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Of the many brain events evoked by a visual stimulus, which are specifically associated with conscious perception, and which merely reflect non-conscious processing? Several recent neuroimaging studies have contrasted conscious and non-conscious visual processing, but their results appear inconsistent. Some support a correlation of conscious perception with(More)
Recent experimental studies and theoretical models have begun to address the challenge of establishing a causal link between subjective conscious experience and measurable neuronal activity. The present review focuses on the well-delimited issue of how an external or internal piece of information goes beyond nonconscious processing and gains access to(More)
Nicotinic acetylcholine receptors (nAChRs) expressed by dopaminergic (DA) neurons have long been considered as potential therapeutic targets for the treatment of several neuropsychiatric diseases, including nicotine and cocaine addiction or Parkinson's disease. However, DA neurons express mRNAs coding for most, if not all, neuronal nAChR subunits, and the(More)
Pentameric ligand-gated ion channels from the Cys-loop family mediate fast chemo-electrical transduction, but the mechanisms of ion permeation and gating of these membrane proteins remain elusive. Here we present the X-ray structure at 2.9 A resolution of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel homologue (GLIC) at pH 4.6 in(More)
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(More)
RATIONALE Tobacco use is implicated in approximately 440,000 deaths per year, making it the leading cause of preventable death in the United States. Although it is generally recognized that tobacco use is correlated with a variety of health-related complications, many smokers are unsuccessful in their efforts to stop smoking using current cessation(More)
The alpha6 subunit of the nicotinic acetylcholine receptor (nAChR) is expressed at very high levels in dopaminergic (DA) neurons. However, because of the lack of pharmacological tools selective for alpha6-containing nAChRs, the role of this subunit in the etiology of nicotine addiction remains unknown. To provide new tools to investigate this issue, we(More)
The subjective experience of perceiving visual stimuli is accompanied by objective neuronal activity patterns such as sustained activity in primary visual area (V1), amplification of perceptual processing, correlation across distant regions, joint parietal, frontal, and cingulate activation, gamma-band oscillations, and P300 waveform. We describe a neuronal(More)
Chronic exposure to nicotine elicits upregulation of high-affinity nicotinic receptors in the smoker's brain. To address the molecular mechanism of upregulation, we transfected HEK293 cells with human alpha4beta2 receptors and traced the subunits throughout their intracellular biosynthesis, using metabolic labeling and immunoprecipitation techniques. We(More)
activity. Between postnatal day 1 (P1) and P10 in this species, spontaneous activity is mediated by nicotinic cholinergic transmission (Feller et al., 1996; Penn et al., 1998) and, in the form of either action potential firing (Meister et al., 1991) or transient influxes of calcium (e.g.,, takes the form of waves that sweep periodically across the retina.(More)