Memory

Before we delve into the highly misunderstood brain function that is memory, we must first look at instinct. Ridley writes about Instinct in chapter 7, looking at language and how language is an innate knowledge that every person is familiar with. Our instincts are genetically-determined, we do not learn to blink or cry for we are genetically programmed to do so. If instincts through evolution have made species genetically advantageous, why then must some things, like vocabulary and driving, still be learned? The answer is because many things are still flexible. However, as Ridley writes, //"Thus, learning gradually gives way to instinct...Perhaps even literacy would become innate eventually if illiterate people were at a reproductive disadvantage for long enough. In effect, since the process of natural selection is one of extracting useful information from the environment and encoding it in the genes, there is a sense in which you can look on the human genome as four billion years' worth of accumulated learning" (221).//

Whether it is dogs, bees, or sea slugs, learning occurs in many things. This leads to the question: What is learning? Electrical nerve signals travel down nerve cells, eventually reaching the synapse (the junction between two nerve cells). When learning occurs, these synapses are strengthened. The molecule in charge of this: cyclic AMP. This molecule works by changing itself when something is learned, activating other molecules, such as CREB, which is responsible for much of learning and memory.
 * "Just as we underestimate the degree to which human brains rely upon instincts, so we have generally underestimated the degree to which other animals are capable of learning" (222).**


 * But what does this have to do with memory?**

Everything. Research leads to an interesting thought that memory is simply the tightening of the connections between neurons. How does this work? After a study done on fruit flies, scientists created the hypothesis that integrins (the things that pass information along) are central to the development of memories. Within the brain lies the hippocampus, and within that is the Ammon's horn. In Ammon's horn there is a large volume of pyramidal neurons, which gather together the inputs of other sensory neurons. Although it is difficult to make these pyramidal neurons fire, if two separate inputs arrive at the same time it will indeed fire. These two inputs are what create associative memories, like the association between France and the Eiffel tower. Long-term potentiation (key in the development of memories, and the reason for associative memories) "absolutely depends on a change in the properties of synapses, in this case the synapses between the inputting cells and the pyramidal cells. That change almost certainly involves integrins" (228). Memory comes in all different forms; associative, procedural, declarative, implicit and explicit. Studies have shown that these different types of memories are formed in different areas of the brain, leaving sufferers of brain damage with the ability to form certain types of memories but not others. Yet, "neuroscientists have gradually narrowed down the search for the most vital of all memory organs to one principal structure, the perirhinal cortex. It is here that sensory information, sent from the visual, auditory, olfactory or other areas, is processed and made into memories, perhaps with the help of CREB" (229).

Still this leaves us with questions. Where are memories stored?

The information processed in the perirhinal cortex, Ridley writes, "is then passed to the hippocampus and thence to the diencephalon for temporary storage. If it is deemed worthy of permanent preservation it is sent back to the neo-cortex as a long term memory" (229). Memory, the tightening of synaptic gaps to remember the ever changing factions of today's society, acts as a counter measure to the impossibly slow changes of the genome responsible for our instincts.

Although it seems like a mess of information and puzzle pieces slowly being put together, we know one thing for certain: memory makes us. media type="custom" key="24931366"