Week 6: Learning and Memory Flashcards
Learning
Permanent change in behavior as the result of experience; change in brain structure and/or function
Neuroplasticity
Physical change in brain due to experience; required for learning; involved in any event that causes change
Sequence of events in learning
Stimulus -> neuronal activity (selective) -> intracellular signaling pathways (events to change) -> gene expression -> protein expression -> structural/functional changes
Types of changes in the brain
Neuronal structure, grey or white matter, synapse strength. All can be identified using neuroimaging (usually MRI)
Changes in neurons
Structure is changed, not amount. Ex: dendritic arborization (growth of dendrites, thus more synapses)
Grey matter change
Dendritic expansion or change to vasculature (supply system to neurons)
Synapse strength change
Key to learning; strength of connection between various neurons; improvement of cell communication
Hebb’s Postulate (1950)
Activating a synapse repeatedly will change it and strengthen it
Bliss and Lomb synapse activation study
Repeatedly activated one axon of one neuron in the hippocampus at a rate of 100 times per second. Found a strengthening of the stimulated neuron. Supported Hebb’s Postulate
Long-term Potentiation (LTP)
Long-term increase in ability for cell A to activate cell B; larger excitatory post-synaptic potential (EPSP) in cell B
Measuring LTP
Looking at field EPSPs (the response of lots of neurons). After stimulation, there is a spike in PTP (post-tetanic potentiation), and LTP outlasts the PTP spike. Used to measure learning, post-synaptic LTP is the most commonly used
Use of LTP in learning
Correlated with learning in many models; fundamental change mechanism across the brain that modifies behavior
Long-term Depression (LTD)
Long-term weakening in synaptic strength, induced by prolonged weak stimulus
Use of LTD in learning
Tunes the network by eliminating obsolete synapses; acts as a built in reset
Rate remapping
Changes in neuron firing rate
Ex: Cell A fires faster than it did before
Population remapping
Changes in neuron firing potential
Ex: Cell C fires in response to cell A, where it didn’t before
Use of animals in neuronal learning study
Animals are primarily used due to ethical concerns. Studying learning at a neuronal level induces great damage to the brain.
London Taxi Driver Study
Argument: learning massive amounts of information should change the brain structure
Method: examining the cortical mass of those who passed the London taxi driver exam and those who did not. To pass you must memorize a massive amount of spatial information
Findings: Larger grey matter amount in those who passed. Increase in posterior hippocampus (spatial info) and decrease in anterior hippocampus (anxiety and stress responses, etc.)
Argument SUPPORTED
Music training age study
Argument: long-lasting change should occur, and earlier age of inception should show more change
Method: Correlative observation of musicians who started playing an instrument at various ages. Examining functional differences and cortical response to activity/training
Findings: Those who started at a younger age have a greater response. Changes were specifically seen in the somatosensory cortex
Argument SUPPORTED
Change in gene expression
Thousands of genes can be changed during the learning process. Aside from neuronal/structure change, gene expression change is likely the driving factor in learning
Memory
Process of information being stored, consolidated, and retrieved. Reconstructive and innacurate