General

In SM, bilateral damage to the amygdala caused a deficit in identifying facial expressions conveying fear. This deficit was later shown to be the result of an inability to automatically use information from other’s eyes to evaluate facial expressions.

Six basic human facial expressions represent emotional states: anger, fear, disgust, happiness, sadness, and surprise.

Another way to describe emotions in the dimensional approach, which, instead of describing discrete states of emotion, describes emotions as reactions that vary along a continuum

 

Brain areas involved in emotion

The papex circuit describes the brain areas that James Papes believed were involvd in emotion. They include the hyothalymus, anterior thalymus, cingulated thalymus, cingulated gyrus, and hippocampus (and sometimes the amgdala, orbifrontal cortex, and portions of the basal ganglia). We no longer think  there is only one curcuit of emotion. Rather, depending on the emotional task or situation, we can expect different neural systems to be involved.

The amygdala is heavily involved in fear conditioning (a form of implicit memory)

Information can reach the amygdala via two separate patways. The ‘low road’ goes directly from the thalymus to the amygdala: the ‘high road’ gores from the cortex to the amygdala.

The amygdala is also important for explicit memory of emotional events. First, the amygdala is necessary for normal indirect emotional responses to stimuli whose properties are learned explicitly., by means other than fear conditioning. Second, the amygdala can enhance the strength of explicit (or declarative) memories for emotional events by modulating the storage of these memories.

The amygdala appears to be necessary for automatically deriving information from the eyes of others when identifying facial expressions. This ability is especially crucial for the proper identification of fear because the defining characteristics of fear isan increase in the volume of the eye whites.

The amygdala is also activated during the categorisation of people into groups. Research into this phenomenon has elucidated how our brains participate in implicit stereotyping.

The amygdaala may also participate in the processing of facial expressions.

Other brain areas are associated with the processing of different emotions. The orbifrontal cortex is activated when identifying facial expressions and hearing angry prosody, and the anterior insula is linked to the identification and experience of disgust.

Ultimately, understanding how we perceive and experience emotion will require studying the interactions of a diverse set of neural structures.

 

Fear Conditioning

· Fear conditioning is a form of classical conditioning in which the unconditioned stimulus us aversive. It is a form of implicit learning.

· The conditioned stimulus is a neutral stimulus that, although classical conditioning, will eventually evoke a response. The unconditioned stimulus is the stimulus that, even without training, evokes a response.

· The unconditioned response is the response naturally elicited  (without training) from the unconditioned stimulus. The conditioned response is the response that is elicited (with training) in the conditioned stimulus. Usually the unconditioned response and the conditioned response are the same (e.g. the startled reaction of the rat), but they ave different names depending on what elicits the response.

· S.P. who, like SM, had bilarteral amygdala damage, failed to acquire a conditioned response during fear conditioning, indicating that the amygdala is necessary for such conditioning to occur.