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Exam 2
Adv. Systems Neuro
202
Other
Graduate
04/12/2020

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Term
hammer tap on the knee causes you to contract _______ & relaxation _______
Definition
quadricep muscle; hamstring muscle
Term
does a reflex involve the cortex?
Definition
no
Term
why don't you get any movement but just are bulging the muscles when you flex (think body builder)?
Definition
you're contracting both muscles
Term
how do all neural structures start?
Definition
sensory inputs!
Term
2 main places sensory cortices receive sensory input from
Definition
1. entorhinal cortex
2. visual cortex
Term
motor cortex sends descending motor commands to which 2 places to move skeletal muscles?
Definition
1. spinal cord
2. lower motor neurons
Term
after a movement, you get _______ feedback into the spinal cord circuits
Definition
proprioceptive
Term
do we have a homunculus for the motor cortex?
Definition
yes (just like sensory cortex)
Term
difference between corticobulbar tract vs corticospinal tract
Definition
corticobulbar = face

corticospinal = upper extremity, trunk, lower extremity
Term
what was learned from the experiment where they stuck an electrode in the brain to record single neuron spiking & EMG recording muscular responses in hand (done in monkeys)
Definition
you can align action potentials from the brain recording with the EMG ramping recorded from the muscles
Term
do we have topology in lower motor neurons in the spinal cord?
Definition
yes! (it's not just in the brain!)
Term
difference between proximal muscles vs distal muscles in terms of their organization in the spinal cord
Definition
proximal = more medial in spinal cord

distal = more lateral in spinal cord
Term
what happens to the somatotopic organization of lower motor neuron pools as you go down the spinal cord?
Definition
you are also moving down your body with which muscle groups are represented
Term
motor neuron (called alpha motor neuron in spinal cord) releases ______ as primary neurotransmitter
Definition
acetylcholine
Term
why can you apply an electrical signal onto your muscle & cause yourself to move without actually using your cortex to do so?
Definition
motor units are electrical units
Term
list the three different types of motor units from highest to lowest force
Definition
1. fast fatigable
2. fast fatigue-resistant
3. slow
Term
what is the trade off in terms of using the different muscle types?
Definition
how much force a muscle type can give you vs how long they can stay working
Term
why do people believe that older marathon runners are better at this long distance stuff but might not be as good at sprinting?
Definition
they have more fast fatigue-resistant muscles
Term
which motor neurons are usually only activated when a large amount of force is required?
Definition
fast fatiguing neurons
Term
why do people who work out look more toned?
Definition
people who work out more usually have better innervation of their muscles...these muscles are activated at any given amount of time
Term
normal vs extensor plantar response (example of sensorimotor reflex)
Definition
normal: touching of the bottom of foot --> toes down (flexion)

extensor: touching of the bottom of foot --> fanning of toes (Babinski sign)
Term
proprioception
Definition
understanding of where your body is in space
Term
what kind of signals tell your body how much you need to flex to hold something in a specific place in space?
Definition
descending
Term
2 instances in which golgi tendon organs are important due to their role in negative feedback regulation of muscle tension
Definition
1. if you catch something too heavy
2. if you catch something too light
Term
is there need for descending input when you're walking?
Definition
no! (you're not really consciously thinking about how you're walking)
Term
cat experiment demonstrating cortical descending input isn't necessary for walking
Definition
experimenters disconnected brain from spinal cord, but if you put the cats on a treadmill they actually would naturally move to walk!
Term
how were tuning of certain motor neurons for movement to specific places discovered?
Definition
monkey experiment: he looks to see where a light lights up & then moves his cursor to where the light is shining
Term
most simple kind of network
Definition
feedforward
Term
"attractor" relationship between two neurons
Definition
they excite each other
Term
"self inhibition" network
Definition
excitatory neuron excited an inhibitory neuron that feeds back onto it to inhibit the initial neuron
Term
"mutual inhibition" network
Definition
excitatory neurons excite inhibitory neurons that inhibit the other excitatory neurons
Term
can neurons have spontaneous firing?
Definition
yes
Term
are all synapses of equal strength?
Definition
no
Term
"recurrent innervation" network
Definition
self excitation
Term
2 examples of how upper motor neurons are directional & also limb specific
Definition
1. left side of the brain tends to control the right side of the body
2. neurons can actually be inhibited in opposite direction from its preferred direction
Term
magnitudes of various neuronal responses at different direction angles allows you to make _______
Definition
population vector plots
Term
what is the train of thought behind brain computer interface (BCI)?
Definition
if we can use tuning curves to decode a motor signal, we can have computer output a motor command to a machine to move something
Term
6 steps in stretch reflex circuitry that helps you adjust when holding something surprisingly heavy (for example)
Definition
1. descending facilitation & inhibition
2. alpha motor neuron
3. muscle (puts out the force required to hold glass)
4. disturbance (addition of liquid to glass...causes a length change in muscle fiber)
5. spindle receptor (disturbance causes an increase in spindle afferent discharge)
6. alpha motor neuron for adjustment
Term
our initial motor command to pick something up comes from ______
Definition
our IDEA of how heavy something is going to be
Term
equation for Bayesian inference
Definition
P(belief | sensory input) = [P(sensory input | belief) * P(belief)] / P(sensory input)
Term
probability vs Bayesian probability
Definition
probability: often used to refer to frequency

Bayesian probability: a measure of a state of knowledge
Term
what does Bayesian probability quantify
Definition
uncertainty
Term
Bayes' theorem
Definition
P(A|B) = [P(B|A) * P(A)] / P(B)
Term
in Bayes' theorem, "A" means _____
Definition
prior hypothesis or belief
Term
in Bayes' theorem, "B" means _____
Definition
sensory input or data
Term
Bayes' theorem: long hair, bathroom line example

A = ?
Definition
belief that you are looking at a woman
Term
Bayes' theorem: long hair, bathroom line example

B = ?
Definition
long hair
Term
2 reasons why Bayesian probability is useful
Definition
1. it allows us to put probability values on unknowns
2. this can show counterintuitive results - e.g. that the disease test may not be useful
Term
3 things we need in addition to sensory inputs to make decisions
Definition
1. memory
2. models
3. cognitive circuits
Term
what do cells in a circuit perform computations between to decide how to enact different results?
Definition
sensory input & memory of how things normally are
Term
is the BG thought of as a singular unit in the brain or as a plurality of things?
Definition
singular unit (even though the word is plural)
Term
how do we interact with the ever-changing world?
Definition
we need learning
Term
3 types of learning
Definition
1. supervised
2. unsupervised
3. reinforcement
Term
6 steps in the agent flow of learning
Definition
1. receives state
2. follows policy
3. selects action
4. obtains reward
5. transitions state
6. repeat
Term
aim of learning
Definition
maximize potential long-term gain
Term
BG: cortex --> excitatory onto ______
Definition
striatum
Term
BG: GPi/SNr --> inhibitory onto ______ --> excitatory back onto ______
Definition
thalamus; cortex
Term
are projection neurons from the basal ganglia inhibitory or excitatory?
Definition
inhibitory!
Term
two pathways in basal ganglia activated by the motor plan
Definition
1. indirect
2. direct
Term
is the striatum a pretty large or pretty small area of the brain?
Definition
large
Term
how are the direct & indirect pathway neurons arranged in the striatum?
Definition
intermixed throughout
Term
how do the direct/indirect pathways interact in the BG?
Definition
act to keep each other in check
Term
in primates, the BG is called the _______
Definition
caudate/putamen
Term
dopaminergic input for the BG comes from the ________ onto the caudate/putamen (AKA striatum)
Definition
substantia nigra pars compacta
Term
SNR has a high firing rate, tonic activity --> projects _______ onto the thalamus (as well as other areas)
Definition
GABA
Term
difference between glutamatergic vs GABAergic
Definition
glutamatergic = positive

GABAergic = inhibitory
Term
direct pathway neurons: _______ dopamine receptor
Definition
D1
Term
indirect pathway neurons: _______ dopamine receptor
Definition
D2
Term
does the BG project to downstream motor nuclei?
Definition
yes
Term
does dopamine cause a cell to fire or to be inhibited?
Definition
no; it is modulatory
Term
if the striatum is at rest, is there excitation of motor cortex?
Definition
no (globus pallidus is tonically active --> thereby inhibiting the thalamus)
Term
why is the motor cortex excited if the striatum is transiently excited?
Definition
globus pallidus is transiently inhibited --> thalamus is disinhibited so other inputs can excite it
Term
how is the caudate involved in eye movement?
Definition
increased caudate activity (direct pathway) --> decrease in SNR activity --> increase in superior colliculus activity --> primate moves its eyes
Term
GABA agonist
Definition
muscimol
Term
2 motor loops BG is involved in
Definition
1. body movement
2. oculomotor
Term
2 non-motor loops BG is involved in
Definition
1. prefrontal
2. limbic
Term
what would happen if we killed off the dopamine input to the BG?
Definition
we would see that the direct pathway drive would be diminished relative to controls & the indirect pathway drive would be increased relative to controls
Term
in a PD brain, you can see a lack of black colored cells in the ______
Definition
SNC
Term
is Parkinson's a basal ganglia disease?
Definition
NO (it is a dopamine circuit disease)
Term
how is DBS set up?
Definition
electrode brain implant is connected back to generators outside of the brain
Term
goal of DBS
Definition
eliminate physical symptoms of PD such as rigidity, tremors, & bradykinesia
Term
2 clinical applications for PD
Definition
1. DBS
2. dopamine replacement therapy (L-DOPA)
Term
do we know why DBS works?
Definition
no!
Term
how is Huntington's disease symptoms different from PD?
Definition
instead of a decrease of movement, you see a lack of "breaking" or an increase in involuntary movement
Term
what does a Huntington's brain look like compared to control?
Definition
can literally see a shriveling up of the caudate/putamen
Term
input nucleus of BG
Definition
striatum
Term
output nucleus of BG
Definition
GPi/SNr
Term
direct pathway MSN receptor
Definition
D1R
Term
indirect pathway MSN receptor
Definition
D2R
Term
4 brain regions involved in motor circuits
Definition
1. motor cortex
2. BG
3. cerebellum
4. thalamus
Term
reinforcement learning
Definition
feedback signal is reward
Term
supervised learning
Definition
tells you HOW to do something with an error signal
Term
unsupervised learning
Definition
no real feedback on your actions
Term
how is the joystick task an example of reinforcement learning?
Definition
we don't tell the animal what it is doing wrong with the reaches when it doesn't get a reward, but when the animal does what we want it gets a reward
Term
how would we make the joystick task supervised learning?
Definition
if the animal was given bigger rewards for bigger reaches
Term
how is making desired movements a form of supervised learning?
Definition
feedback comes if movement is done wrong (ex. if reaching for something is too far to the side or too high up etc.)
Term
how does cerebellar ataxia show symptoms?
Definition
tremors with specific movements
Term
general cerebellum functions
Definition
major role in timing of motor activities & in rapid, smooth progression of movements
Term
general basal ganglia functions
Definition
helps plan & control complex patterns of movement
Term
where is the cerebellum located?
Definition
bottom back of the brain
Term
how is the cerebellum organized?
Definition
lots of folds & deeper structures (deep cerebellar nuclei)
Term
do we have a homunculus representation in cerebellum?
Definition
yes (a couple actually)
Term
does the cerebellum receive many or a few inputs?
Definition
many
Term
does cerebellum send feedback back up to motor cortex?
Definition
yes!
Term
is there a cerebellar cortex on each side of the brain?
Definition
yes
Term
all of the output from the folia (cerebellar cortex) come from _______ cells
Definition
Purkinje
Term
2 different types of APs from Purkinje cells
Definition
1. simple spikes (normal APs)
2. complex spikes
Term
Purkinje cells learn via _____
Definition
LTD
Term
do parallel fibers have relatively large or small synapses onto the Purkinje?
Definition
small
Term
how are climbing fibers organized for synapses with Purkinje?
Definition
wrapped around the large dendrites
Term
2 ways climbing fibers decrease Purkinje firing
Definition
1. coincidence with parallel fibers --> LTD
2. huge depolarization --> bit of silent time when it can't fire another AP
Term
how does cerebellar folia exposed to alcohol look?
Definition
like there is a lack of cells
Term
what does the eye do when viewing a picture?
Definition
the eye actually makes lots of tiny movements in a very specific way
Term
do eyes move very quickly or slowly to match a target?
Definition
quickly
Term
what would happen if the brain didn't turn off visual input while you are making a saccade?
Definition
you would feel like your world is always shifting around
Term
why does your brain predict what the world should look like when your eyes get to the end of their saccade?
Definition
you are not crazy thrown off when your eyes get there
Term
Helmbold's saccade
Definition
forcing a saccade by pushing the eye
Term
2 types of eye movement
Definition
1. saccade
2. smooth pursuit
Term
metrics of smooth pursuit eye movements
Definition
do a catch-up saccade at initial movement of what you're following, then smooth follow its movement
Term
how is feedback involved in smooth pursuit?
Definition
when you're following something, you are getting constant feedback about if you're following it well (or moving your eyes too fast or too slow)
Term
eye muscles for up/down movement
Definition
superior rectus/inferior rectus
Term
eye muscles for outside/inside movement
Definition
lateral rectus/medial rectus
Term
eye muscles for spinning in eye socket
Definition
superior/inferior oblique
Term
how do muscles work together to move your eye in one direction?
Definition
that muscle contracts & the opposing muscle relaxes
Term
if we were to record from neuron in abducens nucleus that innervates lateral rectus muscle: as we want to move the eye laterally --> ?
Definition
there will be a large increase in firing right before movement
Term
if we were to record from neuron in abducens nucleus that innervates lateral rectus muscle: as the eye is wanting to be kept laterally --> ?
Definition
there will be a tonic firing to hold the eye there
Term
if we were to record from neuron in abducens nucleus that innervates lateral rectus muscle: if the eye is wanting to be kept medial --> ?
Definition
there will be a decrease in firing
Term
how do we get both eyes to move to the right at the same time?
Definition
right PPRF bifurcates & one crosses the midline to innervate both eyes
Term
firing rate of neuron that connects to eye muscle = tonic firing --> ?
Definition
holds eye in that position
Term
firing rate of neuron that connects to eye muscle = decrease/stopping in firing --> ?
Definition
eye muscle contracting on the other/opposite side
Term
how do you get eyes to move together?
Definition
same neuron controls the lateral rectus of right eye & also the medial rectus of the left eye
Term
does superior colliculus to ipsilateral or contralateral control?
Definition
contralateral (just like motor cortex)
Term
2 main layers of SC
Definition
1. visual
2. motor
Term
output action of SC
Definition
saccade
Term
how do visual & motor neurons work together to get your eyes to reflexively saccade when something pops into your field of view?
Definition
visual cells fire very quickly to tell you there is something there (LGN input)

short time after, motor cells fire to regulate saccade
Term
if you drive current in a visual cell, what will happen to motor cells?
Definition
it will drive EPSCs in the motor cell to drive an action potential to move eye to direct attention
Term
how are visual & motor layers of SC connected?
Definition
monosynaptic
Term
experiment to determine that saccades are encoded in movement coordinates not retinotopic coordinates
Definition
animal fixated on target, had another target appear, then have animal saccade to that target

HOWEVER stimulated SC to induce a saccade in a different direction
Term
do oculomotor saccade neurons have tuning?
Definition
yes (in either angular direction up/down or side/side neurons have preferred angles)
Term
how is tuning organized for saccades?
Definition
in response to place where you are wanting to move your eye to
Term
pons vs midbrain saccade nuclei
Definition
they exist to innervate neurons responsible for different movements:

pons = horizontal

midbrain = vertical
Term
how is tuning determined for saccade neurons?
Definition
neurons will show strong response to its preferred saccade but low response to saccades out of its range
Term
area in the front of the brain that receives a lot of innervation from motor cortex & is responsible for saccades (**monkey brain**)
Definition
frontal eye fields
Term
are there a lot or a few brain areas involved in visual-motor transformations?
Definition
a lot!
Term
are the sympathetic & parasympathetic systems the same or opponent?
Definition
opponent (govern the functions of organ systems in a homeostatic manner)
Term
is the autonomic nervous system (sympathetic & parasympathetic) under conscious control?
Definition
no
Term
four F's autonomic nervous system (sympathetic & parasympathetic) are involved in
Definition
1. fleeing
2. fighting
3. feeding
4. fucking
Term
parasympathetic system roles
Definition
"rest & digest"
Term
sympathetic system roles
Definition
"fight or flight"
Term
are the same organ systems targeted by both parasympathetic & sympathetic systems or are they different?
Definition
same!
Term
why can the parasympathetic/sympathetic systems be thought of as reflexes?
Definition
not under CNS conscious control!
Term
do sympathetic & parasympathetic have the same or counteracting effects on target organs?
Definition
counteracting
Term
2 different layers of gastrointestinal tract targeted by visceral motor system
Definition
1. Meissner's plexus: secretion of enzymes
2. myenteric plexus: regulates the muscles
Term
what does Horner's Syndrome look like?
Definition
lazy eye/looks sleepy
Term
cause of Horner's Syndrome
Definition
lesion of either the reticular formation or farther down spinal cord (unilateral!) that causes loss of sympathetic innervation
Term
where is the hypothalamus located?
Definition
under the thalamus
Term
how is the hypothalamus organized?
Definition
has different divisions that are in charge of different things
Term
2 things hypothalamus is highly involved in
Definition
1. visceral motor system regulation
2. regulation of hormones
Term
2 sets of inputs to hypothalamus
Definition
1. sensory
2. contextual
Term
4 outputs of hypothalamus
Definition
1. visceral motor
2. somatic motor
3. neuroendocrine
4. behavioral responses
Term
main role of hypothalamus
Definition
compares input to biological set points
Term
7 steps in HPA axis stress response
Definition
1. stress signal
2. hypothalamus
3. CRH onto anterior pituitary
4. ACTH onto adrenal gland/kidney
5. cortisol release
6. metabolic effects
7. negative feedback loop to turn off stress
Term
HPA axis
Definition
hypothalamus, pituitary, & adrenal
Term
basically, sympathetic adrenergic response is involved in _______
Definition
fight or flight
Term
sympathetic responses work primarily through _______
Definition
G proteins
Term
would lesioning different parts of the eye circuit get different phenological effects on eye movements?
Definition
yes
Term
how the shapes of neurons change as they grow
Definition
neurons start round --> grow processes that become axon & dendrites
Term
role of growth cone in neuron growth
Definition
kind of seeks out neurons to synapse onto
Term
growth cone has _______ on the end
Definition
filipodia (look like little fingers)
Term
a stain for actin on growing neurons will stain the _______
Definition
filipodia
Term
a stain for microtubules on growing neurons will stain the _______
Definition
more structural, longer part of the cone
Term
lamellipodium
Definition
the sheet connecting the filipodia
Term
how is calcium involved in neuron growth?
Definition
involved in the growth of filipodia from the lamelliposdium
Term
4 steps in initial neuron growing
Definition
1. starts as a round shape
2. repulsion of efferent axon
3. attraction of apical dendrite
4. branching of dendrites
Term
2 reasons why repulsion is important in neuron growth
Definition
1. self-avoidance
2. get neurons to be nice & tiled between each other for circuit dynamics
Term
role of chemoattractants in neuron growth
Definition
can work to bring pioneer growth cones in a certain direction
Term
2 things that can bring axons in a particular direction when neurons are growing
Definition
1. chemoattractants
2. trophic factors
Term
can a chemical be both a chemoattractant and a chemorepellent?
Definition
yes! can vary within or across neurons!
Term
how does an axon choose which side to go on at the optic chiasm when neurons are growing?
Definition
the presence of a certain receptor on the axon will affect a neuron's attraction or repulsion to a chemical to influence its growth direction
Term
why, if you rotate a frog's eye 180 degrees, will it flick its tongue down below when it sees a fly above it?
Definition
the neurons innervating the bottom of the eye will still be attracted to muscles to move down to the bottom direction (even though topographically that part of the eye is on the top...anything seen with that part of the eye will be connected to muscles telling things to move to the bottom)
Term
how is neuron growth from the retina maintaining its topography as neurons grow to the tectum?
Definition
certain neurotrophic factors are present on the anterior or the posterior of the tectum to map retinotopy
Term
early development neuron to muscle innervation pattern
Definition
many neurons will synapse across many muscles
Term
early on, do many or a few neurons innervate a given NMJ?
Definition
many
Term
early on in development, will a climbing fiber wrap around many or a few Purkinje cells?
Definition
many
Term
are neurotrophins equally attractive to all neurons?
Definition
no (what will attract one neuron will probably not attract another neuron)
Term
chemoattractants vs chemorepellents
Definition
regardless of where a soma is, an axon will be drawn to its chemoattractants & away from its chemorepellents
Term
are chemoattractants the same for all neurons?
Definition
no (what is attractive to one neuron might be repelling to another)
Term
neurotrophic factors
Definition
help neurons grow
Term
Hebb's postulate
Definition
"cells that fire together wire together"
Term
how is synaptic pruning done?
Definition
certain inputs will receive neurotrophic factors & the ones that don't will die off
Term
neuron organization: birth
Definition
lots of neurites initially growing around
Term
neuron organization: 2 years
Definition
TONS of connections
Term
neuron organization: 6 years
Definition
synaptic pruning done, much more organized
Term
firing in retina is tightly coordinated with ________ firing
Definition
V1
Term
what is the significance of the different innervation stripes in layer 4 of V1?
Definition
information represented from the contralateral vs ipsilateral eye
Term
cortical neuron responses to eye input: normal adult
Definition
most neurons respond a little bit to both eyes; some strongly respond to one eye or the other
Term
cortical neuron responses to eye input: monocular deprivation in kitten
Definition
after only two days, you will see that eye no longer represented in the cortex
Term
cortical neuron responses to eye input: monocular deprivation in adult
Definition
after even dozens of days, you get less representation overall but you don't completely lose that eye in the cortex
Term
critical period
Definition
a time in which plasticity can only occur in that time
Term
how does normal eye input look in L4 of V1?
Definition
good, strong arborization in L4
Term
how does deprived eye input look in L4 of V1?
Definition
no firing --> lack of arborization --> looks dead
Term
what happens to tuning as an animal matures?
Definition
becomes sharper
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