limbic system Flashcards
limbic system: explain the structure and function of the limbic system, and identify the functional effects of lesions to individual components of the limbic system
what is the limbic system anatomically
structurally and functionally interrelated areas (rim of limbus of cortex adjacent to corpus callosum and diencephalon) considered as single functional complex, with no parts acting in isolation
4 functions of limbic system
maintain homeostasis, agonistic (defence and attack) behaviour, sexual and reproductive behaviour, memory (emotional processing)
3 ways the limbic system maintains homeostasis
via activation of visceral effector mechanisms, modulation of pituitary hormone release and initiation of feeding and drinking
subcortical structures of limbic system
olfactory bulb, hypothalamus (inc. mamillary bodies), amygdala, hippocampus (in floor of inferior horn or lateral ventricle), thalamus, frontal lobe
what imaging can indicate what happens in disorders of limbic system
functional e.g. diffusion tensor imaging
name and source of afferent pathway of hippocampus
perforant pathway from entorhinal cortex with fibres from all over going across it
source of efferent pathway of hippocampus
to fimbria, which breaks away to fornix
2 functions of hippocampus
memory, learning
2 diseases associated with the hippocampus
Alzheimer’s disease, epilepsy
location of hippocampus, and structure of it
seahorse shape in wavy structure of medial temporal lobe (hippocampus -> fornix -> mamillary bodies, with amygdala anterior)
diagram of hippocampal circuitry
diagram
where does Alzheimer’s disease (cortical atrophy) start, and effect on temporal and frontal lobes, and ventricles
starts at transentorhinal cortex and hippocampus, with temporal lobe atrophic first, then frontal lobes, causing ventricles to enlarge
progression of Alzheimer’s disease (early -> moderate -> late), and clinical significance
predictable by spread and symptoms; early (entorhinal cortex and hippocampus, with short-term memory problems) -> moderate (parietal lobe with disorientation and dressing apraxia) -> late (frontal lobe with loss of decision-making skills)
Alzheimer’s plaques vs tangles
amyloid plaques are clusters that form in spaces between nerve cells; neurofibrillary tangles are a knot of brain cells
