Limbic Syndrome Flashcards
Etiology of Human Kluver Bucy
- post traumatic encephalopathy
- herpetic viral encephalitis
- anoxia
- subarachnoid hemorrhage
- Picks disease
- Alzheimers disease
- bilateral temporal infarction
- focus status epileptics
Limbic system
a group of interconnected cortical and subcortical structure dedicate to linking visceral states and emotion to cognition and behavior. Limbic structures are interposed between the hypothalamaus and neocortex
The limbic system is the site where
-the site where cortical information and hypothlamic impulses are integrated
Functions of limbic system
homestasis (autonomic regulation) , olfaction, memory, emotion
Papez’s circuit
cingulate leads to hippocampus leads to fornix leads to mammillary bodies leads to anterior thalamus
MacLean and the limbic system what did he add to papez circuit
-coined the term limbic system incorporating the ideas of Papez into a model of the limbic system that has remained largely unchanged
- parts of the hypothalamus
- septal areas
- orbitofrontal cortex
- nucleus accumbens
- Amgydala
Papez ciruit
cingulate to hippocampus to forniz to mammillary bodies to thalamus
outer core of the limbic system-cortical structures
cingulate gyrus, orbital frontal lobe, subcallosal area, parts of the temporal lobe (hippocampus, parahippocampal gyrus, uncus)
function of the cingulate cortex
- rostral-emotions and motor
- caudal-visual spatial and memory
- temporal (hippocampus, parahippocampus, entorhinal cortex)-memory
inner core-subbcortical components
- hypothalamus
- amgydala
- septum
Hypothalamus
-pleasure center, autonomic, endocrine integration, neurons project to the pituitary, maternal behavior, blood pressure, feeding, temperature regulation and immune response
amygdala
-“preservation of self” behaviors, emotion, social behavior, aggression and defense response, sexual behavior, affective significance of visual stimuli, affect of faces, affective regulation
Septum
“preservation of species” behaviors, sexual behavior, emotionality
What does the Fornix connect
hippocampus to the mammillary body,
also anterior thalamus, septal nuclei, nucleus accumbens
mammilothalamic tract connects what
originates in the maillary bodies and connects to the anterior thalamus
perforant path
- entorhinal cortex
- dentate (hippocampus0
Main afferent to the hippocampus
perforant path
main efferent of the hippocampus
fornix
anterior thalamic projections connect to
orbitofrontal and anterior cingulate gyrus
cingulum fibers run from amgydala to
parahippocampus to frontal lobe/cingulate
Uncinate fasciculus
connects the anterior part of the temporal lobe with the orbital and polar frontal cortex
What justifies the concept of the limbic system
- common physiologic and neurocheical properties
- intricate anatomic and mostly reciprocal connections
- common behavioral associations
- high density of cholinergic innervation and opiate receptors
- limbic system involved in memory (acetylcholine) and the perception of pain and pleasure (opiates)
- septal nuclei and nucleus basalis of Meynert provide cholinergic input for the brain (memory)
- mesocorticolimbic Dopamine system is critical for positive reinforcing brain mechanisms (drugs and pleasure)
hippocampal-diencephalic and parahippocampal- retrocplenial network
-memory and spatial orientation
temporal amygdala orbitofrontal network
integration of visceral sensation and emotion with semantic memory and behavior
medial default network
autobiographical memory
-introspection/self directed thinking
Human Kluver-Bucy syndrome symptoms
- increased oral activity
- hypersexuality- indiscriminate sexual advances
- hypermetamorphosis- attend and react to every visual stimulus within the visual field and compulsive handling of the object
- Placidity-flattened affect, lack of aggressive behavior or fear
- visual agnosis- loss of recognition of simple, familiar objects (eating utensils) or people
- Bulemia
Interictal personality in temporal lobe epilepsy Geschwind syndrome
- increased concern with philosophical, cosmic or religious issues
- altered sexual behavior (usually hyposexuality)
- hypergraphia- extensive writing that is typically religious or philosophical in nature such as diaries, poems, essays sermons
- viscosity- or a tendency towards interpersonal stickiness, difficulty in breaking off conversation
- progressive overinvestment of perception and thought with affective significance resulting in a bizarrely emotionalized concept of the world
Interictal personality is caused by
hyperconnection
Kluver-bucy syndrome is caused by
disconnection
Amygdala
- plays a major role in the integration of emotions, fear, and memory
- modulation and experience of emotional reactions
- lesions: tameness or reduced emotionality
- amygdala attributes affective significance to visual stimuli
- amygdala supports classical fear conditioning and plays a role in PTSD, a disorder characterized by inability to extinguish fear
- plays a major role in normal social interactions
amygdala and social interaction
- plays a critical role in normal social intereactions
- single cell recording studies show that the amount of activity is related to the amount of emotional significance and degree of ambiguity of a social interaction
- cells that respond selectively to faces in primates an humans
- involved in fear conditioning
frontal lobe syndromes
- orbital frontal
- frontal/convexity or dorsolateral
- medial frontal
orbital frontal
-disinhibited, tactless, bawdy, boastful, grandiose, restless, impulsive, inattentive, perserverative, tendency to dress carelessly and eat gluttonously
frontal/convexity or dorsolateral
-apathic, slow, demonstrating little initiative or spontaneity, responding in an automation like amnner, vacancy of expression
medial frontal
akinetic mutism, inert, speechless, with intact sleep wake cycles, “motionless mindless wakefulness” loss of drive to move or speak
Hippocampus is required for
- declarative memory: acquisition of facts and events
- hippocampal lesions lead to amnestic states
a hippocampal lesion leads to
amnesia
other causes of memory disorders other than a hippocampal or bilateral fornix lesion
- dementia
- head trauma
- stroke
- wernicke Korsakoff syndrome
wernicke korsakoff’s syndrome
- due to chronic alcoholism and nutritional deficiency (thiamine)
- acute state is wernicke’s encephalopathy: confusion, disorientation, oculomotor dysfunction, ataxia
- chronic anterograde and temporally-graded retrograde amnesia
- lesions are in mamillary bodies and thalamus
Septal region
- stimulation leads to increase in sexual drive of rats as measured by crossings of an electrical grid to a sex incentive
- humans-two cases of markedly increased sexual activity following septal damage sustained in the course of placement of VP shunts. shunt tips penetrated the dorsal septal region
brain centers for pleasure, pain and punsihment
- old and Milner implanted an electrode into the hypothalamic and septal regions of a rat and found that rats would forfeit food and water, forget about sex and even accept pain for an opportunity to self stimulate
- catecholamines and dopaminergic systems are implicated in location of effective self-stimulation
- lateral septal regions
- lateral hypothalamus
- medial forebrain bundle
- nucleus accumbens
Addictive drugs
- mesolimbic dopamine system is important for motivational processes
- some addictive drugs produce their potent effects on behavior by enhancing mesolimbic dopamine activity
- heroin increases the neuronal firing rate of dopamine cells
- cocaine inhibits the reuptake of dopamine
Posterior cingulate
-visulospatial and memory functions
anterior cingulate lesion leads to
contralateral neglect (hemi-neglect)
Cingulate gyrus is associated with 5 things what are they
- Tourette’s syndrome
- Obsessive Compulsive disorder
- Chronic pain
- Sociopathy
- Akintic mutism
Tourette’s Syndrome
- abnormalities in the Anterior Cingulate because of its role in affective vocalizations
- complex coordinated movement patterns are evoked by electrical stimulation of the AC
OCD
-cingulotomy has been used to successfully treat severe OCD
Chronic pain
- cingulotomy patients are no longer being bothered by pan
- can withdraw from narcotics with little sign of withdrawal
sociopathy
sociopathic individuals who show blunted autonomic response to emotional stimuli
akinetic mutism-syndrome most commonly associated with bilateral anterior cingulate cortex lesion
anterior cingulate
integration of thought, motivation and emotion with movement are critical aspects of the cingulate function
- Excessive amplification of emotional signals
* anxiety
* OCD - Amplification of motor behavior
* tics
* impulsive behavior
- Excessive filtering of emotions and motor behavior
* apathy
* akinesis
* mutism
