Ongoing Spontaneous Activity Controls Access to Consciousness: A Neuronal Model for Inattentional Blindness

Abstract

Even in the absence of sensory inputs, cortical and thalamic neurons can show structured patterns of ongoing spontaneous activity, whose origins and functional significance are not well understood. We use computer simulations to explore the conditions under which spontaneous activity emerges from a simplified model of multiple interconnected thalamocortical columns linked by long-range, top-down excitatory axons, and to examine its interactions with stimulus-induced activation. Simulations help characterize two main states of activity. First, spontaneous gamma-band oscillations emerge at a precise threshold controlled by ascending neuromodulator systems. Second, within a spontaneously active network, we observe the sudden “ignition” of one out of many possible coherent states of high-level activity amidst cortical neurons with long-distance projections. During such an ignited state, spontaneous activity can block external sensory processing. We relate those properties to experimental observations on the neural bases of endogenous states of consciousness, and particularly the blocking of access to consciousness that occurs in the psychophysical phenomenon of “inattentional blindness,” in which normal subjects intensely engaged in mental activity fail to notice salient but irrelevant sensory stimuli. Although highly simplified, the generic properties of a minimal network may help clarify some of the basic cerebral phenomena underlying the autonomy of consciousness.

A neurocomputational hypothesis for nicotine addiction

“…A cognitive control deficit may be the principle cause of the apparent compulsivity and the long-term relapses to smoking. Such top-down control may be mediated by a reciprocal prefrontal cortex-DA-striatal link, a brain circuit postulated to contribute to the conscious ''neuronal workspace'' (42,55). One may envision that a longterm selective depression by nicotine of this loop (13) disconnects A-S from cognitive control and uncovers the compulsive nonconscious aspects of nicotine addiction.…”

The interplay of attention and consciousness in visual search, attentional blink and working memory consolidation

“…However, unlike ViSA and earlier GW models [16,17], TAC postulates that dynamic control of visual attention is exerted by a higher-order representations in the GW. Moreover, unlike these models, TAC characterizes attentional processing in the visual cortex, and not only conscious access in the GW.…”

“…[114]) map. Rather, TAC endorses dynamic principles from the global neuronal workspace model [17], and extends these to visual attentional processing. Attentional filtering and selection are thus based on amplification and ignition processes involving distributed thalamo-cortical representations and cooperative multi-modular interactions.…”

“…We therefore propose that processes of amplification, ignition, evidence accumulation, all-or-none representation and winner-takes-all competition for target (object) representation in the GW [17,33] are also involved in higher-order selection of executive operations in the GW. For example, the same target, T1, can be subjected to two different executive operations in the GW.…”

“…Inattentional blindness has been modelled in the global neuronal workspace framework in terms of ignition dynamics driven by internal states [17]. Recent studies have, however, shown that the effect of inattentional blindness also takes place when the inattended visual stimuli are expected (e.g.…”