Lecture 5 - The Mind's I
If we were to take two brains and place them side by side, there would be no obvious immediate difference. Yet the two brains would have come from two very different individuals with entirely different character traits, memories and skills. So where is the physical basis of this difference? We are gradually understanding more about how experience can shape the connections between neurons. Extensive work has been done on a much simpler nervous system, that of the sea slug Aplysia. This relatively primitive organism can learn to modify how it retracts its gill in a variety of situations. The basis of this effect is the release of a particular transmitter which acts not to transfer a simple signal, but to modulate certain neurons. This modulation is where neurons are biased to respond in a certain way for a particular time interval, such as one hour. If the release of the transmitter occurs repeatedly, then longer-term changes occur to accommodate a longer lasting change in behaviour. These longer-term changes involve the manufacture of new proteins within the neuron, which will change its way of responding, and even its shape, including the connections it makes with other cells.
Similar processes occur in certain parts of our own brains and are important therefore in complex functions such as memory. There are many different types of memory, processed in different parts of the brain. Even for a particular type of memory, various different brain regions work in parallel. Another important function of our sophisticated brains is language. Again, many different brain regions contribute to language. Everything we are is the product of our brains, but brains composed of specialised, different regions. However, no region works in isolation, but rather in conjunction with one another, like instruments in an orchestra.
About the 1994 CHRISTMAS LECTURES
Then Dr Susan, now Baroness Greenfield (b.1950), presented the 1994 CHRISTMAS LECTURES as a five-part series, entitled 'Journey to the Centres of the Brain'. Our brains are ourselves. Every emotion, prejudice and hope is grounded in a molecular scenario somehow and somewhere in the secretive, silent organ between the ears. These lectures will explore what we know, and what still mystifies us, about the workings of the brain. Starting with no prior knowledge, we shall see what the brain looks like, how it generates electricity, and how it uses chemicals to process information. We shall be left with the thought that we know a great deal about how different brain regions function, but how such regions work together to generate a cohesive, individual individual consciousness, remains a tantalising puzzle.