PSYC211 Learning and Memory

learning

the process by which experiences change our brain and hence our behaviour

memories

changes in our brain and behaviour; can be transient or durable, explicit or implicit, personal or impersonal

neuronal plasticity

the cellular basis of long-term memory - refers to the ability of neurons to change and adapt

intrinsic excitability of neurons

the number of action potentials they exhibit when the cell membrane is depolarized a set amount

synaptic strength

how large the postsynaptic response is when a presynaptic neuron has an action potential

synaptic plasticity

a change in synaptic strength

aplysia

an invertebrate sea slug with a simple nervous system (20,000 neurons)

habituation

a reduced physiological or behavioural response to a repeated stimulus

sensitization

when exposure to a strong stimulus (often painful) results in heightened responses to other stimuli

long-term potentiation (LTP)

an enduring increase in the strength of the connection between two neurons (increased synaptic strength)

long-term depression (LTD)

an enduring decrease in the strength of the connection between two neurons (decreased synaptic strength)

AMPA receptor

the ionotropic glutamate receptor that mediates most of the fast excitatory synaptic currents in the brain; lets in Na+ when open, causing EPSPs and membrane depolarization

NMDA receptor

the ionotropic glutamate receptor that only passes current when glutamate is bound AND the membrane of the cell is above -40 mV; open NMDA receptors are permeable to Na+ and Ca2+, but Mg 2+ clogs the pore if the cell is more negative than -40 mV

CaMKII

the type II calcium-calmodulin kinase; this enzyme gets activated by Ca2+ influx through NMDA receptors

when activated, CaMKII increases the number of AMPA glutamate receptors in the synapse, so it is responsible for long-term increases in synaptic strength (LTP) at glutamatergic synapses

Donald Hebb's famous hypothesis

the cellular basis of learning involves the strengthening of weak synaptic connections that happen to be active when the postsynaptic neuron fires an action potential