Coordinated Plasticity between Barrel Cortical Glutamatergic and GABAergic Neurons during Associative Memory

Figure 10

The coordinated recruitment and refinement of barrel cortical glutamatergic and GABAergic neurons set up their function state for information storage. (a) In addition to receiving whisker signal from the thalamus, associative memory cells in the barrel cortex receive odor signal from the piriform cortex after associative learning. In the glutamatergic neurons (orange), their dendritic spines are enriched, their excitatory synaptic transmissions are upregulated, and their receiving of inhibitory synaptic transmission is downregulated for their recruitments to be associative memory cells. The innervations from GABAergic axons are increased, such that the glutamatergic neurons are not overexcited. In the GABAergic neurons (green), their processes are enriched, their receptive fields of excitatory synaptic transmission are enhanced, and their innervation from the excitatory neurons is increased. Their synaptic outputs are decreased. The GABAergic neurons are homeostasis by coordinating their subcellular compartments. (b) An upregulation in the ratio of the excitatory synapses to the inhibitory synapses drives the digital spike encoding at the excitatory neurons over the threshold (out of “functional silence”) into an optimal state for the recruitment and refinement of associative memory cells. The extreme weakness of inhibitory synapses pushes these neurons to be overexcited for strong memory with no recognition. The curve of digital spikes is simulated based on our data, in which the normalized stimulations are integrated by the ratio of excitatory synapses to inhibitory synapses.

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