Figure 3.

Kainate enhances mossy fiber excitability. (A) Representative traces showing an increase in the presynaptic mossy fiber volley caused by 200 nM kainate, in the presence and absence of SYM2081, which desensitizes KARs. Fiber volleys were recorded in a Ca²⁺-free solution. (B) The time course of the effects in A. Experiments in the absence (●) and presence (○) of the KAR antagonist SYM2081 are shown. (C) Antidromic spikes are recorded in granule cells in whole-cell current clamp. In control conditions, some stimuli fail to elicit an antidromic spike (Left), whereas in kainate, each stimuli generates a spike (Center). The spikes in kainate are not only more reliable, but have a slightly smaller latency (Right). (D) A summary of the increase in reliability is shown for six cells. [Reprinted with permission from ref. 15 (Copyright 2000, The Physiological Society).]