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Neurology Unit 4 - forebrain
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04/10/2013

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Term
Name and function of cortical layer II?
Definition
external granular layer - inputs from cortical (association?) affarent fibers
Term
Name and function of cortical layer III?
Definition
External pyramidal layer - output to cortical association areas and corpus callosum
Term
Name and function of cortical layer IV?
Definition
Internal granular - input from thalamus
Term
Name and function of cortical layer V?
Definition
Internal pyramidal - output to corticopsinal, corticobulbar, corticopontine, corticoreticular, corticostriatal tracts.
Term
Name and function of cortical layer VI
Definition
multiform - notable for cortico-thalamic cells.
Term
What major fiber bundle is the pathway between the thalamus and the cerebral cortex?
Definition
The internal capsule
Term
What is thalamic syndrome?
Definition
After brief contralateral anesthesia, sensations return, but are poorly localized and disagreeable
Term
What is the function of the ventral anterior thalamic nucleus?
Definition
Relay from motor selection system (g.p., s.n.) to premotor cortex (and some to prefrontal cortex)
Term
What is the function ventral lateral thalamic nucleus?
Definition
Relay from motor selection system (g.p., s.n., dentate nuc.) to primary motor cortex (and some to prefrontal cortex)
Term
What does the anterior thalamic nucleus connect with?
Definition
Limbic cortex/cingulate gyrus
Term
What does the pulvinar thalamic nucleus connect with?
Definition
Posterior multimodal assoc. cortices
Term
Name distinct sensory functions for Brodmann areas 3,1,2
Definition
3(a)=pain, 1= texture, 2= size/shape
Term
Where does the visual-spatial sketchpad seem to be located?
Definition
The parietal multimodal associaton area
Term
What is long-term potentiation?
Definition
Stimulating a neuron repeatedly gives higher response from a downstream neuron when future stimulus is applied to the upstream neuron.
Term
What is the significance of NMDA receptors to memory?
Definition
These are necessary for long-term potentiation. Blocking with APV blocks learning (though antagonizing NMDAR in elderly may actually help memory due to "leaky" receptors). These receptors are also used to "couple" two pieces of information in the learning process.
Term
How do NMDAR's function as members of a memory circuit?
Definition
They are couplers, consolidating two pieces of information into one piece of information (an "A and B" packet of info).
Term
What is the polysnaptic intrahippocampal pathway?
Definition
(perihippocampal gyrus) -> Entorhinal cortex II -> perforant pathway -> dentate gyrus -> CA3/4 -> CA1 -> subiculum -> fornix
Term
What is the direct intrahippocampal pathway?
Definition
(perirhinal cortex) ->Entorhinal cortex III -> CA1 -> subiculum
Term
What components of the brain are responsive for emotional stimulus identification/ affective state production?
Definition
Ventral system: amygdala, ventral anterior cingulate cortex, ventral prefrontal cortex, ventral striatum, anterior insula.
Term
What components of the brain are responsible for managing affective state?
Definition
dorsal system: hypothalamus, dorsal anterior cingulate cortex, dorsal prefrontal cortex
Term
What learning process will a lesion of the anterior cingulate cortex eliminate?
Definition
Conditioning
Term
Are amygdala emotional responses conscious or unconscious?
Definition
These are primary subcortical, subconscious responses (direct relay to thalamus)
Term
What lesion is part of Kluver-Bucy syndrome?
Definition
BILATERAL amygdala lesion (inability to learn emotional significance of events)
Term
What is the core emotional defect associated with orbital/medial PFC lesion?
Definition
Insensitivity to emotional consequence of one's own action. Lack of empathy.
Term
Besides upper motor neurons, what other type of fiber is included in the corticospinal tract?
Definition
Fibers from 1ary sensory cortex that modify sensory processing (synapse on spinal cord posterior horn neurons)
Term
What fibers are found in the anterior spinal tract?
Definition
Fibers that are uncrossed members of corticospinal.
Term
What will be a patient's posture if there is a supratentorial lesion that eliminates cortical control of the rubrospinal, vestibulospinal, and reticulospinal tracts? Will these pathways be activated or inhibited?
Definition
Lower extremities will be rigidly extended, and upper extremity (particularly proximal upper extremities) will be rigidly flexed. Each of the aforementioned pathways will be disinhibited.
Term
Which spinocerebellar tract enters cerebellum through the superior cerebellar peduncle?
Definition
The ventral spinocerebellar tract
Term
What is the thalamic relay target of the cerebellum? Of the  basal ganglia
Definition
Cerebellum targets ventral lateral, basal ganglia targets ventral anterior
Term
Do cerebellar + basal ganglia outflow target motor or premotor areas in the cortex?
Definition
Cerebellum -> motor (direct "fine tuning" of movement); Basal Ganglia -> premotor (motor program selection)
Term
What is the output neuron of the striatum?
Definition
Medium spiny neurons
Term
Which structures are the outflow components of the basal ganglia circuit?
Definition
Substantia nigra pars reticulata and globus pallidus interna
Term
Is the globus pallidus interna in tonic excitation or inhibition? Which upstream projections to GPI explain this?
Definition
Tonic excitation - the subthalamus is inherently tonically active, and stimulates the GPI, whereas the striatum is intermittently active, and inhibits the GPI.
Term
What neurotransmitter increases the activity of the indirect basal ganglia motor pathway and decreases that of the direct?
Definition
Acetylcholine, from intrinsic basal ganglia neurons
Term
Which enzyme is the rate-limiting step of dopamine synthesis?
Definition
Tyrosine hydroxylase
Term
Which cell is the primary source of input to purkinje cels?
Definition
Granular cells
Term
What the heck is disdiadichokinesia? What cerebellar lesion could cause this?
Definition
This is a lack of the ability to perform rapid alternating movements. Cerebellar hemisphere lesion can cause this (along with intention tremor and limb ataxia)
Term
What structure in the nasal olfactory mucosa secretes olfactant binding proteins?
Definition
bowmans glands
Term
What are the two cell types in the olfactory bulb that transmit excitatory olfactory signals down the olfactory tract?
Definition
Tufted and mitral cells
Term
What are the main projections of the lateral olfactory tract?
Definition
piriform cortex (=olfactory cortex), amygdala, entorhinal cortex->hippocampus, prefontal cortex, mediodorsal thalamus->frontal lobe
Term
Where is the gustatory cortex located?
Definition
Between the anterior insula and the frontal operculum
Term
What are the 1ary targets of taste neurons in caudal nucleus solitarius?
Definition
VPM of thalamus, amygdala
Term
What are the functions of the preoptic area (hypothalamus)?
Definition
GnRH secretion (medial preoptic nucleus) (also feeding, reproduction, locomotor, regulation of supraoptic nucleus in ADH release)
Term
What is the difference between the paraventricular hypothalamic nucleus and the periventricular hypothalamic nucleus?
Definition
The paraventricular nucleus is more lateral, and is involved in autonomics, releasing hormone secretion and direct neuroendocrine functions. The periventricular nucleus is midline and releases somatostatin.
Term
What is a primary function of the anterior hypothalamic nucleus?
Definition
Temperature regulation
Term
Which hypothalamic nuclei secret neuroendocrine hormones into the posterior pituitary?
Definition
The paraventricular and the supraoptic nuclei
Term
What is the name of the structures by which the amygdala communicates with the hypothalamus?
Definition
The stria terminals and ventral amygdalofugal pathway
Term
What are the symptoms/lesions associated w/ korsakov's syndrome?
Definition
lesion of lateral mamillary nucleus -> short term memory loss
Term
What is the function of the magnocellular neurons of the hypothalamus?
Definition
Neuroendocrine secretion into the posterior pituitary
Term
What circumventricular organs function as osmotic sensors?
Definition
The subfornical organ and the organum vasculosum of the lamina terminals
Term
What is the effect of hyperosmolar conditions on the  output signal of the SFO (subfornical organ) and OVLT (organum vasulosum of the lamina terminalis) to the MnPO (medial preoptic nucleus)?
Definition
Their output increases
Term
What is the function of the MnPO (median preoptic area)?
Definition
It compares the signals from OVLT (organum vascularum of the lamina terminalis) and SFO (subfornical organ) and stimulates the SON (supraoptic nucleus) if they are the same (increases ADH secretion)
Term
What is the significance of the medial forebrain bundle in the release of oxytocin?
Definition
Ascending affarent neurons pass through this structure as they deliver stimulus from nipples to supraoptic/paraventricular nuclei
Term
What neurohormones does the arcuate nucleus release?
Definition
GHRH and dopamine
Term
What neurohormones does the preoptic area release?
Definition
GnRH
Term
What neurohormones does the paraventricular nucleus release (including hormones released into either lobe of pituitary)
Definition
CRH, TRH, oxytocin, ADH
Term
What neurohormones does the anterior periventricular nucleus release?
Definition
SRIH (somatostatin)
Term
What are the parts of the brain that have allocortex? How many layers?
Definition
The hippocampus, entorhinal cortex, piriform cortex (primary olfactory cortex)
Term
What is distinctive about spindle neurons (phylogeny)?
Definition
They are only found in "advanced" mammals, and similarly are found only in particular parts of the human brain involved in social function (
Term
Name and function of cortical layer I?
Definition
molecular: receives modulation signals - from monoaminergic nuclei (eg dorsal raphe nuclei, ventral tegmental area) and interlaminar group of thalamic nuclei
Term
Cortex and thalamus engage in reciprocal communication. Which layer of cortex talks to thalamus?
Definition
Layer VI
Term
brodmann number for primary motor area?
Definition
4
Term
brodmann number for primary somatosensory area?
Definition
3,1,2 (rostral-> caudal)
Term
brodmann number for primary visual region (striate cortex)?
Definition
17
Term
brodmann number for visual association region?
Definition
18,19
Term
brodmann number for Wernicke's area?
Definition
22
Term
brodmann number for primary auditory region?
Definition
41,42
Term
brodmann number for broca's motor speech area?
Definition
44
Term
Where are the fibers that control facial muscles located as they descend through the internal capsule?
Definition
At the genu (along with other corticobulbar fibers)
Term
Which fibers are found in the anterior limb of the internal capsule?
Definition
Corticothalamic/thalamocortical fibers
Term
Which fibers are found in the posterior limb of the internal capsule?
Definition
corticospinal and somatosensory ascending sensory information, and parietalpontine fibers
Term
What fibers are found in the sublentiform and retrolentiform portions of the internal capsule?
Definition
Sublentiform: temporal lobe connections (auditory radiations, temperopontine fibers)
retrolentiform: occipital lobe connectors (optic radiations, occipitopontine fibers)
Term
Which two structures sandwich the reticular nucleus of the thalamus?
Definition
The external medullary lamina (thalamus) and the internal capsule (eg corticospinal and other tracts)
Term
which thalamic nucleus projects to limbic cortex?
Definition
anterior nucleus (NA)
Term
which thalamic nucleus projects to motor/premotor cortex?
Definition
ventral anterior
Term
What is the function of the dorsomedial thalamic nuclei?
Definition
Limbic - project to anterior multimodal association areas
Term
What is the function of the dorsimedial thalamic nucleus?
Definition
Projects to anterior multimodal association cortex
Term
Which thalamic nucleus has cortical input and regulates all other thalamic nuclei? What neurotransmitter does it use?
Definition
Reticular nucleus - GABAergic
Term
What is the function of the centrimedian and parafascicular nuclei?
Definition
These intralaminar group nuclei project to much of cortex to modulate sleep/wakefulness/sensory
Term
What is the name of the gross structure in the 1ary motor cortex to which the leg projects (as opposed to precentral gyrus).
Definition
paracentral lobule
Term
What is the function of Brodmann's areas 1 and 2?
Definition
1: texture discriminative
2: shape/size discrimination
Term
What brain structures are activated by pain?
Definition
SI and especially SII somatosensory areas, anterior cingulate cortex, insular cortex, and other areas.
Term
True or false: the spinothalamic tract neurons synapse in the thalamus in the same location as the DC/ML neurons?
Definition
Somewhat false - though they do synapse in VPL/VPM, they also synapse in mediodorsal, intralaminar, and posterior thalamic complex (includes pulvinar) nuclei. In general, the spinothalamic tract projects much more broadly than does the DC/ML tract.
Term
What are the differences between the ventral and dorsal processing streams?
Definition
Ventral = object recognition information Dorsal = motion/spatial information
Term
What are the terms for loss of language, memory, visuospatial skills, attention, or executive processing?
Definition
aphasia, agnosia, apraxia, neglect, dysexecutive syndromes
Term
What causes conduction aphasia? Symptoms?
Definition
Lesion of arcuate fasciculus
No trouble understanding, fairly fluent speech, difficulty repeating sounds.
Term
Which brain hemispheres pay attention to which visual world hemispheres?
Definition
The right brain pays attention to the whole visual world; the left brain pays attention to only the right visual world
Term
What are the functions of the supraoptic/paraventricular nuclei? Which portion of the hypothalamus are they located in?
Definition
These nuclei make vasopressin and oxytocin
Term
What is the primary function of the anterior nucleus (hypothalamus)?
Definition
Temp regulation
Term
What are the three functions of the paraventricular nucleus (hypothalamus)?
Definition
1) autonomic
2)Tuberoinfundibular tract
3) supraopticohypophyseal tract
Term
What are the hypothalamic nuclei that contribute to the supraopticohypophyseal tract?
Definition
The paraventricular and supraoptic nuclei
Term
What are the nuclei that contribute to the tubuloinfundibular tract?
Definition
The medial preoptic nucleus, the paraventricular nucleus, the suprachiasmatic nucleus, and the arcuate nucleus
Term
What emotion is associated with the dorsomedial nucleus (hypothalamus)?
Definition
aggressive emotional behavior
Term
What is the function of the ventromedial nucleus (hypothalamus)?
Definition
Satiety
Term
What is the main homeostatic function of the mamillary bodies?
Definition
Control of blood pressure
Term
Which portions of the hypothalamus does the posteriomedial group of perforating arteries supply?
Definition
The tubelar and mamillary regions
Term
Which structure sends information through the stria terminalis? The fornix? What is the other pathway that the amygdala uses?
Definition
The amygdala sends information through the stria terminalis, and the hippocampus sends information through the fornix. The amygdala also sends info to the hypothalamus via the ventral amygdalofugal pathway.
Term
What cortical structures stimulate the thalamo-hypothalamic tract?
Definition
prefrontal cortex and anterior cingulate gyrus
Term
What are the components of the Papez circuit?
Definition
Mamillary bodies -> mamillothalamic tract -> anterior thalamic nucleus -> cingulate gyrus -> hippocampus -> fornix -> mamillary bodies...
Term
What part of the amygdala communicates with the hypothalamus through the strium terminalis? Through the ventral amygdalofugal pathway?
Definition
Strium T. = corticomedial amygdala Ventral amygdolofugal = basolateral amygdala
Term
What is difference in function between orbital frontal cortex and lateral frontal cortex?
Definition
Orbital is involved in mood regulation, inhibition Lateral is involved in motivation, psychomotor initiation
Term
What fibers are found in the anterior limb of the internal capsule?
Definition
Frontopontine fibers, fibers connecting dorsomedial/anterior thalamic nuclei with frontal lobe/singulate gyrus
Term
What will be the appearance of limbs below the level of a spinal chord transection
Definition
Spastic (hypotonic?) paresis, in a "withdrawal" position
Term
What structures could be affected by a large acoustic neuroma of the pontomedullary angle?
Definition
Nerve roots of V, VII, VIII, IX, and X; also inferior cerebellar peduncle.
Term
What lesion causes "locked in" syndrome
Definition
Lesion of the (entire) ventral pons
Term
Is the rubrospinal tract crossed or uncrossed?
Definition
crossed
Term
What structures will an occlusion of the MCA lesion?
Definition
Primary motor and somatosensory cortices, internal capsule, visual radiations
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