Augmenting and reducing of visual evoked potentials in Roman high- and low-avoidance rats

Human and cat high sensation seekers tend to show increasing amplitudes (augmenting) of the P1 and N1 components of the visual evoked potential (VEP) to increasing intensities of light flash, whereas low sensation seekers show VEP reducing. Roman high-avoidance (RHA) and Roman low-avoidance (RLA) rats have behavioral traits comparable to human and cat high and low sensation seekers, respectively. RHA rats show greater exploration, activity, and aggression than do RLA rats. Rats of each Roman line and Wistar rats were anesthetized with chloral hydrate and maintained at a stable moderate anesthetic level. VEPs to each of five flash intensities were computer averaged for each rat. The slopes of P1 amplitudes as a function of flash intensity were significantly greater in the RHA than the RLA rats. RHA rats were clear augmenters; RLA rats had almost flat amplitude-intensity functions. The Wistar rats had slope functions that were similar to those of the RLA rats. This study shows that the relationship between sensation-seeking behavior and VEP augmenting and reducing has a heritable base and extends across species from human, cat, and rat. In addition, we demonstrate a rat model of this relationship that yields advantages of genetic homogeneity and a short generational time, and provides access to a wealth of behavioral data and experimental manipulations available for the rat.