(A) VsEPs collected at +6 dB re: 1.0g/ms for three 10-month-old Kcna10Tm45 heterozygotes showed normal waveform morphology while age-matched homozygotes displayed waveforms with poor morphology and only a broad-shaped P1 visible. The initial portion of each waveform (circled region) represents masker artifact since the VsEPs were collected during the presentation of a broadband forward masker (94 dB SPL, 20- to 50-kHz) to eliminate auditory responses. (B) In addition to poor waveform morphology, Kcna10Tm45 homozygotes had significantly elevated thresholds at 10 months of age. At 30 days of age, 3 homozygotes had absent VsEPs. (C) At both ages, Kcna10Tm45 homozygotes showed significantly prolonged P1 latencies compared to heterozygotes. On average, P1-N1 amplitudes were similar for the two genotypes. The asterisks identify statistically significant findings.