Aerobic fitness relates to learning on a virtual Morris Water Task and hippocampal volume in adolescents

Abstract

In rodents, exercise increases hippocampal neurogenesis and allows for better learning and memory performance on water maze tasks. While exercise has also been shown to be beneficial for the brain and behavior in humans, no study has examined how exercise impacts spatial learning using a directly translational water maze task, or if these relationships exist during adolescence--a developmental period which the animal literature has shown to be especially vulnerable to exercise effects. In this study, we investigated the influence of aerobic fitness on hippocampal size and subsequent learning and memory, including visuospatial memory using a human analogue of the Morris Water Task, in 34 adolescents. Results showed that higher aerobic fitness predicted better learning on the virtual Morris Water Task and larger hippocampal volumes. No relationship between virtual Morris Water Task memory recall and aerobic fitness was detected. Aerobic fitness, however, did not relate to global brain volume or verbal learning, which might suggest some specificity of the influence of aerobic fitness on the adolescent brain. This study provides a direct translational approach to the existing animal literature on exercise, as well as adds to the sparse research that exists on how aerobic exercise impacts the developing human brain and memory.

Figure 1

Virtual Morris Water Task Learning a) Percent distance traveled in the target quadrant across the 6 trials. * denotes significantly different from trial 1 (p’s < .05); ** denotes significantly different from trial 2 (p’s < .05). F-statistic of the repeated measures ANOVA and its associated p-value. b) Aerobic fitness (as measured by VO₂ peak) predicts the amount of learning that occurred (δ =percent distance in target quadrant in trial 6 –percent distance in target quadrant in trial 1) during the vMWT task. R² and associated p-value is also reported for this relationship. Higher δ reflects better learning.

Figure 2

Aerobic fitness (as measured by VO₂ peak) predicts right and left hippocampal volumes. Volumes (in mm³) reported controlling for Intracranial Volume (ICV). R² and associated p-values are also reported for each relationship.