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How Emotion can Trigger Thought

July 9, 2012

In my post ‘A Model of The Brain’ I outlined a basic 3 layer model as a useful structure to begin an exploration of thoughts, emotions and behaviour.

Some research in neuroscience suggests that the limbic system, the “emotional brain” (concerned with processing emotion), developed millions of years earlier than the neocortex, the “rational brain” (concerned with rational thinking). As the neocortex gradually developed out of the limbic system innumerable connections emerged between these two areas, and more appear to extend upwards than downwards. This suggests that the limbic system has a major influence on how we think as well as the emotions we feel.

It’s thought that the amygdala evolved within the limbic system as an emotional alarm system. Its role is to increase our chances of survival by alerting us to possible danger and triggering the “fight , flight or freeze” response (effectively to choose combat, retreat or stillness).

The emotional learning and memory functions of the limbic system allow us to build up important stores of data about all kinds of different scenarios and stimuli so that we know how to survive and indeed thrive. This process is known as pattern recognition or matching, and the human brain has gradually developed increasingly sophisticated, complex and flexible pattern recognition technology (neurology).

The gradual development of reasoning capability in the neocortex has allowed us a far greater range of responses to environmental stimuli than would otherwise be possible. For example, I can see a man running towards me quickly on the street and assess that although this could be threatening behaviour, he is wearing sports clothing and is probably out running to get some exercise. Sensory information is relayed to my thalamus which signals directly to the sensory processing centres of my neocortex. Here I can reason that the running man poses no danger and this understanding is then sent out to the limbic system, the hindbrain and the rest of my body so that I remain calm.

However, when the stimulus is one which causes significant emotional arousal — ie someone nearby on the street suddenly shouts out in an aggressive voice — the thinking brain has no role at all in my instant reaction. It is the amygdala which pattern matches and reacts before the neocortex even starts to process this incoming sensory information. This is a relatively recent finding which has greatly influenced the development of psychological theory.

Research by Joseph LeDoux and Jorge Armony has demonstrated that certain fear signals travel from the senses to the thalamus as usual, but then immediately get diverted along a neuronal ‘fast track’ to the amygdala, arriving half a second before signals relayed by the standard route reach the neocortex. That represents a massive difference in brain response times. {LeDoux, J. (1996). The Emotional Brain. New York: Simon and Schuster}.

This makes it possible for our emotions to hijack and overpower our thinking when we experience a situation as being highly emotive . The amygdala can have us reacting before the rational faculties of the neocortex have even had time to consider an appropriate response. This means that some emotional reactions and consequent emotional memories can be formed without any involvement from the neocortex. The amygdala can then possibly hold on to emotional memories and impressions that never come to full conscious awareness and which can be re-triggered unconsciously by the appropriate stimulus.

Therefore, in order to resolve problematic triggering of the amygdala it is often necessary to work with the unconscious using techniques such as hypnotherapy and meditation. There is much more to say on this complex subject and I will develop further ideas in future posts,

Spencer Joseph

From → The Brain, The Heart

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