PMID-18004384[0] A synaptic memory trace for cortical receptive field plasticity.
- nucleus basalis = basal forebrain!
- stimulation of the nucleus basalis caused a reorganization of the auditory cortex tuning curves hours after the few minutes of training.
- used whole-cell current-clamp recording to reveal tone-evoked excitatory and inhibitory postsynaptyic currents.
- pairing of nucleus basalis and auditory tone presentation (2-5 minutes) increased excitatory currents and decreased inhibitory currents as compared to other (control) frequencies.
- tuning changes required simultaneous tone presentation and nucleus basalis stimulation. (Could they indiscriminately stimulate the NB? did they have to target a certain region of it? Seems like it.)
- did not require postsynaptic spiking!
- Pairing caused a dramatic (>7-fold) increase in the probability of firing bursts of 2+ spikes
- Cortical application of atropine, an acetylcholine receptor antagonist, prevented the effects of nucleus basalis pairing.
- the net effects of nucleus basalis pairing are suppression of inhibition (20 sec) followed by enhancement of excitation (60 sec)
- also tested microstimulation of the thalamus and cortex; NB pairing increased EPSC response from intracortical microstim, but not from thalamic stimulation. Both cortical and thalamic stimulation elicited an effect in the voltage-clamped recorded neuron.
- by recording from the same site (but different cells), they showed that while exitation persisted hours after pairing, inhibition gradually increased commensurate with the excitation.
- Thus, NB stimulation leaves a tag of reduced inhibition (at the circuit level!), specifically for neurons that are active at the time of pairing.
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