Ancient brain structures may underpin consciousness, Cambridge scientist says

A Cambridge neuroscientist argues that consciousness may derive from the brain’s oldest structures rather than the cortex, based on a century’s worth of stimulation studies, animal experiments, and neurological case reports. Dr. Peter Coppola conducted a broad review and says the evidence points to the subcortex and hindbrain as potential sources of basic conscious experience. The commentary, published in The Conversation, suggests that consciousness might be more widespread in the brain than once thought and could influence patient care and debates over animal cognition and rights.

Coppola notes that interference with deep brain regions can produce effects on consciousness that rival or exceed those seen when the cortex is disrupted. In stimulation studies, electricity or magnets applied to older brain areas have yielded powerful changes in perception, mood, and awareness. He cites examples such as inducing depression, waking a monkey from anesthesia, or knocking a mouse unconscious. He adds that stimulating the cerebellum—long considered less central to consciousness—can alter conscious sensory perception. "We can induce depression, wake a monkey from anaesthesia or knock a mouse unconscious. Even stimulating the cerebellum, long considered irrelevant, can change your conscious sensory perception," Coppola writes. These observations strengthen the case that the brain’s oldest regions may play a larger role in conscious experience than previously acknowledged.

The analysis also highlights cases in which substantial parts of the cortex have been damaged or are absent, yet some conscious functioning persists. Hydranencephaly, a rare condition in which children are born lacking most of the neocortex, is often described in textbooks as resulting in a vegetative state. Coppola notes reports where such individuals appear to feel upset, interact with others, enjoy music, or recognize familiar people, suggesting that older brain regions may be sufficient for at least basic awareness. In parallel, extreme animal studies—where the neocortex was surgically removed in rats, cats, and even monkeys—showed that animals could still exhibit emotion, grooming, parental behavior, and learning, implying that subcortical circuits can sustain a level of conscious experience without the cortex.

That said, Coppola underscores that the cortex and the cerebellum likely add substantial layers to human consciousness. The newer parts of the brain, he argues, expand and refine the basic building blocks of awareness to yield language, moral reasoning, a sense of self, and creativity that characterize human experience. If correct, this view would not erase the cortex’s contributions but would reposition the locus of foundational conscious experience closer to ancient neural machinery. Such a shift could influence how clinicians assess brain injuries, disorders of consciousness, and the moral status attributed to other animals.

The discussion sits within a broader scientific context in which functional magnetic resonance imaging (fMRI) is used to observe brain activity. fMRI detects metabolic changes, such as shifts in blood flow, to infer which brain regions engage during tasks or experiences. While a powerful tool for mapping function, imaging findings do not by themselves solve the so-called hard problem of consciousness—the question of why brain processes are accompanied by subjective experience. Coppola’s review emphasizes that converging lines of evidence from stimulation, clinical case reports, and animal studies remain essential in evaluating where conscious experience arises. More research across species and clinical contexts will be necessary before the field reaches a consensus about the primacy of subcortical structures in consciousness.