Why is dispersion of memory important*

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Annis Perry
5 years ago
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1 What is memory* It is a web of connections Research has shown that people who lose their memory also lose the ability to connect things to each other in their mind It is these connections that let us understand cause and effect, learn from our mistakes and anticipate the future

2 Why is dispersion of memory important* With memory being dispersed it means that memory is formed in such regions of the brain responsible for language, vision, hearing, emotion and other functions It means that memory (and learning) arise from changes in neurons as they connect to and communicate with other neurons It means that a small reminder can reactivate a network of neurons wired together in the course of registering an event allowing you to experience the event anew. Remembering is reliving (or is it?? more about that soon)

3 What is Memory* The act of memory or remembering something is a process of bringing back on line those neurons that were involved in the original experience Those neurons re present that world of the past. But remembering is imperfect we don t get everyone of the original neurons firing and those that do may not fire with the same intensity etc. (if we did our memories would always be strikingly vivid and realistic) Thus our neuronal representation our memory is a low resolution and often inaccurate copy of the real experience

4 Are there Limits of memory?* Neuroscientists have long tried to measure our maximum mental volume. The brain s exact storage capacity for memories is difficult to calculate. First, we do not know how to measure the size of a memory. Second, certain memories involve more details and thus take up more space; other memories are forgotten and thus free up space. Additionally, some information is just not worth remembering in the first place. Then there is the astounding cognitive feats achieved by dedicated individual trying to improve their memories, and people with atypical brains.

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6 H.M.* The implications of all these findings was enormous. Scientists saw that there were at least two systems in the brain for creating new memories. One, known as declarative memory, records names, faces and new experiences and stores them until they are consciously retrieved. This system depends on the function of medial temporal areas and the hippocampus the parts removed in H.M. Another system, commonly known as implicit learning, is subconscious and depends on other brain systems. This explains why people can jump on a bike after years away from one and take the thing for a ride, or why they can pick up a guitar that they have not played in years and still remember how to strum it.

7 Memory Declarative Memory The sort of memory that involves conscious awareness* This sort of memory involves 4 steps 1/encoding 2/storage 3/retrieval or recall 4/forgetting

8 Memory Declarative Memory: encoding* Encoding is a biological event beginning with perception through the senses. The process of laying down a memory begins with attention (regulated by the thalamus and the frontal lobe) making the experience more intense and increasing the likelihood that the event is encoded as a memory.

9 Memory Declarative Memory: encoding* The perceived sensations are decoded in the various sensory areas of the cortex, and then combined in the brain s hippocampus into one single experience. The hippocampus is then responsible for analyzing these inputs and ultimately deciding if they will be committed to long term memory. It acts as a kind of sorting centre where the new sensations are compared and associated with previously recorded ones. The various threads of information are then stored in various different parts of the brain

10 Memory Declarative Memory: encoding* The connections between brain cells aren't set in concrete they change all the time. Brain cells work together in a network, organizing themselves into groups that specialize in different kinds of information processing. As one brain cell sends signals to another, the synapse between the two gets stronger. The more signals sent between them, the stronger the connection grows. Thus, with each new experience, your brain slightly rewires its physical structure. how you use your brain helps determine how your brain is organized. It is this flexibility, which scientists call plasticity, that can help your brain rewire itself if it is ever damaged.

11 Memory Declarative Memory: encoding Long term potentiation* A phenomenon called long term potentiation allows a synapse to increase strength with increasing numbers of transmitted signals between the two neurons. Think of this phrase Long term & potentiation Simply put there is a facilitation and increase in activity in the cell that receives input from another neuron and this is long lasting

12 Long term Potentiation* Consider two neurons Presynaptic neuron Post synaptic neuron During learning or encoding a memory the goal of the presynaptic neuron is to pass an electrical impulse to the postsynaptic neuron

13 Memory Storage* What we usually think of as memory in day today usage is actually long term memory, but there are also important sensory and short term memory processes, which must be worked through before a long term memory can be established. The different types of memory each have their own particular mode of operation, but they all cooperate in the process of memorization, and can be seen as three necessary steps in forming a lasting memory.

14 Memory storage* Part of the prefrontal cortex appears to play a fundamental role in short term memory. It both serves as a temporary store for shortterm memory, where information is kept available while it is needed, but it also "calls up" information from elsewhere in the brain. So short term memory has the ability to remember and process information at the same time thus often called working memory.

15 Memory Storage* Short term memory acting as this kind of scratch pad for temporary recall of the information which is being processed at any point in time, has been referred to as "the brain's Postit note". It holds a small amount of information (typically around 7 items or even less) in mind in an active, readily available state for a short period of time (typically from 10 to 15 seconds, or sometimes up to a minute).

16 Memory Short term or working memory* The forgetting of short term memories involves a different process to the forgetting of long term memories. When something in short term memory is forgotten, it means that a nerve impulse has merely ceased being transmitted through a particular neural network. In general, unless an impulse is reactivated, it stops flowing through a network after just a few seconds. Now you can see the tie in to LTP!!

17 Memory Long term memory* Long term memory is, obviously enough, intended for storage of information over a long period of time. Despite our everyday impressions of forgetting, it seems likely that long term memory actually decays very little over time, and can store a seemingly unlimited amount of information almost indefinitely. Indeed, there is some debate as to whether we actually ever forget anything at all, or whether it just becomes increasingly difficult to access or retrieve certain items from memory.

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