discrete individual cells, neurons. Neurons may touch one another, but they do not fuse.
importance of Korbian
Brodmann
known for mapping the cerebral cortex and defining 52 distinct regions, known as Brodmann areas, based on their cytoarchitectonic characteristics.
what is cytoarchitecure
the arrangement of cells in a tissue, especially in specific areas of the cerebral cortex characterized by the arrangement of their cells and each associated with particular functions.
ex. neuron size, shape, packing density, etc.
what is a broadmann area
regions of the cerebral cortex that are defined by their cellular structure and organization. These regions, or Brodmann areas, correspond with diverse functions including sensation, motor control, and cognition.
brodmann area 4
primary motor cortex
brodmann area 1, 2, 3
primary somatosensory cortex
brodmann area 39, 40
wernicke’s area
brodmann area 44, 45
broca’s area
brodmann area 22
primary auditory cortex
brodmann area 17
primary visual cortex
Which Brodmann Area includes the majority
of Broca’s area
A. 17
B. 23
C. 44
D. 24
E. 42
44
Which Brodmann Area includes the majority
of the cingulate cortex?
A. 17
B. 23
C. 46
D. 24
E. 42
24
Where do the principle afferents to Brodmann Area 17 originate?
A. The primary visual cortex
B. The thalamus
C. Extrastriate cortex
D. The cerebellum
E. The ventral pathway
brodmann area 17, aka primary visual cortex, receives principal afferents from the lateral geniculate nucleus of the thalamus
draw the neuron. include these terms:
1. cell membrane
2. dendrites
3. cell body (soma)
4. axon
5. axon hillock
6. oligodendrocyte
7. myelin sheath
8. node of ranvier
9. axon terminal
10. synaptic end bulbs
1.2 slide 44
what are the different kinds of neurons
- unipolar
- bipolar
- pseudounipolar – (classified under unipolar)
- multipolar
draw unipolar neuron
1.2 slide 45
draw pyramidal neuron
1.2 slide 45
draw multipolar neuron
1.2 slide 45
draw bipolar neuron
1.2 slide 45
draw purkinje neuron
1.2 slide 45
draw and explain the steps of an action potential traveling down a neuron
1.2 slide 47
describe and draw vessels in the synaptic cleft
1.2 slide 47
draw and describe the sodium potassium pump
online
examples of common NTs
- glutamate
- gaba
- dopamine
- serotonin
- opiods
how many types of NTs are carried by neurons
most neurons contain a single type of NT (the chemical contained in the presynaptic vesicles); some neurons have co-transmitters (more than one). recepters vary in terms of transmitter affinity – a single neuron may have multipke receptor types.
where are action potentials generated at
axon hillock (depolarization) travels down the axon
what kind of synapses are there
electrical and chemical
what is the difference between electrical and chemical synapses
Electrical synapses:
- Direct connection between neurons via gap junctions, allowing for almost instantaneous signal transmission.
- Bidirectional signal transmission.
- Usually found in situations requiring rapid response, like in certain reflexes.
Chemical synapses:
- Signal transmission occurs through the release of neurotransmitters from the presynaptic neuron, which bind to receptors on the postsynaptic neuron.
- More common than electrical synapses.
- Unidirectional signal transmission.
1.2 slide 48
Describe different methods one could use to distinguish
(i.e. divide up) different brain areas and what characteristics/
features would be used to to differentiate areas for each method.
- Cytoarchitecture - cell histology (density/cell type, etc) (structure)
- Sulci/Gyri - bumps and grooves of brain (function)
- Lobes - large scale anatomy/well defined sulci (structure)
- Function - localize by studying function in some way (we will learn more about
later in the class) (function)
what is a randomized control trial
a study design that randomly allocates participants to a specific condition. For example, participants can be assigned to an experimental group to compare to a control group.
pros of randomized control trial
as the study is conducted, any relationship seen between variables can be attributed to the intervention (or the outcome variable being studied). Additionally, this study design is considered to be less biased, compared to other designs.
cons of randomized control trial
it is not always possible and can be expensive or difficult to carry out.
what is a case-controlled study
is retrospective and compares individuals with a specific condition or case to individuals without it (or the controls). These individuals are matched with controls based on several different factors, such as age and sex.
pros of case-controlled study
sometimes this is the only ethical way to test certain questions, which can be especially valuable for individuals with extremely rare conditions.
cons of case-controlled study
it can be hard to draw strong conclusions because there are many factors that can cause differences. It is also difficult to control for all confounds. These cons may be associated with a smaller sample size.
what is a case study
reports on one person (or a small group of people) to explore a rare or unique phenomenon. These designs may look at medical history, treatment plans, symptoms, and other related factors.
pros of case study
can provide a lot of detail on the medical history of the patient of interest and can help give more insight into specific conditions
cons of case study
they may not be generalizable to other cases
what is a cohort study
observational study that follows a group of individuals over time to assess the relationship between exposures and outcomes. It can either be prospective by tracking participants forward in time or retrospective by using past records to analyze outcomes.
pros of cohort study
it can sometimes be the only ethical way to test a certain question.
cons of cohort study
there may be differences besides those of interest that affect the results. Additionally, follow-up after long periods of time may not be feasible.
what is a cross-sectional survey
collects data at a single point in time.
pros of cross-sectional survey
fairly easy to implement. It is also typically more cost-effective, compared to other studies.
cons of cross-sectional survey
may be less accurate, especially with respect to past data. It is also harder to control across groups.
what is blinding
when individuals are unaware of the manipulation of a variable.
what is single blind
only the participants are unaware of group allocation.
what is double blind
both participants and researchers are unaware of group allocation.
describe the placebo effect
the phenomenon where participants experience a perceived or actual improvement in their condition due to their belief in the efficacy of a treatment, even when the treatment is inactive. Thus, a placebo matches the manipulated variable to a null manipulation, such as a sugar pill.
what were the features of HM
- had epilepsy
- Unable to learn any new information after surgery
- Able to remember all memories before his surgery
- Intact short-term/working memory (intact prefrontal cortex)
- Able to learn new procedural skills (intact basal ganglia)
- No change in his intelligence, language, perceptual abilities
- No change in his personality
**demonstrated that the hippocampus is crucial for forming new memories
How might authorship and affiliations be useful for
answering your own questions about the article?
A) Tells you exactly where all the research took place.
B) Can help guide searching for other related articles.
C) Shows that authors typically have one affiliation.
D) All of the above.
B) Can help guide searching for other related articles.
Which of the following sections always follows the
introduction?
A) Materials & Methods
B) Discussion
C) Results
D) Depends on the journal
D) Depends on the journal
You want to assess dementia in a group of patients. What would you do?
A) Check the reference section for the relevant citations.
B) Look up the relevant papers that are listed in the references.
C) Read the relevant papers.
D) Administer the rating scales to the patients.
E) All of the above.
D) Administer the rating scales to the patients.
what are the components of the neurological exam
- mental status
- cranial nerves
- motor system
- reflexes
- sensory system
- coordination / balance
- gait
what do you do for the first part of the neuro exam
mental status exam
- normal x 4 (1. person, 2. place, 3. time, 4. situation)
- if concerns, do MMSE (30/30)
- memory – ask them to remember 3 things and test recall then and five minutes later
- language (looking for broca’s / wernicke’s aphasia)
what is mmse
A Mini-Mental State Examination (MMSE) is a test of ~11 questions. It’s used by to check for cognitive impairment
what is hemispatial neglect
sometimes referred to as “extinction” or “inattention”
a neurological condition where a person, usually following brain damage to one hemisphere, becomes unaware of stimuli on the opposite side of their body or environment, essentially ignoring that side of space, even though they may not have any sensory loss there; it’s primarily associated with damage to the right parietal lobe, causing neglect on the left side.
remember the clock that finished halfway in the circle
2.2 slide 9
broca’s aphasia
difficulty speaking and forming words, even though they can understand it
wernicke’s aphasia
difficulty understanding language, even though the person may speak fluently but with nonsensical content
what do you do for the second part of the neuro exam
test each nerve individually
how to test the first nerve and what is traumatic anosmia
olfactory nerve
- very frequently damaged due to many spiny things in the front of the head by the nerve
ex. traumatic anosmia – head injury causing the brain to hit the front of the skull (causing loss of sense of smell) - parkinson’s presents first with loss of sense of smell
- people typically say that they can’t smell
- assessed by using vials of scent
how do you test the second nerve
optic nerve – visual info
- snellen chart – typical eye exam chart with the letters
occipital infarct
a stroke that occurs in the occipital lobe of the brain, which is responsible for processing visual information
homonymous hemianopsia
a visual field defect that affects the same side of both eyes. It can cause difficulty reading, seeing obstacles, and other visual impairments.
can see things on right side but not left
A patient complains of tunnel vision, i.e. a loss of peripheral vision, in both eyes. Which of the following is
a possible diagnosis?
A) Glaucoma
B) Unilateral stroke
C) Doesn’t listen to enough Kodak Black
D) Pituitary tumor
E) A and D
E) A and D
pituitary tumor
often benign, but they cause problems because they are push on the brain, putting pressure on other things (puts pressure on optic chiasm)
how does unilateral stroke affect vision
A stroke on one side of the brain can cause vision loss in the opposite side of the visual field in both eyes.
ex. homonymous hemianopsia
what is the confrontation test
test eyes separately to look for deficits in the visual field.
anything that is eye specific = before the optic chiasm
anything that is in both eyes, but related to the periphery = at the optic chiasm
anything that is in both eyes and contralateral = after the optic chiasm
draw the pathway for sight
2.2 slide 18
how to test nerves 2 and 3
pupillary response
what is the pupillary response
shine light in one eye and observe contraction in BOTH eyes
how to test nerves 3, 4, and 6
oculomotor, trochlear, and abducens
- look at eye movements – hold head stable and test movement in all directions
what eye movements is the oculomotor nerve responsible for
up, down, and in toward the nose
what eye movements is the abducens nerve responsible for
lateral movements away from the nose
what eye movements is the trochlear nerve responsible for
down toward the nose
how to test nerve 5
trigeminal – motor and sensory components (face sensations and muscles for biting and chewing)
- sensory - touch areas lightly with patient’s eyes closed
- motor have patient grind and clench teeth and feel muscle
how to test nerve 7
facial nerve
look at facial expression movements
bell’s palsy
movement of face on one side of the face
- can occur due to neural damage or can temporarily be there from viral infections
how to tell the difference between cranial nerve damage and cortical (stroke damage) when bell’s palsy is noticed
cortical (stroke):
- forehead spared (there are still wrinkles on both sides of the forehead)
- indicates upper motor neuron lesion
cranial nerve (bell’s palsey):
- forehead weak (wrinkles are not continuous because one half has no sensation)
- indicates lower motor neuron lesion
draw the cortico-spinal tract
2.2 slide 24
are cranial nerves considered upper or lower motor neurons
lower motor neurons
upper vs lower motor neurons
upper = prior to braintsem
lower = other side of the medulla to the spinal cord
draw how upper motor neurons and lower motor neuorns innervate the face differently
2.2 slide 25
how to test the 8th nerve
auditory nerve
rub fingers together near patients ears individually, and ask when they can hear it.
if deficit is noted, can also test hearing loss with tests like weber test
what is interesting about testing the auditory nerve
*is interesting because in each ear, there is coverage from both hemispheres.
for example, stroke doesn’t often show hearing damage unless it happened bilaterally
what is weber test
place vibrating tuning fork on top of head
normal –> equally loud on both sides
obstruction (ex. wax) –> louder on side WITH hearing impairment (bone conducts sound louder than air / less competing sound)
sensorineural –> louder on side without impairment
how to test nerves 9 and 10
glossopharyngeal and vagus
- listen to the voice of patient (sometimes its hoarse)
- have patient swallow and cough
how to test nerve 11
accessory
- shrug and turn head
- rarely abnormal
**trapezius and sternocleidomastoid
how to test nerve 12
hypoglossal
- check for deviations and deflections in tongue
- tongue points to lesion
what do you do for the third part of the neuro exam
motor system
inspect muscles for appearance (atrophy, fasciculations), palpate for tone (spasticity, flaccidity, rigidity), and test muscle strength by asking the patient to perform specific movements against resistance, while observing for any involuntary movements, coordination issues, and range of motion limitations, comparing each side of the body for symmetry
what do you do for the fourth part of the neuro exam
test reflexes
sensory neurons detect the stimulus and send a signal to the spinal cord, which then sends a signal back to motor neurons to produce the response
interneurons are involved in many reflexes, particularly in those that require coordination between sensory and motor neurons
explain the babinski dign
indicates cortico spinal tract damage
toes down = normal
big toe up (dorsiflexion) = babinski sign
indicator of upper motor neuron damage
explain deep tendon reflexes
When the tendon is tapped (for example, the patellar tendon below the knee), the stretch activates sensory neurons that send a signal to the spinal cord. The signal is processed and relayed to motor neurons via interneurons, which cause the muscle to contract
lower motor neuron/muscle/sensory damage = depressed reflexes
upper motor neuron damage = exaggerated reflexes
what do you do for the fifth part of the neuro exam
evaluate reflexes
what do you do for the sixth and seventh parts of the neuro exam
coordination / balance / gait
- reach to target, if they can land there it indicates cerebellum control
- finger to nose / heel to shin tests
- rapid alternating movements –> ex. rapidly tapping their fingers on a surface to look dor irregularities in movement
romberg test –> patient stands with their eyes closed. if they sway or fall, it indicates they were relying on visual feedback to keep them standing.
what is dysmetria
a condition that makes it difficult to control the speed, distance, and range of physical movement (a type of ataxia)
what is gait
the way a person walks or runs
parkinsonian gait
a walking pattern that’s characterized by short, shuffling steps, and a general slowness of movement
Retropulsion
a condition that causes a person to lose their balance and lean backward – having patient stand then pulling them off balance to see if they fall
A patient exhibits shaking in their upper extremities.
How might you determine whether the patient has a
cerebellar lesion or Parkinson’s disease?
A) Look at their eyes
B) Listen to their speech
C) Ask them to follow the tip of your finger with theirs
D) Examine their gait
E) All of the above
E) All of the above
Which of the following describes trepanation?
a) removing a portion of frontal lobe
b) drilling a hole in the skull
c) a popular dance move
d) a non-invasive brain stimulation method
drilling a hole in the skull
Which of the following tenants of phrenology is definitely NOT true?
a) brain cell types are similar for humans and animals
b) different parts of the brain have different functions
c) the brain is the organ of the mind
d) qualities of a person can be determined by the bumps on their skull
d) qualities of a person can be determined by the bumps on their skull
What is the name of the sulcus that divides the temporal lobe from the frontal lobe?
a) the central sulcus
b) the temporal-parietal junction
c) the sylvian fissure
d) the longitudinal fissure
c) the sylvian fissure
Which of the following statements is true?
a) the cerebral cortex has the greatest mass and contains the greatest percentage of neurons in the brain
b) the cerebellum has the greatest mass and contains the greatest percentage of neurons in the brain
c) the cerebellum contains the greatest percentage of neurons in the brain, but does not have the greatest mass
d) the cerebral cortex contains the greatest percentage of neurons in the brain, but does not have the greatest mass
c) the cerebellum contains the greatest percentage of neurons in the brain, but does not have the greatest mass
Which of the following experiment types is considered the “gold standard” for testing a new drug?
a) case study
b) cohort study
c) case-control study
d) randomized double blind control
d) randomized double blind control
Which of the following tests will assess function of cranial nerve 2?
a) confrontation test
b) test for Babinski sign
c) Weber test
d) the UPDRS
confrontation test –> evaluates visual field
test for Babinski sign –> function of corticospinal tract
Weber test –> hearing (nerve 8 - vestibulocochlear)
the UPDRS –> unified parkinson’s disease rating scale – used to asses motor and non motor deficits of parkinsons disease
answer: a) confrontation test
Which of the following is associated with upper motor neuron disease?
a) exaggerated reflexes
b) in cases of facial weakness/paralysis forehead weak
c) in cases of facial weakness/paralysis - forehead sparing
d) both A and C
d) both A and C
What test is used to assess motor deficits in Parkinson’s disease?
a) MMSE
b) UPDRS
c) FMA
d) Face Arm Speech Test
answer: UPDRS –> unified parkinsons disease rating scale – used to assess motor and non motor deficits of parkinsons disease
MMSE –> mini mental state exam – assess cognitive function
FMA –> fugl-meyer assessment – evaluate motor recovery after a stroke
face arm speech test –> used to screen for stroke by assessing facial drooping, arm weakness, and speech difficulties
We learned last time that if a person who uses ASL gets damage to Broca’s area (on the left) they will develop Broca’s aphasia - i.e. they will have difficulty producing signs. What might you expect for a similar patient who gets damage in Wernicke’s area (on the left)?
A) cannot produce signs
B) difficulty understanding signs
C) ability to produce signs, but content does not make sense
D) no impairment
E) B and C
E) B and C
what do electrophysiological signals measure
changes in electrical activity. specifcally, they measure synaptic currents because they last longer, while action potentials are much more brief.
ex. electrode measuring voltage of a neuron
what are synaptic currents
are the electrical currents that flow across the synapse when neurotransmitters are released from a presynaptic neuron and bind to receptors on the postsynaptic neuron. These currents result from the movement of ions through ion channels in the postsynaptic membrane, leading to changes in the postsynaptic cell’s membrane potential.
what are the scales in electrophysiology (smallest to largest)
- single units
- local field potential (LFPs)
- intracranial electroencephalography (iEEG)
- EEG electrode
what scale do single unit measure
~1 micrometer
what scale do LFPs measure
~1 mm
what scale do iEEG measure
~1 cm
what scale do EEG measure
~1 cm
explain single unit scale
you can resolve action potentials from one or a small number of neurons (this is the only scale that we’re studying that can do this). this scale is not used clinically because over time (ex. looking at data the next day) you’re not entirely sure if you’re still measuring the same neuron.
it’s invasive and is done by carefully implanting a very fine, micro-sized electrode, typically made of glass, into the brain tissue. skull and cortex are pierced
explain LFP scale
involves a larger electrode so you detect hyperpolarization / depolarization currents (synaptic currents). electrodes implanted in the brain to measure the summed electrical activity of neurons within a localized region
this is an invasive procedure. it’s done by piercing skull and cortex
explain iEEG scale
placed on cortex. its still invasive but you’re not penetrating the brain.
explain EEG electrode
same size as iEEG, but signal is more diffuse due to more stuff that it has to pass through. Non-invasive; you can put it on your head and it will pass through hair and skull.
which electrophysiology scale has the best spatial resolution
(best): single unit
2. LFPs
3. iEEG
(worst): EEG electrode
what is spatial resolution
the level of detail captured in an image, essentially measuring how small an object can be and still be distinguished within an image. ex. EEG electrode gives you more of a picture of the brain; but the resolution is worse.
which electrophysiology scale has the best temporal resolution
all have good temporal resolution
what do all of the electrophysiology scales that we’ve studied have in common
all of these are extracellular recordings –> an electrode placed somewhere outside of the cell.
who first discovered EEG
Hans Berger
What kind of signals can EEG record?
A) Blood flow
B) Action potentials
C) Summed synaptic potentials from large populations of neurons
D) A and B
C) Summed synaptic potentials from large populations of neurons
what are the requirements for seeing scalp EEG
- Sufficient number of neurons (1000-10,000+) with proper orientation (parallel).
- Active together
- With electric fields that sum, not cancel –> electrical activity generated by neurons must align in such a way that their individual electric fields add up to produce a measurable signal, rather than cancelling each other out due to opposing directions.
what are the three phases of a tonic clonic seizure
- tonic
- clonic
- postictal stupor
explain the tonic phase of a tonic-clonic seizure
- body rigid
- arched position
- arhythmic, high amplitude spiking on EEG
- EEG shows an increase in fast, low-voltage wave activity in both hemispheres of the brain
explain the clonic phase of a tonic-clonic seizure
- convulsions
- EEG oscillates (periodic spikes). high-amplitude spike-and-slow-wave activity. This means that there are bursts of spikes followed by slow waves.
explain the postictal stupor phase of a tonic-clonic seizure
- unresponsive or confused
- very small EEG signal
explain absence seizure
- rhythmic, marked activity in EEG with a frequency around 3 Hz
- hallmarked by staring off in space, much more subtle
- EEG shows symmetrical, generalized “spike and wave” discharges
slide 21
what causes a seizure
any part of the brain that’s a little extra ‘ticklish’ can trigger a seizure –> ex. flashing lights or getting a seizure listening to a led zepplin song –> its a specific pathway of activity
whats a generalized seizure
a seizure that starts in both sides of the brain at the same time. They can cause loss of consciousness, abnormal movements, and other symptoms
- Absence
- Tonic clonic
what is a focal/partial seizure
(one side of the brain)
- Simple (ex. sensation, smell, sound)
- Complex (ex. Person confused, dazed,
unresponsive)
True or False - if you have a seizure that means that you have
epilepsy?
A) True
B) False
B) False
how can EEGs be used during sleep
Raw EEG data can be
used to determine
stages of sleep, and
this can be used to
help diagnose sleep
disorders
what does an EEG look like for an awake person
a pattern of low-amplitude, high-frequency brain waves called “beta waves” primarily seen in the frontal regions, with occasional “alpha waves” (slightly slower, larger amplitude waves) present in the posterior regions of the brain
(low signals overall)
slide
what does an EEG look like for a person in sleep stage 1
a mixed pattern of alpha waves (typical of wakefulness) transitioning to theta waves, with the presence of “vertex sharp transients” (brief, sharp waves) and slow rolling eye movements
what does an EEG look like for a person in sleep stage 2
the presence of “sleep spindles” and “K-complexes”, which appear as distinct bursts of high-frequency activity amidst a background of lower frequency waves, essentially signifying a pattern of rapid, rhythmic brain wave activity interspersed with larger, slower waves
what does an EEG look like for a person in sleep stage 3
large, high-amplitude waves called “delta waves” with a low frequency
what does an EEG look like for a person in REM sleep
a pattern of low amplitude, mixed frequency brain waves that are quite similar to the brain activity seen when awake, often described as “desynchronized” activity, meaning it has a mix of different frequencies with no dominant pattern
what would an EEG look like for someone in a minimally conscious state, with eyes open
it would typically show low-voltage, irregular brainwave activity with a mix of slow waves (delta and theta) and sometimes some faster activity (alpha and beta), often with decreased reactivity to sensory stimuli, indicating a diminished level of cortical engagement despite the outward appearance of wakefulness
what would an EEG look like for someone in a minimally conscious state, with eyes closed
a pattern of significantly slowed brainwave activity, primarily consisting of low-frequency theta and delta waves, with occasional bursts of higher frequency activity like alpha waves, indicating some level of cortical activity, but with a diminished reactivity to stimuli compared to a healthy individual
(overall higher signals compared to eyes open)
what would an EEG look like for someone in a vegetative state
significantly slowed brain activity, with a pattern of low-voltage, irregular waves, often lacking the normal variations in brain wave frequencies seen in a conscious person
what would an EEG look like for someone in a coma
a pattern of significantly reduced brain activity, characterized by slow, high-amplitude waves, often with a dominant “delta” wave pattern, indicating a deep level of unconsciousness (sometimes referred to as burst suppression)
what would an EEG look like for someone with brain death
a “flat line” or “isoelectric” meaning there is essentially no detectable brain activity, showing a complete absence of electrical waves
You collect an EEG on a patient and notice very strong
regular and rhythmic activity. What are some possible
diagnoses?
A) They are in stage 1 of sleep
B) They are in the tonic phase of a seizure
C) They are having an absence seizure
D) They are awake and alert
C) They are having an absence seizure
what is an evoked potential or evoked response
an electrical potential recorded from the nervous system of a human or animal following presentation of a stimulus, as distinct from spontaneous potentials as detected by EEG
why would you average EEG signals together
to get rid of background noise – the more you average, the more confidence you have that the signal you are seeing is the right one to focus on
what is Auditory Evoked Response (aka Auditory Brain Stem Response)
a painless test that measures how well the auditory nerve and brainstem respond to sound
what is an example of the Auditory Evoked Response
Newborn hearing test
Electrodes are placed on the baby’s head and neck, and soft headphones are placed over the ears. Clicking sounds are played and the test measures the brain’s response.
First 3 waves from 8th cranial nerve
(vestibulocochlear) and lower brain stem
regions Waves 4 and 5 from upper brain stem
what is P300 speller
a type of brain-computer interface that allows users to communicate by selecting characters on a screen by focusing their attention on the desired character which triggers a specific brainwave called the P300
explain how Brain Signals can be represented with sine waves
Any signal can be decomposed into sine waves of different frequencies.
This is a good way to analyze brain data, because brain activity naturally ‘oscillates’.
whats the resting rhythm (Hz)
During rest, a rhythm at 8-12 Hz or so
can be seen which is reduced with
movement
how does an EEG look when you are imagining movements / behaviors
Certain behaviors are associated with
changes in certain frequencies
Similar changes in this frequency range are present when movements are imagined
the forward problem
a mathematical method that predicts the value of a measurement based on known physical parameters
The Forward problem is hard, but possible
like asking what -3+4+2+4 equals
think brain to head
the inverse problem
The Inverse problem has an infinite
number of solutions
- like asking what numbers sum to 7
think head to brain
the forward vs. inverse problem in terms of EEG
- the “forward problem” refers to calculating the electrical potential on the scalp based on known brain activity sources (you know what you need to do to figure out an answer)
- the “inverse problem” is the process of determining the location of those brain activity sources by analyzing the measured EEG signals at the scalp (you have the answer, but need to know how)
- essentially working backwards from the recorded data to find the underlying neural sources responsible for the signal
what can EEG not tell us
This means that, although EEG has
good temporal resolution (i.e. can
detect brain changes with very
precise timing,
It has poor spatial resolution - i.e.
telling where brain activity is
coming from is challenging
How do you think you could improve the
spatial resolution of EEG?
A) Build fancy models
B) Put constraints on your data – for example use imaging to
determine a good guess of where a signal is coming from
and then EEG can tell you when it is active
C) Use EEG in cases where you don’t need to know the exact
location
D) Record closer to the source
E) All of the above
E) All of the above
describe Intractable Epilepsy
a type of epilepsy where seizures are difficult to control with medication
Surgery can be considered, but a source needs to be determined
What type of brain activity is used to localize eloquent cortex with electrophysiology?
High-frequency activity (>70 Hz).
Why is high-frequency activity (>70 Hz) useful for localizing eloquent cortex?
It tracks local neural activity accurately.
strength and weakness of EEG (overall)
strength:
- high temporal resolution
- non-invasive
- affordable
- translatable
weakness:
- low spatial resolution
- can’t record action potential
if impaired in front of optic chiasm, what happens
vision impacted in one eye
if impaired past optic chiasm what happens (between occipital lobe and optic chiasm)
vision impacted in both eyes
what are the different perspectives when people are putting images together for mri’s
neurological perspective: standing behind a patient (ex. your right is the patient’s right)
radiological perspective: standing at the patients feet (ex. your right is the patients left)
what does CT scan stand for
computed tomography
describe the process of a CT scan
- glorified x-ray that makes a 3D image
- x-ray rotates around a patient
- CT is sensitive to tissue type differences in the irradiated region because x-rays are blunted differently as they pass through different tissues
- bone blocks a lot, grey matter some, and fluid less
- multiple snapshots are taken using detectors around the circumference of the scammer and merged together using a computer
how would an epidural hematoma look like on a CT scan?
above the dura, so it pushes on the brain a bit more. also has a lenticular shape (like a balloon filled with fluid) pushing against the dura from the outside. doesn’t spread out as much because of how tightly attached the dura is to the brain
what is computed tomography angiography
a non-invasive imaging test that uses X-rays and a contrast dye (typically an iodine rich contrast agent) injected into the body to create detailed pictures of blood vessels and tissues
you may be able to see aneurysms
what is the strength of an MRI
strong
typically between 1.5-10.5 tesla
(earth’s magnetic field is 25-64 microT) – so MRI is stronger
what does the quench button on MRI do
rapidly demagnitizes by funneling helium out through a vent
what type of metal is dangerous in an MRI
ferromagnetic metal (sticks to the fridge)
what does non ferromagnetic metal do during an MRI
it can heat up a little
why might you use higher T MRI
A higher T MRI, like a 3T MRI, is used when you need significantly improved image quality and detail compared to a lower T MRI (like 1.5T) due to its stronger magnetic field, allowing for better visualization of smaller structures and subtle abnormalities, particularly in areas like the brain, spine, and small joints, which can be crucial for accurate diagnosis in certain conditions; this is especially beneficial for neurologic imaging, musculoskeletal scans, and when high spatial resolution is required.
however, higher T is higher cost and some patients may not be able to tolerate the high field. also, you have more susceptibility to artifacts
how do MRIs work
- in your body there are hydrogen protons that are spinning around that are typically oriented differently
- when you enter the magnetic field, the hydrogens all align and their spin becomes parallel.
- MRI sends radiofrequency pulses to excite these protons, which causes protons to go out of alignment, so we can measure properties of how these protons realign.
- As they realign, energy is released and you can measure different properties of how that release happens
- Different molecules and tissues have
different relaxation times and spins.
T1 imaging
Think fat and anatomy
Measures the time it takes for protons in the tissue to return to their original alignment after an RF pulse. Tissues with high fat content (e.g., white matter) have short T1 relaxation times, making them appear bright.
ex. assessing anatomy or a tumor
T2 imaging
think fluid and inflammation
Measures the time it takes for protons to lose their alignment due to interactions with their surroundings. Tissues with high water content (e.g., CSF) have long T2 relaxation times, making them appear bright.
better at detecting edema, inflammation, and stroke
How to tell the difference between T1 and T2 weighted MRI
T1 – white cortex; dark fluid
T2 – dark cortex; white fluid
what is FLAIR
fluid attenuated inversion recovery
uses a specific pulse sequence to suppress the signal from cerebrospinal fluid (CSF), allowing for better visualization of surrounding brain tissues, particularly lesions near the ventricles
looks similar to T1 weighted but it is a bit darker
what does CSF look like in T1 weighted MRI
dark
what does CSF look like in T2 weighted MRI
bright
what does CSF look like in FLAIR MRI
dark
what does white matter look like in T1 weighted MRI
light
what does white matter look like in T2 weighted MRI
dark gray
what does white matter look like in FLAIR MRI
dark gray
what does cortex look like in T1 weighted MRI
gray
what does cortex look like in T2 weighted MRI
light gray
what does cortex look like in FLAIR MRI
light gray
what does fat (within bone marrow) look like in T1 weighted MRI
bright
what does fat (within bone marrow) look like in T2 weighted MRI
dark
what does fat (within bone marrow) look like in FLAIR MRI
light
what does inflammation (infection, demyelination) look like in T1 weighted MRI
dark
what does inflammation (infection, demyelination) look like in T2 weighted MRI
bright
what does inflammation (infection, demyelination) look like in FLAIR MRI
bright
supresses CSF making it easier to see extra fluid
MRI Angiography
similar to CT angiography, you inject contrast to visualize vasculature
ex. you can see aneurysms
aneurysm
a bulge or ballooning in the wall of a blood vessel
structural MRI with contrast
Gadolinium (Gad) is a non-toxic paramagnetic contrast enhancement agent that is injected during a scan. It shortens the T1 showing up brighter on T1-weighted images.
particularly good at showing vascular damage and breakdown of blood brain barrier
diffusion weighted imaging
Detects the diffusion of water protons in tissue. More uniform diffusivity results in bright DWI signals. White matter fiber bundles consist of the tube-like parts of cells that behave like straws constraining water diffusion.
Ischemia causes sodium-potassium pumps to shut down resulting in the influx of water into the intracellular space through osmosis.
What happens to DWI signal acquired in a brain region affected by stroke?
A) It gets darker because the tissue dies.
B) It stays the same because the diffusion of water does not
change.
C) It gets brighter because more water is trapped inside cells.
D) It gets brighter because water bursts through the cell walls.
C) It gets brighter because more water is trapped inside cells.
in normal tissue, theres going to be more free movement of water molecules (darker tissue appearance)
if the tissue has become more pathological, ex. cell death, you’ll get an influx of water ad molecules will be more constraint, giving a brighter color.
what is DTI
diffusion tensor imaging (kind of diffusion-weighted imaging)
specifcally tracts axons using the idea that diffusion (ex. water molecules) is going to be different in axons, compared to gray matter.
Interrogates the 3D shape of diffusion to provide measures of mean diffusivity (direction) and fractional anisotropy (a proxy for white matter tract integrity).
DTI assesses the structural connectivity between brain regions.
Used for surgical mapping, evaluating edema, and detecting tumor boundaries.
becomes complicated by the ‘crossing fiber problem’ of white matter tracts in the brain.
what are the applications of DTI clinically
patient with a tumor. sometimes surgeons do DTI to map out white matter pathways, because sometimes a tumor can displace them and you want to avoid cutting those pathways.
what is ASL
arterial spin labeling
A radiofrequency pulse is applied to the arteries in the brain at the neck in the carotid artery of the blood going up to the brain, then they can trace where that blood actually goes.
brighter colors - more blood flow
astrocytoma
a brain tumor that grows from astrocytes
what are two types of functional neuroimaging and what does it do
Measures metabolic correlates of neural activity.
- Positron Emission Tomography (PET)
- functional MRI (fMRI)
what is PET scan
Positron Emission Tomography (PET)
you inject special radioactive tracer that is built like whatever biomolecule you are interested in studying, but with radioactive element. those tracers behave like the regular biomolecules, but because they are radioactive, they decay and that decay can be measured to understand how those neurochemicals are working.
PET detects pairs of gamma rays released from positron-emitting radioactive tracers, e.g. 15O, 18F.
Tracers are injected into the body and behave like biologically active molecules.
The location of emitted particles can be measured as they are released over the course of radioactive decay.
Many tracers have been developed for specific neuroreceptor subtypes and plaques.
what PET image depicts a patient with Alzheimer’s disease
PET scan measures glucose
PiB PET
Alzheimer’s disease (AD) typically shows reduced glucose metabolism in affected brain regions, especially in the parietal and temporal lobes, using FDG-PET (Fluorodeoxyglucose PET).
T/F PET has high temporal resolution
false
fMRI and what does BOLD stand for
functional MRI
allows you to detect changes in activity related to neurons firing (but not directly)
Detects the change in oxygenated to deoxygenated hemoglobin in the blood - blood oxygen level dependent (BOLD) signal.
Oxygenated hemoglobin is paramagnetic and deoxygenated hemoglobin is diamagnetic. Both are detectable with MR. (Seiji Ogawa, 1990)
BOLD is a proxy for relative changes in neural activity since O2 is metabolized when cells fire and need to replenish energy.
Because the signal is related to blood flow changes it has LOW temporal resolution, despite great spatial resolution
what is neurovascular coupling
is the process that increases blood flow to the brain in response to neuronal activity. This process ensures that oxygen and nutrients are delivered to areas of the brain that are active
what are the clinical applications of fMRI
can be used to guide surgeries. fMRI can localize which side language is on, motor activation, etc. This is especially helpful when tumors remap where functions are localized.
what is MRS
Magnetic resonance spectroscopy
looking at proton spins to measure neurochemicals or metabolites
MRS measures the precession of hydrogen protons (1H) of molecules.
Because many brain molecules exist in relatively low concentrations measurements must be taken from larger regions of interest, usually 1-10 cm3.
Only small mobile molecules >/= 0.5 μmol/g tissue contribute to the MRS signal.
Most neurotransmitters exist below this level of concentration, but some are measurable, e.g. glutamate, GABA, and aspartate.
Instead of forming an image, MRS analyzes the frequency shifts in the MR signal due to chemical environment differences in hydrogen or other nuclei. The spectral data reveal the relative concentrations of metabolites.
what are applications of MRS
This technique can be used to differentiate tumor types, for example, distinguishing between benign and malignant brain lesions. Additionally, MRS can be helpful to assess neurodegenerative diseases or investigate metabolic disorders.
5 advantages of MRI
Advantages:
1) Safety
- Far less radiation exposure compared to CT (essentially none)
- Non-invasive
2) Multiple types of images can be obtained.
3) Easily combined with other techniques.
4) Fast and getting faster!
5) Fairly comfortable. Pulse Radiology Education
4 disadvantages of MRI
Disadvantages:
1) Safety
- Strong magnetic fields pose risks to individuals with ferrous metals in their bodies
- Potential for tissue burns
- Loud! (earplugs)
2) Difficult to use in certain populations, e.g. kids or patients with movement disorders
3) Expensive
4) Different types of images depend on different kinds of expertise.
vagus nerve stimulation
therapy. less invasive than deep brain stimulation, even though it still involves surgery. a battery is implanted under the skin. a wire goes up and wraps around the vagal nerve to stimulate and effect brain activity. seems to reduce seizure activity.
case study 1/29 (brain stimulation for pregnant woman)
typically when you do implantation of brain stimulation, you implant it then you wait a couple of weeks to get surgical recovery before they turn it on. however, in this case study a quicker response was needed (she was pregnant), because they deemed that the risk of having more seizures was greater than the risk of turning it on.
woman had epilepsy, but it got much worse during pregnancy, to the point that she was frequently having seizures, which is dangerous because having these seizures and potentially falling because of them are increasingly severe for her and the fetus.
music case study - what are the alternatives for this type of patient (is there another surgical procedure)
- treat the tumor less aggressively
- they didn’t have to do the extensive mapping
music case study - what tools were used as part of the surgical planning
prior to surgery the did fMRI to understand what was going on, then when they went in they did direct electrical stimulation with recording
music case study - who was involved in the surgical planning
there was a whole teamL neuroscientists (ex., defined the task), surgeon (performed the surgery and stimulation), neurologist (ex., the patients doctor)
music case study - what do you think would be the most difficult part of this type of surgery
- balancing the retention of the tissue that is functional with appropriately treating the tumor.
music case study - why might this information be useful to clinicians
they can show how you can plan to retain special functions (ex., music). also shows you could potentially just use fMRI for mapping before surgeries – rather than just going into the surgery
music case study - why might this information be useful to non-clinicians
someone who is receiving a similar procedure should be able to digest the information and bring it to their doctor
explain the use of a torpedo electric ray
type of ray (fish) that delivers strong electric shocks. in the past, people would use it to treat headaches.
direct cortical electrical stimulation
cortex is stimulated during surgery to map out function and try to preserve healthy function. ex., someone getting surgery, they would stimulate around the healthy tissue as much as possible in hopes of preserving as much healthy tissue as possible.
Mapping is performed with a small bipolar
electrode placed on the surface of the cortex.
Numbers are placed directly over areas that disrupt behavior or alter sensation when stimulated.
Requires patients to be awake during surgery.
how did neurologists come up with the humunculous
using direct cortical electrical stimulation
they would stimulate and see if people would move / stop moving or if they had perceptual feeling
explain limitations for direct electrical stimulation
still considered the gold standard, but there are some limitations
- stimulating randomly, so you actually are getting action potentials going in both ways in the neurons (you dont have that refractory period) – makes it less similar to nature
- you can accidentally hit passing fibers
- cells can be impacted, even if they are a bit further from the target cell. Direct electrical microstimulation influences a sparse population of cells.
describe electroconvulsive therapy
- Small electric currents are passed through the brain to induce a seizure as treatment of Psychiatric disorders including severe depression, mania, catatonia, and aggression in patients with dementia.
- Used for people who have medication-resistant disorders or for populations that cannot take medication. Also works quickly.
- Patients are under general anesthesia and a muscle relaxant during stimulation.
- Electrodes are placed bilaterally on the head or unilaterally, with one electrode over the temple and one over the vertex.
- Stimulation is brief typically just a few milliseconds to ~6 seconds. (quick therapy)
- the thought process behind this was that people with some conditions get stuck in sort of the same brainwave pattern, so this would hopefully help break it up (disrupting electrical activity in hopes of it ‘ressetting’).
describe transcranial magnetic stimulation and who pioneered it
non-invasive brain stimulation method
uses magnetic fields to generate electric field and alter brain activity.
Faraday was the first person to create a coil to induce a magnetic field
explain the physics of TMS
TMS = transcranial magnetic stimulation
electric current is sent through the coil. opperates under the property that a change in a magnetic field induces an electric field. if you place the coil to the head, magnetic field travels easily through the skull to induce an electric field. – you can stimulate neurons (ex., neuron pathways that will make your finger twitch)
describe the coil shape in TMS
The geometry of the coil determines the focality of the magnetic field and of the induced current, and hence also of the targeted brain area.
Superficial layers (cortex or gray-white matter junction)
the shape creates a more focal magnetic fields. figure 8 shape = consolidated circle; ring = giant ring
how does coil orientation effect anatomical focality of TMS
- determines the direction of the induced current
- relationship between current direction and cytoarchitecture will determine the extent of neural firing
how does output intensity effect anatomical focality of TMS
- greater intensity = reduced focality
- effective intensity is also determined by scalp-cortex distance
how can the motor cortex be stimulated
stimulating over motor cortex can excite the pyrimidal neurons, excitation travels down the corticospinal tract and can be recorded with surface EMGs
what things can you analyze with surface EMGs (Electromyography)
MEP = motor evoked potential ** most important
SICI = short-interval intracortical inhibition
ICF = intracortical facilitation
Motor TMS in neurological disorder
on average, certain diseases are associated with reduced motor evoked potentials
repetitive event related TMS
- Unlike standard TMS, which delivers pulses at a consistent rate, event-related TMS precisely times the stimulation to coincide with the moment of interest in an experiment, like when a specific visual image appears on a screen. (e.g. 10 Hz)
- Transiently disrupts targeted brain region
- Provides approximate information about when a brain region “comes online” (likely have to test many different time-points to be confident in timing)
- Determines if a brain region is necessary
- people sometimes call it a “temporary lesion”
A pregnant person is experiencing severe depression. Which of the following treatment options is safest for the fetus?
A) ECT
B) Medication
C) TMS
D) All of the above.
E) A and C
C) TMS
describe Transcranial Direct Current Stimulation (tDCS)
non-invasive stimulation method
- Hypothesized to cause a polarity dependent shift of the resting membrane potential, i.e. make neurons more or less likely to fire an action potential.
- Anodal tDCS is believed to enhance excitability, and cathodal tDCS is believed to reduce excitability.
- After-effects have been reported to last on the order of an hour.
- Many studies have assessed interactions with pharmacology.
- A couple published trials in epilepsy and major depression.
what is the downside of electric fields compared to magnetic fields
electric fields can’t pass through the skull as easily as magnetic fields
why do people question the efficacy of tDCS
recent work questioned the efficacy. study used cadavor to add electrodes to see if neural activity could be evoked.
- A study placed electrodes on cadavers and found that tDCS did not generate enough electric fields to evoke neural activity.
- Since cadavers lack active neurons, this study suggests that tDCS may not generate strong enough currents in living brains to reliably influence neural firing.
what are the different kinds of ways that tDCS can be delivered
tDCS = direct current
tACS = alternating current
tPCS = pulsed current
tRNS = random noise
t = transcranial
S = stimulation
describe deep brain stimulation
invasive
- Involves surgical implantation of electrode leads targeted at specific neuroanatomical structures (more on this in the next lecture).
- These electrodes deliver continuous electrical pulses to modulate abnormal neural activity.
- DBS is used to treat motor disorders, epilepsy, chronic pain, OCD, and mood disorders.
- Stimulation parameters vary in voltage (1~3.5 V), frequency (130~185 Hz), and pulse width (60~210 μs).
*extra slack is given so that if theres tugging it wont come out of the brain
how can DBS be optimized
- Tailoring stimulation programming on an individual basis.
- Consideration of symptoms, side effects, interactions with medication, and battery life (avoid frequent surgical replacement).
- Methods for improving DBS include using recordings of patients’ own brain activity to detect signatures of pathology and then adjust stimulation in a ‘closed loop.’
Which of the following treatments for depression acts right away?
a. TMS
b. vagal nerve stimulation
c. medication
d. ECT
d. ECT
What is the Montreal Procedure?
a. method of direct cortical stimulation for mapping
b. a way to perform an outpatient lobotomy
c. a procedure used to treat epilepsy with TMS
d. placing a torpedo fish on the head to treat headaches
a. method of direct cortical stimulation for mapping
For which of these scans is CSF the lightest/brightest?
a. T1 weighted MRI
b. T2 weighted MRI
c. FLAIR
d. MRS
b. T2 weighted MRI
Which of the following is a disadvantage to fMRI ?
a. It has low temporal resolution
b. it involves significant radiation exposure
c. it is invasive
d. all the above
a. It has low temporal resolution
Which of the following describes the concept that if you know source of brain activity, you can predict how the signals would manifest with EEG?
a. the inverse problem
b. synaptic potentials
c. electrocorticography
d. the forward problem
d. the forward problem
Which of the following involves use of an “event-related” (or “evoked”) potential?
a. monitoring of sleep stages
b. the newborn hearing test
c. determining arousal level (i.e. distinguishing coma from a minimally conscious state)
d. diagnosing epilepsy
b. the newborn hearing test
Which of the following is a disadvantage of fMRI?
a. it has low temporal resolution
b. it is invasive
c. it requires high levels of radiation exposure
d. it cannot be used in healthy people
a. it has low temporal resolution
explain “buzz juice” case study (case study 1)
A 31-year-old previously healthy woman developed altered mental status and multi-organ failure, including hypotension, renal failure, hemolytic anemia, and fevers, after inhaling vaporized synthetic marijuana (“Buzz Juice”) over two days; her neurologic exam revealed confusion, visual hallucinations, ataxia, dysarthria, and hyperreflexia, while MRI findings were consistent with toxic leukoencephalopathy. Buzz Juice contained JWH-081, a potent CB1-receptor agonist that impairs cognitive function and reduces GABA release, leading to neurotoxicity, cardiovascular instability, renal failure, and respiratory depression; similar radiographic findings have been seen with other recreational drugs like heroin and toluene, likely due to oxidative myelin damage. Her husband, who inhaled the drug in a much smaller quantity, remained asymptomatic, suggesting either individual variability in toxicity susceptibility or a dose-dependent effect, highlighting the need for further research on synthetic cannabinoids’ clinical and radiographic correlations.
dementia patient after a fall case report (case study 2)
An 89-year-old male with vascular dementia presented to the ER after a fall, with family reporting a rapid cognitive decline, aggressive behavior, word-finding difficulty, and staring spells over the past six months. Brain imaging (T1 and T2 weighted MRI) revealed an extra-axial fluid collection in the right frontal, parietal, and occipital regions, causing mass effect, midline shift (11 mm), subfalcine herniation, and septations in the subarachnoid space. The most likely diagnosis is arachnoid cysts.
blue collar worker case study (case study 3)
A 44-year-old man with a history of postnatal hydrocephalus treated with a ventriculoatrial shunt developed mild left leg weakness, which had previously occurred at age 14 and resolved after shunt revision. Neuroimaging revealed massive ventricular enlargement, a thin cortical mantle, and a posterior fossa cyst, with a diagnosis of non-communicating hydrocephalus likely due to Magendie’s foramen stenosis. After partial improvement with neuroendoscopic ventriculocisternostomy (they made a small hole in 3rd ventricle to improve flow), his symptoms recurred but resolved completely following a ventriculoperitoneal shunt, though his IQ (75) and neuroimaging findings remained unchanged.
nocturnal epilepsy case study (case study 4)
Nocturnal frontal lobe epilepsy (NFLE) is a sleep-related seizure disorder often misdiagnosed as parasomnia, requiring nocturnal sleep EEGs for accurate diagnosis. In Case #1, a 14-year-old boy experienced generalized tonic seizures exclusively during sleep, with conventional EEGs showing no abnormalities until a sleep stage II EEG revealed sharp wave bursts in the right frontal lobe, leading to an NFLE diagnosis and symptom resolution with CBZ. In Case #2, a 12-year-old boy had a history of night terrors and a single daytime seizure; his nocturnal sleep EEG revealed high voltage sharp wave bursts in the frontal lobe, confirming NFLE, and his symptoms resolved after switching from CBZ to ZNS due to auditory side effects.
supercellar lesion case study (case study 5)
A 54-year-old man with a 3-year history of loss of libido, erectile dysfunction, and anxiety, along with recent polyuria, nocturia, and polydipsia, presented with signs of visual failure, including left temporal hemianopia, impaired color vision, temporal disc pallor, and right optic nerve enlargement. Clinical findings showed hypo-gonadotrophic hypogonadism and mildly elevated prolactin, prompting a brain MRI. The most likely diagnosis is one of the following: spindle cell oncocytoma (tumor in the pituitary gland)
vagus nerve stimulation case study (case study 6)
A 21-year-old pregnant woman with refractory epilepsy, experiencing 3–7 seizures per week despite multiple antiepileptic drugs (AEDs), underwent vagal nerve stimulation (VNS) implantation at 32 weeks of pregnancy to improve seizure control while minimizing fetal risk. The procedure, performed under general anesthesia with obstetric oversight, resulted in a significant seizure reduction and an uncomplicated cesarean delivery of a healthy baby at 37 weeks. While VNS has been shown to be effective in reducing seizure frequency in refractory epilepsy, this case highlights its successful use during pregnancy, warranting further studies on long-term maternal and fetal outcomes.
saxophonist case study
A 26-year-old musician (Patient AE) with a low-grade tumor in the right temporal lobe underwent pre-operative fMRI, which localized music processing to the right posterior superior temporal gyrus (STG), and later underwent awake intraoperative brain mapping during a melody repetition task. Electrical stimulation of the right STG induced “music arrest” and pitch errors without affecting language, providing causal evidence for the functional segregation of music and language processing in the brain. The study confirms the right STG’s specific role in melody processing and suggests interactions with the right inferior frontal gyrus via the arcuate fasciculus, with future research needed to explore real-time neural dynamics in music processing.
5 patients case study (case report 7)
Five patients with trigonal (lateral ventricle) tumors underwent preoperative navigated transcranial magnetic stimulation (nTMS) motor and language mapping, corticospinal and optic radiation tractography, and neuronavigation-based surgical planning between 2014 and 2016. Four patients proceeded with surgery via a transparietal approach, guided by nTMS and tractography to avoid eloquent brain structures, with favorable neurological outcomes except for one case of temporary dysarthria and another of persistent mild hemiparesis. One patient refused surgery, but overall, the study demonstrated that integrating nTMS and tractography into neurosurgical planning enhances surgical precision and helps mitigate risks to motor, language, and visual functions.
lobotomy
used to treat mental illnesses. initially removal of parts of cerebral cortex in 1930s focused on frontal lobe. lobotomy involved cutting fibers / connections between prefrontal cortex and rest of the brain
ice pick lobotomy
orbitoclasts were inserted through eye sockets and used to sever brain connections. allowed the procedure to be done outside a hospital
why might neurosurgery be needed
reduced intracranial pressure
- hydrocephalus
- removing skull following trauma
remove diseased / damaged tissue
- tumor resection
- gamma knife
- epilepsy removal
- lesion for movement disorders
treat function
- DBS, ultrasounds
intracranial pressure
caused by any kind of build up of pressure in the skull
characterized by:
- headaches
- nausea / vomiting
- gait problems
sometimes: hypertension, bradycardia
hydrocephalus
- CSF isnt draining properly putting pressure on the brain
- babies are extra susceptable because their skull isnt fully closed so it keeps getting bigger and bigger
function of a shunt
- treatment for hydrocephalus
- a valve
- can be implanted to drain excess CSF into the abdomen when pressure reaches a certain level
- CSF is either funneled into abdomen or to heart
pressure from blood - trauma
- blood build up causes intracranial pressure
- treated using burr hole or decompressive craniectomy
decompressive craniectomy
swelling after trauma can take months to heal. piece of skull is removed and either stored on ice or inside a patient while they wait for swelling (pressure) to go down. skin is replaced but is squishy so brain can expand
what precautions would you recommend for a patient who recently had a hemicraniectomy after a bike accident
a. that they wear a protective helmet as often as possible until the skull is replaced to protect their brain
b. that they take an anti-epileptic medication
c. that they get tDCS
d. A and B
e. A, B, and C
D
what are the two types of strokes
ischemic and hemorrhagic
ischemic stroke
more common
blockage of blood vessel from plaque or clot causing blood to stop going to an area. as a result, tissue dies – blood thinners okay
hemorrhagic stroke
burst of blood vessel causing blood to pool. blood is leaking into brain –> causing less blood to get to tissues – no blood thinners
what may cause hemorrhagic stroke
brain aneurysm
brain aneurysm
- weakening or bulge in blood vessel of the brain
- unruptured is usually without symptoms, although occasionally large ones can cause symptoms if it is pushing on the brain or nerves.
- rupture is a medical emergency (hemorrhagic stroke or subarachnoid hemorrhage)
causes of aneurysm
- weakened blood vessel
- high blood pressure
- congenital or can develop later in life – ateriovenous malformation (AVM) tangle of abnormal blood vessels in the brain which are more prone to rupture
brain aneurysm surgery
after rupture
- surgery may be done to stop bleeding or reduce intracranial pressure
before rupture
- clipping aneurysm –> putting a clip that prevents blood from accessing polyp (bulge) of blood
- endovascular repair (“coiling”) –> wire inserted into the polyp (bulge) of blood to prevent blood from going in there and promotes clotting
remove damage or diseased tissues – brain tumors
- typically arise from spreading from other body parts or from glia cells, rarely neurons
- surgery to remove the tumor is the usual treatment
- less defined boarders on cancerous tumors because its spreading
benign brain tumors
- some brain tumors like meningiomas are benign so they will not spread
- however surgery is sometimes still necessary to reduce intracranial pressure and reduce symptoms which may result from the mass pushing on the brain
- getting the whole tumor out may be less critical in this case
- more defined boarder on tumors – less necessary to get it ALL out (you can leave a lil bit)
preserving healthy eloquent tissue
- gold standard to use electrical stimulation and look for motor or speech arest
- sometimes fMRI or intercranial EEG is now used
- wada test can also be used to localize language hemisphere
wada test
localize language hemisphere. barbituate injected into carotid artery that goes up and puts one hemisphere to sleep but not the other. they will then see if person loses the ability to talk or not
Your right-handed patient has a meningioma in their right frontal
lobe. You perform a Wada test on the left which shows language
impairment. However, when doing cortical mapping near the tumor
you observe speech arrest for a site you intended to resect. What
does this mean and what should you do?
A) The Wada test was correct, but the right hemisphere must have some language, related involvement too. The left will probably compensate so go ahead and aggressively resect.
B) The Wada test was correct, but the right hemisphere must have some language, related involvement too. We don’t want to lose function so just take a small portion of the tumor.
C) Wada test was probably wrong. Close up and order an fMRI.
D) Wake up the patient and explain the situation.
B
**meningioma so less aggressive cancer – its okay if we leave some in there
gamma knife surgery
- uses radiation to kills cells in a targeted way
- gamma ray radiation is sent to converge on a target, so outside of that target there is minimal impact on nearby tissues
- not effective enough for large malignant tumor, but smaller benign tumors works well for this. cells die slowly and it takes a while for waste to get removed
neurosurgery to treat function
nothing structurally wrong but something is altered with function
in epilepsy sometimes tissue may appear healthy but neurons fire abonrmallu
parkinson’s disease is thought to be caused by excessive neuronal activity in certain regions
lesioning for parkinsons disease
- Lesions can be placed in one of these three areas: STN (Subthalamaic Nucleus) or Gpi (Globus Pallidus Internus) (occasionally thalamus) to
reduce symptoms. - Down side is that they are not
adaptable/reversible –> can be useful if someone can’t come back to the hospital often
deep brain stimulation to treat function issues
it is reversible and adjustable. DBS is more than just a lesion. One way DBS may work is by reducing pathological brain rhythms.
how can neurons be “listened to”
Correct placement in Gpi or STN is often determined by “listening” to the neurons firing (in addition to imaging)
explain intra-op testing of DBS
while doing DBS in surgery, doctor asks patient to raise hand and bring toward mouth like they are drinking water. with DBS off, patient is extremely shaky. withe DBS on, patient is no longer shaky at all.
lesion alternative
doesn’t involve cutting
- Focused ultrasound can be used to lesion tissue
- A good approach for people for whom surgery is not a good option.
- Most applicable to tremor.
- Similar approaches can be used to treat other disorders where damaging tissue is the goal.
- Not adjustable like DBS, but no hardware to
manage.
An older patient with Parkinson’s disease which is no longer adequately controlled
by medication is seeking a surgical consult. He lives in a remote area and, during a
previous surgery, had been prone to infection. What approach might you
recommend for him and why?
A) Continue with medicine alone
B) Recommend DBS
C) Recommend focused ultrasound
D) Recommend traditional lesion
C) Recommend focused ultrasound
