The ancient part of your brain that controls your consciousness, found by scientists

For decades, scientists have thought that human consciousness arises from the newest and most sophisticated parts of the brain.

But a Cambridge scientist now claims that the fundamental basis of our experience may be controlled by a far more primal structure.

In a review of over a century of scientific research, neuroscientist Dr Peter Coppola examined stimulation studies, animal experiments, and neurological case reports.

Based on this wide-ranging evidence, Dr Coppola argues that consciousness might arise from our ancient 'lizard brain'.

If true, that would mean that consciousness is not such a uniquely human trait as scientists had once thought. 

Writing in The Conversation, Dr Coppola says: 'These reports are striking evidence that suggests maybe the oldest parts of the brain are enough for basic consciousness.

'In turn, this may influence patient care as well as how we think about animal rights.

'In fact, consciousness might be more common than we realised.'

The human brain is a little like a Russian nesting doll, with the parts that evolved most recently on the outside and the older, more basic parts nestled towards the centre.

The recently evolved outermost part of the brain is known as the cortex, which is responsible for complex tasks like memory, thinking, learning, reasoning, and problem-solving.

Meanwhile, the inner region, known as the sub-cortex, hasn't changed much in over 500 million years of evolution.

Often referred to as the 'lizard brain', these primal areas are responsible for monitoring basic impulses and sensations such as hunger, thirst, pain, pleasure, and fear.

Previously, scientists thought that the most recently evolved areas of the cortex, known as the neocortex, were the likely origin of conscious experiences.

The subcortex was considered necessary for consciousness, like how electricity is necessary to make a television work, but not sufficient to create consciousness by itself.

However, Dr Coppola says that scientists have been underestimating the importance of the brain's oldest regions.

Dr Coppola looked at a type of experiment called a stimulation study in which electricity or magnets are used to interfere with parts of the brain.

Interfering with the neocortex produces powerful effects, including changing your sense of self, creating hallucinations, or affecting your judgment, but affecting the patterns of the deeper regions produces even more profound effects.

Dr Coppola says: '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.'

This was a strong hint that the older regions of the brain were very important for consciousness, but it wasn't enough to show that the lizard brain alone was capable of producing consciousness.

To make that jump, Dr Coppola looked at cases where people and animals have had parts of their brains damaged or removed.

Damaging the cortex and neocortex produces changes in conscious experience, but damage to the subcortex and other deep regions often leads to the total destruction of consciousness through death or coma.

Even more strikingly, there are rare cases of children born with a condition called hydranencephaly that causes them to lack most of their cortex.

Dr Coppola says: 'According to medical textbooks, these people should be in a permanent vegetative state.

'However, there are reports that these people can feel upset, play, recognise people or show enjoyment of music.'

Likewise, Dr Coppola refers to a number of 'extreme' experiments on animals in which rats, cats, and monkeys had their neocortex surgically removed.

Even without this supposedly vital part of the brain, the animals were able to show emotion, groom themselves, parent their young, and even learn.

This suggests that the subcortex alone is sufficient to produce some level of conscious experience.

However, this doesn't mean that the cortex and neocortex aren't adding anything to our human consciousness.

Dr Coppola says: 'The newer parts of the brain – as well as the cerebellum – seem to expand and refine your consciousness.'

These regions take the basic building blocks of awareness and add in the language, moral reasoning, sense of self, and creativity that make human consciousness unique.

That would explain how the richness of human consciousness is able to emerge out of such primitive pieces of brain machinery.  

But, if Dr Coppola is correct, this means that a basic level of consciousness is likely older and much more widespread than anyone had previously thought.