Big Quiz 4 Flashcards
projection neurons
neurons from a particular brain region that communicate with neurons from others (important for interregnal communication)
brain regions related to emotional processes
prefrontal cortex, cingulate cortex, oribitofrontal cortex temporal lobe, insula, amygdala (areas located in the gyre of the cortex or deep within the brain)
amygdaloid complex
basolateral amygdala: receives and sends neural messages
central nucleus: information received from the BLA and uses projector neurons
how do these circuits of communication influence fear response?
basolateral amygdala
sub-region of the amygdala that sends and receives neural messages
central nucleus
sub-region of amygdala that communicate with other brain regions via projector neurons; communication with the lateral hypothalamus triggers parasympathetic activity
central nucleus communication
- later hypothalamus: sympathetic activation
- periaquaductal gray area: activates freezing behaviors (shock)
- periventricular nucleus: the release of CRH (ACTH -> cortisol); downstream effects on hormonal processes
Pavlovian Conditioning
How can this technique be used to induce fear?
- unconditioned stimuli: stimulus that incites unlearned autonomic responses
- pair neutral stimuli with unconditioned stimuli
- association creates conditioned response to previously neutral stimuli (conditioned stimuli) independent of unconditioned stimuli
Threat Processing in the Amygdala
neural pathways of Pavlovian conditioning; convergence of two different neural pathways in the amygdala that communicate information about the UCS and the CS through the amygdala
unconditioned neural pathway
exposure to UCS sends neural signal to the spinal cord-> thalamus (high functioning regions) -> BLA (where the convergence occurs)
conditioned neural pathway
exposure to neural (conditioned) stimuli is picked up by the medial geniculate nucleus in the thalamus -> auditory cortex->neocortex -> BLA oh shit! ->Ce-> various areas of the brain and body triggering reactions in quick succession strengthening associations (is the amygdala required for fear conditioning)
Prather et al.
is fear a learned response or an autonomic experience?
- administered injected chemicals into the amygdalas of three infant monkeys that resulted in specific neuronal cell death
- they were placed back with their mothers and were naturalistically observed for 8 months , then observed fear conditioning behavior is the lab
- did the monkeys with these lesions reach over a snake for food? Monkeys with lesions (relative to controls) showed the same low levels of hesitancy to go for food in the absence or presence of the snake
Prather et al. second condition
the three monkeys were paired with unfamiliar companions and responded fearfully to their presence; more fear grimaces and screams that controls (intact amygdala)
results: fear BEHAVIOR was still intact but fear learning was compromised (unable to learn from dyadic interactions; can’t learn social cues communicating potential threat)
Patient SM
calcified amygdala
experiment 1: watched horror clips and experienced less fear than the control group; experienced similar levels of other emotional responses (sadness, anger, happiness, disgust)
experiment 2: visual and auditory cues were paired with a blow horn. Patient SM was aware that the negative stimuli was coming after the cue, but did not experience any physiological fear responses in anticipation of the horn
experiment 3: controls and patient SM inhaled a mixture of o2 and c02 to induce a suffocating feeling; more c02 to o2 ratio. Patient SM and the controls had panic attacks and felt afraid DURING. Her skin conductance was higher! In anticipation of another trial SM had no conductance but the controls did
Other Comparisons
hippocampal (learning + memory) damage - physiological response but cannot explain the association between the cue and the horn, which elicited the response
hippocampal + amygdala - no physiological response, no association
regional projections + outcomes
autonomic responses - physiological changes
behavioral responses - action tendency
hormonal responses - subjective feelings
Janak & Tye et al.
the amygdalas of mice contain:
aversive (defensive) neuronal circuits - neurons projected to the Ce from the BLA trigger response suppression, and negative affect-like
appetitive - neurons projected to the NAc trigger approach and reward seeking behaviors; seeking pleasures
amygdala meta analysis
the amygdala was activated across a range of emotions; higher activation in response to disgust!
nucleus accumbens (NAcc)
parts: core, shell
NOT specific to award anticipation ; increase and decrease liking expressions
different regions are also involved in aversive and appetitive behavior
Samanez et al.
cues indicated how much money was gained or lost, there was a small delay, then a target that had to be responded to quickly to either win or lose the amount indicated by the cue.
Results: NAcc activity increases with the amount of the reward. When younger and older adults were compared their NAcc activation was similar (risk taking and thrill seeking behaviors don’t depend on age
Berridge et al.
is there a neural basis for facial expressions relative to reward?
implanted electrodes directly into the NAcc of rats, and found that when they stimulated “hedonistic [red]hot spots” liking expressions were elicited. When they stimulated “hedonic cold spots” liking behaviors were suppressed. When given sweets and stimulating these areas at the same time, the rats liking expressions were suppressed
Pt 2: placed rats in different contexts (chill/stressful)and stimulated the same groups of neurons and found that they changed (red to green). The neurons CHANGED what behavior they produced depending on what context they were in!
Orbitofrontal cortex
OFC; multiple components including Broadmanns areas and the orbital proisocortex
reversal learning
learned associations lead to behavioral changes when the association is no longer present; lizards don’t demonstrate this (not moving to the blue dot to check for the reward) changing how we respond
