brain and behavior learning and memory part 2

what do memories require formation of?

new synapses or birth of new neurons

what creates memories?

cellular and molecular changes; synapses and receptors

synapses

changes in synaptic connections

receptors

changes in synaptic effectiveness

synaptic changes

they can be measured physiologically and may be presynaptic, postsynaptic, or both. they increase neurotransmitter release, inactivate the transmitter, they have a greater effect due to changes in receptors, they are influenced by other neurons.

long term memories structural changes

new synapses can form or old ones die back and training can bring about reorganization.

neuroplasticity

the ability of the nervous system to change in response to experience or environment. its present in developing brains

what are the 3 housing conditions?

standard condition (SC), impoverished condition (IC), enriched condition (EC)

animals housed in EC

developed heavier, thicker cortex, enhanced cholinergic activity, more dendritic branches and spines on cortical neurons, larger cortical synapses, more neurons in the hippocampus, and enhanced recovery from brain damage.

long term habituation

fewer synapses

non associative learning

involves only one stimulus with no association

habituation

a decrease in response to a repeated stimulus is studied in aplysia.

short term habituation

results in less transmitter released in the synapse results in less retraction

long term habituation

fewer synapses

extinction

after repeated representation of the conditioned stimulus without the unconditioned stimulus- no longer causes blink. the connection between the cerebellum and cranial motor nuclei are reduced.

Hebbian synapses

they act together to store memory traces.

connections from cells that fire out of synchrony

they are less effective at driving the postsynaptic cell and tend to die off.

long term potentiation

a stable and enduring increase in the effectiveness of synapses.

tetanus

an intense volley of action potentials from a presynaptic cell. it causes postsynaptic neurons to produce larger EPSPs, even after normal action potentials.

where does the LTP occur?

at the pathways in the hippocampal formation, formed by the dendate gyrus and the hippocampus proper. (CA1)

CA1 cells in the hippocampus contain…

both NMDA and AMPA channels and they both respond to GLU

correlational observations

time course of LTP is similar to that of memory formation

somatic intervention experiments

pharmacological treatments that block LTP also impair learning

behavioral intervention experiments

fear conditioning leads to LTP in amygdala