Wednesday, 31 October 2007

Learning & Memory (1)

They very day we open our eyes to this world, our brain stars learning. Some believe that even in the fetal form we become sensitive to surroundings and can listen to voices. Along with the ability to feel, see, and hear comes the capacity to learn and remember. Some studies reveal that, these activities can be rudimentary, automatic, even biochemical. For example, a fetus, after an initial reaction of alarm, eventually stops responding to a repeated loud noise. The fetus displays the same kind of primitive learning, known as habituation, in response to its mother's voice. So it means that even before our eyes are open we start interacting with this world.

If we go down to the ladder of animal kingdom, i.e. if one reads the development of nervous system, we find series of pattern and that to step wise. Amoeba - the simplest animal responds to light, chemicals, and temperature but no receptors has been found on it, its single cell body is specialized to perform the function for sense response. Climbing up we find sensory receptors (Euglena), nerve net (hydra), interconnected nerve nets (hydra, jelly fish etc) , ganglia and nerve cords (like in planarians, snails, crab, bivalves), and then the development of brain starts from crustaceans and further in arthropods... and taking it up to mammals.

If we observe the trend carefully, that simple cell like in Amoeba performed all the functions of the life but with increased multicellularity cells become specialized for one or two functions.This also paved the way for tissues and then oraganism and organ systems later on for particular fuctions rather than single cell performing all the functions. Nature has carefully bestowed this function attributing to the survival of the organism.

Now back to my topic of learning and memory, whether primitive or specialized nervous system, all organisms learn from their environment and thus perform their tasks according to the changes in the nature, but I doubt that whether lower invertebrates I mean other than mammals have memory to. Well birds and fish migrate, it is their memory that they follow almost same path each year or just response to stimuli. I need to search on this, if I get, next time I will post on this.




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