Real Time Multiplicative Memory Amplification Mediated by Whole-Cell Scaling of Synaptic Response in Key Neurons
Fig 6
The amplification mechanism multiplied the net synaptic current.
A. The net synaptic current is the sum of the inhibitory and excitatory currents. Multiplication of both the inhibitory (upper panel) and excitatory currents (middle panel) multiplies the net synaptic current (lower panel). Therefore, if the net synaptic current is positive this multiplication will further depolarize the cell and if negative will further hyperpolarize the cell. B. The ratio of the activation frequency of inhibitory to excitatory synapses was varied by decreasing the activation frequency of each inhibitory synapse from11Hz to 3Hz, and increasing the activation frequency of each excitatory synapses from2Hz to 10Hz by 0.5Hz (x-axis). Each point on the graph is the average of 10 simulations. The different ratios of activation frequencies (inhibitory activation frequency divided by the excitatory activation frequency x-axis) resulted in different net synaptic currents (y-axis). The amplification mechanism increased the net-synaptic current while maintaining its polarity. A significant multiplicative effect was mainly observed at positive net synaptic currents, thus primarily when the effect of the net synaptic current was excitatory. This figure is a result of one simulated cell. C. Multiplication factors of the net synaptic current as a function of the average membrane potential. The simulation protocol is as described in B, where each color indicates a different set of simulations (in total 10 different sets of simulations). The sets of simulations differed in terms of intrinsic characteristics (resting potential: -90 - -60 mV) and the average strength of the synapses (excit/inhib: 0.6–1.3). Each dot in a set of simulations is a result of a different activation frequency of the inhibitory and excitatory synapses, as was described in B.