Plasticity Flashcards
Describe what critical periods are
It was once believed that changes in the brain were restricted to critical periods during childhood. Once someone reached adulthood, the brain became fixed. This is not true
Describe how Merzenich studied plasticity in Owl Monkeys
Showed changes in the mapping of somatosensory cortex after amputating a digit; the surrounding fingers take over extra cortex
Why do amputees experience phantom limbs?
Shortly after amputation, the cortical representation of the limb still exists.
What are referred sensations?
A mix of sensations as the cortical representation moves. For example, a person who has lost their hand may experience sensation along the phantom limb when stimulating the face.
Describe unmasking
When existing connections can be expressed due to a reduction in inhibition; an immediate change. This inhibition is what allows ‘borders’ in the brain between limbs.
How is use-dependent plasticity different from unmasking?
use dependent plasticity still moves borders, but slowly, as it is due to the formation of new collaterals in unoccupied territory
What proof is there that plasticity is functional?
Vibration discrimination experiments done in monkeys. Stimulated middle digits with 2 different frequencies and monkeys had to discriminate. Only the monkeys who learned had an increase in cortical area devoted to the middle digits. HUMAN studies show that musicians have larger digit representations than nonmusicians.
What are some of the negative consequences of plasticity
some musicians get focal hand dystonia, which is caused by the rapid movements and sensory input to the digits. When all the digits are moving so quickly in a short period of time, the representation can actually look like one big finger, and they cannot move them individually. To treat this, you must do individual hand exercises.
What is meant by blind people being able to “hear” with their visual cortex
in an experiment done with blind people and controls, participants used echolocation to locate objects in a room. The blind participants visual cortex showed a large amount of activity during echolocation, but the controls did not.
