Figure 4.
Application of NEURON-based model to determine the effects of [K+]o accumulation. a, Schematic diagram of the modeled layer 2/3 pyramidal neuron containing 74 compartments with eight synapses (with AMPA and NMDA currents), one at each distal dendrite. b, Increasing glutamate levels at each of the eight synapses (top trace representing kinetics of synaptic glutamate level) elicits AMPA-mediated (middle trace) and NMDA-mediated (bottom trace) currents under control conditions (black) and under reduced astrocytic potassium clearance (under a 10-fold decrease of astrocytic K+ clearance, blue trace). c, Maximal K+ concentrations recorded in the vicinity of a distal dendritic compartment during repetitive stimulation as a function of [K+]o clearance and stimulation frequency. d, Percentage change of total charge transfer by NMDA (black) and AMPA (blue) receptors during stimulation at 20 and 100 Hz. e, Somatic EPSPs under control conditions (black) and under reduced astrocytic potassium clearance (10-fold reduction of control levels, blue trace). f, Fifth EPSP (elicited by stimulation at 4, 20, and 100 Hz) decay time constant at different levels of astrocytic potassium clearance rates. g, Ratio of fifth to first EPSP amplitude (P5/P1) at stimulation frequencies of 4–500 Hz at different levels of astrocytic potassium clearance rates. h, Same as in g with GNMDA = 0.