Attention, consciousness, and electrical wave activity within the cortical column

The triangular circuit theory of attention is extended to activity of pyramidal neurons in cortical columns. The expanded theory accounts for both the brief attention of locating and identifying objects and the sustained attention of preparation for and maintenance of attention to objects, attributes, and locations. It is proposed that sustained attention is expressed in a cortical column by repeated surges of current in the long apical dendrites of pyramidal neurons, which form a wave. When (he wave is sufficiently intense in a cluster of these neurons, it can be measured at the scalp as EEG oscillations. The wave of attention may or may not produce output pulses from the neuron. Selective attention may be expressed as enhanced processing of pulses arriving at the basal dendrites and leaving at the soma of these pyramidal neurons. It is also proposed that wave activity in the apical dendrites of cortical pyramidal neurons generates subjective experience. When wave activity is produced by the attention circuit in a cortical area beyond the primary sensory areas, it generates our foreground experience of an object. When wave activity is produced in the primary sensory areas by signals from sensory receptors, it generates our background experience, or consciousness. (C) 2001 Elsevier Science B.V. Ail rights reserved.