Amygdal And PTSD Flashcards
Range of behavioral disturbances with complete amygdala damage such as placidity, loss of behavioral inhibition, hyperplasia, reduced/absent fear of new environments
Kluver-Bucy syndrome
What connects amygdala with septal nuclei and bed nuclei of stria terminalis (BNST)
Strai terminalis
What are the 3 major subdivisions of the amygdala
- Cortical/medial subdivision
- Basolateral division
- Central divsion
Cortical/ medial subdivision of the amygdala
- primary olfactory sensory region
- possible role in reproductive behavior
Basolateral divsion of the amygdala
- receives sensory input from sensory cortex, including pain, viscerosenstion
- receives input from hippocampus
- involved in anxiety/fear and associative learning
- reciprocally connected with orbitofrontal cortex: behavioral regulation
- projects to central divsion
Central division of amygdala
- receives input from basolateral divsion
- regulates anxiety/fear, freeing or flight behavior, autonomic and glucocorticoid responses to stressful stimuli, via projections to septum, BNST, hypothalamus, brainstem, and spinal cord
Kluver-Bucy syndrome: signs related to loss of interaction with orbitofrontal cortex
- extremely placid/docile
- loss of behavioral inhibition
Kluver-Bucy syndrome: signs related to loss of interaction with hypothalamus
Hyperphagia
Oliver-bucy syndrome: signs related to loss of interaction with cortex and hippocampus
Reduced/absent fear of new place
Normal emotional functions of the amygdala
Activity correlates with subjective level of anxiety/fear, strongly influenced by brainstem norepi projections to amygdala
Sensory role of amygdala
Activated by stimuli that are novel or emotionally significant in a positive or negative way
Memory and amygdala
Enhances memory for highly positive or negative stimuli/events
Associateive learning and amygdala
Simple stimulus-response behaviors triggered by emotional neural stimuli after then beceom predictive of rewards or danger
What kind of response to stress does amygdala drive
Behavioral, autonomic, and hormonal responses
What are the normal functions of the amygdala regulated by
Interactions between the amygdala and prefrontal cortex
Hallmark symptoms of PTSD
- more intense/frequent anxiety
- hyper vigilance
- insomnia/nightmares/flashbacks
- triggers
Secondary symptoms of PTSD
- avoidance
- volatile emotional reactions
- difficulty concentrating
- longer than 1 month of symptoms
- disruption of life from symptoms
What causes the post PTSD in men
Rape
Combat
Molestation
What causes the most PTSD in women
Rape
Threat with weapon
Molestation
What is elevated amygdala activity related to
Elevated anxiety-related symptoms
What causes excessive amygdala activation
Emotionally negative stimuli
What drug shows elevated amygdala activity and fear response
After injection of yohimbine, a blocker of a pre synaptic norepinephrine auto-receptor
What does yohimbine trigger
Re-experiencing in some PTSD subjects
What do drugs of abuse that are often used by PTSD patients known to do
Dampen norepinephrine neurotransmission
Other than heightened norepinephrine, what else is associated with PTSD
Sympathetic nervous system is also hyper-responsive and basal release of cortisol is reduced in PTSD
First line RX for PTSD
Selective serotonin re-uptake inhibitors (SSRIs)-boosting reward/safety neurocircuitry
-usual application for SSRIs is depression
2nd line Rx for PTSD
Other anti depressants other than SSRIs
Clinical research on next generation of Rx for PTSD
-most promising so far is prazosin: alpha-1 norepinephrine receptor antagonist
Psychological therapies for PTSD
Cognitive behavioral therapies
What are triggers for PTSD
Something that causes them to have an episode. Can be similar scenario, or can be very different visual environments, but one common sensory feature with an inappropriate learned fear response
Amygdala and circuitry mediating “fear learning”
During training phase, they give mouse 4 repetitions over 10 minutes of electrical shock with a sound coming before it. After some time, the mouse is conditioned to freeze just when hearing the sound
Extinction of conditioned fear
-learning that the conditioned stimulus (cuts, CS) no longer predicts shocks
Triggers in PTSD and “extinction”
They are failure of extinction of conditioned fear
What all acts on the amygdala in the training phase
- dorsal anterior cingulate cortex
- hippocampus (contexts)
- auditory pathways
- pain pathways
What’s acts on the amygdala in the extinction phase
- perigenual cortex
- hippocampus (contexts)
- auditroy pathways
What is the main thing that tells the amygdala to cool it during extinction phase
Perigenual cortex
What part of the cingulate cortex increases fear (conditioning)
Dorsal anterior cingulate
What part of the cingulate gyrus reduced fear (extinction)
Peri-genual cortex
What happens the the dACC (dorsal anterior cingulate cortex)
Hyperactive
What happens to the peri-genual cortex in PTSD
Hypoactive
Mediation of PTSD
Treated by psychiatrists and psychologists along with enhancement of medication
-exposure therapy
