4 3 Memory continued  by akshayranga

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									Memory continued-



       Eric kandel- he studied an animal called sea slug. Sea slug has 2000 neurons so one can teach a
        sea slug to get it sensitized to a certain stimulus. He noticed 3 different things at the neuro level.
             1. When we form a memory we get more branching on the neurons (between axons and
                the dendrites)
             2. We also increased the number or synapses.
             3. Also increase the amount of neuro-transmitter. (And these changes can be permanent
                and thus we can form long term memories).

This whole process is called long term potentiation.



       H.M had his hippocampus bilaterally removed. He subsequently unable to form new explicit
        long term memories.
       He could form implicit memories. E.g. he could improve his performance on various tasks
        through practice.
       If you don’t have hippocampus you can have short term memories but you cannot retain them
        and make them long term.
       Clive wearing: had a brain virus that destroyed parts of his brain. He can’t remember the past or
        form new memories. But he can still play music.
       Endless memory (superior autobiographic memory)




Mirror neuron-

       In 1990’s researchers in Italy were studying in behavior of motor neurons in monkeys, using
        single neuron recordings. {These neurons were in a part of the brain that helps plan
        movements}.
       These neurons were very specific in actions which they mediated, for example, one might fire
        when the monkey was using pincer grip (thumb+forefinger). Another might fire when the
        monkey was using a whole-hand grip, etc.
       One day, a pincer grip neuron fired, but not when the monkey was doing something. The
        monkey was looking at the researcher pick up a peanut with his thumb and fore finger.
       A motor neuron that fired when the monkey performed the action also fired when the monkeys
        watched the action.
   They called this neuron a mirror neuron.
   Motor/mirror neurons were extremely specific in terms of the actions they responded to.
   A neuron that responded to a pincer grip did not respond when the action was performed using
    a tool.
   Actually, it turns out that most mirror neurons respond to the goal of the action (e.g. grasping),
    regardless of how the goal is achieved (e.g. precision grip)
   Mirror neurons can also respond to anticipated actions.
   Investigators taught a monkey to pick p and either eat a piece of food or place it on the cylinder
    9 the presence of absence of the cylinder indicated which action was to be performed)
   Particular motor/mirror neurons fired when the monkey picked up the food with the intent (or
    plan) of eating it; others fired when the monkeys intent was to put it on the cylinder.
   When the monkey watched someone pick up some food which neuron fired depended on the
    apparent intent (eat or place cylinder) of the individual being watched.
   So in watching someone, we are internally enacting the actions to come.
   What if the action is hidden from view?
   Mirror neurons that responded to a specific action also responded when the action was
    completed behind a screen.
   E.g. I pick up a ball vs. I make the moved to pick up a ball that is now hidden behind a screen.
   The same mirror neurons are firing in both cases.
   A mirror neuron that fires in response to the sigh of a particular action may also fire in response
    to a sound associated with that same action. A mirror neuron in a monkey that fires when the
    monkey cracks open a peanut also fires when a. the monkey sees someone else cracking a
    peanut. And b. when the monkey heard the sound of a peanut cracking.

What about humans?

   Using brains scans researchers have found mirror system in humans in.
   Motor areas but also in sensory and emotion areas.
   Thanks to mirror neurons, watching someone else perform a skill can help us get better at it. We
    are actually practicing as we watch, on the neural level. When someone is experienced in a
    particular skill, then the motor neurons associated with that skill will not fire more strongly
    compared to someone who is not experienced in that skill.
   E.g. dancers are trained in a particulars style show stronger activation when watching others
    dance in that style than other dancers or untrained individuals.

								
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