Wednesday, March 19, 2014

The memory function of human brain

Human memory is not a single ‘vessel’ to be filled but rather a complex set of interrelated memory systems. All the memory systems are interdependent and have information going in both the directions. Short –term or working memory is the most critical memory system. All incoming information is organized and processed in the working memory by interaction with knowledge in long-term memory. The working memory processing capacity is only a relatively small number ( 5- 9) psychological units at any one moment.

Multiple memory  system of human brain

Memories are stored in the brain as three dimensional constructions.
Sensory memory –impressions of senses – the sensory register receives lots of information from one or more body’s sensory receptor (e.g., sight, smell, touch, sound and taste). Sensory impressions first registered. The act of selective perception takes place within in the sensory register. The information remains in the sensory register for  milliseconds to seconds and then disappears through decay or replacement.
Short- term memory (STM) –After a sensory impression has registered, it then passes into the STM. The memory can be retained in STM for up to 20 seconds or more if rehearsed repeatedly. STM can hold up to 7 plus or minus 2 items. The capacity of the working memory can be increased if the material is chunked into meaningful parts. STM contains our thoughts of the present moment and limited in capacity. It is like a desk top upon which sort out more valuable information.
Long – term memory (LTM) – if the information is repeated, may then be moved to LTM for long-term use.LTM has unlimited capacity of memory. Semantic coding takes place upon rehearsal of the information to be stored and the information is permanently stored in LTM and is subject to search and retrieval.  It can be thought of as a file. To get the information stored in LTM, it requires that it can be ‘encoded’ in some form.  Paivio (1978, 1986) proposed a theory of dual coding for memory banking i.e. a verbal system and an image system. Verbally presented material is encoded only in verbal system, while visually presented material is encoded in both the verbal and image systems. Moreover single coding is used for ‘text’ and pictures have ‘dual coding’.
 Response generator – the processes of search and retrieval are performed by the response generator, which initiate recall directly from LTM or move information in to working memory. The response generator forwards the message to the effectors / muscles or glands to perform the action (response).
Human mind tries to identify and grasp the properties of similarity, symmetry, depth and continuity.

Storage format of information

 Human brain stores information in 3 major methods.
Analogical method - the object is represented as a picture in the memory.
Propositional method – the relationship is represented in abstract and language like statements.
Distributed model –objects are represented as nodes and the relationship is given as arcs.

Registration of information

Information is registered in the brain in 3 ways: from seeing (visual memory), hearing (auditory memory) and doing (kinaesthetic memory). Most auditory memories are stored in the left side of the brain’s neocortex; visual memories are stored in the right side of the neocortex. Kinaesthetic memories are stored in the cerebellum. The general trend is that memory constitutes 65% visual, 20% auditory and 15% kinaesthetic. When a memory is encoded visually, auditorily and kinaesthetically, it will remain in a maximum number of brain cells.

Basic mechanics of memory formation

Memories are stored in the form of patterns of electrical impulses. Short term memory is laid down by electrical mechanism and the impression is created by the temporary strengthening of synaptic connections. The effect fades away minutes or hours later. Long term memories are registered in place for weeks or years with changes in the amount and composition of the protein molecules that reinforce the synapses connecting the nerve cells. Even long term memories, however erode with time. A messenger molecule called cyclic AMP plays a central role in memory formation. Another intriguing molecule CREB is also critical for learning and memory.

Modes of memory formation

Receiving information – sensory input causes a message to travel down a neuron to a synapse, then to receptors.
Connecting neurons – the transmitting neuron signals the molecule Cyclic AMP to relay the message to the cell’s nucleus through chemical cascade.
Strengthening connections – now activated, the memory molecule CREB stimulates the production of new proteins.
Storing memories – once the proteins go back up to the synapse and strengthen the connection between the two neurons, a memory is formed.
Memory is a biological process that can be manipulated like anything else. Hippocampus is crucial for converting immediate perceptions into memories.You can not only disrupt it, you can improve it. The brain is subject to the ‘use it or lose it law’.
Three broad aspects of memory improvement
1.       Surveying the requirements of the task.
2.       Organizing the material and
3.       Repeating what has been learned.

Improving memory by good learning

Whole learning and spaced learning should be adopted. Sufficient time interval is given for the process of fixation and consolidation of memory (retention) after learning. The learned material is recalled after a brief period time (recall). A habit of careful observation to details should be developed (recognition).

"Memory is the treasure of the mind." - English proverb.

"Memory the mother of all wisdom." -Aeschylus.

" the diary that we all carry about with us." -Oscar Wilde.

"Memories are timeless treasures of the heart."

1 comment:

  1. Thanks for the update you have nicely covered this topic. keep it up
    Smallest Expandable Memory