Essay question (5 points each)
1. Choose and compare three different types of Golgi type II cells and compare them. The more similar the cells
you choose, the less credit you will receive.
Amacrine cells are small type II cells confined to he retinal interplexiform layer; they are devoid of axons and their
processes project laterally, linking bipolar cells with specific types of ganglion cells, and they consist of many
neurochemical subvarieties. Thalamic type II cells are GABAergic, and often have a secondary non-Cl- and slower
second transmitter; they provide local inhibition to thalamocortical cells, including contributions to center-surround
RFs. Cerebellar granule cells use glutamate as a transmitter and provide feedforward excitation via their T-shaped
parallel fibers onto the intermediate and distal dendrites of Purkinje cells. The range n size, shape, and functional
organization of these subtypes captures te diversity of type II cells.
2. Compare the effects of amyotrophic lateral sclerosis, Tay-Sachs disease, and Huntington’s disease.
ALS is a disease of axonal dystrophy in which the axoplasm of corticospinal neurons is vacated by pathological
processes, causing loss of power and precision in voluntary movement. It has a non-Mendelian pattern of
transmission and afflicts primarily males in their thirties. Tay-Sachs is a sex-linked (male) malady of metabolic
lysosomal storage that has catastrophic effects on all descending neurons in childhood and early a adolescence and is
lethal, causing muscular incoordination; it afflicts preferentially those of Sephardic extraction. Huntington’s disease
also mainly afflicts males in their 40s and its symptoms are involuntary, repetitive movements of limb or trunk that
are repetitive, stereotyped, and reflects a deficit on chromosome 4. In none of the ailments is their a satisfactory
therapy.
3. What are the several targets of the spinothalamic system, and why are they important functionally?
The first synapse of the ST tract is in the superficial or deep dorsal horn; the former is paleospinothalamic, and
decussates to form the spinothalamic lemniscus which terminates in the central gray and reticular formation. The
CG ending activates the raphespinal system for descending pain control, and continues rostralward to the
hypothalamus, where it influences respiration, heart rate, gastric motility, and neurosecretion of stress-related
hormones. Input to the reticular formation elicits changes in arousal through the reticulothalamocortical system,
changes in EEG, and re-directs attention to the site of trauma. The neospinothalamic tract targets he posterior
thalamus and projects widely from there to the thalamic intralaminar nuclei and to the cortex, where the nature and
quality of pain are evaluated and descending projections to the hypothalamus and amygdala have global effects on
arousal and longer-term responses.
4. What different effect in the cerebellum does information ascending in the spinocerebellar pathway have with that
in the spinoolivocerebellar pathway?
The SC pathway sends subconscious information from skin (e.g., Meissner and Merkel), joints (Ib), and muscle (Ia)
receptors as mossy fibers to the distal dendrites of Purkinje cells, where they generate simple spikes of uniform
amplitude and duration through mossy fibers. This SC data feedforward to the deep cerebellar nuclei, red nucleus,
and VA/VL odor thalamus and finally reaches premotor cortex to provide feedback from ongoing movement for
subsequent motor planning. The SOC pathway is unique in that any Purkinje cells receives just one or a few
climbing fibers from SOC cells, and these ramify along the soma and main dendritic trunk of the Purkinje cell, here
they elicit complex spikes of graded amplitude and duration. The former are thought to be crucial for monitoring
learned motor behaviors, while the complex spikes are brief and seem to be critical in the acquisition and mastery of
new and novel motor tasks.
5. Distinguish between the functional roles played by Ia and Ib circuitry in spinal function.
The Ia circuit uses the muscle spindle to control all homonymous (~300) motoneurons about a joint, activating the
agonist and synergists and inhibiting the antagonist by integrating the input from one length receptor/muscle into a
single executive command. In contrast, the many Ib Golgi tendon organs are sensitive to the rate of change inn the
tension of muscle fibers, and hence are arranged in parallel rows to the muscle’s long axis. Second, all their central
connections are via interneurons: through excitatory type II cells to their agonist and synergists, and inhibitory
interneurons to their antagonists. Ia commands regulate muscle length, I commands influence tone; they cooperate
such that when length s reduced (and the Ia spindle concomitantly unloaded) the Ib system ‘fills in’ the ‘missing Ia
input, thereby maintaining tension in an otherwise partially deafferented muscle. at the systems are complementary
and integrative in their influences.
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6. Identify the subdivisions of the trigeminal nerve and describe their specific functions.
The spinal nucleus of V has an inverted representation of the head and sends coarse touch and nociceptive
information to the central gray, reticular formation and posterior thalamus. The mesencephalic nucleus is
proprioceptive for bite force, with pressure receptors in the tooth beds and their ganglion cells beside the central
gray, to which hey project as well as to the trigeminal jaw extensors to reduce bite force when unanticipated
resistance is encountered. The main sensory nucleus has its semilunar/Gasserian ganglion beside the brain stem and
is functionally analogous to the dorsal column system, terminating somatopically in the main sensory nucleus of V,
with RFs scaled in a like fashion to the body, e.g., lips and tongue corresponding to fingertips, back of head to back
of body in size, shape, and conduction velocity. The motor nucleus of V contains  and  motoneurons whose
functions are analogous to cells in the spinal ventral horn and which represent the final common pathway to the
muscles of mastication.
7. What behavioral and perceptual roles does the superior colliculus play?
The SC is part of a massive neurobehavioral network that participates in multisensory integration, in the initiation of
eye movements as in saccades, and in the behavior of toward ‘where’ related components of the extrastriate visual
system. In mammals it has three main layers and many sublayers. The superficial layer receives retinal input that is
organized topographically, with the fovea on the midline and extrafoveal visual field subdivisions progressively
more laterally. Likewise, the intermediate layers contain multisensory regions devoted to audition and somatic
sensation, and these are also arranged topographically, with proximal auditory regions and central body parts
medially; thus a vocalizing bird in flight elicits a series of responses located medially, while lateral-lying events are
represented more peripherally. The output cells of the deep layers constitute the tectospinal tract, which
coordinates head, eye, and neck movements. Further ascending projections reach the pulvinar, which projects to SC
reciprocally to enable eye movements and itself contributes to visual tracking in saccadic and smooth pursuit
movements whose accuracy requires intermodality coordination.
8. Draw a diagram of the organization of the visual cortex, showing its inputs, outputs, layers, and physiological
organization.
Primary visual cortex
INPUTS
1. From thalamic P/X/ ganglion cells and terminating in layer IVc as part of the form pathway
2. From thalamic M/Y/ ganglion cells and terminating in layer IVc as part of the motion pathway
3. Locus coeruleus and terminating in all layers (noradrenergic): for regulating tonic output
4. Dorsal raphe and terminating in all layers (serotinergic): for regulating tonic output
5. Nucleus basalis and terminating in all layers (cholinergic): for regulating tonic output
6. Corticocortical input ending mainly in layers I-III for interhemispheric monocular processing
7. Commissural and ending in layers III and V for coordinating global perceptual vision
OUTPUTS
1. Feedforward projections to VII, areas MT, MST for higher order motion processing
2. Connections with posterior parietal fields for movement in extrapersonal space
3. Intralaminar outputs for the local analysis of orientation selectivity
4. Vertical intrinsic projections for the analysis of columnar interactions in cortex
5. Formation of thin- and thick-stripe domains for higher order motion processing
6. Corticothalamic arising from layer VI to gate and regulate thalamic output
7. Corticopontine from layer V to influence the visuocerebellum
8. Corticostriatal from layer V to influence movement initiation in the nigrostriatothalamic system
9. Contrast the roles of the hypothalamus and amygdala in the control of smooth muscle and behavior.
Both the amygdala and hypothalamus are part of Papez’ circuit, and thus key players in emotion, sexuality, feeding,
territorial, and social behavior. They differ in that the hypothalamus receives direct afferent information relevant to
organismal state: blood pressure, blood temperature, dissolved fat, sugar, and other afferent streams ascend
polysynaptically to reach specific subdivisions of the hypothalamus which in turn can affect visceral, sexual,
autonomic, and appetitive behavior. Damage to it results in severe and specific deficits in these spheres which
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normally cannot be regulated by other structures. The hypothalamus, from a neurosecretory perspective, has direct
access to the mammary gland, kidney, viscera, and blood vessels, to mention just a few of its targets which are under
either neural or humoral control or some combination of these. The amygdala, in contrast, has no direct input
(except olfaction) from primary sensory modalities, and it has few direct contacts with visceromotor centers.
Rather, because of its extensive input from olfactory and auditory and other sensory centers, it integrates the input
from several modalities and then conveys these influences to the hypothalamus, which it affects profoundly.
Amygdalectomized animals are passive, often asexual, lose their dominance in the social hierarchy, and show severe
personality changes. In contrast, animals with large hypothalamic animals are unable to autoregulate the most basic
autonomic processes, and large lesions of this system are incompatible with life. The amygdala has a critical role in
the formation of conditioned responses to sound via a direct interaction with the auditory system via the medial
geniculate body.
10. Contrast the behavioral effects of lesions to the lateral versus the ventromedial hypothalamus.
Damage to the lateral hypothalamus often results in hypophagia, a condition in which food once-palatable is refused
and inanition follows. The animal becomes, at best, a finicky eater discouraged from eating by any contact with an
unappetizing foodstuff, such as a bit of pepper on an otherwise once-relished food. It has extensive
intrahypothalamic connections with the ventromedial nucleus, in which overactivity culminates in severe overeating,
even of foodstuffs that are less appetizing than they might ordinarily be. One hypothesis contributing to
understanding the lateral hypothalamic syndrome is hay damage to the associated trigeminothalamic fibers passing
nearby towards the ventroposteromedial nucleus might partially denervate the face or damage the ascending solitary
nucleus fibers ascending to the gustatory thalamus, thus leading to what amounts to neglect of foodstuffs.
11. What is Papez circuit, and what is its importance for thinking about limbic function?
Papez's circuit is both descriptive and analytic, though not equally powerful in these roles. It is descriptive in that it
uses a set of experimentally verified, logical relations between the cerebral cortex, the autonomic cortex, the
amygdala, the hypothalamus, and the hippocampus, to predict specific behaviors and to account for the effects of
particular lesions. A descriptive theory aligns data and structures and experimental observations, and infers causal
relations but cannot specify the nature of that causality. A more powerful, analytic theory that is better developed
than limbic system operations is the vesicular theory of neurotransmitter release, whereby the transmitter can be
visualized in the presynaptic axon terminals, the postsynaptic receptors can be identified, and the process of
transmitter release can be captured by specialized methods designed to reveal exocytotic events. While Papez's
circuit predicts what will happen after amygdalectomy and after amygdaloid stimulation, it is unable to explain why,
at a cellular level, these events occur. Thus, while it has some analytic features, it cannot as a rule account for causal
relations and hence is weaker than theories like exocytosis.
12. How do visceral and autonomic influences from the hypothalamus affect brain stem nuclei?
There are many routes by which hypothalamic influences can reach remote brain structures. Among the major fiber
tracts are the medial forebrain bundle, which carries information bidirectionally between the caudal and ventral brain
stem and hypothalamus, while the dorsal longitudinal fasciculus conveys nociceptive information rostrally from the
central gray to the hypothalamus and from the hypothalamus caudally towards the central gray and associated
medullary targets, including the raphespinal system. A second route for hypothalamus influence is neuroendocrine,
of which several subvarieties exist. One is direct secretion of oxytocin or vasopressin into the circulation via the
long portal vessels. A second subroute involves the fenestrated capillaries of the median eminence, which then
redistribute specific hormones to particular targets, or cause releasing factors to exert their actions. In its broadest
form, neurosecretion can act direct on structures (e.g., glomerular complexes in the kidney far from the hypothalamic
origin of the secretogen), or it might act to elicit the secretion of follicle-simulating hormone from cell groups in the
local hypophysial system. Finally, it can respond to local chemicals (e.g., pyrogens) or blood temperature (within
local vessels to elicit sweating or shivering, respectively through neuroendocrine interactions.
13. Describe Chomsky’s theory of language acquisition and evaluate it critically.
Chomsky proposed that there are innate (but unspecified) neural mechanisms in the human brain whose ontogenetic
expression was primed by and required early exposure to language. These mechanisms are latent developmentally
and consist of grammar-recognition (essentially pattern analysis) tools and word memory circuits for the acquisition
of vocabulary. Once exposure occurs, the child can acquire and derive the linguistic rules for sentence construction
and for the derivation of meaning. The major difficulty with the theory is that it cannot be directly tested except by
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reference to feral children, of which the few available published reports indicate that the failure to achieve linguistic
competence is marked in humans whose language experience is severely restricted during the first 5 years of life,
which suggests that there is a critical period for early acquisition of competence. Attempts to test the theory with
reference to primate and bird communication signals indeed supports the hypothesis that there is a critical
developmental window for acquisition, but sheds little light on the mechanisms which underlie these processes.
Thus, like Hubel and Wiesel’s proposal that binocularity in VI is achieved by convergence of left- and right-eyed
layer IV ocular dominance column neurons above and below layer IV, this idea awaits experimental analysis and
verification.
14. Contrast the roles of the direct and indirect basal ganglia pathways on motor behavior.
The basal ganglia have a key role in organizing motor behavior. The direct pathway facilitates movement in the
striatonigrothalamocortical pathway by ultimately disinhibiting VA/VL thalamic neurons and facilitating
transmission to premotor cortex; this involves d1 receptors whose postsynaptic effects are facilitatory. In contrast,
the indirect pathway engages the subthalamic nucleus, which adds an excitatory input which normally facilitates
inhibition in the thalamocortical loop and decreases movement; this involves d2 receptors such that the nigrostriatally
released dopamine effectively blocks the thalamocortical excitation elicited in the facilitatory pathway. Normally,
the direct and indirect pathways have an interplay which contributes to the smooth execution of movement and its
equally smooth inhibition. Lesions to the nigra or the pallidum (chemical or genetic) that impair the initiation of
movement can be ameliorated by surgical intervention. Both pathways integrate cortical influence, directly via
corticostriatal input and indirectly via corticopontocerebellar connections.
15. Write a descriptive essay on the life history of a neuron’s development, from birth to maturity.
As the neural tube closes it is transformed by various molecular factors to initiate a long period of neuronal birth and
proliferation. This event occurs in the ventricular zone, a special proliferative area, that forms about the closed
lumen of the tube. At each level—hindbrain, midbrain, or forebrain—neuroblasts emerge from their progenitors in
the wall of the tube. Thus, motoneurons that make up the hypoglossal motor nucleus are born in a wave of cell
division in the hindbrain in the basal plate, then migrate to their presumptive adult location where further
development and differentiation of the nucleus takes place. For the hypothalamic neurons, the ventricular zone in the
vicinity of the third ventricle would be the origin for these cells, while cerebral cortex cells arise in the walls of the
lateral ventricles. For the forebrain a subventricular zone also contributes in which some neuroblasts can withdraw
from DNA synthesis to give rise to certain classes of glial cells and some neurons. Various molecules such as glial
growth factor regulate the number of glial cells that develop so that there is an appropriate balance between
peripheral Schwann cells and ganglion cells. Neuroblast migration may follow one of two strategies. Radial glia
whose endfeet span the internal and external surfaces of the tube can act as guideposts to allow neurons to migrate
accurately from zone of origin to final target. Alternatively, in regions devoid of radial glia, free amoeboid
perikaryal translocation allows neurons considerable migratory freedom as they are presumed to follow chemical
gradients toward their appropriate target nuclei. As they reach their terminal zone they traverse neuroblasts in an
inside-out pattern, such that the earliest to arrive take up what will be the deepest cortical layers first. Later-arriving
neuroblasts must migrate through these to establish subsequent layers. Thus, the sheets of arriving neurons are added
a layer at a time, suggesting that the cells in specific layers can recognize one another. The postmigratory neuroblast
arrives at its presumptive target, probably as a result of chemical and genetic cues that interact to direct it. After
arrival, the neurites begin the process of local differentiation into axon and dendrites; the former is unique and the
only process to myelinate, the latter are multiple and initially smooth but later develop spines along their surface
which become postsynaptic. Next, the neuron’s axon sprouts a growth cone, which seeks an appropriate synaptic
target, either locally or remotely. The axon may make numerous contacts that prove inaccurate or inappropriate;
these may be reduced through cell death, programmed or experience-related, or by activity-driven processes in preand postsynaptic sites. The cell finally establishes, and receives, a normal constellation of synaptic inputs. In
maturity and old age, the cell refines these synapses based on learning-induced plasticity, and in old age, axons and
dendrites are lost and the neuropil volume decreases.
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Matching (1 point each)
f
b
i
g
j
h
a
d
e
c
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
radial glia
periglomerular
CCK
fear conditioning d.
amacrine
crest
paleocortex
dentate nucleus h.
bipolar
intermediate zone j.
a.
olfactory
b.
inhibition
c.
future white matter
motor planning
e.
ON or OFF
f.
migration
g.
amygdala and MGB
ganglion cell
i.
visceral motility
axonless
Multiple choice (2 points each)
__E___26. SI consists of
(A) Areas 3c, 6π, 17, and 9.
(B) Input from Pacinian corpuscles segregated in layer II and from Merkel’s discs in layer IV; above and
below they combine to become multisensory.
(C) At least seven representations of the ipsilateral palm and three of the contralateral digits, in which thick
slowly adapting strips alternate with thin rapidly adapting ones.
(D) Seven separate representations of the body, each of which receives critical feedback from SII for
texture discrimination.
(E) None of the above.
__E___ 27. Schwann cells
(A) Are derived from neurons that withdrew from the cycle of cell division.
(B) Have a phagocytic role after axonal lesions and interact with tubulin, which induces their neurites to
extend and to secrete NGF.
(C) Form the epineurium but not the perineurium in mature cells.
(D) Can be transfected into shiverer mice to induce hypermyelination.
(E) None of the above.
__C__28. Slowly adapting mechanoreceptors
(A) Form thick columns in primate SI across which different types of mechanoreceptors form local circuits.
(B) Form layers in the ventrobasal complex of equal thickness to those for rapidly adapting
mechanoreceptors.
(C) In primates form thin columns in SI alternating with thick columns for rapidly adapting
mechanoreceptors.
(D) Saturate at frequencies above 5 Hz so that the animal perceives such input as vibrations.
(E) None of the above.
__B___29. Glomeruli are
(A) Found in the hypothalamus and mediate neurosecretion through large vesicles.
(B) Found in the cerebellum and olfactory bulb, where they are surrounded by a glial covering.
(C) Specialized regions in the cerebral cortex where perceptual decisions for across fiber processing are
made.
(D) The zone of transition between the central and the peripheral nervous system, separated by Schwann
cells and oligodendroglia, respectively.
(E) None of the above.
__B___30. Corticopontocerebellar and spinocerebellar input
(A) Enter through the inferior peduncle and terminates as end bulbs.
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(B) Terminate as mossy fibers exclusively.
(C) Forms calyces of Held which make delicate axodendritic endings in synaptic glomeruli that provide
phasic control of Purkinje cell excitability.
(D) Decussate in the middle cerebellar peduncle, enter the red nucleus, decussate again, and then project
somatotopically through the entire cerebellar cortex as parallel fibers.
(E) None of the above.
__E___31. Ib interneurons can be
(A) Excited by GABAergic Renshaw cells.
(B) Excited by nociceptive afferents acting presynaptically onto primary afferents.
(C) Disinhibited by Renshaw cells.
(D) Autogenetically excited by contralateral intrafusal fibers acting phasically.
(E) None of the above.
__E___32. Limb rigidity and spasticity after cortical lesions are probably caused by
(A) Hyperfacilitation of tonically active extrafusal Ia endings.
(B) Hypoactivity in Ib phasic fibers that ‘fill out’ when intrafusal fibers are deafferented.
(C) Demyelination in the corticospinal tract that tonically excites group IV afferents and phasically drives
muscle into hyperactivity.
(D) Bilateral projections from the hypothalamus and raphespinal tract that occupy terminal sites vacated by
the cortex and become dyskinetic.
(E) None of the above.
__E___33. The Edinger-Westphal nucleus
(A) Projects to the cervical sympathetic ganglion for the regulation of medial rectus tone.
(B) Terminates in the geniculate ganglion and is responsible for ipsilateral salivation and for ‘crocodile’
tears.
(C) Projects to the superior colliculus where it instructs the tectospinal tracts in the deep layers to direct the
eyes into the contralateral visual field.
(D) Contains preganglionic sympathetic fibers that project to the sympathetic chain ganglia and which then
re-ascend to terminate with the pupillodilator muscles.
(E) None of the above.
__A___34. Gustation involves ganglia associated with the
(A) Seventh, ninth, and tenth cranial nerves.
(B) First, fifth, and twelfth cranial nerves.
(C) Ciliary nerve, the ipsilateral tensor tympani, and the autonomic outflow through the unsympathetic
chain ganglia.
(D) Sharp tuning for salty, sweet, bitter, and umami in the dorsal nucleus of the vagus.
(E) None of the above.
__C___35. The mesencephalic nucleus of V
(A) Lies at spinal level C2 where it can carry bite velocity information to ganglion cells in the trigeminal
ganglion.
(B) Lies next to the medial longitudinal fasciculus and carries proprioceptive information about bite
strength to the facial motor nucleus.
(C) Lies next to the central gray and carries proprioceptive input from Ib receptors to the trigeminal motor
nucleus.
(D) Is essential for normal smiling and is often damaged in cases of Bell’s palsy and polio.
(E) None of the above.
__C___36. The otolith organs are
(A) Affected only by acceleration and deceleration.
(B) Are only active tonically when the body moves against the action of gravity and resists counterrotation.
(C) Tonically active to the effects of gravity and phasically driven by vertical acceleration and deceleration.
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(D) Distributed uniformly throughout the semicircular canals with an inner phasic row and outer tonic row.
(E) None of the above.
__A___37. The vestibular system
(A) Operates such that one anterior canal and the ‘matching’ opposite posterior canal behave as a pair.
(B) Has a vestibulotopic projection to the lumbar spinal cord that is crossed and has rapid conduction
velocity.
(C) Has vestibulotopic projections only from the horizontal canals and which terminate mainly among the
leg and forelimb representations.
(D) Has no direct spinal projection and exerts most of its effects through the reticulospinal tracts and the
vetsibulospinal cortex.
(F) None of the above.
__E___38. Bushy cells
(A) Are non-spiking, generating only EPSPs.
(B) Fire repeatedly after stimulation, then discharge only tonically for the duration of the stimulus, like
octopus cells.
(C) Behave like Renshaw cells, and provide autogenetic inhibition to the ipsilateral medial superior olive.
(D) Are the source of the olivocochlear projection to the inner hair cells that regulates their length and
excitability.
(E) Have a few short dendrites and receive massive axosomatic synapses and represent stimulus
onset/offset events.
__D___39. The medial geniculate body has
(A) Connections with the central gray that are responsible for inhibiting the startle reflex through the
raphespinal tract.
(B) At least 8 tonotopic maps, all of which are complete representations of the ipsilateral cochlea.
(C) Thin and thick strips of neurons that represent sustained or intermittent sounds, just like slowly- and
rapidly-adapting mechanoreceptor columns in SI.
(D) Zones in which EE and EI neurons alternate across single frequencies within the tonotopic map.
(E) All of the above.
__E___40. The locus ceruleus
(A) Is an enormous nucleus with many thousands of neurons which project topographically only to primary
sensory areas.
(B) Lies next to the corticospinal tract and uses histamine as a transmitter and terminates in all motor
structures in the forebrain.
(C) Has just a few neurons and these project exclusively and with thick axons only to the motor nuclei of
the thalamus.
(D) Lies next to the seventh nerve and provides sympathetic input to the salivatory glands and to the
muscles of facial expression; is activated only in periods of intense emotion.
(E) None of the above.
__ E__41. The oculomotor nuclei
(A) Have no Ia receptors and are recruited on the basis of size, with large movements activating the
smallest motoneurons first.
(B) Are active in all eye movements, have no stretch reflexes, and have many muscle spindles.
(C) Are active only during voluntary eye movements; when unconscious, eye movements are controlled by
the mesencephalic reticular formation.
(D) Have minute stretch reflexes, like those for the middle ear, that withdraw the eye from possibly harmful
stimuli and protect it from possible damage.
(E) None of the above.
__A___42. Which of the following structures is not involved in saccadic eye movements?
(A) Middle temporal, medial superior temporal, and striate cortex.
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(B)
(C)
(D)
(E)
Dorsolateral pontine nucleus and vestibular nuclei.
Frontal lobes, inferior temporal cortex, and the subthalamic nucleus.
Striate cortex, and cerebellar flocculus and vermis.
None of the above.
__E___43. The sole normal disconjugate eye movements are
(A) Pupillary constriction mediated by Renfrew cells.
(B) Pupillary constriction and dilatation when they are voluntary.
(C) Exvergence.
(D) Intorsion.
(E) None of the above.
__E___44. Cones release neurotransmitter
(A) Onto only ON bipolar cells.
(B) Only onto ON and OFF bipolar cells.
(C) Onto only ganglion cells since preganglionic contacts within the retina are mediated only by gap
junctions.
(D) Onto ON rods, OFF cones, and all populations of amacrine cells.
(E) None of the above.
__E___45. A single layer in the lateral geniculate body has
(A) Mainly binocular neurons.
(B) Monocular and binocular neurons intermixed.
(C) Columns about 500 µm wide that run across the long axis in a single layer and represent left- or righteyes alternating, checker-board like fashion.
(D) Magnocellular input to its upper half and parvocellular input to its lower half.
(E) None of the above.
__E___46. The targets of M/Y/ß cells are mainly
(A) In layer IVc and in the superior colliculus.
(B) In layer V and in the Edinger-Westphal nucleus.
(C) In the pretectum and superior cervical ganglion, where they carry information
forward to the lacrimal nucleus for the control of tearing.
(D) In layers II and III where they contribute to orientation selectivity by terminating in
columns.
(E) None of the above.
__A___47. The most popular model of how complex cells in visual cortex work is
(A) That simple cells with similar receptive fields and orientations sensitivities converge selectively onto
complex cells to create classes of neurons with unique properties.
(B) That left- and right-eyed layer IV monocular neurons converge onto postsynaptic cells and that an
inhibitory interneuron (basket cell) creates sensitivity.
(C) That the interior, and never the edges or perimeters of receptive fields, form the dominant input to all
cells with more complex properties.
(D) That a computation process between centers and surrounds from neurons in creates a computational
map in which orientation selectivity emerges by connecting cells with the same orientation.
(E) None of the above.
__E___48. Blobs (pegs) are
(A) Orientation sensitive domains in VI (area 17) whose input arises mainly from VII.
(B) Ocular dominance-sensitive domains concentrated in layer IV in VI.
(C) Motion-sensitive domains about 3 mm wide and running across all layers in VI.
(D) Color sensitive domains in which orientation sensitivity is absent in layer IV in VI.
(E) None of the above.
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__E___49. The supporting, sustentacular, or basal cells in olfaction
(A) Respond to one and only one odor.
(B) Cannot replace aged or damaged primary receptors, just as receptors in other modalities are not
replaced after peripheral trauma.
(C) Have a kinocilium which, when displaced in one direction, inhibits the cell, and when displaced in the
opposite direction, excites it.
(D) Terminate their axons in the cribriform plate, where they contact granule cells and excite them to
convey odorants to olfactory thalamus.
(E) None of the above.
__A or E___50. One theory of the function of the vomeronasal organ is that
(A) It projects to hypothalamic regions involved in reproductive behavior and has a different scheme of G
protein-coupled transduction than the main olfactory bulb.
(B) It uses lipid-soluble agents to activate amygdaloid neurons involved in rage and territoriality to trigger
aggressive behavior.
(C) It has powerful input to the suprachiasmatic nucleus that influences seasonal migration due to the
concentration of airborne particles related to feeding and aggression, thereby influencing the accumulation
of fat stores.
(D) It is present only in non-human species where it regulates seasonal affective behaviors such as
migration, hibernation, and territoriality.
(E) None of the above.
__E___51. Taste buds responding to specific tastants are
(A) Distributed randomly across the tongue and pharynx.
(B) Organized in a sequence consistent with the size of amino acid residues rather than a purely gustotopic
organization.
(C) Concentrated with sweet receptors at the front of the tongue, salty at the ides, and bitter and sour
progressively further back.
(D) Organized in clusters about 1 mm wide, with each cluster containing the full range of all taste
receptors.
(E) None of the above.
__D___52. The nucleus solitarius has
(A) A role in loneliness.
(B) Has intermixed representations of taste and respiration.
(C) Has subregions segregated for taste and olfaction and has only ascending projections.
(D) Has segregated respiratory and gustatory subdivisions and projects to the spinal cord.
(E) None of the above.
__E___53. The insular cortex participates in
(A) Olfaction, olfactory seizures, and odors associated with reproductive reflexes.
(B) Taste, and in corticofugal projections to the gustatory subdivision of the ventrobasal complex, and
roles as upper autonomic motoneurons.
(C) Obsessive-compulsive behavior, Klüver-Bucy syndrome, rage, and territoriality.
(D) Olfaction through its projection from the vomeronasal organ, analysis of specific, sharply tuned taste
sensation analogous to small receptive fields on the fingertips.
(E) None of the above.
__E___54. Epilepsies can be caused by
(A) An excess of or by too few GABAergic neurons.
(B) Blunt trauma to the head, anoxia, or abnormal synchronization of neuronal discharge.
(C) Obsessive-compulsive disorders, dysmyelination, and Tourette’s syndrome.
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(D) Allergic reactions to certain odors or foods that trigger membrane changes to which the brain cannot
adjust and which the evoke paroxysmal; hyperpolarizing shifts analogous to the graded spikes of complex
fibers in the cerbellar cortex.
(E) A and B.
__E___55. The normal spontaneous discharge rate for unstimulated neocortical neurons
(A) Is approximately 40 spikes/second and is down-regulated by the powerful effects of autogenetic and
feedback inhibition.
(B) Is about 50 spikes/second and is driven most strongly by inputs to the ‘surround’ part of the receptive
field.
(C) Depends largely on whether basket cells (which have high rates of spontaneous discharge) or bipolar
cells (which have low rates of such discharge) dominate. In reality, there are low- and high-spontaneous
rate populations of cortical neurons.
(D) Is a reflection of the degree of resting potentials, the spontaneous discharge of the cell, and whether the
animal is unconscious (high rate) or conscious (low rate).
(E) None of the above.
__D___56. In a Jacksonian march
(A) The seizure recruits muscles on the basis of their size (small muscles first) and threshold (lowest
threshold first).
(B) The seizure begins bilaterally and is perfectly symmetrical once it is coordinated across the corpus
callosum by Renwick cells.
(C) The seizure is triggered often by an intense odor or a taste that is normally pleasant but which, because
of the increase in excitotoxicity, is more potent than normal.
(D) The tremors and muscle contractions are largely ipsilateral and follow the sequence of ipsilateral
connections within and between the areas of the motor cortex.
(E) None of the above.
__D___57. In the autonomic nervous system
(A) All organs have a dual parasympathetic and sympathetic innervation.
(B) In most organs the parasympathetic input is about twice as large as that of that of the sympathetic
projection.
(C) Parasympathetic ganglia lie at greater distances from their ultimate ‘synaptic’ targets.
(D) The superior cervical ganglion carries sympathetic impulses to pupillodilator muscles.
(E) None of the above.
__B___58. Dale’s principle would be most heavily violated by which of the following facts?
(A) That slow- and fast-acting transmitters are found in the autonomic system.
(B) That a given neuron might contain several different transmitter types, each acting specifically and
differentially on postsynaptic neurons.
(C) That an autonomic ganglion might contain interneurons that modulate the output of the postganglionic
neurons.
(D) That in spinally damaged humans the autonomic ganglia are often capable of a remarkable range of
complex behavior if synaptic contact between them and their ganglion cells and the associated receptors is
maintained.
(E) None of the above.
_ E _59. Peptidergic neurons in the posterior hypothalamus
(A) Can release oxytocin or vasopressin directly into the neurohypophysial vessels for fluid volume
control, and uterine contraction and milk ejection, respectively.
(B) Follicle stimulating hormone reaches the medial eminence where it directly enters the bloodstream and
promotes hair growth and joint repair and stability.
(C) Affect sham rage in decerebrated cats by freeing the hypothalamus from normal inhibitory cortical
control, facilitating rage reflex that normally are suppressed.
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(D) Can, through hyperactivity, cause dramatic changes in feeding behavior, leading to hyper- or
hypophagic animals without normal peptidergic control of gut hormones.
(E) None of the above.
__A___60. The connections between the hypothalamus and the brain stem include
(A) The periaqueductal gray and the nucleus ambiguus and the solitary nucleus and tract.
(B) The ventral motor nucleus of the vagus, the nucleus postpositus hypoglossi, and the mesencephalic
reticular formation.
(C) Superior colliculus, the brachium of the inferior colliculus, and the subthalamic nucleus and substantia
nigra.
(D) All of the above.
(E) None of the above.
__C___61. Brain stem transections behind the mammillary bodies in cats
(A) Produce a constant state of rage.
(B) Produce unconsciousness which can only be overcome by epinephrine administration.
(C) Produce sham rage and deficits in thermoregulation or feeding and social behaviors.
(D) Produce a modified form of Klüver-Bucy syndrome, in which the animals are hyperresponsive to oral
stimuli, sexually hyperactive, and unable to inhibit behaviorally inappropriate activities.
(E) None of the above.
__B___62. Patients with Wernicke’s aphasia often show
(A) Dysfluency, dysarthria, normal comprehension, and excellent repetition.
(B) Press of speech, poverty of comprehension, profound deficits in repetition.
(C) Impoverishment of spontaneous speech, poor comprehension, impaired repetition.
(D) Virtual absence of spontaneous speech, inability to comprehend or execute simple sequential
commands, and excellent repetition of simple speech.
(F) None of the above.
__E__63. The d1 receptor
(A) Normally facilitates voluntary movement and is under the control of the subthalamic nucleus.
(B) Acts chiefly on the oculomotor segment the basal ganglia–cortex loop and checks abnormalities in
saccadic and smooth pursuit movements via an error-correction circuits involving under- and overshoot of
saccades.
(C) Is released by the caudate nucleus and acts on limbic subdivisions of the basal ganglia.
(D) Is severely damaged, along with the d4 receptor in Parkinson’s disease, producing symptoms such as
inability to initiate movement as well as deficits in checking movement.
(E) None of the above.
__D___64. Which of the following are not progeny of the neural crest?
(A) Sensory neurons, parasympathetic neurons.
(B) Sympathetic neurons, Schwann cells.
(C) Smooth muscle, enteric neurons.
(D) All are progeny of the multipotent cell.
(E) None are progeny of the of the neural crest cell.
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