Exam III

Question 1

If a bullet damaged the following area of the nervous system, what brain function or pathways would be impaired? HIPPOCAMPUS

Answer 1

Spatial Memory

Question 2

If a bullet damaged the following area of the nervous system, what brain function or pathways would be impaired? THE LATERAL GENICULATE NUCLEUS OF THE THALAMUS

Answer 2

Vision

Question 3

If a bullet damaged the following area of the nervous system, what brain function or pathways would be impaired? THE BASAL GANGLIA

Answer 3

Movement

Question 4

If a bullet damaged the following area of the nervous system, what brain function or pathways would be impaired? AREA MT IN THE CORTEX

Answer 4

Vision

Question 5

If a bullet damaged the following area of the nervous system, what brain function or pathways would be impaired? THE OVAL WINDOW

Answer 5

Hearing

Question 6

If a bullet damaged the following area of the nervous system, what brain function or pathways would be impaired? VENTRAL HORN OF GREY MATTER OF THE SPINAL CORD

Answer 6

Movement

Question 7

Fill in the blanks: Astrocytes take up (1)___________________ ions from the extracellular space around neurons. They do so because neurons lose some of this ion every time an (2)_________________________ occurs. Since the extracellular concentrations of this ion determines the (3)_________________________ of the neuron, this action of astrocytes prevents (4)____________________ of the neuron and production of spontaneous action potentials. Astrocytes can also take up (5)_________________________ from the extracellular space around synapses.

Answer 7

(1) Potassium (2) Action Potential (3) Resting Membrane Potential (4) Depolarization (5) Neurotransmitters

Question 8

Why would you have to use imaging of a calcium sensitive dye rather than fMRI to determine whether a particular individual neuron in the visual cortex of a monkey brain responds to a colored stimulus?

Answer 8

fMRI does not have the spatial resolution to image an individual neuron.

Question 9

Explain briefly why action potentials do not degrade over time as they propagate down an axon in contrast to graded potentials.

Answer 9

Because at every point along the axon, voltage-gated sodium channels open and renew the action potential, contributing to it and adding to the depolarization.

Question 10

A neuronal cell body has a voltage-gated sodium conductance and a leakage chloride conductance ONLY. Based on the ion concentrations in the cell, the equilibrium potential for sodium is +50 mV and the equilibrium potential for chloride is -60 mV. At rest, the voltage gated sodium channels are not open. What is the membrane potential of the neuron? How much current flows through the chloride channels under these conditions?

Answer 10

-60 mV because only leakage chloride channels are permeable and they would not have any current because the equilibrium potential equals the resting membrane potential.

Question 11

A neuronal cell body has a voltage-gated sodium conductance and a leakage chloride conductance ONLY. Based on the ion concentrations in the cell, the equilibrium potential for sodium is +50 mV and the equilibrium potential for chloride is -60 mV. When some of the sodium channels are open, in addition to the chloride channels, which way do the chloride ions flow?

Answer 11

Into the cell. They will want to lower the resting membrane potential which will raise when sodium enters the cell.

Question 12

Is this a true statement: “The random events called miniature end-plate potentials arise from the random opening and closing of ion channels.”

Answer 12

Not essentially. The timing of the MEPP’s is determined by random release of vesicles of neurotransmitter not the activation of individual neurotransmitter-gated ion channels.

Question 13

Why might we see a star better at night if viewed from the corner of our eye rather than viewed straight?

Answer 13

We are using the rods in the peripheral retina.

Question 14

Why would a mutation in the tip-link protein in the ear result in deafness?

Answer 14

Because the K+ channel would not open.

Question 15

Match the following structures in the visual system to the properties listed. There is only one match for each structure: 1. Retinal Ganglion Cells 2. Lateral Geniculate Nucleus 3. Horizontal Cells. 4. Photoreceptor. a. makes inhibitory synaptic contact with photoreceptors b. receives excitatory connections from bipolar cells. c. destruction of this group of cell bodies on the left side of the brain results in loss of some of the visual field in both eyes. d. expresses one of three visual pigments.

Answer 15

1b, 2c, 3a, 4d

Question 16

If NMDAR antagonists were infused into hippocampus during the training trials, what would happen to the rodent in the Morris water maze?

Answer 16

There would be NO learning of platform location.

Question 17

If NMDAR antagonists were infused into hippocampus during the “probe for memory” trial, what would happen to the rodent in the Morris water maze?

Answer 17

There would be NORMAL memory of platform location.

Question 18

Injection of radioactive proline into one eye of a juvenile cat would reveal what about the anatomy of layer IV of the feline visual cortex?

Answer 18

Ocular dominance columns and that they are monocular.

Question 19

Briefly describe a physiological experiment that would confirm an anatomical response of injection of radioactive proline into one eye of a juvenile cat

Answer 19

Neuronal response seen when one eye is stimulated not the other.

Question 20

A newly identified Aplysia learning mutant “Homer” is unable to demonstrate sensitization of the gill withdrawal reflex. To determine the learning deficit that resides at the synapse between the siphon sensory neuron and the motor neuron, where would you place the stimulated electrode and the recording electrode?

Answer 20

Sensory neuron would hold the stimulated electrode. Motor neuron would hold the recording electrode.

Question 21

What stimulation would you give to an Aplysia learning mutant to demonstrate heterosynaptic depression?

Answer 21

Multiple tail shocks.

Question 22

You want to demonstrate that a single exposure to cocaine induced LTP in the medium spiny neurons of the striatium. How would you demonstrate that there are more AMPARs at the excitatory synapse from cortex to medium spiny neuron?

Answer 22

You could pharmacologically isolate AMPA component of EPSC and measure current OR you could apply AMPA and measure current.

Question 23

You want to demonstrate that a single exposure to cocaine induced LTP in the medium spiny neurons of the striatium. How would you demonstrate that these synapses are closer to the “ceiling” for synaptic strength after cocaine exposure?

Answer 23

They show larger response to low-frequency stimulation.

Question 24

Name one reason why the peripheral nervous system is more successful at recovering from nerve transection than the central nervous system.

Answer 24

(1) No glial scarring (2) Growth promoting factors (3) Good debris clearing.

Question 25

Make two comparisons between Broca’s and Wernicke’s aphasia.

Answer 25

Broca’s Aphasia: halting speech and “logical” comprehension. Wernicke’s Aphasia: fluid speech and “illogical” comprehension.

Question 26

What is the evidence to support the theory that the transition from c-fos (long form with short half-life) to Δfos (short form with long half-life) is involved in the development of addiction?

Answer 26

Over-expression of Δfos-b makes mice behave as if addicted. 1.) Hyper-locomotion/sensitized 2.) stronger place conditioning/prefernece.

Question 27

Describe the locations of the neuronal cell bodies in the pathway that transmits information from the dendrites of mechanosensory neurons to the skin of the S1 somatosensory cortex.

Answer 27

Neuron 1: dorsal root ganglion Neuron 2: medulla Neuron 3: thalamus (VPN)

Question 28

What is meant by “saturation” of a receptor cell’s response?

Answer 28

The maximum response that can be produced by intense stimulation.

Question 29

Name any sensory receptor mentioned in lecture that saturates at LOW intensities of stimulation.

Answer 29

Any of the following: rods, merkel discs, olfactory receptors, etc.,

Question 30

Explain why chili peppers can produce a burning, painful sensation.

Answer 30

1.) Capsaicin binds to a channel in the nociceptor 2.) The channel opens 3.) Cations enter and the nociceptor depolarizes 4.) Activity in this nociceptor is labeled by the CNS as indicating pain, so that is what we perceive.

Question 31

Describe the two general ways by which the central nervous system can control lower motorneuron activity to provide a contraction of appropriate strength.

Answer 31

Alter frequency of action potentials in motor units Alter type of motor units activated.

Question 32

A neuronal cell body has a voltage-gated sodium conductance and a leakage chloride conductance ONLY. Based on the ion concentrations in the cell, the equilibrium potential for sodium is +50 mV and the equilibrium potential for chloride is -60 mV. Draw the equivalent electrical circuit for this neuron.

Answer 32