Week 11

This week we covered learning and memory. We learned (now insn't that wierd learning about learning?) about the different kinds of memory and amnesia. What I found to be most interesting was the work of Carl Lashley and Wilder Penfield. Lashley was searching for the physical location of memories, also called engrams. By using a technique called ablation, where parts of the brain are lesioned or removed, Lashley was able to conclude that the memory deficits caused by the lesions were not related to their location on the cortex of the brain, but rather to the size of the lesion itself. Thus all parts of the cortex contributed equally to learning and memory. Subsequent research however, has shown that this is not entirely true.

Wilder Penfield was a neurosurgeon who would stimulate the brain's of his patients while they were undergoing neurosurgery. Patients are awake when this type of surgery occurs so when portions of their brain are stimulated they can talk about what sensations are being evoked. Penfield found that when the temporal lobes were stimulated complex memories and sensations would be produced. This would lead one to the conclusion that memories are stored in the cortex of the temporal lobes. However, more research found that when areas of the temporal lobe associated with a particular memory were removed that same memory could be evoked when the cortex was stimulated elsewhere. It is also important to consider that many of Penfield's patients were epileptics who had abnormal cortex on thier temporal lobes.

Memory gets much more complicated once you venture to the structures inside the brain such as the hippocampus and realize that the internal structures communicate with the neocortex, and that lots of different chemical events are occurring for each kind of memory that we have (declarative, procedural, short-term, long term and working). It gets even more confusing when you think about the fact that many people who suffer from amnesia still have the ability to learn and remember new things!