Latest Findings in the Mechanisms of Cortical ‘Arousal’: ’Enabling’ Neural Correlates for All Consciousness

This paper differentiates traditional "cortical arousal" concepts into separate components for the functional states termed REM ("rapid-eye-movement sleep"), Quiet-Waking, and Active-Waking, and traces their involved mechanisms in the neuronal and biochemical level, i. e., skipping from consideration any more fundamental issues such as quantum or relativistic biophysics. In a short review of the latest findings, these "classical" mechanisms include (a) basal forebrain acetylcholine "final path" projections to the cortex for "basic arousal" in Electroneurobio log ía vol. 14 (2), pp. 199-210, 2006 200 REM and quiet wakefulness; (b) brainstem neurotransmitter systems allowing incoming stimuli to activate "arousal", and recruiting additional systems to turn "basic arousal" into the fuller arousal and capacities of Active Wakefulness state; (c) thalamic intralaminar-nuclei cortical projections that connect anterior and posterior cortex for processing sensory stimuli; (d) thalamic reticular-nucleus which can shut down perceptual transfer between thalamus and cortex or allow gated transfer; and (e) circadian mechanisms in the basal forebrain, hypothalamus and pineal gland that direct transitions from waking to slowwave sleep to REM and back. (f) More speculatively, it is considered that circadian clocks alternating control between left and right hemispheres may be involved in rotations between slow wave sleep (SWS) and REM sleep.