Presentation on theme: "Applications of Plasticity :"— Presentation transcript:
1Applications of Plasticity : Sensitive Periods for LearningDevelopmental PlasticityAdaptive Plasticity
2Sensitive & 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.
3Sensitive PeriodsDefinition: Time an organism is more responsive to certain stimulationLack of stimulation can lead to long term deficitE.g. closed eye from birth leads to later blindness even when eye eventually openedLanguage 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!
4Review: Developmental Plasticity Changes as a result of experience and maturationSynaptogenesis – new neural connectionsSynaptic pruning – removal of synaptic connections that are no longer neededAdults have less neural connections than a 3 year old!
5Review: Adaptive Plasticity The brain reorganises the way neurons in different regions operate in response to a deficitDeficits can occur from birth or as a result of brain damageBrain plasticityNeuroplasticity
6Damage from Birth - Congenital Congenital – E.g. People who are blind from birth may have occipital lobes that are used for senses other than visionThis may explain why people who are blind from birth have very good hearing or tactile sensitivity
7Damage from InjuryWhen 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 damageNerve cells do not regrow, rather other neurons take over the functions of the damaged cellRerouting – neurons near damaged area seek new active connections with healthy neuronsSprouting – new dendrites growMay occur near damaged area of in other parts of brainAllows shifting of function from damaged area to healthy area‘Relearning’ tasks like walking, eating etc. helps these new connections form
8Adaptive Plasticity and Experience Why is it so?Musicians have enhanced motor and sensory areasTaxi drivers have enhanced functioning of their parietal lobesDancers motor areas are enhanced