Modern theories of the brain and Memory

The understanding of the brain and memory was aided to a large extent by advances in technology and methodology in the twentieth century.

The exact location of areas of the brain responsible for memory is even today proving a difficult task, as is the accurate understanding of the function of memory itself.

Many theories are saying that we should stop emphasising 'memory' and concentrate more on the study of 'forgetting'. Their position is that we do not so much remember as gradually forget. . The duplex theory of remembering and forgetting states that there are two different kinds of information retention: long-term and short-term.

For example, you have probably experienced a different 'felling' in the way that you recall a telephone number that has just been given to you and the way that you recall your own telephone number. The short term memory is one in which the idea is 'in' the brain but has not yet been properly coded and is therefore more readily forgotten. The long term memory however has been completely coded, filed and stored, and it will probably remain there for years, if not for life.

Research into direct brain stimulation by Dr Wilder Penfield indicates that the brain records most if not every item to which it pays conscious attention and that this record is basically permanent, although it may not be recalled easily using ordinary methods of information retention.

This theory is supported by electrical stimulation of the brain. When performing craniotomies (removal of a small section of the brain) in order to reduce epileptic attacks, Penfield had first to remove a portion of the skull lying over the side of the brain. Before operation, Penfield conducted a systematic electrical stimulation of the open brain, and the patient, who remained conscious, reported his experience after each stimulation. In an early case Penfield stimulated the temporal lobe of the brain, and the patient reported a re-created memory of a childhood experience.

Penfield found that stimulating various areas of the cortex produces a range of responses but that only stimulation of the temporal lobes leads to reports of meaningful and integrated experiences. These experiences are often complete in that when re-created they include the color, sound, movement and emotional content of the original experiences.

Of particular interest in these studies is the fact that some of the memories stimulated electrically by Penfield has been unavailable in normal recall. Also the stimulated experiences seemed to be far more vivid and accurate than normal conscious recall, which tends to be a generalization.

More recently, theorist have returned to a position similar to that of flourens, in which they are suggesting that every part of the brain may include all memories. British scientist David Bohm and others are suggesting that the brain is more like a mulit-brain in that every one of our multimillion brain cells may, in fact, act as a minibrain, recording in some complex way, as yet indiscernible to our measuring instruments, whole experiences.

Complementing this modern research has been the new discover that we have not one brain but many. Professor Roger Sperry recently received the Nobel prize for his breakthrough work in this area. Sperry discovered that each one of us has a brain that is divided into two upper physiological section, each dealing with different mental functions.

In the 1980s Sperry's work has been continued by Professor Eran Zaidel, who has shown that the range of cortical skills is much more widely distributed than had originally been thought. Zaidel has demonstrated that both cerebral hemispheres seem to have a latent ability to perform the full range of cortical skills.

These skills, which we now know are attributable to the entire cortex, were originally thought to be divided into the left and right hemispheres in the following way: