Lateral excitation between mitral cell dendrites in the glomerulus is modulated by T-type Ca²⁺ channels. A, Antidromic stimulation of the LOT by a bipolar electrode (see schematic drawing on the left) evoked an LLD in olfactory mitral cells. Inhibition of GABA_A-R (middle; PTX, 50 μm) and NMDA-R (right; AP-5, 50 μm) revealed a fast-onset EPSP. B₁, Z941, a specific T-type channel antagonist (10 μm, gray), reduces the initial EPSP amplitude compared with control (black) elicited by a pair of brief LOT stimulation (20 Hz). Inset, Second EPSPs adjusted according to the baseline. Both traces are averages of multiple trials from a representative experiment. B₂, Summary chart shows the Z941 effect on the EPSP amplitudes and the paired-pulse ratio (PPR). Black circles connected by thick black lines represent the mean of five experiments. PTX (50 μm) and AP-5 (50 μm) were present in all experiments. *p < 0.05. **p < 0.01.