MT1 Sample Flashcards
The action potential and synaptic potential are actually special cases of the membrane potential
True
Name 3 properties of ion channels
ion selectivity, kinetics (time they stay open, etc) state (active, deactivated, etc.)
The neurotransmitter GABA: A. is inhibitory B. opens Cl- channels C. is excitatory D. is a neuromodulator E. depolarizes post-synaptic targets F. A and B G. C and E
a. inhibitory b. allows Cl- ions into cell, K+ out of cell
What kind of activity is measured at the level of a nucleus? A. fMRI B. EMG C. graded potential D. action potential E. none of the above
none of the above (EEG)
Name the 5 properties of ion channels
ion selectivity (what does it let in?) gating mechanism (how does it open?) kinetics (how long does it open) state (is it available to be opened?) location (where is it?)
Dopamine is a neurotransmitter that is directly excitatory
False Dopamine is a neuromodulating neurotransmitter
Membrane potential is a special case of equilibrium potential
False Equilibrium potential is a special case of membrane potential
During action potential, _____ rushes into the cell, followed by ____ rushing out
Na+ rushes in, then K+ rushes out
If Neuron A fires an action potential after simultaneously receiving an EPSP from Dendrite 1 and Dendrite 4, it is an example of: a. IPSP b. temporal summation c. spatial summation d. local summation e. none
c. spatial summation
Dorsal root ganglian cell is located in the spinal cord
False. The dorsal root ganglian is a cluster of nerve cell bodies (a ganglion) in the posterior root of a spinal nerve. Their axons are afferents that relay sensory information into the central nervous system. The differ from majority of neurons in that an action potential in a posterior neuron may initiate in the distal axon, bypass the cell body, and continue to propagate along the proximal axon until reaching the synaptic terminal. Bare nerve ending in the distal end, possibly covered by meissner or pacinian corpuscle.
What are the characteristics of a pacinian corpuscle? shallow/deep ? small/large receptive field? high/low frequency? transient/sustained?
A pacinian corpuscle (onion skin) is: deep large receptive field high frequency transient //sensitive to vibration and pressure //respond to sudden disturbances // ~250 Hz
//unmylenated end of DRG is wrapped by skin cells like an onion
What are the characteristics of a Meissner’s corpuscle?
shallow small receptive field low frequency transient //~10-50 Hz // gripping objects //epidermis with unmylinated end of DRG wrapped around it
There is a higher density of Merkel disks on your finger than your arm
true
What are the characteristics of Merkel disk cells?
shallow placement
small, spotty field
sustained
two point discrimination
//sensitive to form, edges, texture
What two types of mechanoreceptors are probably involved in reading Braille?
merkel disks
meissner’s corpuscles
Where do we FIRST start to get direction selectivity from a single cell?
a. S2
b. S1
c. VPN
d. spinal cord
e. none of the above
S1
S1 is located in the precentral gyrus
false
S1 is located in the (parietal lobe-somatosensory cortex) postcentral gyrus.
It is the main sensory receptive area for TOUCH
Signals from mechanoreceptors in your left hand end up in your right brain hemisphere
true!
signals from mechanoreceptors in your right hand cross over to the left brain hemisphere too
Weigert stain stains for
a. soma
b. axons
c. whole neurons
d. whole glia
e. none of the above
Weigert stain stains for AXONS
Generator potentials are analogous to [synaptic] / [action] potentials
‘Microslip’ events are best detected by the _______ of touch receptor.
meissner’s corpuscle
Recordings of neurons along [oblique] / [vertical] trajectories through visual cortex yield neurons with different directional tuning preferences.
Which type of bipolar neuron is depolarized by the neurotransmitter glutamate?
Ganglion cells of which type have responses to light that are analogous to Pacinian corpuscle responses to touch?
Ocular dominance columns in the left V1 alternate between inputs from the left and right eyes (t/f)
TRUE
The pinwheel map contains information for color. (t/f)
FALSE; pinwheel map refers to orientation of stimulus (e.g. orientation of bar)
MST neurons show selectivity for what type of stimuli?
(medial superior temporal region)
moving stimuli in a certain direction
The action potential and synaptic potential are actually special cases of the membrane potential.
true
On an otherwise dark field of view, light in the form of a plus sign in the upper-left field of view will excite neurons in the
RIGHT LOWER V1
Ganglion cells of which type have responses to light that are analogous to Pacinian corpuscle responses to touch?
pacinian corpuscles have a TRANSIENT response… just as MAGNOCELLULAR ganglion cells in the visual system
Which type of bipolar neuron is depolarized by the neurotransmimer glutamate?
OFF bipolar cell
(circle the appropriate word) Recordings of neurons along [oblique] / [vertical] trajectories through visual cortex yield neurons with different directional tuning preferences.
OBLIQUE
neurons in a single cortical column (vertical) have the SAME directional tuning preferences
‘Microslip’ events are best detected by the _______ of touch receptor
meissner corpuscle
Generator potentials are analogous to [synaptic] / [action] potentials.
SYNAPTIC
The ‘Pinocchio Effect’ involves a resolutioon of contradictory information supplied by which two sensory systems of the brain?
proprioceptive
somatosensory
Which area of parietal cortex is known to integrate both tactile sensation and visual information?
area VIP (ventral intraparietal)
[monkey experiment with fixed gaze, touching monkey, then presenting visual stimuli in same field; same firing pattern in single cell recording; integration of somatosensory and visual “personal space”
As visual information moves from V1 to later processing stages along the ‘what’ pathway, the features being processed become increasingly specific. (T/F)
FALSE
as you move from V1 you get increasing generalization across stimulus features (increasingly abstract) due to convergence of different types of information. start to lose retinotopy, receptive field sizes increase, start to respond to shapes, etc.
Ocular dominance columns were found by staining for what enzyme?
cytochrome oxidase. it is needed to produce ATP
Where does integration first occur between the proprioceptive and somatosensory systems?
S1 (think pinnochio effect)
There are more neurons in V1 dedicated to the ______ of gaze. This phenomenon is called ______ expansion.
(center) ; foveal expansion
In which layer of the visual cortex is sustained and transient information first integrated?
layer 4
Magnocellular information comes into layer ______, and magnocellular neurons are _______adapting
layer 4;
magnocellular is transient; rapidly adapting
Left LGN has information coming from which eye?
BOTH eyes
Left LGN has information coming from which field of view?
RIGHT field of view
An object in your right visual field ends up where on your retina?
left side of retina; both eyes
What is the ratio of number of cones in fovea to cones in periphery in these humans, primates, rats
90: 1
60: 1
6: 1
In the knee jerk reflex, the motor neuron innervating the hamstring is __________ by an interneuron. This prevents what?
inhibited; this prevents your lower leg kicking back (prevents the hamstring from contracting and stretching the quadriceps muscle, which would activate the knee jerk reflex over and over again in a continual loop.)
In the proprioceptive system, a muscle’s dorsal root ganglion cell (also known as the ______) wraps itself around the _______ portion of the ______ muscle fiber
muscle spindle afferent;
non-contractile; intrafusal muscle fiber
The muscle spindle afferent fires action potentials when the muscle is (contracted/elongated)?
elongated
when muscle is elongated, the contractile portions contract, stretching the muscle spindle afferent, causing generator potentials, and then action potentials.
The response of a muscle spindle afferent is (sustained/transient)?
transient
there’s a motor fiber that synapses on contractile portion, causing them to reset to the original state after elongation, which resets the non-contractile portion, making it ready for the next elongation
The golgi tendon organ carries
(sustained/transient) information
SUSTAINED
Golgi tendon organ registers tendon _______, which happens when muscles ________.
stretch, contract
Deflecting stereocilia of hair cells away from kinocilium produces (excitation/ inhibition)? This information is (sustained/transient).
inhibition
transient
Due to the orientation of hair cells in semicircular canals on the left and right side of the head, if you move your head to the left, hair cells on which side experience excitation?
LEFT (because the fluid moves to the right)
The otolith organ provides (sustained/ transient) information about the orientation of the head with respect to gravity, and is analogous to the ______ of the visual system.
otolith = sustained
…
same as…
parvocellular (vision)
merkel (somato)
golgi tendon (motor)
Golgi tendon organ detects ___ stimuli:
sustained
When you flex your biceps, the intrafusal muscle fibers are the ones moving your arm
no, EXTRAFUSAL move the arm,
intrafusal detect the state
1a sensory fibers synapse on
A.golgi tendon organs
B.extrafusal muscle fiber
C.merkel disks
D.pacinian corpuscle
E.none of the above
E.none of the above
intrafusal muscle fiber
Gamma motor fibers synapses on what specific portion within a muscle spindle?
contracile portion of intrafusal muscle fiber
The cupula is located in what structure?
A.utricle
B.saccule
C.muscle spindle
D.semicircular canal
E.none of the above
semicircular canal
Deflection towards the kinocillium does what to the hair cell?
excites the hair cell
If you turn your head to the left, the cupula in your right semicircular canal shows what kind of activity?
inhibited (steriocilia away from kinocilia)
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What structure gives sustained vertical movement information?
sacule
What primary cortex does vestibular information end up in?
S1
Light excites photoreceptors
false; light ON hyperpolarizes photoreceptors, resulting in LESS glutamate being released
Which is hyperpolarized by glutamate?
bipolar ON
(light ON = less glutamate released
less glutamate released = depolarized
depolarized = firing
firing -> light ON
= bipolar ON)
What type(s) of cells fire action potentials?
A.retinal ganglion cells
B.dorsal root ganglion cells
C.bipolar cells
D.photoreceptors
E.none of these
ganglion cells:
retinal ganglion
dorsal root ganglion
What type(s) of cells signal sustained stimuli
A.parvocellular ganglion cells
B.magnocellular ganglion cells
C.bipolar cells
D.photoreceptors
E.none of these
parvocellular
bipolar cells
photoreceptors
also…
sacule
otoliths
merkel disks
golgi tendon
Information received by the left eye goes to both V1 hemispheres
TRUE
Information received by the left LGN goes to both V1 hemispheres
FALSE
rapidly adapting
deep placement
very large field
high frequency vibration
Pacinian Corpuscle
rapidly adapting
shallow placement
3-5 mm response field (small)
low frequency vibration
Meissner Corpuscle (slip/grip control)
slowly adapting
shallow placement
small, spotty field
form, texture, edges
Merkel Disks
In which structure do signals from the DRG (dorsal root ganglion) transfer to the other hemisphere of the brain?
medulla
Cortical Layers of Somatosensory
slowly (sustained) adapting information comes into layer __. rapid comes into layer _ and projects up to layer _, where information about change and constancy is first integrated. then transmitted down to cortical layers and transmitted out for different functions
slow into layer 2
rapid into layer 4
integrated in layer 2
transmitted down and out
where does RA/SA (transient/sustained) information FIRST integrate in the somatosensory cortex?
in layer 2
sustained into 2,
transient into 4,
integrated in 2
What happens to the nature of somatosensory information as it moves from S1 to S2
the response fields generalize across digits, but remain directional selectivity
describe the knee jerk reflex, from the DRG onward
When the DRG is stimulated, it stimulates motor neuron that triggers quad,
as well as a local interneuron that
inhibits the hamstring from kicking back
describe the parts of the somatosensory cortex
What kind of information is carried by the muscle spindle afferent?
carry information about -transient- elongation of the muscle.
There is a particlar type of motor fiber that synapses on the contractile regions which cause them to reset to their original state, which can then reset or restretch the noncontracile portion. This allows the muscle spindle afferent to
trasmit only transient information rather than be stretched the entire time the muscle is elongated
how does the intrafusal muscle fiber function?
2 parts: contracile and noncontractile portion
DRG/muscle spindle afferent wraps around the the non contracile portion, of intrafusal mf is the muscle spindle afferent.
when the contraclie region contracted, the noncontracile portion is stretched which causes deformation of the unmylenated portion of the DRG and causes generator and action potentials depending on the degree of elongation
Name 4 functions of proprioception
joint-protecting reflexes (e.g., knee-jerk)
adjustment of musclec ontraction/recruitment
kinesthesia: detection of body positio nand movement
coordination of motor commands
Name 3 functions of the vestibular system
Postural reflexes
Gaze adjustment
Assessment of self-motion
hair cells ____ at rest
tonically release neurotransmitter
if you move your head to the right… which
semicircular canal will be inhibited?
LEFT will be inhibited
oriented vertically
gives horizontal head
change info
utricle
sustained information
vestibular system
otoliths!
(utricle and saccule)
HCs oriented horizontally,
vertical information
saccule
how do the otolith organs work?
otoliths pushing down on gelatin causing excitation
of hair cells
the constancy of the excitation results in sustained information
about the head’s orientation relative to gravity
describe the vestibular pathway
who came up with the idea of cortical columns?
Vernon Mountcastle
primary visual cortex is also known as
v1 / striate cortex/ area 17
all neurons in a cortical column
share the same ….
response field,
sensitive to input on the same area
of the retina
neurons in adjacent cortical columns share…
similar or co-located
response field
different orientations
describe OPTOGENETICS
new technique taking
genetic manipulations (viral vector) to
create neurons that have ion channels
that can be controlled with laser
stimuluation (Na+ to , Cl- in to
silence them)
Calcium imaging
measures the flow
of calcium into neurons (indicator of flow
of Ca that is required to fire an AP)
tells you which neurons are active
in which direction are photoreceptors oriented in the retina?
oriented
toward the back of
the eye
photoreceptors at rest ….
… tonically release glutamate
light does what to photoreceptors
hyperpolarizes them… they release LESS glutamate
hyperpolarization of photoreceptors to glutamate is an example of
disinhibition
what is the order of connectivity in the visual system?
photoreceptor > bipolar cell > ganglion cell > LGN > V1
where do we see the first action potential in the visual system?
in the retinal ganglion cell
when a light is ON… what happens to ON bipolar cells?
photoreceptors release LESS glutamate…
ON BIPOLAR CELLS….
… hyperpolarized by glutamate
….receiving less of it
… is less hyperpolarized
… INCREASES voltage
when a light is ON… what happens to OFF bipolar cells?
when light is ON…
OFF bipolar cells…
…receive less glutamate
… are depolarized by glutamate
… voltage decreases
When light is OFF, what happens to the photoreceptors?
when light is OFF …
Photoreceptors are NOT hyperpolarized…
… release MORE glutamate
when light is OFF what about ON bipolar cells
decrease voltage when light is OFF
… receive MORE glutamate
… are hyperpolarized by glutamate
… become more hyperpolarized
… so decrease voltage
When light is OFF what happens to OFF bipolar cells
OFF bipolar cells are depolarized by glutamate
when light is OFF
receive MORE glutamate from photoreceptors
are depolarized by glutamate
so voltage INCREASES
what are the relative distribution of :
parvocelluar
magnocellular
koniocelluar
… cells in the brain?
80% parvo (sustained)
10% magnocellular (transient)
10 % koniocellular (color)
what does a PARVOCELLULAR-X-ON
look like during an ON stimulus
