Limbic System Flashcards
the limbic system is the border between the
diencephalon and cortices
called the visceral brain due to influence on visceral function and also called emotional brain because of function linked to motivation, emotion, olfaction, social behavior and memory
limbic system
what are the 5 structures that make up the limbic system
- hypothalamus - homeostasis
- limbic cortex - cingulate gyrus, parahippocampal gyrus, uncus, septal nuclei
- hippocampus - memory
- amygdala - emotions
- orbitomedial prefrontal cortex - social behaviors
what connections does the limbic system have
- receives input from all 5 senses, somatosensory association areas, and visceral sensory input from the ANS from hypothalamus and brainstem
- info passes through hippocampus and/or amygdala on to hypothalamus
- hypothalamus regulates behavioral responses to stimulus, modulates ANS and endocrine systems, and influences activity of immune system
the limbic system is composed of 3 lobes of gray matter around the thalamus on medial hemisphere, what are the 3 lobes
- cingulate gyrus
- parahippocampal gyrus
- uncus
receives info from prefrontal and parietal association areas and thalamus and sends information back to them and to hippocampus
limbic cortex
what are the functions of the cingulate gyrus
alterations of BP, HR, RR; dilation of pupils; piloerection (goosebumps) when afraid; anxious or pleasured; motivation based on previous experience
what do lesions to cingulate gyrus cause and what are they
- akinesia: no physical response to stimuli
- apathy: lack of concern or attention
- incontinence
- mutism: doesn’t speak but not due to loss of motor aspects of speech
involved in interpretation of smell from olfactory bulbs
parahippocampal gyrus
lesions to prehippocampal gyrus and what are they
- anosomia: cannot smell; early sign of brain cancer
- cacosmia: sensation of unpleasant smells prior to seizures (epilepsy) or olfactory hallucinations
reciprocal projections to hypothalamus and amygdala and hippocampus; involved in autonomic regulation and influences social-emotional behavior (difficulty shifting perspective when social situations does not work as expected; inability to connect decision making to appropriate emotional response
orbitomedial prefrontal cortex
where does amygdala receive info from and where does it send info to
- receives: olfactory cortex, frontal and parietal and temporal association areas of brainstem
- sends: to prefrontal and premotor cortex, hypothalamus, thalamus, and brainstem nuclei
what will lesions to amygdala cause
lack of caution, increased libido (sex drive), compulsive eating, loss of appropriate social behavior, visual agnosia
olfactory function of amygdala
emotional connection to smell
autonomic function of amygdala
modulates endocrine function and connects emotions to ANS responses
cortical function of amygdala
- involved in emotions, memory and learning by way of connections with prefrontal cortex
- attaches meanings to sensory stimuli
- heavy influence on protective emotions (fear, rage, libido)
- interpretation of facial and vocal expressions of others, socially acceptable behaviors
are subjective experiences with physical quality
emotions
what are positive and negative emotions associated with
- positive: L prefrontal
- negative: R prefrontal
thoughts and emotions influence visceral actions via ANS neurotransmitters (epinephrine, norepinephrine and cortisol)
gut feelings
negative or stressful situations over prolonged periods of time will result in
increased levels of cortisol in blood (stress response)
what effect does cortisol have on immune system
- depresses immune system
- more susceptible to inflammation, allergic conditions, injury or cancer
what 3 systems are involved with stress response, describe them
- somatic NS: increased motor neuron activity leads to muscle tension which leads to chronic pain
- autonomic NS: sympathetic activity increases blood flow to muscles and decreased blood flow to skin, kidneys and digestive tracts
- neuroendocrine system: sympathetic stimulation of adrenal cortex leads to increased HR, BP, metabolic rate
ways to balance stress and what does it lead to
- group therapy, meditation, prayer, relaxation exercises, nature
- parasympathetic
is an important emotion to brain function and leads to a whole brain experience because it sets the brain up for a series of parallel synaptic happenings
humor
explain how is humor a whole brain experience
- language center in L hemisphere makes sense of words
- R frontal lobe to thank about logic or illogic presentation - makes experience funny
- limbic system connects an emotion or memory to joke (domapine released = feel good)
- motor system to laught
- ANS changes in HR, RR, laugh till cry
what are the positive effects of humor on the brain
- improve memory
- result in learning
- improve creative thinking
- has positive effect on healing and immune system
where is the hippocampus located
temporal lobe
functions of hippocampus
- assembles sensory info and sends it to brainstem
- memory associated with smell
- highly involved in memory due to connection with temporal lobe
lesions to hippocampus
amnesia, alzheimers
modification of behavior in response to an experience
learned responses
have to be stored and recalled when needed; are survival functions
memory and learning
what are the 3 different memory forms and describe them
- Emotional or Reflexive Memory: hard-wired stereotypical response to a previous experience (elation at birth of my child even 40+ years later)
- Declarative Memory: recalling events that happened yesterday or years ago (episodic memory) and knowing factors or concepts (semanitc memory)
- Procedural Memory: knowing how to ride a bike
remembering something that happened yesterday or years ago; remembering events
episodic memory
knowing facts/concepts
semantic memory
what structures are involved in declarative memory
hippocampus, nearby cortical areas, diencephalon
skills and habits, emotional associations, conditioned reflexes are what type of memory and what structures are associated with them
procedural memory
- skills/habits: striatum, motor areas of cortex, cerebellum
- emotional associations: amygdala
- conditioned reflexes: cerebellum
what brain structure is associated with working/short term memory
prefrontal cortex
recollections that can be verbalized; conscious, cognitive memory
declarative memory
what lobes are involved with declarative memory
frontal and temporal
found in temporal lobe and processes memory from short to long term
hippocampus
what are the 3 stages of memory acquisition
- immediate
- short-term
- long-term
lasts only 1-2 seconds because no significance is attached to experience
immediate memory
what processes immediate memory
sensory and sensory association areas - NO limbic system involvement
brief storage of stimulus in chunks, loss of info unless material is rehearsed
short-term/working memory
relatively permanent storage; has been processed by STM (______) first with formation of new synaptic connections
- long term memory
- consolidation
what has to be involved to have something stored in long term memory
hippocampus –> making new synapses
what are the 3 mechanisms for declarative memory
- acquisition
- storage
- retrieval
sensory experiences are directed to temporal lobe; if significant is attached to the experience that it is programmed for storage
acquistion
short vs long term; performance depends on context and emotions attached to the event
storage
how you retrieve information
retrieval
what is consolidation
from STM –> LTM
what is the difference between recall and recognition
- recall: able to retrieve memory without a cue
- recognition: cued by seeing the item or attachment to another piece of information
refers to recall of skills and habits; nonconscious memory; requires practice to store these memories; won’t need attention once skill or habit is learned, will be automatic
procedural memory
what brain structures are associated with procedural memory
amygdala, basal ganglia, motor cortex and cerebellum
primary functions of the limbic system
- regulates feeding and drinking
- regulates aggressive and defensive behavior
- regulated reproductive behavior
- influences memory and emotions
what pathologies can impact limbic system
TBI, stroke, cancer, alzheimers
lesion to limbic cortex
Inappropriate risky behavior, poor judgement, difficulty conforming to social norms, impulsive, emotional outbursts, violent behavior, difficulty making decisions, no emotional concern about outcomes
lesion to prefrontal area and amygdala
Depression, emotional lability (uncontrolled expressions of emotion), inability to recognize emotions in others, poor social behavior
hippocampus lesions
amnesia (retrograde or antegrade)
what are hippocampal lesions related to
thiamine deficiency (alcoholism)
