Long Term Memory The Info example essay topic

The Human Memory The reason people exist is because of two important things: memory and language, which have been vital in the evolution of humanity. (Our ancestors needed language to explain how to light a fire to keep them warm and a memory to remember how to do it). So we have a memory because if we did not we would never have evolved far enough for you to ask this question in this place. So how does it work?

The process involve in the human memory are very complex... I will present you the neuralgic and biologic part then Aurelie will talk about the characteristics of our human memory and then Sebastien will explain the troubles of the memory... Despite big advances in recent years, memory is still a bit of mystery and there are disagreements among the experts about exactly what is going on. But now memory is seen as a function of the brain, and is not placed any more in the heart... It's defined as the ability to store and retrieve information. Codes of memory The new ways of communication taught us that information could be on different supports: Email, lettre, disc...

The memory acts in the same way and info are supported by specific codes: sensorial codes, motor codes and symbolic codes. A special memory exists to each different info: tactual, visual, auditory and olfactory but these codes don't have the same importance. Visual and auditory codes are the most important codes because they are the primary means of language in the memory. The auditory code is concerned with longer times than the visual one.

(You remember longer a sequence of letters if you hear them than if you see them). Olfactory codes are very difficult to study and motor codes are not studied at all. These codes seem to be transitory and the info driven is encoded in the visual way or a linguistic way... That's why you probably heard about the visual memory and the auditory memory. In the long term memory the info learned becomes more and more abstract with time. The language arrived to a conceptual memory, the visual memory arrived to an ana logic memory: visual- spatial but in fact an info is encoded with the two means: verbal and visual (a picture is named).

These two codes are very complementary; visual codes are good for global spatial info but bad for a sequential order and verbal codes are good for the order of encode and analyze. (refer to image 1) Learning and memorization Learning could unclench two parallel series of events: The first one with the encode, consolidation and storage of info linked to the task (episodic info, sensorial stimuli) and exogenous environment (colors, odors, shapes, sounds, ). The restitution of a special event depends of the context in which info where memorized. The second series of event is transformation in the endogenous state (neurotransmitters, neuro modulators, hormones). To increase the restitution rate of an event, the subject must be replaced in the same endogenous context than for the learning phase. A list of words was presented under the surface to divers and then they were asked to the words on the beach an under the surface; the restitution on the beach decreased of about 40 percent. The process of memorization occurs in four steps: A brief sensorial step: retention of info is destroyed in three hundreds milliseconds a short term memorization: for some seconds this step is a bottleneck in our storage capacities.

They can't treat as much as info they receive. A long term memorization: great capacity of absorption but occurs with the income of new info with a continuous reorganization of the recollections. The remembering process is a second bottleneck limiting the capacities of the human memory: it appears that there is more info present in the memory than available info. Localization of the memory Ways of study: it exists two ways of study psychophysiologic ly the human memory: The direct way: study of the memory in a normal subject or looking for correlation in neuralgic patients. The indirect way: by elaborating theoretic models or study transformations while learning in the brain.

Process of memory: some observations: We can see troubles of the memory only about recent events (Korsakoff syndromes, cranial trauma) they give amnesia for some hours before the accident and touch all the events. More ancient recollections can be influenced by electric stimulation of temporal areas in the cerebral cortex. The destruction of certain parts of the temporal lobe makes it impossible to memorize words, the destruction of others parts makes it impossible to memorize faces or music. These observations show us that we have to consider two process of memorization: A primary process of immediate apprehension and a secondary one which works for permanent and definitive. These two process or mechanisms let us consider two hypothesis: The mechanisms of memorization can be placed in all the brain: rats have as much difficulty to memorize something as much of their cerebral cortex is destroyed. The mechanisms of memorization can be localized in certain areas of the brain.

In fact, we think that the brain, in long-term memory, works in its totality. Scientists have seen that when a learning action occurs, the action of neurons are modified all over the brain but these modifications are different with respect to the area: I mean that the whole cortex would participate to the learning action but specifically from an area to an other. Scientists prefer make the difference between three types of memory, related to different areas in the brain (you will see with Aurelie more specific memories and their localization) the three type of memory are: The association memory located under the cortex and which is de multiplied when septum and hippocampus are destroyed. The representation memory which let you remember past events and comportment, this memory would be located in the temporal structures: prefrontal cortex and hippocampus. The abstract memory which let you remember logic process and manipulation concepts, this memory is based in the temporal, occipital and parietal neo-cortex. (refer to image 2) Now I will talk about the physical mechanisms of the memory. A sensorial info enters the central nervous system and stays there for some times thanks to groups of neurons, after that permanent synaptic modifications occur in the neurons involved in these circuits.

Scientists mainly studied neurons and their functional modifications for learning. These modifications occur on the synaptic characteristics of neurons. They let the nervous influx create new ways in the brain and when these ways are stabilized, they constitute the organic subtract of the memory. Phenomenons of synaptic plasticity are very important for the learning and restitution process.

Experiences showed that transmission through particular cerebral synapses increases significantly for some days after a given learning. We don't know yet if the creation of new nervous connections in a structure is due to all the neurons or to specialized cells: memory cells. Scientists showed that when many nervous influx pass through a synapse, the synapse becomes easier to get through; this process can't explain the long term memorization, we have to find long term modifications in the neurons. Maybe the ribonucleic acid can be involved in synthesizing specific proteins in each neuron. These proteins could be the basis of the memory.