Midterm Flashcards
why might we want to study the brain
- most complex organ
- how the brain produces both behaviour and consciousness is still not understood
- understanding the brain helps us to explain and possibly cure behavioural disorders
cardiocentric hypothesis
past belief that the heart was responsible for our thinking. purposed by aristotle, believed the brain was used as a cooling unit for the blood and to regulate the temperature of the heart
phrenology
the bumps on the skull are correlated to what parts of your brain you used the most
what did the original cephalocentric hypothesis entail
believed the pineal gland was responsible for behaviour, and that the mind regulates behaviour by directing the flow of ventricle fluid to the appropriate muscles
problems with descartes cephalocentric theory
the pineal gland is involved in biological rhythms, not intelligence or behaviour control - and it is not essential (people can have it removed and live normally)
fluid is not pumped from the ventricles to control movement
monism/materialism
behaviour can be explained as a function of the nervous system without trying to think about the mind. the brain simply produces the mind. without brain function, there is no soul/mind
this theory was supported by the phineas gage incident - which suggested a link between brain trauma and personality change
shortcomings of the phrenology theory of psychology
- cranioscopies where invalid reflections of cortical surface area
- it wasnt falsifiable
- it would seek confirmation for behaviours, not empirically test
- localized the wrong faculties
the theory of equipotentiality was overturned by this new neurological study method
electrical stimulation - showed that stimulations in certain regions caused reactions in certain parts of the body - especially the bilateral nature of the brain
cytoarchitectonics
neurons of similar shape and size tend to group together
Who came up with the very famous map using cytoarchitectonics
broadmen - broadmens map organized the brain into 52 distinct areas based on neuron shape
What was Moniz’s leucotomy
an early type of lobotomy involving severing the connections between the frontal cortex and thalamus to alleviate symptoms of psychosis and depression
what were the stats for the outcomes of Walter Freeman’s lobotomized patients
33% improved, 33% remain unchanged, and 33% worsened
why can the brain be described as inconsistent
variability between brains of one person to the other
inconsistencies in how it is described (naming structures based on what it looks like, where they are, who discovered them)
structures referred to as more than one name
three types of glial cells
astrocytes - regulate how far NT spreads
oligodendrocytes - produce myelin
microglia - remove debris
an electrical signal from an action potential gets converted to a ____ signal when Nt are released
chemical signal
ipsilateral
same side
afferent neurons
move towards the CNS (A=Approach)
a tract refers to a large collection of
axons
a fissure in the brain refers to
a very deep cleft in the cortex that reaches all the way down to the ventricles
a sulcus in the brain refers to
a more shallow cleft
a gyrus in the brain refers to
a ridge in the cortex
the precentral gyrus is the
motor cortex
the precentral gyrus lays right in front of (anterior to) the
central fissure
grey matter is the innermost or outermost layer
outermost
T/F the CNS is encased in bone
true
three major divisions of the brain
forebrain, midbrain, hindbrain
cerebellum, pons, and medulla are all structures of the
hindbrain
cerebellum
coordinating movements and balance, motor learning
medulla oblongata
breathing, BP, heart rate, other autonomic functions
pons
sleeping, breathing, other unconcious processes
cerebellar agenesis causes
impairment of motor functions, especially relating to the coordination of voluntary movement - clumsy, delays in motor development, low muscle tone
the superior and inferior colliculus are located in
the mid brain
superior colliculus
directing gaze and object directed behaviour
thalamus
relay centre of the brain - filters motor and sensory signals and relays them to the cortex. regulates sleep, alertness, wakefulness
hypothalamus
regulates basic functions:
body temp, hunger, thirst, mood, sex drive, blood pressure, sleep
cerebral cortex
higher cognitive functioning
basal ganglia
motor functioning and learning
limbic system
emotion, memory, spatial navigation
the primary motor cortex is also referred to as
the pre-central gyrus
three main areas in the frontal lobe
primary motor cortex (voluntary muscle movement)
prefrontal cortex (executive functions, behaviour, personality)
Broca’s area (muscles of speech, production of speech)
the Broca’s area is also referred to as
the inferior frontal gyrus
main function of the temporal lobe
auditory processing (including hearing, analyzing, recognizing, and memory of auditory stimuli)
main function of the parietal lobe
somatosensory - awareness and processing of somatic sensation, proprioception - combines information from multiple senses into a usable form
main function of the occipital lobe
awareness and processing of visual stimuli
basal ganglia function
fine-tuning of voluntary movements, and the initiation of movements
also decision making, reward, and addiction
limbic system
behavioural and emotional responses
callosal agenesis
person born with no corpus callosum (large bundle of myelinated nerves connecting the left and right hemispheres)
ventricular system
the cerebrospinal fluid provides support for the brain
single cell recordings
study done in animal models where electrodes are inserted into an indivudual neuron
most neurons are tuned to a _____ stimulus and have a ___ level of basal activity
most neurons are tuned to a particular stimulus and have a low level of basal activity
advantages of the single cell recording
greater precision
can be used to model disease processes
can conclude casuality
limitations of single cell neurorecordings
they may not be generalizable due to differences in humans and non-human animals, as well as the complexity of the brain and behaviour compared to a single neuron
cortical stimulation
electrodes placed on the surface of the brain
subcortical stimulation
stimulating white matter pathways
deep brain stimulation
implant electrodes into brain regions of interest
- can be used to treat conditions like depression, OCD, epilepsy, parkinson’s
pros of brain stimulation
allows for detailed examination of brain - behaviour relationships
you often have a high level of control of the stimulation
cons of brain stimulation
its invasive, usually involves some degree of brain damage, human methods rely on patients not healthy volunteers
difference between controlled and acquired brain lesion studies
controlled brain lesion studies use animals, whereas acquired ones use patients
controlled ones are nice because you can pick the exact location and extent of the damage, giving you the ability to make statements about casaulity - but not all processes can be examined by this and not all of the animal models will generalize to human systems
acquired ones are useful because we can otherwise study lesions in human participants, but they are subject to individual differences and we may not always know the premorbid function
which brain imaging techniques show electrical activity
EEG and ERPs
which brain imaging techniques show structural imaging
CT, MRI, DTI
which brain imaging techniques show functional images
PET, fMRI, TMS
beta waves on an EEG
high frequency, low amplitude
person is alert
alpha waves on an EEG
lower frequency, high amplitude
person is relaxed
delta waves on an EEG
less frequent, higher amplitude waves
sleep
what do partial seizures look like on an EEG compared to generalized seizures
spikes and sharp waves in only a specific brain area. Generalized seizures also display spikes and sharp waves but these are spread over the brain
event-related potentials
measuring brain response to a specific event and averaging the activity over many trials to see when information gets processed in the brain
brain computer interfaces allow patients with this disease to operate a computer using brain waves, allowing them to speak, send emails, and texts
ALS
advantages and disadvantages of EEGs and ERPs
they’re non-invasive and have great temporal resolution, inexpensive, good for both clinical and healthy patients
they have poor spatial resolution, vulnerable to movement artifacts, signal can be distorted by skull variations
CT scan
computed tomography - uses X ray to create pictures of the skull and brain - high density regions absorb more so they appear as lighter (skull)
low density appear darker (grey matter and fluid)
advantages vs disadvantages of CT scans
theyre fast and non-invasive, provide structural images in vivo, and can be used in both clinical and healthy populations
they have por station resolution, give no information about functioning, and radiation may limit repeated scanning
whatis Magnetic Resonance Imagining, and what are its pros vs cons
using strong magnets to measure magnetic fields to create images via hydrogen atoms in the body
non invasive and has good spatial resolution, but cannot be used with anything metal, its loud, bad for claustrophobic
diffusion tensor imaging
mapping white matter pathways that detects how water travels along tracts
first neuroimaging technique
person on a precariously balanced table, getting them to think would increase blood flow to their head and table would tilt head down
PET SCAN
positron emission tomography
- use radioactive substances known as radiotracers to visualize and measure changes in metabolic processes (utilization of dopamine for example)h
how does a pet scan work
find a molecule used in the brain
make it radioactive
inject it into the brain
measure where the tracer is being metabolized
advantages vs disadvantages of PET scan
can be used on many molecules , but it is radiation so you can only do 4-5 scans a year and it is expensive
functional MRI
measures changes in brain activity by detecting changes in blood flow. Hemoglobin is an oxygen carrier so oxygenated Hb repels magnetic fields. Compares the relative ratios of OHb to dOHb
pros: non invasive and no radiation, can use standard MRI equipment and you can do a regular MRI and fMRI simultaneously
Cons it is expensive, has slow temporal resolution, and does not work for claustrophobic people or those with implanted metal
transcranial magnetic stimulation
applying a strong magnetic field at the surface of the skull to change electrical activity in adjacent neurons to stimulate or inactivate neurons, allowing researchers to infer the function of the area from the behavioural changes induced. can also treat pain, movement disorders, and depression
three types of somatosensory receptors
nociception - pain and temp
hapsis - fine touch and pressure
proprioception - awareness of body in space
the spinothalamic tract is responsible for
transmission of pain, temperature, and crude touch to the brain
DCML pathway is responsible for
conveying sensations of fine touch, vibration, pressure, two point discrimination, and proprioception
the corticospinal tract is responsible for
carrying movement-related informatin from the motor cortex to the spinal cord (walking, reaching, fine finger movements)
the S1 brain region
primary somatosensory cortex - the post-central gyrus
- tactile representation of the opposite side of the body
posterior parietal association cortex
integration of body position information with location of objects in space
dorsolateral prefrontal cortex
active in the planning of movement - tells secondary and primary motor areas what movements to make
the M1 brain region
primary motor cortex
controls movements of the muscles - organized somatotopically (homunculus map)
secondary motor cortex’s role and its three associated areas
the production of voluntary movement
- supplementary motor area - self generated movement
- premotor cortex - externally generated movement (reflexively watching an ambulance drive by)
- cingulate cortex - conflict resolution
explain the integration of motor movement via the parietal, prefrontal, premotor, and motor cortices
the parietal cortex will receive and inetegrate sensory info and initiate movement, the prefrontal will plan the movement, the premotor will organize the movement sequences, and the motor cortex will produce the movements
basal ganglia’s role in movement
initiates movement and stops undesired movements
why can surgeons do brain surgery while a patient is conscious
the brain has no pain receptors
four major classes of apraxias
ideomotor apraxia - cannot execute simple GESTURES when asked to (both intransitive gestures like waving goodbye and transitive getures like practical motions like flipping a coin)
ideational - cannot fathom how to do a task, the necessary actions and which ORDER they should be performed in - more extreme
comstructional - cannot build, assemble, or draw objects - cannot use their visuoperceptual information to guide voluntary movements, bad spatial processing
oral - inability to perform intricate movements with the face/pharynx/larynx on command - can do it on their own (subconsciously)
tactile agnosia/astereognosis
loss of the ability to identify an object by touch – their sensation awareness is correct, they could describe the features of an object but not identify it
callosal apraxia
selective impairment of the ability to carryout verbal requests with the left hand, because the verbal information is processed on the left hemisphere but the right hemisphere controls the left hands
probable cause of phantom limb syndrome
cortical reorganization - areas of the brain which no longer receive sensory input start to accept input from adjacent areas
treatment for phantom limb pain
meditation and relaxation techniques, drugs, but mirror therapy seems to be the best
xenomelia/foreign limb syndrome
the desire for an amputation - study using MED showed that the foot and thigh areas of their brain showed reduced activation in the limb desired to be amputated
optic nerve
a bunch of ganglion cell axons that leave the eye at the optic disk, also called the blindspot
optic chiasm
the point of crossover for half of the visual projections (information from the left visual field sent to the right visual field)
retino-geniculate-striate pathway
this is responsible for conscious vision.
eye > optic chiasm > LGN (lateral geniculate nucleus of the thalamus > primary visual cortex
V1 and V2 regions of the brain
the primary and secondary visual cortices.
involved in orientation, spatial frequencies, and binocular vision
V4 area of the brain
vision association cortex - involved in colour
MT / V5 region of the brain
the middle temporal region - involved in motion
Hemianopia
loss of vision in half of the visual field due to damage to the primary visual cortex
scotoma
loss of vision in one point due to damage in the primary visual cortex - also called blind sight - they are perceiving information but they do not know it - this happens because the brain rewires itself to use the tecto - pulvinar pathway
quadrantanopia
loss of vision in a quarter of the visual field due to damage to the primary visual cortex
ventral visual stream
the “what” pathway - recognizes the name and function of objects
dorsal visual stream
recognizes the where and how - location of objects and how to interact with them
Inferotemporal (IT) cortex
part of the cerebral cortex in the lower portion of the temporal lobe which recognizes objects. implicated in Agnosia - failure to recognize objects
neurons in the IT complex respond well to this kind of stimuli
respond well to hands, faces, or objects - not to spots or lines
parahippocampal place area - responds well to
places like pictures of a house
double dissociation
when one perceptual function can be damaged without affecting the other - for example the ability to recognize faces but not recognize objects (prosopagnosia vs agnosia)
apperceptive visual agnosia
inability to recognize an object because of the inability to perceive it - cannot recognize the visual stimuli
associative visual agnosia
inability to associate objects with meaning - can draw an object but could not tell you its function - show a doctored image of a made up animal and wouldn’t be able to tell you if it exists or not
prosopagnosia
inability to recognize familiar people by their face - often caused by right hemisphere damage
optic aphasia
impaired ability to name objects, but they know what it is and what it does - a tip of the tongue like sensation
motion blindness
rare neurophysiological disorder in which affected indviduals cannot perceive motion - damage to V5/MT
list and describe the three processes of memory
encoding - attending to information
consolidation - storing information
retrieval - accessing information from where it is stored
difference between short and long term memory
short term memory holds information beyond the duration of the stimuli but does not hold it permanently, only for a few seconds. Can only hold about 7 items
long term memory can be hold for years and is relatively permanent and unlimited
what is working memory
information that is going to be acted on (where you parked your car) or used (information retrieved from LTM)
three components of working memory
- central executive - attention
- phonological loop - inner speech repeating the info
- visuospatial sketchpad - visuospatial information
explicit vs implict memories
explicit memories - facts and events that can be easily communicated
implicit memories - skills and habits which cannot be easily communicated
three classes of long term memory
episodic - temporally distinct, unique past experience and autobiographical memory
semantic - knowledge that is not personal to you (name of a colour)
implicit / procedural - how to do things
the hippocampus and frontal lobes are particular associated with this class of memory
explicit
the basal ganglia and cerebellum is especially correlated with this class of memory
implicit
what did we learn from patient HM
had epilepsy so they removed small section from both of his temporal lobes which ended up being his hippocampi. the epilepsy stopped but he had permanent anterograde amnesia - impairment in the learning aspect of memory. he was able to learn some new things like a floor plan or short navigation routes bc this was procedural. we learned that memory systems are distinct in behaviour and associated brain regions and that the storage and retrieval of LTM is not in the hippocampi, nor is the location of immediate STM, but the hippocampus is somehow involved in converting STM to LTM.
retrograde amnesia is commonly associated with damage to the
hippocampus and temporal lobes (episodic and declarative memory)
what is the difference between temporally extensive and temporally limited retrograde amnesia
extensive covers decades of memories and is often caused by dementias, PD, HD
whereas limited can be (and is most frequently) a week lost, but can stretch to a couple years. can be caused by TBI, electroconvulsive therapy
Highly superior autobiographical memory
allows individuals to remember every detail of their lives - with increased grey matter in the temporal and parietal lobes and connecting white matter connections
