[Affectivity in the nervous system]

Affectivity is an ambiguous term, related altogether to, mood, well-being, ill-being, emotional states, and at the same time to individual sensitivity, capacity to feel moved, as well as feelings and passions. We want to show that those states, as different as they may seem, belong to the perception by the central nervous system of past or present modifications, of an organism reacting to situations it has to cope with. Opposite to common opinion, this affectivity is not "generated" by the cerebral cortex but by the central brain. It results from memory input by the limbic system and from information processing by the hypothalamus and the reticular system, and from processing of mood and emotional rates provoked by self reactions in order to perpetuate survival, protection or one's own species. Considered as "favourable" or "unfavourable" after analyses by the limbic cortex, those states become in the central brain "pleasure" or "aversion", and generate motivation for action, to follow-on or to stop. From the limbic cortex, those motivations are transmitted to the contiguous prefrontal cortex. The prefrontal cortex is a center for action imitation. One may imagine it as a center for conscious cortical activity and for affective memory. This organisation of affectivity and affective memory settings in 2 different centers and at two different levels of the nervous system: the limbic cortex and the prefrontal neo-cortex. The prefrontal neo-cortex only is conscious, but the limbic cortex, although unconscious, is a source of motivation. One is led to describe an unconscious affectivity. It is impossible to talk about this affectivity without mentioning Freud's unconscious.