Limbic System, Cerebral Cortex, Neuroembryology Flashcards Preview

Neuroscience I Test 3 > Limbic System, Cerebral Cortex, Neuroembryology > Flashcards

Flashcards in Limbic System, Cerebral Cortex, Neuroembryology Deck (46)
Loading flashcards...

reticular formation

-contrains the principal discharge pathways for the olfactory/limbic systems and the hypothalamus
-plays an important role as a mediator of somatic and visceral motor components of autonomic, emotional, and behavioral responses


components of emotional expression:

-hippocampus: memory recall
-neocortex: modify rxn
-hypothalamus: effector of emotional behavior


brainstem ascending reticular activating system

-glasgow coma scale
-level of consciousness

-sends info to intralaminar reticular nuclei-->cortex (EEG and cognition) and prefrontal cortex (Broca's, Prefrontal Lobe Syndrome)


septal areas

-pleasure (+), punishing (-)


olfactory input

goes straight to septal areas and amygdala


hypothalamic circuitry

-most of ascending input into the hypothalamus is from reticular formation
-most of descending influences are mediated by reticular formation


lesions of hypothalamus

-personality changes
-diabetes insipidus
-temp maintenance problems
-hormonal problems


Korsakoff's Syndrome

-bilateral destruction of mammillary bodies and dorsal medial nucleus of thalamus
-may result from long term alcoholism or pituitary tumors
-if pituitary tumor, may cause bitemporal hemianopsia
-primary deficit is impairment of recent memory
-pts report confabulation to fill the gaps in their memory


Paper Circuit

cortex-->entorhinal cortex of uncus-->hippocampus-->fornix-->mammillary body-->anterior nucleus of dorsal thalamus-->cingulate gyrus-->parahippocampus

olfactory input-->amygdala and hippocampus and septal area
-hippocampus and amygdala goes thru the stria terminalis to the septal area-->hypothalamus-->midbrain tegmentum


medial forebrain bundle

-interconnects septal area, hypothalamus, and midbrain tegmentum


primary olfactory cortex or pyriform lobe

-lateral olfactory gyrus
-amygdaloid nucleus and pariamygdaloid area
-entorhinal cortex: uncus and parahippocampus
-connects sensory info going over the cerebral cortex and puts it into memory


entorhinal cortex

-chief input into the hippocampus
-acts as a critical integrator and mediator of info to hippocampus
-cortical electrical impulses cascade over the surface in a spiral like pattern that converges on the entorhinal cortex
-important link in Paper memory circuit
-neocortical representation of external sensory world and a person's memory seem to merge in entorhinal cortex



-fibers from olfactory tract and pyriform cortex terminate here
-convey emotional and motivational component of odors--pheromones
-pivotal processing center for olfactory, somatosensory, viscerosensory, and emotional expressions
-relays info to the hypothalamus, dorsomedial thalamic nucleus, septal areas, or midbrain tegmentum



-refers to any defect in memory but most assoc with cases of severe and relatively isolated memory deficits like in Korsakoff's
-anterograde--unable to learn new material
-retrograde--is an inability to recall events from recent past


hippocampal amnesia

-bilateral lesions of hippocampus
-pts IQ and formal reasoning were normal but unable to master new facts, recognize new acquaintances, or adjust to new surroundings
-pyramidal cells of CA1 region of hippocampus are vulnerable to hypoxic or ischemic injury
-axons form the fimbria-fornix pathway and send recurrent collaterals to entorhinal cortex


olfactory hallucinations

-an imaginary, disagreeable odor, movements of lips and tongue, and dream state of consciousness
-sensations may be mildly pleasant or curious
-odors (hallucinations) may disturb the individual, and disrupt activities especially sleep


uncal herniation

-any unilateral lesion that inc the hemispheric volume is likely to cause herniation of uncus thru IPSILATERAL central notch
-compresses oculomotor N: pupillary dilation, external strabismus, and complete ptosis
-compresses abducens N: gaze is down and in
-compression of cerebral peduncle: pushes contralateral cerebral peduncle against shape edge of tentorium cerebella and spastic hemiplegia occurs on same side of ipsilateral lesion
-compression of PCA: contralateral incongruous homonymous hemianopsia with macular sparing


encephalization of sensory and motor system

sophisticated sensory and motor systems are dependent on cortical areas which could discriminate, analyze, interpret, and respond to specific stimuli
-upward shifting of fcns to cortex is encephalization


language and the cerebral cortex

-derivative of neocortical evolution
-development of brain for reception, comprehension, and expression


lateralization of cortex

-language underwent lateralization which was allowed by the corpus callous
-specific fcn residing in one hemisphere yet still share its info with other side


layers 1-2 of cerebral cortex

-form the most superficial layers of cortex
-layers play a role in important roles in assoc and higher cognitive fcns such as memory, interpretation of sensory input, and certain discriminative fcns


layers 3-4 of cerebral cortex

-receive most of afferents into cortex
-only 1% of these afferents are thalamocortical fibers
-remaining are corticocortical fibers


layers 5-6 of cerebral cortex

-innermost layers of cortex of cortex are source of efferents from cortex such as assoc fibers, commissural fibers, and projection fibers


superior longitudinal fasciculus (SLF)

-AKA arcuate fasciculus
-interconnects frontal, parietal, and occipital lobes
-critical link for language association areas
-lesions result in conduction aphasia
-fluent with minor word finding pauses and paraphasia, and can't repeat words or sentences
-comprehension and reading ability intact but writing has errors



-interconnects septal area, cingulate, parrahippocampal gyro to entorhinal cortex


uncinate fasciculus

interconnects base of assoc areas of frontal lobe to inferior temporal lobe


genu of internal capsule

-fibers: corticobulbar fibers
-lesion: supra nuclear facial palsy


posterior limb of internal capsule

-fibers: corticospinal fibers
-lesion: contralateral spastic hemiplegia

-fibers: somesthetic fibers
-lesion: contralateral hemianesthesia


retrolenticular of internal capsule

putamen and globus pallidus
-fibers: optic radiations
-lesion: contralateral homonymous hemianopsia


Brock's Aphasia

-nonfluent speech
-full comprehension
-right sided paralysis