Return to the Brain
A neurone is another name for a brain cell. It consists of a cell body projecting from which are a number of short branches called dendrites. The dendrites receive messages from other neurones and the message is transmitted though the axon which is a tubular extension of the cell. This message ( or nerve impulse ) can only travel one way. Furthermore a cell may receive many impulses before it transmits its own impulse and, interestingly, does not know from which of its neighbouring cells it has received the impulse. As each neurone is small compared to the size of the brain it is apparent that a nerve impulse must pass through many neurones in transmitting the information.
As mentioned there are a million billion connections between the brain cells resulting in a vast number of neural pathways. Many of these pathways will be redundant or will serve no useful purpose. It follows that the brain must have a means of selecting only those pathways which produce useful behaviuor.
If we look at the early movements in infants, the grasping response is the result of 'firng patterns' of messages transmitted between the nerve cells. Initially the patterns are random. When trying to grasp a toy with one hand, the other hand and legs also move. When the movement is successful the pattern which produced it is reinforced, increasing the number of connections and thus making it more likely that in the future the correct pattern will be repeated. As the baby continues to experiment more and more successful patterns are produced and the unsuccessful ones weaken. The creation of the strong links also speeds up the response time and makes it less likely that the pattern will be lost.