Scientists have just discovered, for the first time, a giant neuron wrapped around the entire circumference of a mouse's brain. The neuron was one of three found to be densely connected across both hemispheres and may finally explain the origins of consciousness. This discovery was found using a new imaging technique.
This new imaging technique could help us figure out if similar structures have gone undetected in our own brains. In a recent meeting, the Brain Research Through Advancing Innovative Neurotechnologies in Maryland, a team from the Allen Institute for Brain Science, described how this neuron wraps around the brain's circumference like a crown of thorns.
It has been discovered that all three giant neurons emanate from a part of the brain that has been shown to have intriguing connections to human consciousness in the past - the claustrum - a thin sheet of grey matter that could be the most connected structure in the entire brain. This region of the brain communicates with almost all regions of the cortex to achieve many higher cognitive functions such as language, long-term planning, and advanced sensory tasks, such as seeing and hearing.
In 2014, a 54-year-old woman checked into the George Washington University Medical Faculty Associates in Washington DC for epilepsy treatment, which involved gently probing various regions of her brain with electrodes to narrow down the potential source of her epileptic seizures. When they started stimulating the woman's claustrum - an area of the brain that has been referred to as the conductor of consciousness, they found that they could effectively switch her consciousness off and on again.
When this area of the brain was zapped with high frequency electrical impulses, the woman lost consciousness. She stopped reading and stared blankly into space. Furthermore, she didn't respond to auditory or visual commands and her breathing slowed. The moment the stimulation stopped, however, she regained consciousness with no memory of what just happened. During two days of experiments, the same thing happened again and again. It was later noted that this kind of abrupt and specific stopping and starting of consciousness had never been seen before.
In another experiment conducted in 2015, the effects of claustrum lesions on the consciousness of 171 combat veterans with traumatic brain injuries were examined. It was found that the claustrum damage was associated with the duration, not frequency, of loss of consciousness, implying that it could play an important role in the switching on and off of conscious thought, yet another region could be involved in maintaining it.
Nevertheless, while it's been discovered that new giant neurons are connected to the claustrum, it doesn't mean that the researchers hypothesis about consciousness is correct. There's still a long way to go. It is also important to note that these neurons have only been detected in mice so far, and the research has yet to be published in a peer-reviewed journal.
Still, the discovery offers an intriguing piece of the puzzle that may help make sense of this part of the brain and its relation to the human experience of conscious thought.
Bonus video: What Is Consciousness
