Performance of juvenile baboons on neuropsychological tests assessing associative learning, motivation and attention

Abstract

The CANTAB (Cambridge Neuropsychological Test Automated Battery), a system developed for human neuropsychological testing, has previously been used to assess cognitive function in two species of nonhuman primates, common marmoset monkeys and rhesus macaques. We describe the application of the system to the juvenile baboon, a nonhuman primate species offering specific investigative advantages. Juvenile baboons were trained and tested on a progressive ratio task to assess motivation, simple discrimination and simple reversal tasks to assess associative learning, and intra- and extra-dimensional set-shifting tasks to assess selective attention and attentional set-shifting, respectively. Study subjects were 8 juvenile baboons (Papio sp.), 4 females and 4 males aged 3.0+/-0.1 (mean+SEM) years and weight 8.2+/-0.4 kg. All baboons were easily trained, readily learned the neuropsychological tests and exhibited a stable performance. Applying a method such as the CANTAB has significant implications for expanding on the translational utility of the baboon in studies of neurodevelopment.

Figure 1

CANTAB testing configuration. A) Baboon reaching through the testing cage bars to interact with B) the CANTAB computer touch screen monitor. C) Schematic illustration of the camera placement, home cage (left box), testing cage (center box) and CANTAB monitor (right box).

Figure 2

Overview of the 8 IDED stages. Figure adapted from Pearce et al. (1998). Plus signs indicate positively reinforced stimuli, while negative signs indicate incorrect stimuli.

Figure 3

Total responses made in the progressive ratio task over 10 session showing stable performance with no effect of session over time (n=4 males, n=4 females, p>0.05). Data presented as group averages (+ SEM).

Figure 4

A) Analysis of the performance, as measured in number of errors to criteria across the eight SD tasks (SD1 – SD8) revealed a significant effect (p<0.05). B) An effect was found across the SD/SR tasks, with post-hoc indicating more errors made in the SR1 versus SD6 and SR2 versus SD7 task (n=4 males, n=4 females; *, p<0.05). Data presented as group averages (+ SEM).

Figure 5

Analysis of performance on the intra- and extra-dimensional set-shifting test, as measured by errors to criteria, for each of the 8 stages revealed differences; * indicates a difference as compared to all other stages and # a difference between ED versus ID stages (n=4 males, n=4 females; p<0.05). Data presented as group averages (+ SEM).