Glutamate• It is the most abundant excitatory neurotransmitter in the nervous system• It plays a key role in learning (LTP), highly concentrated in Hippocampus, amygdala• Stored in the vesicles of the presynaptic neuron• Nerve impulses (action potential) triggers release into the synapse• Glutamite then binds with specialised receptors on the dendrites of the postsynaptic neuron
NMDA (N-methyl D-aspartate)• A specialised receptor (found on dendrites) that receives Glutamate (vital to LTP)
NMDA (N-methyl D-aspartate)• Evidence: Morris water maze experiment - NDMA blocked - rats unable to spatially learn (no LTP)• Tissens (2000) study on modified NMDA receptors of mice
Hippocampus• largely responsible for LTP• Consolidation of declarative memories• involved in spatial learning and navigation• Along with the thalamus & amygdala – it is responsible for intiating and processing fear response• Evidence: MRIs indicate a larger right hippocampus area of London cab drivers compared to population• Morris water maze experiment with removal of Hippocampus
Amygdala• Responsible for emotional learning,• fear conditioning (classical conditioning),• It is also involved in positive conditioning• Evidence: fMRI show greater amygdala activity when consolidating memories more emotional (stressful) in nature in comparison to semantic type memories• People who have had their amygdala removed (for example in treatment of extreme cases of epilepsy) not only lose their ability to fear, they also do not recognize anger in others.• Anxiety disorders/ phobias = greater activity in amygdala• Bipolar patients have reduced volume in amygdala
Thalamus• Thalamus: is one of the brain structures for initiating & processing fear response (part of classical conditioning)• It is also responsible for spatial learning• Evidence - rats with damaged thalamic regions showed no improved in formation of repetitive maze task.
Cerebellum• Involve in motor learning (making fine adjustments to movements)• involved some emotional functions such as regulating fear and pleasure responses,• it is even involved in triggering some reflexive motor responses (conditioned responses) such as an eye blink in response to a conditioned stimulus such as a tone• Evidence: Neuroimaging - show higher cerebellum activity when observing/ imagining a sequence of movements