Interactions between the cortex (frontal lobe) and limbic system; the anterior cingulate and insula
There is another important part of the mid-brain (adjacent to the amygdala) that has a function in registering threat and helping to lay the foundations of trauma. It’s called the Anterior cingulate cortex (ACC) and is important as a filtering system. It is another part of the brain that is functionally degraded as a result of trauma. It possesses structures called spindle cells which wrap around the nerve bundle of fibres linking the left to the right sides of the brain. These connections between left and right may be very important for how emotions are integrated and the meaning made of the emotional events in our lives– and it may be key to why techniques such as EMDR which stimulate better integration allow re-wiring to occur .
The Anterior Cingulate Cortex ACC is primarily involved in fear conditioning as it normally inhibits the amygdala, which as we know is the primary area for threat encoding. However, it also appears to play a role in emotionality, selective attention, and certain social functions, including emotional attachments and parenting, as well as generation of the concept of the self in relation to society. It is my contention that this is the part of the brain that fails in attachment disorder, and other more chronic relational trauma disorders. I have particularly noticed that the sense of self is often highly distorted, even in very outwardly functional people. They operate despite their own self-loathing to become very respected/hard-working/ achieving people but when questioned they cannot see that anything they have done has any worth. If you press them they will acknowledge grudgingly that it might have value but they do not feel that emotionally, it is more of an intellectual awareness. The ACC might be the part of the brain that we bring ‘online’ in trauma treatment, as when we do EMDR. We rewire the responses by a process of extinguishing the conditioned response of self-hating or limiting. I will discuss this within the tools section.
The insula (another part of the cortex just behind the PFC) is an area that helps interpret incoming sensation, rating it dangerous or not. It is highly involved in our subjective experience of pain, for example, and can become active just by imagining pain as well as in more pleasant experiences like music appreciation. It monitors incoming signals from the body (particularly the physiological experience of emotions like sadness, fear, anger, etc) and combines this information with the limbic system and brainstem to generate appropriate responses. As we will see later, when the signals get scrambled by unresolved emotional memory, stress is able to overwrite any inhibitory stimulus and most incoming signals are interpreted as painful, dangerous or life-threatening, causing all sorts of chronic pain and stress-related diseases.
Left and right sides; the Corpus callosum connection
Despite the fact that the cortical structures are split into left and right hemispheres, the brain remains undivided at the level of the lower reptilian brain structures – sometimes referred to as the ‘subcortical bridge’ In treatment, the client and therapist may also be able to capitalise on this. Nonverbal information, including “unconscious or preconscious codes, nuances we can never attach a name to,” cross most readily (Austin, 1999) . Using somatic experience as an entry point in therapy and maintaining mindful awareness of the body may facilitate information processing by enhancing information transfer between the hemispheres. This is what is aimed for in clinical hypnotherapy intervention by engaging the imaginative right hemisphere. However, there is controversy in hypnotherapy as to the nature of hypnosis as we have already shown with regard to whether it is a state separate from normal everyday experience or not. This was developed further by the great hypnotherapist and psychologist Pierre Janet.
We have already intimated that in subjects with PTSD and other lesser traumatically encoded states, the amygdala may become hyperactive towards “a generalisation of the fear response” or conversely underactive which “may allow continued functioning in situations characterized by ongoing threat” such as that experienced by a child who is under threat from their caregiver. That this may be in part to do with the alteration in function of the left and right hemispheres and specifically their inter-communication is an ongoing debate with psychotherapy.
This is an extract from my book The Scar the Won’t Heal – available now on amazon. In the next instalment I look at Interactions between the cortex and the limbic system.