What we learned from gruesome decapitation experiments.
The relationship between mind, brain, and body has kept philosophers and scientists busy for centuries. Some of the first interesting – albeit gruesome – experiments on the role of the body in human consciousness considered life after decapitation.
In 1905, French physician Gabriel Beaurieux believed he had communicated with prisoner Henri Languille after his head had been severed from his body.
Writing of the experience, Beaurieux said:
“I called in a strong, sharp voice: ‘Languille!’ I saw the eyelids slowly lift up, without any spasmodic contractions – I insist advisedly on this peculiarity – but with an even movement, quite distinct and normal, such as happens in everyday life, with people awakened or torn from their thoughts.”
Almost two decades later, Soviet scientist Sergei Brukhonenko reportedly kept a dog’s severed head alive for nearly six months using a primitive heart-lung machine.
Video footage allegedly shows the head responding to light, sound and citric acid stimuli.
Consciousness and non-physical properties
Investigations into human consciousness have moved on since these initial observations – though we haven’t got away from decapitation just yet. More recently, however, neuroscientists have questioned just how it is that physical matter comes together to make the mind.
In 1995, Francis Crick wrote in The Astonishing Hypothesis that we are nothing more than an “immensely complex collection of neurons”.
This hypothesis is a form of reductive physicalism – a philosophical position to which modern neuroscience typically subscribes – that everything in existence is no more than its physical properties.
Again using animal decapitation, though this time with rats, neuroscientists have explored the question of how long brain activity is observed after death – a step forward from just consciousness.
In a 2011 experiment, it was reported that decapitated rats’ time to unconsciousness – defined by a decrease in cognitive activity of 50 percent – was 4 seconds.
The researchers also observed a very large and much later slow wave in brain activity. This was interpreted as what they called a “wave of death” – when all the brain’s neurons died at the same time – and perhaps, the ultimate border between life and death.
But some believe that the mind is more than just the sum of its physical brain cells. A contrasting position to physicalism is the dualist assumption that the physical and the mental are fundamentally different substances.
Furthermore, some philosophers and scientists have suggested that “information may be the key to consciousness“.
Consistent with this idea is integrated information theory, which accepts the existence of consciousness, but controversially implies that anything at all may be conscious – even a smartphone – if it possesses a sufficiently high “phi”: a measure of information in a system which cannot be reduced to that specified by its parts.
From psychological moments to mortality
While I have left out many important details in this fascinating discussion, better understanding the link between mind, brain and body has been the focus of my own research, in recent years through looking at the functions of the vagus nerve.
Higher vagus nerve function (measured and indexed by heart rate variability) supports a person’s capacity for emotion regulation, social engagement and cognitive function.
By contrast, impaired vagal function – and lower heart rate variability – may play a role in the onset of depression…