Stimulation of axons within the corpus callosum evokes the release of glutamate. (a) Response of an NG2+ cell to paired stimulation of corpus callosum axons (50 ms ISI), recorded at room temperature (22–24 °C) and near physiological temperature (36 °C). Evoked responses were blocked by GYKI 53655 (100 μM). (b) Series of responses evoked with stimuli of different intensities (left, traces) and plot of the peak amplitude of the responses versus stimulus intensity (right, graph). Stimulation intensities: 5, 10, 12.5, 15, 20, 30, 50 and 70 μA. (c) Averaged responses and plot of peak amplitudes of evoked AMPAR currents recorded from an NG2+ cell in response to paired stimulation. Responses were blocked by cadmium (Cd, 30 μM, blue trace) and NBQX (10 μM, red trace). Open circles, first response amplitude; closed circles, second response amplitude. (d) Bursts of EPSCs recorded from a callosal NG2+ cell in the presence of gabazine (5 μM).