Figure 7.

(S)-MK-26 has only lesser effects on reference memory. (A) Schematic of the hole-board maze, a paradigm for the evaluation of spatial learning and memory (left) with depictions (right) of dimensions (an animal at approximated size scale relative to the size of the hole-board arena is schematized); localization of proximal clues; spatial distribution of the holes; and representation of baited and unbaited holes (see also Materials and Methods). (B) Flow diagram representing the methodological strategy used during the preparation and implementation of the hole-board test. (C) Performance of aged rats (19 months old) in spatial memory task over thirteen trials (over 4 days) in the (S)-MK-26-treated and control vehicle-treated control groups showed significance though frail enhancement of reference memory induced by (S)-MK-26 (p = 0.0202) detected by Sidak’s test following repeated-measures ANOVA). (D) Representative traces of locomotor activity recorded during the H3 session in each treatment group. (E) (S)-MK-26 increased distance travelled in 15 min habituation session (p = 0.0053, unpaired t test) (H1, H2—drug free; H3—first treatment). (F) Total number of hole dips in the 15 min habituation sessions. Values are presented as mean ± SEM; n = 10–12; * p < 0.05, ** p < 0.01.