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Flashcards in Limbic system Deck (19):

Describe the limbic system

- Brings together short-term memory and learning (hippocampus), expression of primal emotions such as fear and libido (amygdala), responses to odors (olfaction) and higher older modulatio of autonomic NS (hypothalamus)

- Related to behavior responses, both motor and visceral, appropriate to the sensory stimulus and cortical thought process

**Concered with memory, defense, and reproduction**


define the limbic structures

- Cingulate gyrus

- parahippocampal gyrus

- subcallosal gyrus

- hippocampus (memory)

- Amygdala (emotions)

- septal area/nuclei

- hypothalamus and uncus-olfactory cortex

**concerned with memory, defense and reproduction**


describe the olfactory input

- via medial and lateral stria from OLFACTORY TRACT/BULB

- Piriform lobe (UNCUS) considered primary olfactory cortex

--> DIRECT input to amygdala (emotions and drives)

--> INDIRECT input to hippocampus (memory)

--> from hippocampus connextions to hypothalamus (visceral responses to odors)

--> orbitofontral cortex (conscious awarness of odors)

--> anterior olfactory nucleus in tract sends axons through anterior commissure to both sides which FINE TUNES olfactory sensitivity


what is the inputs to hippocampus

- amygdala

- cingulate gyrus

- prefrontal cortex via entorhinal cortex

- alvear and perforant pathway is MAJOR INPUT PATHWAY to DENTATE gyrus ("input" gate") of hippocampal formation


describe the Outputs of hippocampus


- fornix to hypothalamus and septal region

- recurrent path to entorhinal area (repetition, reinforcement leads to consolidation of memories?)


Which interal field is most vulnerable to anoxia and ischemia

- CA (1)

- belived to be trigger zone for temporal epilepsy


describe function of hippocampus

- temporary memory until conscious decision to memorize or strong emotional overtones stimualtes hippocampus to fire neuron circuits repetitively producing a memory code PERMANENTLY establish in association cortex of cerebral hemisphere



define working memory

- Found in cortex

- immediate information like adding a series of numbers to get a balance

- typically, quickly forgotten unless there is repetition or decision to memorize


define declarative memory

- Found in Hippocampus

- Semantic: facts, figures, names and other MEMORIZED information

- Episodic: remembering personal events; hippocampus CONVERTS short term to long term memorys (consolidation) to be stored in cerebral association cortex thought to be related to original mode of sensory input

--> ex: visual memories sotred in areas 18 and 19, visual assocaition cortex


define Wernicke-Korsikoff syndrome

- Manifestation of thiamine (vitamin B1) deficiency

- Mainly causes vision changes, ATAXIA and IMPAIRED MEMORY

- often secodnary to alcohol abuse


describe the major nuclei in amygdala

- basolateral and corticomedial nuclei = INPUT GATEWAY to amygdala

- Central nuclei - OUTPUT GATEWAY from the amygdala


describe major input to amygdala

- general and special sensory cortex (sights, sounds, smells, tastes, touches, pain) = monitoring sensoyr input for threats to survival

- OLFACTORY = arrtibute emotional significance to odors

- cigulate cortex = sense of physical and emotional comfort level

- thalamus

- hypothalamus = visceral sensory

- olfactory DIRECT input to corticomedial


major output of amygdala

- STRIA TERMINALIS provides RECIPROCAL connections with septal area and hypothalamus (MODULATING VISCERAL RESPOSNES)

- Cingualte cortex connects to all cerebral lobes = emtoions can affect decision-making (frontal lobe)

- VENTROAMYGDALOFUGAL pathway to central striatum (nucleus accumbens) and brainstem ALLOWS EMOTIONS to INFLUENCE movements and brainstem nuclei (VII, X)


what role does ventromedial prefrontal cortex play in amygdala

- Ventromedial prefrontal cortex integrates EMOTIONS with DECISION-MAKING

- also, conscious control of emotions


describe function of amygdala

- Provide appropriate behavior responses and reactions to sensory information (especially if threatening or dangerous)

- Assess sensory input to determine if non-threatening, frightening, enraging, sexually arousing

- visceral responses called from hypothalamus (autonomic rxns) and septal area

- motor respones from MOTOR CORTEX

- Conscious perceptions of
how we feel about it formed in the cingulate gyrus and prefrontal cortex


damage to the amygdala results in...

- inability to express appropriate behavioral and visceral respones to known stimuli, and INABILITY TO LEARN appropriate resppones to noval stimuli

- MAY los the ability to read facial expressions (ability to interpret their emotional content and meaning)


what is the function of the septal area

- relate emotions to respiratory, cardiovascular centers, salivatory nuclei and autonomic centers

- Pleasure/reward centers?


describe the major inputs and outputs of septal area

- INPUT = from hippocampus via fornix; Amygdala via stria terminalis

- SENS RECIPROCAL connections with hypothalamus, amygdala and cingulate gyrus

- OUTPUTS = medial forebrain bundle to hypothalamus and brainstem nuclei


describe papez circuit

- transfers information within limbic system

- although amygdala is part of limbic system, IT IS NOT PART OF PAPEZ CIRCUIT!!!

- hippocampus, forniz, septal area, hypothalamus, mammilothalamic tract, thalamus, thalamocingulate tract, cingulate gyrus, cingulum, parahippocampal gyrus, back to hippocampus