Wednesday, October 3, 2012

The ‘Amygdala Hijack’

 "When a man lies down on the psychoanalyst’s couch, a horse and an alligator lie down with him." -- Arthur Koestler 

In 1970, the neurologist Paul MacLean proposed a three-part structure to the brain, reflecting different stages in our evolution.

The brainstem or ‘reptile brain’

The ‘reptile brain’ processes anger, fear, and the territorial instinct. These basic emotions provide a ‘quick and dirty’ way for primitive animals to ‘decide’ to move away from danger, and towards what they wanted (such as food), as well as to protect their territory. These ‘fight or flight’ responses can motivate us to extraordinary efforts in time of need – but they also need to be kept under control, or they can lead us to do things we might regret later.

The limbic system or ‘mammalian brain’

As we move up the evolutionary scale, we see an expansion in the limbic system. These structures enable more complex emotions such as ‘caring’ which provide motivation for animals and birds to nurture their young. Animals that live in complex social groups also need a way of ‘reading’ the emotional state and likely behavior of each other group member – the limbic system provides that ability in a fairly reliable way.

The cerebral cortex or ‘reasoning brain’

At the human level, our language and reframing abilities allow us to experience more shades and nuances of emotion, tremendously expanding our emotional palette. We can have ‘thoughts about our feelings’; we can use language to motivate others by inspiring emotions in them; and, crucially, most of the time we can reframe our raw emotional impulses to get them under control and put things into perspective.

Stress and the triune brain

Although we are capable of reason and emotional control, we don’t operate in this mode all the time. Under stress or the influence of alcohol or other drugs, it is all too easy to regress right back down to the ‘reptile brain’ level. Common examples would include road rage, territorial disputes between neighbours and barroom brawls.

Criticisms of the triune brain model

The triune brain model is a mainstay of Accelerated Learning, which is where you are most likely to come across it. More recent neuroscientists have criticized the model as being too simplistic. We have included it here for completeness, but although it should not be taken too literally, it remains a useful metaphor for how reason and logic can break down under stress.

Recognising emotions – left and right brains

Focus on the nose of each face in turn, and decide which one looks happier.

Most people find the right hand face looks happier. For ‘normally’ wired up people, the right hemisphere of the brain (which processes the left half of the field of vision) specialises in processing facial signals to judge emotions. Consequently we tend to judge how someone is feeling based on the expression of the right (from their point of view) half of their face.
When baboons square up for a confrontation, each will keep the other in the left half of their field of vision, so they can judge more accurately if the other is bluffing.

The ‘amygdala hijack’ 

The amygdala hijack

When we are scared or thrilled, memories are imprinted with particular vividness. The part of the brain called the amygdala scans incoming sensory impressions, pattern matching present experience with these vivid past memories to decide ‘Is this something I fear? Is it something I hate?’ If there is even a rough pattern-match, the amygdala instantly triggers the body into a crisis reaction.

This match doesn’t have to make logical sense – sensory input reaches the amygdala before it reaches the neocortex, the seat of the conscious, reasoning mind. As long as the match is close enough, the emotional reaction is triggered.

Pathways from the cortex to the amygdala are overshadowed by the pathways from the amygdala to the cortex. Emotional arousal therefore tends to dominate thinking. Although thoughts can easily trigger emotions, by activating the amygdala, we are not so good at consciously turning off emotions (by deactivating the amygdala).

Any strong emotion makes us stupid – leading to black/white, either/or, right/wrong thinking. To allow the higher centres of the brain space to do the reframing which is essential to any therapeutic change, you have to achieve a degree of detachment first.

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