First comparative approach to touchscreen-based visual object–location paired-associates learning in humans (Homo sapiens) and a nonhuman primate (Microcebus murinus).

Abstract

A recent study suggests that a specific, touchscreen-based task on visual object-location paired-associates learning (PAL), the so-called Different PAL (dPAL) task, allows effective translation from animal models to humans. Here, we adapted the task to a nonhuman primate (NHP), the gray mouse lemur, and provide first evidence for the successful comparative application of the task to humans and NHPs. Young human adults reach the learning criterion after considerably less sessions (one order of magnitude) than young, adult NHPs, which is likely due to faster and voluntary rejection of ineffective learning strategies in humans and almost immediate rule generalization. At criterion, however, all human subjects solved the task by either applying a visuospatial rule or, more rarely, by memorizing all possible stimulus combinations and responding correctly based on global visual information. An error-profile analysis in humans and NHPs suggests that successful learning in NHPs is comparably based either on the formation of visuospatial associative links or on more reflexive, visually guided stimulus-response learning. The classification in the NHPs is further supported by an analysis of the individual response latencies, which are considerably higher in NHPs classified as spatial learners. Our results, therefore, support the high translational potential of the standardized, touchscreen-based dPAL task by providing first empirical and comparable evidence for two different cognitive processes underlying dPAL performance in primates. (PsycINFO Database Record

Age affects procedural paired-associates learning in the grey mouse lemur (Microcebus murinus)

“…Within the age groups, the sex-ratio was balanced (n = 3 per sex and age group). Five of the subjects (three young and two old) were trained in a session-based protocol and some aspects of their training have been reported and discussed in a comparative context (in comparison with rodents and humans), before 15 . The remaining seven subjects (three young and four old) were trained in a home cage-based protocol with 24-h access to the setup on working days (for more details on the training protocols see below).…”

“…Different from the CANTAB PAL test, the animal versions usually require repeated training and positive reinforcement for the animals to achieve high performance levels (e.g. [11][12][13][14][15] ). Despite this conceptual difference, there is evidence for overlap in the brain areas involved in human CANTAB PAL and rodent dPAL, with a prominent role of hippocampal and medial prefrontal areas in both tasks (for a detailed overview see 5 ).…”

First experimental evidence for olfactory species discrimination in two nocturnal primate species (Microcebus lehilahytsara and M. murinus)

“…Dropout rates are relatively rarely reported in cognition studies. However, one other learning study on captive mouse lemurs reported the dropout rates during the training (7 of 12 (58%) animals excluded 90 ). Animals in that study were locked in a small cognitive test chamber and had to interact with a touchscreen 90 .…”

“…However, one other learning study on captive mouse lemurs reported the dropout rates during the training (7 of 12 (58%) animals excluded 90 ). Animals in that study were locked in a small cognitive test chamber and had to interact with a touchscreen 90 . Another study on wild mouse lemurs reported dropout rates in the initial familiarization to a maze (21 of 86 (24%) animals excluded, eight of which could be familiarized on a subsequent day) 81 .…”

“…The error rate was plotted in individual learning curves (for the raw data see Supplementary Tables S3–7) according to previous learning studies 89,90 . The first day of each new learning step was skipped (even the first two days of TS1a were skipped in GND and GIN due to low trial numbers) when plotting the learning curve and for the statistical analyses, because no 20 trials were available on Day 1 of each learning step due to the maximum of 15 trials/day.…”