Lecture 16: Learning and Memory l Flashcards
learning
the process by which experiences change our nervous system and hence our behaviour
memories
changes in our nervous system that occur as a result of learning.
Can be transient or durable, explicit or implicit, personal or impersonal
memory retrieval
Accessing memories
neuronal plasticity
the ability of the nervous system to change and adapt
what is the cellular basis of long-term memory?
neuronal plasticity
what do researchers use to identify neuronal plasticity?
intrinsic excitability & synaptic strength
intrinsic excitability
the number of action potentials a neuron exhibits in response to an influx of positive current
synaptic strength
the amount of positive (or negative) current that enters the postsynaptic neuron when a presynaptic cell has an action potential.
synaptic plasticity
A change in the strength of the synaptic connection between two neurons
how is intrinsic excitability determined?
by the number and type of ion channels (leak channels and voltage-gated channels) expressed by the neuron
what happens if a neutron starts making fewer potassium leak channels?
its resting membrane potential will be slightly depolarized, which means the neuron will be more excitable in general (will exhibit more action potentials)
Long term potentiation (LTP)/ Long term depression (LTD)
enduring changes in synaptic strength
main difference between LTP & LTD
LTP makes the synapse stronger; LTD makes the synapse weaker
EPSPs
Membrane depolarizations that are driven by neurotransmitter release and postsynaptic receptor activation.
presynaptic plasticity changes
the amount of voltage-gated calcium channels on the presynaptic membrane influences how many vesicles will be released following an action potential.
postsynaptic plasticity changes
the amount of neurotransmitter receptors influences the sensitivity of the postsynaptic cell to neurotransmitter.
two types of synaptic plasticity changes
presynaptic and postsynaptic
habituation
reduced physiological or behavioural responding to a repeated stimulus.
sensitization
Increased sensitivity to a stimulus
apylsia
an invertebrate sea slug with a simple nervous system. It has a large gill for respiration, and a siphon through which it expels water.
habituation in apylsia
Repeated light touching of the siphon will reduce the magnitude of the reflex until the Aplysia completely ignores this stimulus.
sensitization in apylsia
the sea slug’s response to an electrical shock often becomes greater with additional exposures.
does the sensory neuron of aplysias become less sensitive to the touch?
No, it depolarizes the same amount
Has the excitability of the sensory neuron changed in apylsias with the gill withdrawal reflex?
Yes, fewer action potentials (1 vs 2) occur when the siphon is touched
Has the synaptic connection weakened between the sensory and motor neurons as a result of the gill withdrawal reflex?
yes