Midterm Quiz and Lecture Questions
What happens to the 1a activity after the tap is completed?
The action potential frequency stops abruptly as the leg extends.
What happens next as the leg goes back to its resting position?
The activity quickly returns to its previous baseline value
Which part of most neurons occupies the most volume?
The axon
What happens to the membrane potential of a 1a sensory axon when a sodium channel opens upon stretch?
The axon depolarizes
If there is no driving force, as the conductance for an ion increases _____.
the net current for the ion is 0
If the result of the phototransduction cascade is that cGMP-gated channels close, then...
the photoreceptor hyperpolarizes in response to light
What value is the reversal potential of an inhibitory synapse opened by the neurotransmitter GABA?
-65mV
Facilitation is - due to residual Ca++ in the presynaptic nerve terminal - due to residual Na+ in the presynaptic nerve terminal - when the second of two closely timed subthreshold EPSPs is bigger than the first response - 1st and 3rd answers - 2nd and 3rd answers
1st and 3rd answers
In the mayotatic stretch reflex, what is the approximate time latency between hitting a tendon and getting a muscle contraction ?
20 milliseconds
Based on what we just described about vesicle hypothesis, you might conclude
1 vesicle is the anatomical equivalent of 1 quantum
What is the definition of a motor unit?
A single motor neuron and skeletal muscle fiber innervated by that motor neuron's axonal terminal
Which of the following is not a component of the phototransduction signaling cascade initiated by light falling on a rod? - Activation of protein kinase A - A photon of light isomerizes 11-cis retinal - A conformational change in the rhodopsin protein - Dissociation of the alpha subunit of transducin from the beta/gamma complex
Activation of protein kinase A
What did Knudsen observe when he affixed the barn owl with glasses to shift the visual field of the owls?
Adult owls could usually learn to hunt, given the right motivation or previous experience
Which of the following would not cause an increase in quantal content? - A decrease in the number of voltage gated K+ channels in the presynaptic terminal. - An increase in number of vesicles released. - An increase in the amount of Ca++ in the presynaptic terminal. - An increase in the number of neurotransmitter molecules in a vesicle.
An increase in the number of neurotransmitter molecules in a vesicle.
Of the following options, when is the driving force on K+ the highest (given typical neuronal concentrations)? - At the equilibrium potential for Na+ - At the equilibrium potential for K+ - At resting membrane potential - 0mV
At the equilibrium potential for Na+
Which of the following statements is true? - Axons wrap around glia to form myelin. - Axons contain Nissl bodies. - Axons have spines. - Axons contain microtubules. - All of the statements are false.
Axons contain microtubules.
At the optic chiasm- - axons from each nasal retina decussate - all axons from both eyes converge and then randomly segregate to each hemisphere - all axons leaving the eye cross over to the contralateral side - axons from each temporal retina decussate
Axons from each nasal retina decussate
What is the way that motor neurons are mapped within the ventral horn?
Based on the physical location of the muscles in the body
Why are neuromuscular junctions such reliable synapses? Choose the correct option. - Because the presynaptic terminal contains a single active zone. - Because the quantal content is so high, evoked release muscle always depolarizes the muscle above action potential threshold. - Because the presynaptic terminal releases just 1-2 vesicles after each action potential. - Because the axon terminal is is covered by a Schwann cell.
Because the quantal content is so high, evoked release muscle always depolarizes the muscle above action potential threshold.
How does myelin speed up the conduction velocity?
By reducing membrane capacitance and increasing membrane resistance
At rest, rank Na+, Cl-, K+, and Ca++ in terms of their driving forces from the smallest driving force to the largetst
Cl- (0mV), K+ (15mV), Na+ (125mV), and Ca++ (185mV)
According to the Law of Dynamic Polarization, a neuron receives input primarily on its _____.
Dendrites
Which best represents the membrane response of an OFF bipolar cell to a spot of light in the center of its receptive field?
Depolarizes (inhibited by light in the center of its receptive field)
How can increased postsynaptic calcium concentration lead to both LTP and LTD?
Differences in the time course and magnitude of calcium increases trigger different cascades
Ocular dominance columns in layer IV of V1 segregate input by
Different eyes
When to K+ rectifier channels start to open?
During the overshoot of the action potential (the peak)
Why have insights into motor control of behavior lagged knowledge of sensory systems?
Easy to know the muscle output but not the origin of movement in the brain
At the equilibrium potential of an ion the two gradients that are in equilibrium are:
Electrical and chemical gradient of one ion
Mini End-Plate Potentials (mEPPs) typically require a presynaptic action potential.
False
T/F: All neurons in layers 2/3 respond to activation of both eyes equally
False
T/F: Depression is associated with decreased blood flow and activity in the major areas of the brain
False
T/F: Depriving an eye of vision for weeks in an adult has a much more profound effect on that eye's visual acuity than a similar deprivation in a young child
False
T/F: Each specific neuron type can be identified by expression of a single gene.
False
T/F: The firing of primary motor cortical neurons occurs precisely at the onset of muscle contraction?
False
T/F: The light microscopy has finer resolution (can see more details) than electron microscopy
False
T/F: The number of different motor axons that innervate each muscle fiber steadily increases as young mammals mature
False
T/F: Your "consciousness" likely resides in a single brain region
False
Which of the following statements about LTP is false? - LTP involves an enhancement in synaptic efficacy that can last for hours, days, weeks or even longer - The requirement for coincident pre- and post-synaptic activity was predicted by Donald Hebb in 1949 - If one synapse (A) is very strongly stimulated (sufficient to cause LTP), and a nearby synapse (B) on the same cell is weakly stimulated a few seconds later, then the second synapse (B) will also show LTP - Calcium may activate a signaling cascade that causes the insertion of glutamate receptors into the post synaptic membrane
If one synapse (A) is very strongly stimulated (sufficient to cause LTP), and a nearby synapse (B) on the same cell is weakly stimulated a few seconds later, then the second synapse (B) will also show LTP
Nonlinear summation would have what effect on the measurement of the quantal content?
For a large EPSP, it would suggest that the quantal content is smaller than it actually is
The equation used to calculate membrane potential when there are multiple permeant ions is called the _____ equation.
Goldman, Hodgkin, Katz
Which of the following statements about the clinical case of H.M. is false? - H.M.'s intellectual functions, as measured by intelligence tests, sharply declined after his surgery - H.M.'s nondeclarative memory was intact - It showed that bilateral medial temporal structures are important in the formation of declarative memory - H.M. was unable to remember clinicians who worked with him for many years
H.M.'s intellectual functions, as measured by intelligence tests, sharply declined after his surgery
If you block enkephalin release, how would your pain levels change?
Increase
Which of the following would not be expected to result from sympathetic nervous system activation? - Increased uptake of glucose by the liver - Decreased blood flow to the GI tract - Increased blood flow to the heart - Increased heart rate
Increased uptake of glucose by the liver
Which of the following modifications to the presynaptic terminal would not lead to the release of more vesicles?
Increasing potassium conductance
Certain chloride channels are always open in neurons; what happens to the chloride current when the membrane potential approaches +60mV?
It increases as chloride flows into the cell
Given that an inhibitory synapse onto a neuron prevents that postsynaptic neuron from reaching threshold, what do you think are potential ionic conductances that are increased at the ligand-gated ion channels of inhibitory synapses?
K+ or Cl-
Which of the following axons would have the fastest conduction?
Large caliber myelinated axon
Given what you know about the equilibrium potentials of ions, the membrane-spanning channel pore of an AChr, an excitatory synapse receptor, should be:
Lines with negatively charged amino acids
What is Henneman's Size principle?
Motor neurons innervating the same muscle are recruited to activate different sets of muscle fibers sequentially with the smallest fibers activated first
What does an axon that conducts action potentials via saltatory conduction have that is unique from axons that do not conduct via saltatory conduction?
Myelin
Which type of sodium channel has a higher conductance: a closed channel or an inactivated channel?
Neither - both have zero conductance
The idea that neurons are discrete units, rather than a continuous network, is a fundamental idea of the ______ .
Neuron Doctrine
Which one of the following answers, correctly completes the sentence? Sensory transduction at the spindle fiber in the myotatic stretch reflex _____ . - None of the statements are correct - converts electrical signals into chemical signals - converts mechanical signals into humoral signals - converts electrical signals into mechanical signals
None of the statements are correct
The frontal lobe is _______ to the parietal lobe. - ventral - rostral - caudal - dorsal
Rostral
Which lobe contains most of the areas responsible for processing visual information?
Occipital
Which step happens first in normal (evoked) synaptic transmission?
Opening voltage gated calcium channels
What is the most direct pathway for the transmission of visual information from the eye to the brain?
Photoreceptor -> bipolar cell -> ganglion cell -> brain
If the concentration of a cation is higher on the outside of the neuron compared to the inside, the equilibrium potential will be _____ .
Positive
What would immediately happen to a neuromuscular junction synapse's quantal content if the cleavage enzyme were blocked?
Quantal content would not change
If a membrane is permeable to all ions, ion flow will eventually ______. - increase - stop completely - reach equilibrium
Reach equilibrium
A person with damage to the ventral stream will have the most trouble with which task?
Recognizing a familiar face
The hallmark of Parkinson's disease is
Reduced movements that the patient cannot control (hypokinetic)
Which of the types of short term plasticity do you think underlies habituation in Aplysia?
Short term depression
What advantage would a GPCR type receptor add to phototransduction?
Signal amplification
If an axon at resting membrane potential was exposed to tetrodotoxin (TTX), the result would be:
TTX will have little or no effect on the resting membrane potential
Which of the following explains the unidirectional propagation of action potentials? - The voltage dependence of the sodium channels - The voltage dependence of the potassium channels - The polarized orientation of microtubules within the axon - The inactivation of sodium channels at a location where an action potential has just passed
The inactivation of sodium channels at a location where an action potential has just passed
What will happen to a glial cell's resting potential (which is based on K+ resting leak channels) if the extracellular solution has 4-fold more potassium than usual?
The membrane potential depolarizes (becomes less negative)
What will the resting potential of a glial cel lbe if we raise the extracellular K+ concentration to 100mM
The membrane potential will be 0mV (the intracellular concentration of potassium in glial cells is always 100mM)
If Chloride permeability increased in a neuron, what would happen to the membrane potential?
The membrane potential will be unchanged
Based on the GHK equation, what would happen to a neuron's membrane potential if the Na+ permeability suddenly increased to be many-fold higher than the K+ permeability?
The membrane potential would depolarize so much that the membrane potential would be positive rather than negative
If the relative amount of Na+ channels suddenly increased in a neuron, what would happen?
The neuron would depolarize
Why would it be less useful if the Golgi stain labeled all the cells in the brain?
Too stained (the stained brain would just be a big brown lump. The Golgi stain is useful/powerful because of the contrast of the stained cell on the unstained background
Which of the following statements about center-surround receptive fields in the retina is false? - The surround portion of the receptive field is typically an annulus (or donut-shaped ring) that surrounds the circular center - Cells that are excited by light in their center are inhibited by light in their surround - The best stimulus for an on-center cell is light in its center and darkness in its surround - The spatial extent to which a cell can be influenced by light never extends beyond the physical extent of its dendritic field
The spatial extent to which a cell can be influenced by light never extends beyond the physical extent of its dendritic field
Which of the following would be most likely to occur if a scientist blocked translation (protein synthesis) in a neuron and then performed a high frequency stimulation protocol that typically induces LTP? - LTD would be stimulated - no LTP would occur - The synapse would potentiate, but last for a shorter time than typical
The synapse would potentiate, but last for a shorter time than typical
Which one of the following statements about EPSPs is true? - They have a slow rise and a fast fall - Their shape is altered by concurrent synaptic inhibition - They prevent neurons from reaching action potential threshold - Their amplitudes always sum in a linear way
Their shape is altered by concurrent synaptic inhibition
Which of the following is the most likely reason that RGCs and thalamic neurons in the LGN both have center surround receptive fields?
There is probably very little convergence of different types of RGCs onto the same thalamic neuron
Which of the following statements about action potentials is false? - They can transmit signals over long distances. - They are typically elicited by hyperpolarization. - They are all-or-none. - They occur at threshold
They are typically elicited by hyperpolarization.
T/F: A target neuron will secrete as much neurotrophic factor as is required to ensure survival of all neurons synapsing onto it
True
T/F: Procedural memory can occur without conscious awareness
True
If there were an inhibitory synapse that used a rise in potassium conductance rather than chloride conductance, would you be able to tell by looking at the post synaptic membrane during the IPSP?
Yes, the membrane potential would slightly hyperpolarize during the potassium-based IPSP pushing the entire red trace slightly more negative
What is a morphogen?
a signaling molecule that determines which genes are activated depending on its concentration
Which of the following is the best definition of amblyopia? - a clouding of the lens which leads to decreased vision - inability to properly focus light - a visual impairment akin to blindness but without any physical problem in the retina or lens - retinal detachment
a visual impairment akin to blindness but without any physical problem in the retina or lens
Which condition(s) usually need to be met to induce LTP? - the postsynaptic membrane must be depolarized for a period of time - glutamate must be released from the presynaptic terminal - glutamate must open the postsynaptic NMDA receptors - all of the above
all of the above
If a cell's membrane were permeable to only one type of ion, its membrane potential would
be exactly the Nernst potential of that ion
The reversal potential for acetylcholine receptors (AChRs) is:
between Ena and Ek, when the Na+ current is equal and opposite to the K+ current.
The Nernst equation calculates each ion's equilibrium potential based on its _____. - charge - both charge and ratio - ratio of intracellular and extracellular concentrations - neither
both charge and ratio
Miniature end-plate potentials, or MEPPs, are produced ____.
by spontaneous release of neurotransmitter
Which mechanism used in hippocampal LTD is not part of the hippocampal LTP mechanism? - calcium-dependent activation of protein phosphatases - calcium influx - NMDA receptor activation - calcium-dependent activation of protein kinases
calcium-dependent activation of protein phosphatases
Cortical areas that plan and initiate motor sequences- - all fall within the primary motor cortex - comprise five functionally distinct and anatomically isolated regions - comprise several functionally distinct but highly interconnected regions - all receive direct inputs from the basal ganglia
comprise several functionally distinct but highly interconnected regions
The ability or ease of an ion to flow is the _____ .
conductance
Short term memories are converted into long term memories by a process known as
consolidation
Which of the following is an example of a second messenger? - cyclic AMP - enkaphalin - opiates - K+ and Na+
cyclic AMP
Enkephalins dampen pain signals by
decreasing the conductance of voltage-gated calcium channels at the presynaptic terminal of pain sensory neurons which results in less neurotransmitter release
If you reduce the potassium conductance at rest, the membrane potential will
depolarize
Which of the following is not associated with Alzheimer's Disease? - extension of critical periods - formation of amyloid plaques in the extracellular space - aggregate of tau (tangles) form within neurons
extension of critical periods
T/F: A neuron can divide into more neurons
false
Why does the "trigger zone" or "initial segment" have the lowest threshold of any part of the neuron?
highest density of Na+ channels
Which of the following mechanisms would lead to long-term potentiation? - holding the post-synaptic cell at -70mV while activating a strong synapse repeatedly - holding the post-synaptic cell at 0mV while activating a weak synapse repeatedly - Repeated stimulating a group of strong synapses after removing calcium from the extracellular fluid - holding the post-synaptic cell at 0mV without stimulating any presynaptic axons
holding the post-synaptic cell at 0mV while activating a weak synapse repeatedly
Which of the following would not cause a change in synaptic strength? - increasing the quantal content - increasing the number of post-synaptic receptors - increasing the conductance of a synaptic receptor - increasing the myelination and conduction speed of the presynaptic axon
increasing the myelination and conduction speed of the presynaptic axon
Growth cone collapse- - occurs when an axon contacts a substrate that repels it - occurs when an axon contacts a substrate that is a good site for synaptogenesis - is the well known homolog of dendritic spine collapse - is the first sign that a neuron is about to undergo apoptosis and is often used as a sign of disease in the nervous system
occurs when an axon contacts a substrate that repels it
What makes the cell membrane permeable to specific ions?
ion specific channels
Which is not a method by which the nervous system initially establishes regionalization? - chemicals released from one end forms a gradient - restricted expression of transcription factor to segments - ions concentrated at one end forms an electric gradient
ions concentrated at one end forms an electric gradient
At a typical neuronal resting potential, the net movement of potassium ions through leak channels _____.
is outward
When recording from a hippocampal place cell, what happens when the rat runs through the cell's preferred area?
it fires more frequently
Glial cells are normally permeable to ______. - just K+ - just Na+ - K+ and Na+ - no ions
just K+
How would the axonal arborization of auditory neurons in the tectum of owls who were exposed to both prisms and normal vision compared to control animals?
larger arborization
In humans, the part of the visual field that is seen by both eyes (binocular area) is
located primarily on the temporal portion of both retinas
NMDA receptors are permeable to all of the following except- - calcium - magnesium - potassium - sodium
magnesium
The parvocellular and magnoceulluar layers of the lateral geniculate nucleus- - receive input from the contralateral and ipsilateral halves of the visual field respectively - may belong to different parallel pathways - analyze the same kind of information from the visual field - are connected to the nasal and temporal halves of the retina respectively
may belong to different parallel pathways
Which ON-center cell is more active? (black grid question)
more active when there is more dark in the OFF-center area because less inhibition
Stimulating two adjacent areas in M1 will result in- - movement of two muscle groups that are close in size on the contralateral side of the body - movement of two adjacent areas on the ipsilateral side of the body - movement of two muscle groups that are close in size on the ipsilateral side of the body - movement of two adjacent areas on the contralateral side of the body
movement of two adjacent areas on the contralateral side of the body
Which statement describing the distribution of netrin and slit across the ventral midline spinal cord is correct? - netrin is secreted on the ipsilateral side and slit is secreted on the contralateral side - slit is secreted on the ipsilateral side and netrin is secreted on the contralateral side - netrin and slit are secreted on both sides of the midline
netrin and slit are secreted on both sides of the midline
At the optic chiasm, retinal axons must remain in the same hemisphere or cross to the opposite hemisphere. This is an example of-
pathway selection
Which of the following is not true about hemispatial neglect syndrome? - patients may believe as if one half of the entire universe had abruptly ceased to exist - typically damage to the right results in an unawareness to the left side of the body - patients also typically present with many other cognitive deficits
patients also typically present with many other cognitive deficits
Which part of the retina would be best to detect a faint star at night?
periphery
Laminin in the extracellular surface is-
permissive
The two main components of emotion are
physical expression and conscious perception
Which of the following is not a way to extend the critical period? - increase attention and motivation - use incremental learning - a small bit at a time - premature expose animals to sensory experience - manipulate experience temporarily during the critical period, then re-expose to the manipulated experience after the critical period
premature expose animals to sensory experience
An IPSP located ______ to an EPSP may block the EPSP's signal at the axon initial segment due to shunting inhibition. - proximal (closer to soma) - distal (farther from soma)
proximal (closer to soma)
Spatial and perceptual reasoning typically "resides" in the
right hemisphere
What two sensory cues does the owl have to precisely map together to detect its prey?
sight and sound
Local potentials (like receptor potentials) vary proportionally to the _______ of the stimulus. - no relationship - duration - size and duration - size
size and duration
An axon with a larger diameter will propagate an action potential faster than one with a smaller diameter (all else being similar), because _____ .
the larger axon has less internal (axial) resistance.
If a second subthreshold EPSP arrives during the falling phase of a prior subthreshold EPSP, the total amplitude may be _______ adding the peak amplitudes of each EPSP - slightly less than - exactly equal to - much great than
slightly less than
Short term depression would result in
smaller quantal content
If a neuron is at rest (and the channels are all in their resting state), which of the events happens first during an action potential?
sodium channels open
Upper motor neurons- - have cell bodies that are located in the ventral horn of the spinal cord - synapse on local circuit neurons and/or lower motor neurons - affect motor patterns only indirectly via their inputs to the basal ganglia - control the upper half of the torse
synapse on local circuit neurons and/or lower motor neurons
Which one of the following structures is unique to neurons? - rough ER - mitochondria - synaptic vesicles - Golgi apparatus
synaptic vesicles
The protein that is thought to bind calcium and trigger synaptic vesicle release is called
synaptotagmin
GABA channels are considered inhibitory because ___.
the channel is selective to chloride and ECl- is hyperpolarized compared to threshold, thus it keeps neuronal potential near the resting potential
Hubel and Wiesel hypothesized that complex receptive fields could emerge from _____ of simpler receptive fields
the convergence
Which of the following statements is true about both NMDA and AMPA receptors: - they both normally bind glutamate - they are both voltage dependent - they are both typically permeable to calcium - they both typically desensitize
they both normally bind glutamate
A response to a _____ constitutes a conditioned fear response in the rat
tone paired repeatedly with a foot shock
Gap junctions may exhibit all of the following features except for the ability to - pass hyperpolarizing currents - transform electrical signals into chemical signals - pass small molecules - pass depolarizing currents
transform electrical signals into chemical signals
The critical period is
when the brain can learn efficiently
