Norden - Limbic System Flashcards
The hippocampal formation is part of the limbic system’s cortical areas, it consists of )_____
Hippcampus proper
Dentate gyrus
Subiculum
Function of hippocampus and dentate gyrus?
Critically involved in learning and memory
One of the few areas of the human brain that continues to have significant neurogenesis throughout life
Dentate gyrus
Areas of cortex involved with limbic system
Prefrontal association cortex
Orbito-frontal association cortex
Insular cortex
Entorhinal cortex
Cingulate gyrus/cingulum
Hippocampus gyrus
Critical player in learning and memory. First cortical area to degenerate in ALZ
Entorhinal cortex
The posterior part of the _____ is what has the default mode network
Cingulate gyrus
The ability to appreciate how others feel and are motivated to act is called what? And is located where?
Theory of mind
Insular cortex and anterior cingulate gyrus
The role of the orbito-frontal- association cortex:
Personality
Emotional behaviour
Functions of the prefrontal association cortex?
Working memory
Executive function
Stimulation of the prefrontal cortex, like that in talk therapy, can decrease activation of ?
Amygdala
The amygdala’s function?
Emotional response to stimuli (especially fearful)
What is commonly seen regarding the amygdala in anxiety patients?
Hyperactivation.
What pathway, in the limbic system, allows for reward for basic drives?
Ventral tegmental area ——dopamine——> nucleus accumbens septi
Thalamic nuclei involved with the limbic system are ??
Anterior nuclei
Mediodorsal nuclei
Connections here allow for a “body response” (blushing) to emotional stimuli
Hypothalamus
Mammillary nuclei role in Limbic system?
Memory circuits
Provides the major dopaminergic input to the meso-cortical and meso-limbic areas
Ventral tegmental area
Nondeclaritive or implicit memory (procedural memory) is what?
What areas are involved?
Unconscious skills, habits, and acquired behaviors.
Basal ganglia nuclei ; caudate (habits), cerebellum, (learned skilled motor movements)
Limbic structures; amygdala
Declaritive / explicit memoryy is what?
Conscious memory of facts/events/experiences.
Limbic system is major role
What are the two main limbic subsystems for declarative or explicit memory?
Medial temporal lobe structures - association cortex , entorhinal cortex, hippocampal formation
And
Medial diencephalic structures - mammillary bodies and anterior nuclei and mediodorsal nuclei of thalamus
What are the structures involved with the medial diencephalic structures (declarative memory)
Mamillary body
Thalamus - mediodorsal and anterior nuclei
What are the structures involved in the medial temporal lobe structures? (Episodic/ declarative memory)
Association cortex
Entorhinal cortex
Hippocampal formation
Deep brain stimulation of what can improve memory in patients w/ early stage ALZ dz
Fornix
Bilateral damage to either the MDS or MTLS (which are interconnected) caused what?
Declarative memory loss
This is typically referred to as amnesia
Unilateral damage to the left (dominant hemisphere) MTLS or MDS can cause?
Deficits in verbal memory
Unilateral damage to the non-dominant hemisphere MTLS or MDS causes ?
Spatial memory loss
Head injury on the side of the head?
Coup injury
Injury on the opposite side of the head, caused by blow to the side of head which can cause bilateral damage to hippocampus which results in memory loss and seizures
Contre coup
What artery supplies the MDS and MTLS?
PCA
Local, temporal lobe seizures cause?
Amnesia
Generaliz, repeated seizures can cause?
Death of hippocampal neurons, permanent loss of memory
The loss of hippocampal neurons along with dense astrocyte scars.
Occurs in about 65% of people with temporal lobe epilepsy
Can also occur from prolonged fever or injury
Caused significant memory impairment
Hippocampal sclerosis
Temporary loss of the ability to form new memories in elderly/middle aged people
No other symptoms and resolves w/in 4-12 hours
Commonly in pt w/ hx of Migraine
Common onset —> high stress or strenuous activity.
Transient global ischemia
Degeneration, prominent in the MDS nuclei
Decreased volume and metabolism of the prefrontal cortex
Permanent memory loss and psychosis.
Patient’s confabulate
Wernicke korsakoff syndrome
How does memory loss occur in people with psychiatric disease?
- Schizo pt’s are missing hippocampal interneuron
- Some psych dz’s caused continual activation of HPA (hypothalamic-pituitary-adrenal) system. This leads to increased levels of hormones in bloodstream. Excess cortisol binds to hippocampal neurons decreases memory formation and retrieval. Also, chronic elevation of HPA axis causes decreased neurogenesis in dentate gyrus.
