A central debate in philosophy and neuroscience concerns whether prefrontal cortex (PFC) activity is essential for consciousness. This synthesis of research using intracranial electrical stimulation (iES) in humans shows that stimulating only certain prefrontal regions—the orbitofrontal cortex and anterior cingulate cortex—reliably alters conscious experience. In contrast, stimulating anterolateral prefrontal sites, often emphasized by higher-order and global workspace theories, rarely produces reportable changes in consciousness. The variety of iES-elicited effects (emotions, thoughts, olfactory and visual hallucinations) shows no clear relation to the immediate environment, challenging the idea that the PFC is the basis for conscious perception. The findings suggest a specific role for orbitofrontal and anterior cingulate cortices in supporting emotional aspects of conscious experience.
Electrical stimulation of the orbitofrontal cortex (OFC) in 22 neurosurgical patients with epilepsy produced a range of subjective experiences, mostly neutral or negative (aversive smells, tastes, sadness, anger). Negatively valenced experiences were more common with left-hemisphere stimulation, while neutral effects were strongly right-lateralized. Most elicited effects came from stimulation around the transverse orbital sulcus, with no effects from the most anterior OFC. The findings suggest a dissociation between a silent anterior OFC and a responsive middle/posterior OFC, and support a causal role for the OFC in integrating affect with multimodal sensory experience.
Different styles of meditation produce distinct patterns of brain activity and deactivation, according to a systematic review and meta-analysis of 78 functional neuroimaging studies. Four common styles—focused attention, mantra recitation, open monitoring, and compassion/loving-kindness—showed reliably dissociable activation patterns consistent with their psychological aims. Some brain areas, such as the insula and dorsal anterior cingulate cortex, were recruited across multiple techniques, but convergence was the exception. A preliminary effect-size analysis found medium effects for both activations and deactivations, suggesting potential practical significance. The review also raised methodological concerns and suggested avenues for future research.