Fig 1.
Schema of the CS measurement using 2AFC-VDT combined with the staircase method.
(A) Schema and (B) photo of the experimental box. (C) Schema of the 2AFC-VDT. A rat pulls up the central lever to begin the task, by which a grating patch is presented on the right or left side of the display. The rat is rewarded with water by pulling the lever corresponding to the stimulus location. (D) The contrast changes in one session if the rat pulls the correct lever in all trials. (E) Typical result from one session in the 2AFC-VDT combined with the staircase method. In this session, the rat was able to detect 27.3% contrast (horizontal line, Cthreshold = 27.3%), therefore CS was assessed as 3.66.
Fig 2.
Effects of FLX on CS in the 2AFC-VDT combined with the staircase method.
(A)–(B) Typical data from one session of the 2AFC-VDT at two different SFs: 0.1 cpd (A) and 0.5 cpd (B) for one rat (black circles, control; white squares, FLX). Solid and dotted horizontal lines indicate the Cthreshold of the control and FLX conditions, respectively. (C)–(D) Average contrast changes over all sessions for the same rat as (A)–(B). Black circles and white squares indicate the mean contrast value calculated for each trial number. Horizontal lines indicate the geometric mean of Cthreshold (solid line, control; dotted line, FLX). Error bars are SEM.
Fig 3.
Population data of FLX effects on CS.
The population data of CS (n = 7) obtained from control and FLX conditions (black bar, control; white bar, FLX). CS was significantly increased by FLX at 0.1 cpd (*p = 0.022, Holm–Bonferroni’s multiple comparison test), but not at 0.5 cpd. Error bars are SEM. The vertical axis is shown in logarithmic scale.
Fig 4.
Effect of FLX on water intake and activity level.
(A) Water intake for 5 min under control and FLX conditions (black bar, control; white bar, FLX). No significant difference was observed (p = 0.369, paired t-test). (B) Total moving distance of rats in an open field arena for 5 min was also unaffected by FLX administration (p = 0.570, paired t-test).