Limbic System Flashcards
Limbic Structures
- Hippocampus
- Amygdala
- Mammillary bodies
- Cingulate cortex
- Hypothalamus
- Septal Nuclei
Limbic Cortex (cingulate, parahippocampal cortex)
- two-way communication between prefrontal cortex and lower limbic structures to control behavioral responses
- damage: less well regulated behavior (Phineas Gage)
Salience Network
- detects behaviorally relevant stimuli and responses
collection of regions of the brain that select which stimuli are deserving of our attention
Hippocampus (function)
consolidation of info from short –> long term memory and in spatial memory / navigation
Hippocampal formation
- Hippocampus
- Alveus
- Fornix
- Fimbria
- Hippocampal commissure
Alveus
axons from hippocampus –> forms fimbria –> joins together to become fornix –> project to mammillary bodies –> anterior nucleus of thalamus
Hippocampal commissure
how hippocampi communicate w/ each other
damage to fornix
long term memory loss, but not fact-based/ spatial memory
Association areas
process sensory input, produce conscious awareness of emotional feelings
Pre-frontal and limbic association areas (function)
conscious, learned control of reflexive behavioral patterns
Pre-frontal cortex (function)
plans and guides behavior, suppresses amygdala-induced emotional/fear responses that may be inappropriate for the situation
Sensory Over-responsibility
- extremely common in those w/ autism
negative reaction to/ avoidance of sensory stimulus (auditory and tactile most common)
Dentate Gyrus
location of neural stem cell population in adult hippocampus
Cornu Ammonis areas
dentate gyrus –> CA4 –> CA3 –> CA2 –> CA1
Entorhinal cortex (function)
declarative / spatial memory consolidation during space
- input of signal to hippocampus
Hippocampal Output
Fornix –> amygdala, mammillary bodies, thalamus, hypothalamus, cingulate / frontal cortex
Anterograde Amnesia
can’t form new memories
Retrograde Amnesia
can’t retrieve stored memories for a specific time
Hippocampal Injuries
- memory loss of function, anterograde amnesia
- no recall of declarative memory (especially spatial)
Amygdala (functions)
social interactions, anxiety, aggression, fear, rewards
lesions = block memory formation, can’t discriminate emotions in facial expression
Medial Nuclei
linked to olfactory system
associated w/ aggression, repetitive behavior
Central Nuclei
linked to hypothalamus and periaqueductal gray
controls body’s physiological emotional response
Basolateral Nuclei
links sensory experiences, memory and emotional response
continuous w/ parahippocampal gyrus, links to central nuclei
Hyperthymesia
enhanced autobiographical memory
greater amygdala-hippocampus connectivity
GABAergic neurons (in medial nuclei)
fear and aggression
Glutamatergic neurons (in medial nuclei)
repetitive behaviors
Mammillary Bodies
memory recall, add smell to memories
lesions = amnesia syndromes
Wernicke-Korsakoff syndrome
thiamine deficiency leads to retrograde and anterograde amnesia
Hypothalamus
regulate emotions, produces autonomic responses associated with emotions (unconsciously controls endocrine glands)
Septum Pellucidum (of Hypothalamus)
part of walls of lateral ventricles
Septal Nuclei (of Hypothalamus)
processes rewarding experiences; learning and memory
receives afferent connections from other limbic structures
also sends projections
