Figure 5.

Visual field and visual perceptual thresholds in animals with enduring enhancement. A, Visual field-selective OKT SF thresholds in schematic illustrations. The length of arching arrows represents the visual field segment in which the grating was present during the measurement of OKT (binocular and monocular fields delimited by dotted lines radiating from the head of the rat). Combined monocular- and binocular-field stimulation in animals tested from P25 (right) resulted in a threshold of 0.52 c/deg. Restricting the stimulus to the binocular field resulted in the same threshold, and monocular-field responses were lower (0.46–0.48 c/deg) regardless of the width of the stimulus within the field. Combined monocular- and binocular-field stimulation in rats with testing from P15 resulted in a threshold of 0.84 c/deg (68% above animals tested from P25). Binocular-field stimulation alone resulted in the same enhanced threshold, whereas monocular responses were only modestly (26%) augmented. B, Selective enhancement of visual motion perception. Left, Visual acuity measured with stationary stimuli in the VWT did not differ between groups of animals with OKT testing from P15 (black bar) and P25 (white bar). Animals with OKT testing experience from P15 were superior at discriminating the SF of gratings drifting at 12°/s. Right, The dot motion coherence threshold to discriminate between kinematograms consisting of large (2.98°) dots did not differ between the groups, but animals with OKT testing experience from P15 were able to discriminate between fields of smaller dots moving at maximum coherence.