Limbic Cortex Flashcards
Hippocampal lesion prevents the conversion to memories resulting in _________
anterograde amnesia
Bilateral hippocampal formation lesion seen in _____________
heart attack, near downing, severe hypoglycemia, or cerebral ischemia
What is the most vulnerable location in the hippocampal formation to anoxia?
CA1 (Sommer sector, in pathologic conditions)
Alzheimer disease (AD) is characterized by…
Presence of neurofibrillary tangles, neuritis plaques, and specific brain region neuronal loss
In AD, what are the first places affected?
Subiculum and entorhinal cortex –> impede relay of information through hippocampus
What is declarative memory loss?
Poor recall or incorporation of new memories
Divided into semantic and episodic memory (fact/concepts, events/experiences)
AD progresses to …
long-term memory impairment and behavioral changes
Why is the procedural or implicit memory spared in AD?
(motor skills for performing tasks)
Basal ganglia and cerebellum are spared
Prolong thiamine deficiency is often seen in cases of…
Korsakoff psychosis
chronic alcoholism, cancer cachexia, or any prolonged state of malnutrition; causes a characteristic pattern of degeneration
- degradation of mammillary bodies, dorsomedial nucleus of the thalamus, and the columns of the fornix
- also a loss of neurons in the hippocampal formation
Symptoms of Korsakoff psychosis (alcoholic dementia) are:
- defect in short-term memory and consequently also in long-term memory for events occurring since the onset of the disease
- anterograde and retrograde amnesia
- appear demented
- prone to confabulation
This is IRREVERSIBLE
What is Wernicke encephalopathy?
An acute thiamine deficiency
- triad of eye movement abnormalities (ophthalmoplegia), ataxia, and confusion
REVERSIBLE with thiamine administration
What is Wernicke-Korsakoff syndrome?
A severe case where patients may present with the Wernicke triad accompanied by profound memory loss
Which nucleus is associated with addiction?
Nucleus accumbens
Aversion center stimulation –>
Fear, sorrow
Gratification center stimuation –>
Pleasure
The hippocampus and amygdala have an abundance of _______; the nucleus accumbens has an abundance of _______
aversion centers; gratification centers
Large lesions in the amygdala, hippocampus, fornix, or cingulate or prefrontal cortex lead to… (very generally)
flattening of emotions (as reflected by the fact that emotional extremes, like joy and anxiety are reduced)
- due to the loss of both aversion and gratification centers
Bilateral lesion to the anterior part of the cingulate gyrus causes…
Akinetic mutism; diminished emotional responses of patient
- potentially leading to immobility, muteness, and unresponsiveness (but NOT in coma)
Some people with cingulate damage may be alert but …
with no idea who they are or be unable to recall order of past events; may also be unable to recall the order in which past events occurred
What is Kluver-Bucy Syndrome?
Bilateral temporal lobe lesion (specifically amygdaloid complex)
Symptoms of Kluver-Bucy Sydrome?
- memory deficit (from lesion to BOTH hippocampus and amygdala)
- visual agnosia
- possibly tactile/auditory agnosia
- hyperorality (tendency to examine objects excessively by mouth) or smell objects
- hypermetamorphosis (compulsion to intensively explore the immediate environment)
- overreaction to visual stimuli
- placidity (no longer show fear/anger)
- hyperphagia (eat excessively, or objects that are not food)
- hypersexuality
- additional symptoms are amnesia, dementia, aphasia (all depending on the extent of temporal lobe damage)
What is the most common cause for complex partial seizures?
Damage to mesial temporal lobe (mesial temporal sclerosis)
What is a complex partial seizure?
Seizure that starts in a specific area of the brain, resulting in a wide range of physical and emotional behaviors with alteration of consciousness. Partial seizures are often associated with a warning or an aura.
Seizures starting in the uncus may be associated with uncinate fits, which are:
olfactory or gustatory hallucinations
Seizures starting in areas of the limbic system may be associated with:
- uncinate fits
- visual illusions
- sensations of impending doom
- déjà vu (unfamiliar seems familiar),
- jamais vu (familiar seems unfamiliar)
- autonomic disturbances
Temporal lobes can be damaged by:
HSV encephalitis, trauma, hypoxia
Some symptoms of HSV encephalitis?
high fever, confusion, personality changes, seizures; hemorrhage/necrosis of temporal lobes –> inability to form new memories
What is epilepsy?
Recurrent seizure activity
Related to malfunction of hippocampus
_____ is most resistant to seizure activity, _____ are most vulnerable
CA2; CA4 and Sommer sector
Poorly-controlled seizures can lead to…
memory impairment and emotional problems
Layers in the dentate gyrus:
granular, polymorphic, molecular
Layers in the rest of the hippocampus:
polymorphic, pyramidal, molecular
What is a Duchenne versus Pyramidal smile?
Smiling muscles affected by limbic system vs. the voluntary pyramidal tract
