Figure 2.
TC afferents evoke larger EPSCs onto FS as compared to RS cells. A, Bulk stimulation of TC afferents evokes EPSCs onto an FS and an RS cell recorded simultaneously in voltage clamp at the reversal potential for IPSCs (EIPSC). Insets show the recording configuration and response to 800 ms step depolarizations in current clamp. B, Left, Top, Fifty-one superimposed EPSCs sequentially evoked by minimal stimulation of TC afferents and recorded in an RS cell voltage clamped at EIPSC. Note the presence of success and failures. Bottom, The EPSC amplitude is plotted against trial number, with stimulus intensity displayed beneath. Note that progressively increasing stimulus intensity leads initially to a reduction in failures without increasing the amplitude of successes. Further increases in stimulus intensity lead to a step-like transition to a larger EPSC. Right, Same experiment for an FS cell, 76 superimposed sweeps. Note the larger unitary amplitude of TC EPSCs onto the FS cell. C, Summary data of amplitude, latency, and paired pulse ratio of EPSCs evoked by stimulation of TC afferents and recorded in FS and RS cells.