The limbic system Flashcards
what is the function of the limbic system
emotion, appetite and homeostasis - endocrine and autonomic nervous system control, memory function and recall, olfaction
engages the person with the environment, reference to past experience, present situation
what is the limbic system
interconnected discrete structures within the brain and brain stem forming a ring around the corpus callosum
what four catergories can the limbic system functions be divided into
emotions and drives via the amygdala
homeostasis and motivation (hypothalamus)
olfaction (olfactory cortex)
memory (hippocampus)
where is the amagdala
found at the anterior tip of the hippocampus, provides and emotional component to experiences and memory and teh ability to recognise fear
what inputs go to the amygdala
frontal temporal and parietal lobes receiving cognitive information
what are the efferents from the limbic system
hypothalamus and limbic cortex providing and emotional cognisance, and visceral/ homeostatic information
what can amygdala lesions cause
loss of recognition of fear and anger in other people
stimulation causes fear and aggression
what is Kluver-bucy syndrom
bilateral temporal lobe lesions (including the amagdala) in all mammals produces
visual recognition impairments
hypersexuality
loss of fear conditioning
oral tendencies
flattened emotions
describe hypothalamic circuitry
parasympathetic to viscera
sympathetic
feedbacks to the limbic system about environments both internally and externally
what subgroups can effects of the hypothalamus be broken into
vegetive (visceral)
endocrine (control over anterior pituritary release
behavioural functions
what is the mesolimbic dopamine system
reward system
found in the ventral tegmental area of the midbrain
where does the mesolimbic dopamine system project to
medial prefrontal cortex, amygdala, hippocampus, nucleus accumbens, ventral pallidum
describe the effects of recreational drugs on the limbic system
thought to have a common dopaminergic pathway in the limbic system
what is the anterior insular cortex
provides introspeciton which allows the interpretation of sensation as joy or disgsust
what is huntigntons
a progressive frontal cortex degenerative disease
what is the periaquaductal grey
the primary control centre for descending pain modulation
encaphalin producing cells which suppress pain
The PAG is able to reduce activity in the
ascending pain pathway
describe the limbic system’s effect on pain
involved in pain perception such as the PAG
what chemicals agonise the effect of PAG on pain
opiates and endorphins
what can electrical stimulation of PAG cause
analgesia
what is the effect of nalaxone
blocks opiate receptors- used to counteract opiate pain medications
what limbic structures are involved in depression
ventromedial portion of the prefrontal cortex
cingulate gyrus
what is the ventromedial portion of the prefrontal cortex
goal setting, forward planning and ascribing meaning to perception
reduced mass in individuals with familial depression
describe the state of the ventromedial portion of the prefrontal cortex in bipolar disorder
inactive during depressive states
hyperactive during manic phases
what is the function of the cingulate gyrus
involved in emotion and cognition
describe the state of the cingulate gyrus in mental illness
reduced during depression
more active in depressive phases of bipolar patients and less active in manic phases
involved in schizophrenia, mood swings
what neurotransmitters may be imbalanced in depression
serotonin, dopamine, norepinephrine
what hormone is elevated as a response to prolonged stress
glucocorticoid, released from the adrenal glands
what part of the brain detects glucocorticoid
hippocampus which then activates the hypothalamus into releasing corticotropin releasing hormone
what hormone does corticotropin releasing hormon release
adrenocorticotrophic hormone which causes the release of more glucocorticoids
why may glucocorticoids be elevated in people with depression
cortical receptors feedback which blocks the production of CRH but this may not work
this affects serotonin receptors
