Neuro Exam (Lectures) Flashcards
ependyma
thin epithelium-like lining of the ventricular system and central canal
some develop into the choroid plexus
oligodendrocytes
surround and insulate some CNS nerve processes
can simultaneously myelinate MANY axons
astrocytes
wrap around capillaries and neurons to provide structural support, repair processes, facilitate metabolic exchange between blood and neurons, and help form the BBB
microglia
resident immune cells of the nervous system
resting membrane potential
what does it result from?
1) selective permeability
2) differential ionic concentrations across the plasma membrane
maintained by active ion transport Na/K pump
signal transduction
chemical, temperature, pH, mechanical > electrical > chemical (NTs/peptides)
shape of an action potential
1) Na+ channels open, Na+ enters cell
K+ channels open, K+ begins to leave cell
2) Na+ channels close
K+ leaves cell
3) K+ channels close
Excess K+ outside diffuses away
action potential properties
1) All or none
2) AP amplitudes can differ across neurons and neuron types but are a FIXED property of a given neuron
3) frequency of firing encoding information
Where are Na+ and K+ channels concentrated on an axon?
Nodes of Ranvier
benefits of myelin
1) decrease capacitance
2) increase membrane resistance
together this increases conduction velocity
3) less biological demand on the neuron
> less channels/pumps expressed
> less energy demand to maintain membrane potential
Proteins involved in vesicular release?
v-SNAREs and t-SNAREs
botulinum and tetanus toxins are zinc-dependent proteases that cleave VAMP
mechanisms for removing neurotransmitter from synaptic cleft
1) degradation
2) reuptake
2) diffusion
degradation example
acetylcholinesterase cleaves ACh into choline and acetate
note: edrophonium short-acting AChE inhibitor used to distinguish clinical btwn MG and Lambert-Eaton syndrome
reuptake example
monoamines (serotonin, dopamine, glutamine)
note: SSRIs work by inhibiting this mechanism!
postsynaptic response
1) receptors
2) synaptic integration
3) modulation
ionotropic receptors
RAPID/TRANSIENT
Nicotinic ACh
NMDA
AMPA
GABAa
metabotropic receptors
SLOW/SUSTAINED
G-protein coupled
mGlu
GABAb
Muscarinic ACh
B-adrenergic
AMPA
major mediator of EXCITATORY synaptic transmission
NMDA
conducts Na+ and Ca2+
Mg2+ blocks the channel and cannot pass current even when NT bound to the receptor
what factors influence summation?
1) spatial distribution of inputs
2) temporal nature of the inputs
endocannabinoid modulation
endocannabinoid allows for communication from the post-synaptic cell to the pre-synaptic cell
NMJ vs. CNS
INPUTS
NMJ: one
CNS: many
NMJ vs. CNS
NT
NMJ: ACh
CNS: many
NMJ vs. CNS
TRANSMITTER REMOVAL
NMJ: AChE
CNS: high affinity transporters
NMJ vs. CNS
POST-SYNAPTIC RECEPTOR
NMJ: nicotinic ACh receptor
CNS: metabotropic and ionotropic receptors
NMJ vs. CNS
SAFETY FACTOR
NMJ: very high
CNS: relatively low
NMJ vs. CNS
SYNAPTIC EFFICACY
NMJ: high
CNS: low
NMJ vs. CNS
excitatory vs. inhibitory
NMJ: excitatory only
CNS: both
10 Functional Components of Nervous System
- lateral corticospinal
- DCML
- anterolateral
- basal ganglia
- cerebellar
- visual
- cranial nerves
- limbic
- diffuse
- cerebral cortex
specific afferent fibers for sensory detection of fast, well-localized pain
A-delta fibers
specific afferent fibers for sensory detection of slow, diffuse pain
C-fibers
specific afferent fibers for sensory detection pleasurable touch
A-beta fibers
allodynia
pain from a stimulus that does not normally evoke pain
hyperalgesia
exaggerated response to a normally painful stimulus
taxonomy of pain
nociceptive
inflammatory
neuropathic
dysfunctional
nociceptive
no pathology
requires ongoing noxious stimulus
evoked by HIGH-intensity stimuli
inflammatory
tissue injury w/inflammation
allodynia, hyperalgesia and spontaneous pain
evoked by LOW and HIGH-intensity stimuli
neuropathic
PNS or CNS lesions
allodynia, hyperalgesia, spontaneous pain
sensory amplification
evoked by LOW and HIGH-intensity stimuli
dysfunctional (centralized)
altered CNS function (no known lesion/no peripheral pathology)
allodynia, hyperalgesia, spontaneous pain
Somatosensory
specialized receptors
pacinian corpuscles
meissner’s corpuscles
c fibers
visual
specialized receptors
photosensitive molecules (e.g., rhodopsin) in photoreceptor cells
auditory
specialized receptors
sterocilia on hair cells
Somatosensory
receptive field of first order sensory neurons
a discrete spot on the skin discrete temperature pH taste odor
visual
receptive field of first order sensory neurons
a discrete spot in the visual field (center-surround)
auditory
receptive field of first order sensory neurons
a pure tone (single frequency)
Somatosensory
mechanism of potential change in neurons
physical properties
compression of skin opens FORCE-GATED ion channels
temperature opens THERMAL SENSITIVE channels
visual
mechanism of potential change in neurons
light-activated rhodopsin G-protein mediated effect
auditory
mechanism of potential change in neurons
mechanical displacement of hair cell cilia from sound waves opens FORCE-GATED ion channels
visual adaptation (physical changes in receptors)
tuned for change, ignore “white space”, sense motion
auditory adaptation (physical changes in receptors
accommodate to loud noises, hear a voice over a drone
somatosensory
location of first order neuron
DRG
visual
location of first order neuron
ganglion cells of the retina synapsing with photoreceptors (rods and cones) in retina
auditory
location of first order neuron
spiral ganglion synapsing with hair cells
somatosensory
higher processing in second-order neurons
shapes, edges of objects being touched
visual
higher processing in second-order neurons
orientation/edges of visual stimuli
auditory
higher processing in second-order neurons
localization of stimulus _ tone; focus on individual speakers over a crowd
right-left auditory discrimination
- right-left ear discrimination of TIME LAG
2. right-left ear discrimination of SOUND INTENSITY
up-down auditory discrimination
angle sound hits pinna
common causes of otitis media
H. influenzae
S. pneumo
Moraxella catarrhalis
motor system function: cortex
planning and initiation of voluntary movements and integration of inputs from other brain areas
motor system function: basal ganglia
enforcement of desired movements and suppression of undesired movements
motor system function: cerebellum
timing and precision of fine movements, adjusting ongoing movements, motor learning of skilled tasks
motor system function: brainstem
control of balance and posture, coordination of head, neck and eye movements, motor outflow to cranial nerves
motor system function: spinal cord
spontaneous reflexes, rhythmic movements, motor outflow to the body
motor system function: muscles
movement of body, sensory organs-muscle spindle and golgi tendon organs
motor unit
a single neuron and all the muscle fibers it innervates
smallest division that the system can control individually
either SLOW or FAST
innervation ratio
number of muscle fibers per neuron (variable)
eye (low ratio)
quad (high ratio)
slow twitch, type 1
darker
aerobic metabolism
contract more slowly
generates less force
fast twitch, type 2
paler
anaerobic metabolism
contract quicker
generates more force
fast fatigue-resistant
properties that are intermediates between the other two types
what does the muscle spindle sense?
length or stretch
what does the golgi tendon sense?
tension
encapsulated structures mechanically connected in parallel with muscle fibers?
muscle spindles
encapsulated structures mechanically connected in series with muscle fibers?
golgi tendon
three main components of muscle spindle
- intrafusal fibers
- afferent sensory neurons
- efferent motor neurons (gamma neurons)
dynamic bag fibers
respond primarily during CHANGES in the length of the muscle
static bag and nuclear chain fibers
primarily signal the length if the muscle without the phasic changes
types of infrafusal fibers
dynamic bag
static bag
nuclear chain
type of sensory fibers
primary (Type Ia) -terminate on all three types of intrafusal fibers
secondary (Type II)-terminate only on static bag and nuclear chain fibers
Note: cell bodies of sensory afferents in the DRG
function of the gamma motor neurons
cause the polar ends of the intrafusal fibers to contract …maintains the sensitivity of the spindle even when the muscle is shortening
UMN Clinical Correlates
lesion above alpha motor neuron
Weakness
No atrophy
Exaggerated reflexes, Positive Babinski
Spasticity
LMN Clinical Correlates
lesion of the alpha motor neurons
Weakness
Atrophy
Diminished reflexes, Negative Babinski
No spasticity
Examples of Neurogenic Diseases
ALS
Polio
Guillian-Barre Syndrome
Example of Myopathic Diseases
Muscular Dystrophy
Polymyositis
Etiology of Neurogenic vs. Myopathic Diseases
Neurogenic-damage to motor neurons
Myopathic-degenerations of muscle
Atrophy?
Neurogenic vs. Myopathic Diseases
YES BOTH!
Fasciculations?
Neurogenic vs. Myopathic Diseases
Neurogenic -YES
Myopathic-NO
Loss of Reflexes?
Neurogenic vs. Myopathic Diseases
YES BOTH!
Creatine Kinase?
Neurogenic vs. Myopathic Diseases
Neurogenic-Normal
Myopathic-Elevated
Group 1a Interneuron function
mediate muscle-spindle inhibition of ANTAGONIST muscles in the stretch reflex
receive input from descending tracts
allow for coordination of agonist-antagonist muscles
Group 1b Interneuron function
mediate golgi-tendon inhibition of AGONIST muscle
prevent excessive tension
receive multiple muscle, cutaneous, proprioceptive and descending inputs
C3, C4, C5
keep the diaphragm alive
C5
deltoid
C6
biceps
C7
triceps
C8-T2
Fingers
L4
Quads
L5
Foot Dorsiflexion
S1
Plantar Flexion
S2-S5
Sphincter Control
UMN + LMN Disease
ALS
amyotrophy-muscle atrophy
sclerosis-scarring
nerve typically affected first in ALS
hypoglossal nerve
what can cause BG dysfunction?
stroke-lacunar infarcts (GPi/Putamen)
multiple sclerosis
tumor
idiopathic and/or familial
Classic Parkinsonian Signs
TRAP Tremor Rigidity Akinesia, Bradykinesia Postural instability (ataxia)
Basic Life Functions Coordinated by Hypothalamus
Energy metabolism Fluid and electrolyte balance Thermoregulation Reproduction Arousal and Stress Responses
Hypothalamus gathers information from
1. Exteroceptive visual somatosensory visceral (gustatory) olfactory multimodal-limbic
- Interoceptive
local: temp, Na, osm, glc
circumventricular organs
circumventricular organs
lack a normal BBB
ex. median eminence, pineal gland
flip flop switch
mutual inhibition between VLPO and the ascending monoamine systems (no intermediate states!)
VLPO inhibits LC, TMN, Raphe
LC, TMN, Raphe inhibits VLPO
reinforces the waking state
orexins (hypocretins)
Orexin activates LC, TMN, Raphe
VLPO inhibits orexin
what drives the homeostatic sleep drive?
when is it at its peak?
adenosine
right before sleeping
when is the circadian sleep drive at its peak?
upon waking
hypothalamic output
autonomic: PNS, SNS
endocrine: pituitary
behavior: motor automatisms, arousal, autonomic influences
diffuse projecting systems key principles
- cell bodies occupy very small space
- projections spread wide
- branch diffusely
- secrete NTs and communicate by volume transmission
- modulate behavioral states
- evolutionarily conserved
synthesis, biogenic amines
amino acid precursor actively transported across BBB
modifying enzymes convert AA to NT
NT
- serotonin
- dopamine
- norepinephrine
- histamine
storage, biogenic amines
VMAT2 integral membrane protein transports monoamines into vesicle where they accumulate
release, biogenic amines
voltage-dependent calcium channels
calcium influx
vesicle release
modulation, biogenic amines
- high affinity reuptake transporter
- autoreceptors (can decrease firing and decrease synthesis)
- degradation/inactivation (oxidation, methylation etc)
METH
lipophilic weak base, MAOi
can readily cross BBB looks like dopamine and can be taken up by DAT and transported into synaptic vesicles by VMAT2 alkalinizes vesicle DA goes back into cytosol, builds up DAT reverses direction
massive DA action and then crash (bc autoregulators)
Cocaine
dopamine reuptake inhibitor thus blocking action of DAT
increase of DA in synaptic cleft
autoregulators shut down production of DA
massive DA action and then crash
coma
occurs with lesions of the ascending system or with diffuse, bihemispheric dysfunction
what determines level of consciousness
ascending system of connections from brainstem and hypothalamus
what is wakefulness?
awareness of self and one’s environment
REM Sleep is?
unconscious but cortex active
dreaming
paralysis
saccadic eye movements
NREM Sleep is?
unconscious with little cortical activity
somnogens
adenosine
increased during inflammation…more relevant in times of illness
prostaglandin D2
TNF-alpha
activity of state-regulatory nuclei
WAKE
Monoamines
Acetylcholine
Orexin
activity of state-regulatory nuclei
NREM
Monoamines
GABA
activity of state-regulatory nuclei
REM
Acetylcholine
GABA
what kind of memory does sleep improve
declarative (facts)
procedural (skills)
also helps with consolidation
cataplexy
sudden, brief episodes of muscle weakness triggered by strong emotions
dysfunction in visual unimodal association area
- visual object agnosia
- prosopagnosia
- simultanagnosia
visual object agnosia
cannot recognize visually presented object
a) appreceptive form
impaired ability to perceive the elementary shape of the object
b) associative form
intact ability to perceive the elementary shape of the object
prosopagnosia
associated with fusiform gyrus
inability to recognize faces
simultanagnosia
inability to perceive more than one object simultaneously
Ballints syndrome
simultanagnosia ocular apraxia (trouble directing eyes) optic ataxia (impairment in making visually guided arm movements)
what visual pathway
temporal
where visual pathway
parietal
lesion in unimodal somatosensory association cortex
tactile agnosia
lesion in unimodal auditory association cortex
1) nonverbal auditory agnosia (impaired auditory recognition)
2) pure word deafness (isolates primary auditory cortex from language centers)
dysfunction in unimodal motor association cortex
1) low-level apraxia: finely graded finger movement
2) middle-level apraxia: learned skilled movements
2) high-level apraxia: series of acts or sequence
Gerstmann’s syndrome
lesion in left angular gyrus (junction btwn parietal and temporal)
AGRAPHIA
ACALCULIA
FINGER AGNOSIA
RIGHT-LEFT DISORIENTATION
key early events in cerebral cortex development
neural tube closure
specification/regionalization of neural tube
stages of cerebral cortex development
…and broad type malformations
- proliferation
- > too much
- > too little
- migration
- > premature termination
- > overmigration
- neuritic outgrowth/axon guidance
- > incorrect projections/connections
- synapse formation and pruning/neurotransmission
- > too much
- > too little
- behavior
malformations of cortical development lead to a range of phenotypes but severe malformations often result in varying degrees of with TRIAD OF SYMPTOMS?
Intellectual Disability
Developmental Delay
Seizures
ethanol affects which stage of brain development
ALL
extracellular cues binds to receptors at the growth cone guide what?
axonal growth
note: growth cone only transiently present
many more synapses are produced than are necessary. what glial cell types is responsible for tagging synapses for deletion?
astrocytes
cerebral cortex progenitor cells line what structures?
list zones starting from this structure …
lateral ventricles
ventricular zone subventricular zone intermediate zone cortical plate marginal zone
cortical plate formation
name order of layer formation
1 > 6> 5> 4> 3> 2
migrates to final location via radial (excitatory neurons) and tangential (inhibitory neurons) migration
three frontal regions
- lateral prefrontal cortex
- orbital frontal cortex
- medial prefrontal cortex
lateral prefrontal cortex
involved in working memory
executive function
mental status exam: verbal fluency
cognitive neurosci. task: categorizing, wisconsin card sort test
orbital frontal cortex
emotional judgments and regulation
cognitive neurosci. task: iowa gambling task
medial prefrontal cortex
initiation, error detection and monitoring of behavior
cognitive neurosci. task: serial reaction time task
working memory
the ability to maintain information online and manipulate it to guide behavior
dopamine is critical for function
LPFC Circuit
LPFC
medial dorsal nucleus thalamus
lateral GPi/SNr
Caudate Nucleus
input: sensory what and where pathways at LPFC
what is verbal fluency? what does it test?
list all the words they can that begin with a specific letter in a minute
normal scores dependent on age and education (12-16/minute)
working memory, LPFC
OFC Circuit
OFC medial dorsal nucleus thalamus ventral GPi nucleus accumbens OFC
inputs: olfactory, taste, internal body, amygdala @ OFC
outputs: hypothalamus and periaquaductal gray
- cardio
- gastric
- respiratory
- sexual
medial frontal regions
frontal pole (unknown function) anterior cingulate (monitoring) supplementary motor (initiate/sequencing) subgenual cortex (depression)
causes of aphasia…
stroke (most common cause)
dementia
trauma
brain tumors
how are aphasias classified
1) fluency
- ease of speech production
- long phrase length (at least 7 normal)
- small connector words (is, and, the) present
2) comprehension
3) repetition
broca’s aphasia
comprehension intact
non-fluent speech
poor repetition
associated signs
- right hemiparesis
- apraxia
sometimes called “expressive aphasia”
wernicke’s aphasia
poor comprehension
fluent speech, non-sensical
poor repetition
poor insight/angry at listener
associated signs
-right homonymous hemianopia
conduction aphasia
good comprehension
fluent speech w/phonemic paraphasias
poor repetition
role of right hemisphere in language
prosody (non-verbal cues)
humor
theory of mind (ability to attribute mental states to oneself)
goal of image-guided neurosurgery
complete resection
no neurological injury
want to see:
- lesion and define margins
- critical structures
- relationship btwn lesion and eloquent areas
accomplish:
- preop planning
- surgical decision making
diffusion tensor imaging is a way of mapping what in vivo?
white matter tracts
usual localization of tumor in adults vs. children
adults: supratentorial
children: infratentorial
what is the only firmly established environmental risk factor for brain tumors?
ionizing radiation
parinaud’s syndrome
failure of upgaze
pupillary dilation
poor reactiveness to light
retraction nystagmus
assoc. with pineal gland tumor
brain tumor diffuse symptoms
Headache Vomiting Lethargy Irritability Behavior change Increased head circumference Seizure
when does a headache become concerning?
change in prior headache pattern unresponsive to prev. effective therapy focal symptom or sign worse at night, bending, sneeze, valsalva vomiting awakens child from sleep papilledema
signs of hydrocephalus
bulging fontanelle
sundowning
increased head circumference
brain tumor differential diagnosis
stroke/cerebral hemorrhage abscess/parasitic cyst demyelinating disease (MS) metastatic tumors primary CNS lymphome
differential of late-life dementia
alzheimer's disease vascular dementia parkinson's disease with dementia dementia with lewy bodies frontotemporal dementias (incl. Picks) CJD and related prion dementias
alzheimer’s disease defining characteristics
amyloid plaques neurofibrillary tangles inflammation (microgliosis and astrocytosis) selective neuronal degeneration synaptic loss multiple NT deficits
neurofibrillary tangles
intraneuronal
composed of highly phosphorylated forms of the microtubule-associated protein, tau
amyloid plaques
extracellular
composed of 40- and 42-residue amyloid beta-proteins
mechanisms of disease in proteinopathies
- excessive production
- decreased clearance
- mutations (missense; expansion)
- certain biochemical conditions (e.g., extreme pH)
- failure of chaperone systems
- prolonged time (age)
genetic factors predisposing to AD
APP mutations (ch21)
ApoE4 polymorphism (ch19)
Presenilin 1 mutations (ch14)
Presenilin 2 mutations (ch1)
simple, partial seizure
focal, consciousness intact
complex, partial seizure
focal, unconscious
generalized, absence
motionless starring
loss of awareness
no postictal confusion/immediately resume back to normal behavior
Rx: ethosuximide
generalized, tonic-clonic
tonic-stiffening
clonic-rhythmic jerking
generalized, atonic
drop seizure, loss of muscle tone
can focal-onset seizures become secondarily generalized tonic-clonic?
YES
what is the most common site of focal-onset seizures in adults?
medial temporal lobe
- deja vu
- olfactory and gustatory hallucinations
- fear, anxiety
- nausea
epilepsy
tendency towards recurrent, unprovoked seizures
diagnosed after two unprovoked seizures
what factors can affect CNS excitability?
1) intrinsic neuronal factors
(problem with neuron)
2) synaptic or extrinsic/extraneuronal factors
(ex. toxins)
3) neuronal circuit or network factors
(abberant circuits lead to hyperexcitability)
Factors important related to recurrence
type
etiology
EEG
categories of treatment for epilepsy
vagus nerve stimulation brain surgery hormonal therapies ketogenic diet deep brain stimulation
stroke ischemic vs. hemorrhagic
85% ischemic
15% hemorrhagic
T1
CSF dark
good for
- atrophy
- cortical dysplasias
- subacute hemorrhage
T2
CSF white
good for
- chronic infarctions
- demyelination
- white matter lesions
- edema/inflammation
Flair
T2 with CSF brightness removed
good for edema
Types of Declarative Memory
1) Episodic: ability to re-experience past events
2) Semantic: system for receiving, retaining, transmitting information about meaning of words, concepts and classification of concepts
3) Working: ex. remembering a new phone number while dialing it
Types of Non-declarative memory
Procedural (skills)
disorders of semantic memory
Is this normal in aging? What diseases are associated?
Spared in normal aging
rare
Viral brain infections
Unusual types of strokes
Semantic dementia
Alzheimers
disorders of working memory
Is this normal in aging? What diseases are associated?
Commonly declines in normal aging
commonly affected in neuropsych disorders
CVD MS TBI PD Depression Schizophrenia
encoding
what is needed?
the learning of new info
basic attention and working memory are necessary
storage
when does storage happen?
“consolidation”
as time passes, information is less dependent on medial temporal lobe
this happens during sleep
retrieval
names two types
recall (fill info recovered)
vs.
recognition (multi-choice)
processes involved in episodic memory
encoding
storage
retrieval