UNIT 9 - LIMBIC SYSTEM Flashcards
LIMPIC SYSTEM IS:
Not a structure but rather a phylogenetically* (Regarding evolution)
- Motivation and emotion
- Learning and memory
Raphe Nucleus
Control temperature in the body (Hypothalamus)
Hypothalamus + autonomic nervous system regulate?
Physiological changes associated with emotional response
It is in contract with the limbic system that is responsible for the perception and feeling of emotion
Limpic system - PAPEZ CIRCUIT (1937)
First neuroscientific theory: a neural circuit responsible for the expression of emotion
PAPEZ CIRCUIT HOW IT SENDS (oversimplification)
- We start with the hippocampus,
- then fibers travel via the fornix to the mammillary body via mammal oath Olympic
- tract to the anterior nucleus of the thalamus,
- then to the cingulate gyrus in the cingulum the internal cortex
And finally back to the hippocampus
The late additional region was added to this circuit, now called LIMPIC SYSTEM.
Limpic system consist of:
Consist of: Limbic cortex, Amygdala, Hippocampus, Mamillary bodies of the hypothalamus and the Septum.
Important connections: Hypothalamus Anterior Nucleus of the thalamus Orbitofrontal cortex Olfactory bulb
Surrounding of lympic system:
Cingulate cortex
Medial Temporal lobe
Amygdala (anterior to hippocampus)
Plays a role in emotional processing
responsible: for giving emotional significance to these stimuli and coordinating the emotional response (fear aggression)
Amygdala - Role in emotion
- Behavioural
- Autonomic
- Hormonal
Behavioral Response: fight or flee
Autonomic response: facilitates behavioral response (SYPMA increase - PARA decrease
Hormonal response: release of adrenalin and noradrenalin > medulla
Amygdala Nuclei
Central Nuclei - 12
- Lateral nuclei
- Basal nuclei
- Central nuclei
Lateral nuclei: it is via these routes that sensory information about the external world reaches the amygdala
> Lateral sends a signal to the BASAL nucleus of the amygdala & DM = Process emotion and mood
Central nuclei: main output channel of amygdala: important brain structure for the expression of emotional response
Central nucleus of Amygdala
Is important in the expression of emotions: if it is removed then there are no longer emotions of fearful behavior
suggesting that behavioral, autonomic, and hormonal emotional responses are somewhat under the influence of the central nucleus.
Kluver-Bucy syndrome / Case
Syndrome: similar symptoms but also amnesia, aphasia (disrupted language), visual agnosia (disrupted ability to recognize objects)
WHEEN DAMAGE IS BOTH HEMISPHERES
CASE: Epilepticus patient developed this syndrome - which made weird behavior like eating paper towels, plans, urine, etc.
Lateral nucleus is responsible for:
Learning stimulus that is threatning
Olafactory system
The medial nuclei of the amygdala receive input from the olfactory cortex and olfactory bulb and play a role in the olfactory system.
(Pheremones chemical that carries messages from one animal to another)
Hippocampal formation
For memory and learning
= Hippocampus and limbic cortex
Hippocampal Formation - Anatomy
- Dentate gyrus
- Hippocampus proper
- Subiculum
A cross-section of the hippocampus shows the hippocampal formation: a composition of the dentate gyrus, CA fields* and subiculum
Intermediate layer:
- Excitatory pyramid cell neurons in the hippocampus and excitatory granule cells in the dentate gyrus: project axon to allow them to communicate
- The stratum lacunosum molecular (inner layer) of the hippocampus and the molecular layer of the dentate gyrus contain dendrites of pyramidal and granule cell
Hippocampal formation (AFFERENT)
> Entorhinal cortex < receive signal from the amygdala, and processed sensory info.
Cia is the neighboring perirhinal cortex or the parahippocampal cortex.
>Alveus: medial entorhinal: axon to subiculum + CA1
>Perforant: Lateral entorhinal: all other sections of the hippocampus
Hippocampal formation (EFFERENT)
Fornix: efferent pathway of the hippocampal: pyramid axon info to hypothalamic mamillary bodies
Korsakoff syndrome
Chronic alcohol consumption.
Symptom: confabulation: by fabricating or guessing memory
What influences consilidation?
Hippocampus efferent; influence memory consolidation
Learning and memory
Declarative memory (explicit) memory refers to the conscious recollection of fact and experiences or event
Consolidation
Encoding (Learning > Consolidation (memory) > Storage (memory) > Retrieval (memory)
Consolidation in memory:
Memory is in episode instead of isolated memories: The order in which event occurred, the context in which a stimulus was encoded
Flashbulb memories
Emotionally significant memories form quickly, e.g highly arousing event such as romantic encounters, danger, tragedy, etc
Patient HM
Removed temporal lobe removed
- Surgery eliminated seizures but experienced amnesia.
- Non-Declarative (implicit) riding a bike
- Access to new memories but not old
- Hippocampus NOT THE SITE of long term memory
- Hippocampus for declarative memories
