GLOBAL AND SERIAL NEURONS FORM A HIERARCHICALLY ARRANGED INTERFACE PROPOSED TO UNDERLIE MEMORY AND COGNITION

It is hypothesized that the cholinergic and monoaminergic neurons of t he brain form a global network. What is meant by a global network is t hat these neurons operate as a unified whole, generating widespread pa tterns of activity in concert with particular electroencephalographic states, moods and cognitive gestalts. Apart from cholinergic and monoa minergic global systems, most other mammalian neurons relay sensory in formation about the external and internal milieu to serially ordered l oci. These ''serial'' neurons are neurochemically distinct from global neurons and commonly use small molecule amino acid neurotransmitters such as glutamate or aspartate. Viewing the circuitry of the mammalian brain within the global-serial dichotomy leads to a number of novel i nterpretations and predictions. Global systems seem to be capable of t ransforming incoming sensory data into cognitive related activity patt erns. A comparative examination of global and serial systems anatomy, development and physiology reveals how global systems might turn sensa tion into mentation. An important step in this process is the permanen t encoding of memory. Global neurons are particularly plastic, as are the neurons receiving global inputs. Global afferents appear to be cap able of reorganizing synapses on recipient serial cells, thus leading to enhanced responding to a signal, in a particular context and state of arousal. Copyright (C) 1996 IBRO.