Altered states of consciousness (ASC) can occur spontaneously, be evoked by physical or physiological stimulation, induced by psychological means, or caused by diseases. Psychological and neurobiological approaches reveal four dimensions characterizing ASC: activation, awareness span, self-awareness, and sensory dynamics. Neurophysiologically, different states of consciousness arise from compromised brain structure, transient changes in brain dynamics (disconnectivity), and neurochemical and metabolic processes. Environmental stimuli, mental practices, and self-control techniques can also temporarily alter brain functioning and conscious experience.
An interdisciplinary group of experts argues that progress in understanding and treating neuro-psychiatric disorders requires an integrative, multi-perspective approach that acknowledges differences between system levels, their complex interactions, and domain-specific languages. They review the past decade and find that many research programs remain reductionist and fail to critically examine neurobiological explanations and interdisciplinary interfaces. They call for establishing an interdisciplinary neurophilosophy that develops a critical philosophical stance within neuroscience, applying complex systems science to integrate knowledge. An ecological perspective is needed, viewing the brain as a regulative organ in a situated organism extended to tools, technologies, and social structures. The debate about free will illustrates that respecting complexity and irreducibility of mental phenomena avoids inappropriate reductionist and deterministic assumptions.
Inhibitory repetitive transcranial magnetic stimulation (rTMS) at 1 Hz increased the frequency of abnormal body perceptions (ABP) compared to excitatory 15 Hz rTMS in 35 healthy adults, but the stimulation site—right temporo-parietal junction (rTPJ) versus a control site—did not affect ABP frequency. Responses to an own-body transformation task were slower with 1 Hz than 15 Hz rTMS, also regardless of site. ABP from rTMS at either site was accompanied by electroencephalographic power decreases across all frequencies at left anterior and central cortical sites. These results suggest that inhibitory rTMS can induce ABP, but the rTPJ may not have a specific role in this process.