A Test of Memory: The Fish, The Mouse, The Fly And The Human

Abstract

Simple mazes have provided numerous tasks for assessing working memory. The discrete nature of choices in the T-maze has provided a robust protocol with sensitivity to cognitive deficits, whilst the continuous Y-maze reduces manual handling and pre-trial training. We have combined these attributes to develop a new behavioural task for assessing working memory, the Free-movement pattern (FMP) Y-maze. Using sequentially recorded left and right turns we demonstrate that zebrafish and mice use a single dominant strategy predominantly consisting of alternations between left and right choices trial-to-trial. We further tested this protocol with Drosophila and discovered an alternative invertebrate search strategy. Finally, a virtual human FMP Y-maze confirmed a common strategy among all tested vertebrate species, validating the translational power of the task for human research. The FMP Y-maze combines robust investigation of working memory and high translational power, generating a simple task with far-reaching impact.

Moderate early life stress improves adult zebrafish (Danio rerio) working memory but does not affect social and anxiety‐like responses

“…Critically, the FMP Y‐maze is conceptually more comparable to a series of discrete choices as would be the case in a series of trials in a T‐maze, or in a two‐choice guessing task (Cleal & Parker, 2018; Fontana, Cleal, Clay, & Parker, 2019; Fontana, Cleal, & Parker, 2019). We have demonstrated that alternations in turn‐direction are reduced following administration of memory‐impairing drugs (e.g., MK801 and scopolamine), suggesting that alternations are indicative of working memory (Cleal et al., 2020). Fish ( n = 48) were placed, individually, in a Y‐shaped maze (6.5 cm length × 1 cm width; three identical arms at a 120° angle from each other) with white opaque walls (Figure 1b) and recorded for 15 min.…”

“…The use of the overlapping tetragrams (four choices) was used as it gives a higher chance of identifying random search patterns than using sequences of two or three choices (Frith & Done 1983). Therefore, FMP Y‐maze behavior was analyzed through 16 possible four‐trial outcomes (tetragrams) for each fish as a proportion of the total number of turns to examine, in detail, their behavior patterns (Cleal et al., 2020; Cleal & Parker, 2018; Gross, Engel, Richter, Garner, & Wurbel, 2011). If behavior was fully random, it would be predicted that each choice would be equally likely (i.e., the predicted frequencies would be equal for each tetragram).…”

“…and scopolamine), suggesting that alternations are indicative of working memory (Cleal et al, 2020). Fish (n = 48) were placed, individually, in a Y-shaped maze (6.5 cm length × 1 cm width; three identical arms at a 120° angle from each other) with white opaque walls ( Figure 1b) and recorded for 15 min.…”