Seite - 116 - in Cyborg Mind - What Brain–Computer and Mind–Cyberspace Interfaces Mean for Cyberneuroethics

116 • Cyborg Mind Thus, for Locke, because consciousness of different times can be equated with memory, the existence of memory in an individual is a necessary con- dition of personal identity. For him, ‘as far as this consciousness can be extended backwards, to any past action or thought, so far reaches the identity of that person; it is the same self now, it was then; and it is by the same self with this present one, that now reflects on it, that that action was done’.61 However, what a memory is in terms of its physical reality in the brain remains elusive. Psychologists can demonstrate how memories can be manipulated, created and falsified, but understanding the biological science behind these memories is still in its infancy, although it is accepted that they are made up of many elements, which are stored in different parts of the brain. As already indicated, neurons propagate signals through a combination of electrical pulses that are sent down fibre-like extensions to the point where each neuron touches and connects with another neuron (a synapse). All the action in the brain of an individual occurs at these synapses, where electrical pulses carrying messages are transferred across the gaps between cells. This means that although a memory begins with perception, it is encoded and stored using the language of electricity and chemicals with the connections between brain cells being readily created and changed. They are not fixed and, as messages are sent through these connections, the fine structure of the brain changes slightly. In other words, as each new experience is recorded in a brain, it is slightly rewired. This plasticity is a key part in the brain’s normal daily work, but it can also help the neurons rewire themselves if they are damaged. Furthermore, if the same message is repeated a number of times in the brain, more signals are sent between the neurons and the connection grows. When, for example, a person hears a song, he or she may remember some part of it. If, on the other hand, the song is played repeatedly, it will be more firmly lodged in the memory of the individual. In this way, memories are stored in innumerable cells and synapses, with the brain organising and reorganising itself with every new experience. Neurons in the brain analyse all of the inputs from a person’s sensory organs, such as eyes, ears, taste buds and touch sensors. Their first ‘decision’ is whether or not the input is worth remembering. Indeed, the brain delib- erately ignores vast amounts of information that it receives so that a person does not quickly become overwhelmed.62 Different types of sensory input then get directed to different parts of the brain where each is stored. How they are pulled back together is, at present, poorly understood. In short, it is very important at this stage to not exaggerate scientists’ understanding of the functioning brain. It is one thing to recognise that neurons reconfigure their network and reposition their synapses as a way of 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.