Presentation on theme: "Applications of Plasticity : Sensitive Periods for Learning Developmental Plasticity Adaptive Plasticity."— Presentation transcript:
Applications of Plasticity : Sensitive Periods for Learning Developmental Plasticity Adaptive Plasticity
Sensitive & Critical Periods for Learning Definition: refers to a very narrow period of time in an animal’s development in which the animal is pre- programmed for learning to occur. For example, ethnologist Konrad Lorenz studied how young birds imprint (form an immediate attachment) to the first moving object they see after they hatch from the egg. Lorenz found that greylag geese hatchlings imprinted on him and followed him wherever he went. For these geese, the critical period was the first few moments of their life (Lorenz 1937). In humans these critical periods are often referred to as sensitive periods because the time in which they occur is more flexible and broad than critical periods for non-human animals.
Sensitive Periods Definition: Time an organism is more responsive to certain stimulation Lack of stimulation can lead to long term deficit E.g. closed eye from birth leads to later blindness even when eye eventually opened Language acquisition has a sensitive period (0 – 12 years) Learning a new language in teen years can lead to the development of a second Broca’s area!
Review: Developmental Plasticity Changes as a result of experience and maturation Synaptogenesis – new neural connections Synaptic pruning – removal of synaptic connections that are no longer needed Adults have less neural connections than a 3 year old!
Review: Adaptive Plasticity The brain reorganises the way neurons in different regions operate in response to a deficit Deficits can occur from birth or as a result of brain damage Brain plasticity Neuroplasticity
Damage from Birth - Congenital Congenital – E.g. People who are blind from birth may have occipital lobes that are used for senses other than vision This may explain why people who are blind from birth have very good hearing or tactile sensitivity
Damage from Injury When a particular brain area is damaged e.g. stroke other brain areas can ‘take up the slack’ This is what happens when people ‘recover’ from brain damage Nerve cells do not regrow, rather other neurons take over the functions of the damaged cell Rerouting – neurons near damaged area seek new active connections with healthy neurons Sprouting – new dendrites grow May occur near damaged area of in other parts of brain Allows shifting of function from damaged area to healthy area ‘Relearning’ tasks like walking, eating etc. helps these new connections form
Adaptive Plasticity and Experience Why is it so? – Musicians have enhanced motor and sensory areas – Taxi drivers have enhanced functioning of their parietal lobes – Dancers motor areas are enhanced