Topographic Analysis of Flash Visual Evoked Potentials in Dogs

Abstract

ABSTRACT. Visual evoked potentials by flash stimulation (flash VEP) were analyzed in dogs using a topographic method. The flash VEP consisted of 3 positive (P1, P2 and P3) and 2 negative (N1 and N2) components by 150 msec after the flash stimuli. On the topographic mappings, a negative response area was observed in the frontal region of the scalp in the stimulated site followed by the shifting of the area to the contralateral frontal region and occipital region, during the first 100 msec. The negative response area in the frontal region in the stimulated site, contralateral frontal and temporal region, and occipital region were corresponded to N1, P2, and N2 on the flash VEP, respectively, according to their latencies. In the dogs with experimentally impaired the right lateral geniculate body, the latency of P2 was prolonged, and N2 and P3 were disappeared after the left eye stimulation. On the topographic mapping, only the early negative response area was detected on the stimulated site of the frontal region of the brain. Therefore, it is concluded that P1 and N1, P2, and N2 are referred to the retinal potentials, the potentials from the retina to the brainstem included the lateral geniculate body, and those from the brainstem to the visual cortex, respectively. KEY WORDS: canine, flash stimulus, lateral geniculate body, topographic mapping, visual evoked potential.

Age-Associated Changes of Flash Visual Evoked Potentials in Dogs

“…The bandpass filter was set at 1 Hz low and 1,000 Hz high. In this study, consecutive 30 responses were averaged and the latencies of flash VEP components were measured.Quadratic regression analysis was used for statistical significance between the latency or amplitude of the components in VEP and the aging.The flash VEP waveforms showed 3 positive and 2 negative components as reported previously [11]. Figure 1 shows typical flash VEP waveform in young (1-year-old), middle (9-year-old), and old (15-year-old) aged dogs.…”

“…The flash VEP waveforms showed 3 positive and 2 negative components as reported previously [11]. Figure 1 shows typical flash VEP waveform in young (1-year-old), middle (9-year-old), and old (15-year-old) aged dogs.…”

“…The latency of the positive peak 2 (P2 :mean latency was 100 msec) and the later components were significantly delayed, although the similar results were sometimes detected in aged human. The flash VEP recorded in dogs showed 3 positive (P1, P2 and P3) and 2 negative (N1 and N2) components by 150 msec after the flash stimuli, like as those reported in human [11,17,19]. In addition, various age-associated pathological and/or physiological changes were commonly observed in aged dogs as well as aged human [5,10].…”

“…From the results of our previous report [11], P1 and N1, P2 (mean latency was 53 msec), and N2 (mean latency was 81 msec) in flash VEP were referred to the retinal potentials, the potentials from retina to brainstem, and those from brainstem to visual cortex, respectively. In this study, the latency of P2 and the later peaks were significantly delayed, and the amplitudes of N2-P2 and P2-N3 were decreased with age advanced.…”

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“…The functional assessment of the post-retinal visual pathways has long been carried out in humans and in dogs using Visual Evoked Potential Testing. Unlike ERG, VEP testing provides functional information mainly with regards to lesions of the optic nerve and of the central visual pathways (Bichsel et al 1988, Sims et al 1989, Strain et al 1990, Kimotsuki et al 2005a, Kimotsuki et al 2005b, Itoh et al 2010). In birds the use of visual evoked potentials was carried out with invasive techniques, with the aim of determining the origin of the potential of the individual structures of the visual pathways.…”