What if much of what we believe about consciousness is based on a fundamental misdirection, focusing too much on the newest parts of the brain, and neglecting the oldest?
That’s the provocative suggestion in a recent review of a century’s worth of neuroscience research, which argues that theories of consciousness may have overemphasized the cortex at the expense of deeper, more ancient structures.
Most dominant theories pin consciousness to the neocortex (the outer, evolutionarily recent layer of the brain). After all, many of our higher cognitive capacities; language, abstract thinking, planning, are clearly grounded there.
But the review highlights evidence that deeper regions of the brain, notably the subcortex and even the cerebellum, may play more than just a supporting role, they might be fundamental to consciousness itself.
One line of evidence comes from brain stimulation studies. Researchers have shown that applying electrical or magnetic stimulation to the cortex can alter perception, self-experience, or rational judgement. But altering activity in subcortical or cerebellar regions can also profoundly affect conscious experience: from shifting sensory perception to shifting states of awareness, including waking someone from anesthesia or inducing unconsciousness. The fact that stimulating the cerebellum, a region long dismissed as irrelevant to consciousness, can modulate conscious perception is especially intriguing.
The review also weighs cases of neurological injury and extreme brain development. People born without a neocortex, contrary to what classical theory would predict, can sometimes exhibit behaviors consistent with awareness: responding emotionally, recognizing others, or enjoying music. Meanwhile, animals whose neocortices have been surgically removed retain surprising capacities: they continue to play, interact, parent, learn, and express emotion. These observations imply that consciousness, or at least a basic form of it, can persist with just the more primitive brain regions intact.
Putting all this together, the author argues for a shift in perspective: the cortex may refine or expand consciousness, but the deeper, more primitive brain structures may be doing the heavy lifting. Instead of being mere “platforms” keeping the higher brain online, the ancient parts of the brain might themselves be sufficient (or at least essential) for consciousness at the most basic level.
This isn’t just academic hair-splitting. If consciousness depends more on ancient structures than assumed, it could reshape how we approach brain injury, patient care, and even ethical questions about animals, artificial systems, and what it means to be conscious. In short: we might have to rebuild our theories of what consciousness really is, and where it really lives.