Its all physical!

 Basic structure of the NS is set before birth  Neurons are however flexible living cells that can grow new connections  The ability of the brain to reorganise the way it works is referred to as plasticity

Axon terminals Myelin sheath Axon Synaptic knob synapsesynapse

 Learning results in the creation of cell assembles or neural networks  ‘neurons that fire together wire together’  When a neurotransmitter is repeatedly sent across the synapse this can effect the strength of these connections  Neurons that do not fire together weaken their connections

New Receptor Formation Long Term Memory New Synapse Formation Late LTP

 Pool of milky water with platform to stand on (just under the surface)  3 groups of rats - Group 1 – frontal lobe damage - Group 2 – hippocampus damage - Group 3 – no damage

 Results display the importance of the hippocampus in allowing LTP - Group 3 – no damage – located platform more quickly each trial - Group 1 – frontal lobe damage – performed about as well as group 3 - Group 2 – hippocampus damage – never got better, showed no evidence of learning

 Drugs that enhance synaptic transmission tend to enhance learning  NDMA (N-methyl-D-aspartate) a neurotransmitter found on dendrites in the hippocampal region  NDMA specialised to work with the neurotransmitter glutamate  Important role in LTP

 Genetically engineered rats with more efficient MDMA receptors  Better memory  Faster learning  As compared to rats with normal NDMA receptors

 The brain is adaptive  It changes as a result of experience (learning)  Remember LTP?  New connections  New neural networks  Genes govern overall brain structure  Unclear whether or not all brain structures are as plastic as the sensory and motor cortices?

 Babies born with all 100 billion nerve cells  Each cell at birth synapses with around 2500 other neurons  By late childhood the number of connections increases to around 15,000 per neuron  By adulthood this number decreases to around 8,000 as unused connections are destroyed  Children’s brains show greater plasticity than adults, this might explain why children learn languages faster than adults

 Lab rats placed in 3 different environments after birth with different opportunities for learning - 1 – standard environment – simple communal cage with food and water - 2 – impoverished environment – simple small cage housed alone - 3 – enriched environment – large, social, with lots of stimulus objects

 All rats stayed in their cages for 80 days  When their brains were dissected the rats with enriched experience had thicker, heavier cerebral cortex

 Differences were largest in the occipital lobes and smallest in the somatosensory cortex  Also showed new synapse formation  Thicker bushier dendrites  More neurotransmitter acetylcholine  Later studies showed changes in adult rat brains also placed into different environments

 Brain weight increase as much as 10%  Neural connections increase as much as 20%  Being raised in enriched environment can increase problem solving ability  Humans raised in isolation from proper stimulation can become severely retarded  genie & victor – the wild children

 The brains of university graduates have approx 40% more neural connections than those who leave school early!  Intellectual stimulation can protect against dementia!  This is even true for twins who have identical genetic make up

 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!

 Sensitive period – time an organism 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) remember genie!  Learning a new language in teen years can lead to the development of a second Broca’s area!

 The brain reorganises the way neurons in different religions operate in response to a deficit  Deficits can occur from birth or as a result of brain damage

 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

 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

 Musicians motor and sensory areas  Taxi drivers parietal lobes  Dancers motor areas

 Well learned responses  Neural network ‘transfers’ to the basil ganglia

 Relevant to operant conditioning  Behaviours that produce a positive consequence make us ‘feel’ good  Release of dopamine at a neural level