Seite - 33 - in Cyborg Mind - What Brain–Computer and Mind–Cyberspace Interfaces Mean for Cyberneuroethics

Presentation of the Brain–Mind Interface • 33 The Brain The brain is the most complex organ in the human body and is protected by the skull against any outside interference other than the neurons in the spinal cord and the brainstem, as well as hormonal changes in the blood supply.3 It is the organ that most profoundly distinguishes human beings from other species, including other primates, and is an extremely complex network of neuronal structures supporting specific personal aspects and character- istics. These include an individual’s identity, self-awareness and his or her capacity to reason and make meaningful relationships. This is why so much importance is attached to the human brain and to understanding the very grave concerns that are associated with any direct intervention on any of its parts.4 Structure of the Brain At its peak, a human brain has around one trillion (1012) neurons, each of which is capable of up to 10,000 interconnections with other neurons. This gives the human brain 10 quadrillion (1016) possible connections, enabling, for example, a person to recognise any changes in his or her environment and communicate these variations to other neurons, thereby directing a bodily response. However, as a person becomes older, some of these neurons begin to die so that by adulthood, only about one quadrillion connections remain.5 As already mentioned, different functions of the brain are generally asso- ciated with distinct areas of this brain. This structure–function relationship occurs not only at the macro-scale, in which the areas are composed of hundreds of millions of neurons, but also at a neuronal micro-scale. As such, the functioning of the brain in terms of processing signals, storing memo- ries and triggering actions is intrinsically associated with the one-to-one linkages formed between the neurons, the types of chemicals used to carry messages between the cells and the relative timings of the exchange of these chemicals. Given that there are billions of neurons, each of which makes tens of thousands of synaptic connections, the complexity of this network is massive. It is possible to consider the brain as if it were a computer, with a binary 0 and 1 code driving the processing, but this is an inadequate comparison. Computers are, undoubtedly, highly capable and their power continues to expand exponentially. However, the brain’s multi-layered complexity makes it a difficult organ to understand at an individual neuronal level. This means that it will take a long time for computers to begin to function at the same level. The pattern and strengths of connections continually change as a person meets new challenges and goes on to record and process each day’s This open access edition has been made available under a CC-BY-NC-ND 4.0 license thanks to the support of Knowledge Unlatched. Not for resale.