Limbic System HY Flashcards
papez circuit original proposed pathway
hippocampal fibers –> mammillary bodies –> anterior nucleus –> cingulate gyrus –> hippocampal formation
Kluver-Bucy syndrome
- behavioral syndrome
- due to bilateral removal of medial temporal lobes in monkeys
- fearless/placid
- hypersexuality
- excessive sniffing/oral examination
SHOWED IMPORTANCE OF INTACT LIMBIC STRUCTURES AND CONNECTIONS TO APPROPRIATE BEHAVIORAL PATTERNS
(note: amygdala was also taken)
Papez circuit - updated structures
addition of:
- prefrontal cortex
- association cortex
- amydala
- DMN thalamus
- hypothalamus
hippocampal fibers –> mammillary bodies –> anterior nucleus –> cingulate gyrus –> hippocampal formation
function of orbital and medial prefrontal cortex
planning and choosing appropriate responses to life situations
septal nuclei
- pleasure center
- cholinergic input to hippocampus
lesion = rage
hippocampus has been implicated in:
- memory function
- Alzheimer’s disease
- schizophrenia
- hippocampal sclerosis and epilepsy
- autism
- depression
- modulating endocrine functions (via input to hypothalamus)
- modulation of aggressive behaviors
role of hipppocampus in emotion
- INDIRECT role in emotion
- via connections to limbic cortex, amygdala, septal nuclei, and regulation of stress axis
hippocampus is essential for _________
hippocampus is essential for FACTUAL/DECLARATIVE MEMORY
which part of the limbic system contains stem cells?
DENTATE gyrus
- part of hippocampal formation
- everyone (except Alz pts) have v prolific stem cells
HM research patient
- seizures
- experimental surgery to take out medial temporal structures, hippocampus (and surrounding cortex) bilaterally
After
- few seizures
- unable to form new long-term memories
- profound retrograde amnesia
functional elements of declarative memory
experience –> short term memory –> consolidation process –> long term storage
- consolidation process requires hippocampal formation
- formation of long term memory requires sleep
amygdala is implicated in:
- temporal lobe epilepsy
- schizophrenia
- Alzheimer’s
- autism
- anxiety states/PTSD
- affective disorders
- panic disorders
- emotional memory
functions of amygdala
- determining affective perception of sensory stimuli
- attaches emotional significance to various stimuli perceived by association cortex
- plays central role in fear and fear conditioning
“low road” to amygdala
emotional stimulus –> sensory thalamus –> amygdala –> emotional responses
- reflexive
- keeps us alive in dangerous situations
- problematic in police force
“high road” to amygdala
emotional stimulus –> sensory thalamus –> SENSORY CORTEX –> amygdala –> emotional responses
-normal route
effect of chronic stress on amygdala
- no feedback to stop stress response
- cannot protect from damage
missing amygdala
SM
- has no fear
- cannot recognize fear
- cannot draw fear
role of amygdala in memory
EMOTIONAL MEMORY Amnesic patient: -Dr shook hands w/ thumbtack -pt never shook hand w/ Dr again -did not recognize Dr
David (pt)
- could not recognize anyone
- drawn to those who were nice to him
implicit vs explicit emotional memory
IMPLICIT
- amygdala
- emotional response (panic, fear)
EXPLICIT
- hippocampus
- facts, details
role of noradrenaline
- released during stress
- thought to stabilize/strengthen memories
effect of stress on memory
- mild stress enhances memory
- chronic stress interferes w/ memory (via hippocampus)
