ABSTRACT
The limbic system, sitting like a fist under the cushion of the cerebral cortex, has often been referred to as the emotional brain. The term ‘limbic’ comes from the Latin word limbus which means border or edge. As in the phrase ‘being in limbo’ the limbic system is somewhere ‘in-between’; it is essentially in-between our outer world of sensory input and our inner world of thinking. We could say that the limbic system is a centre of integration where the top-down demands of the higher cognitive functions of the cerebral cortex and the bottom-up demands of the visceral body and senses coalesce with services prioritising the protection and defence of the things that we most value. In terms of our organisation metaphor, the limbic system forms the middle-management level of our organisation. Middle-management tries to find a way of ensuring that both the strategic demands of upper management and the operational needs of the body and the environment are met as far as possible without compromising our core values. This can be a delicate juggling act. In order to achieve this, the limbic system has several specialised areas. One such area monitors the sensory information coming in along various neural pathways integrated via the thalamus. These monitoring or surveillance services reside in an area called the anterior cingulate cortex (ACC). The questions considered by such services are: ‘Have we seen such sensory information before?’; ‘Is the sensory information suggestive of danger?’; ‘How should we respond to this situation?’ Other parts of the limbic system help to answer such questions: the hippocampus accesses memories, the amygdalae recognise danger signals, the periaqueductal grey area (of the midbrain rather than limbic system) monitors our neurochemical balance-sheet, signalling to the limbic system our bodily needs in order to optimally perform. The insula provides access to many possible behavioural response frameworks together with cognitive priorities to help select an action plan.
