Gray matter differences correlate with spontaneous strategies in a human virtual navigation task - PubMed (original) (raw)

Comparative Study

Gray matter differences correlate with spontaneous strategies in a human virtual navigation task

Véronique D Bohbot et al. J Neurosci. 2007.

Abstract

Young healthy participants spontaneously use different strategies in a virtual radial maze, an adaptation of a task typically used with rodents. Functional magnetic resonance imaging confirmed previously that people who used spatial memory strategies showed increased activity in the hippocampus, whereas response strategies were associated with activity in the caudate nucleus. Here, voxel based morphometry was used to identify brain regions covarying with the navigational strategies used by individuals. Results showed that spatial learners had significantly more gray matter in the hippocampus and less gray matter in the caudate nucleus compared with response learners. Furthermore, the gray matter in the hippocampus was negatively correlated to the gray matter in the caudate nucleus, suggesting a competitive interaction between these two brain areas. In a second analysis, the gray matter of regions known to be anatomically connected to the hippocampus, such as the amygdala, parahippocampal, perirhinal, entorhinal and orbitofrontal cortices were shown to covary with gray matter in the hippocampus. Because low gray matter in the hippocampus is a risk factor for Alzheimer's disease, these results have important implications for intervention programs that aim at functional recovery in these brain areas. In addition, these data suggest that spatial strategies may provide protective effects against degeneration of the hippocampus that occurs with normal aging.

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Figures

Figure 1.

Figure 1.

Two views of the virtual environment used in this study. Note the tree and mountains that are part of the landscape in one view and the sunset in the other. Another tree and large mountain were present in the virtual environment.

Figure 2.

Figure 2.

The diagrams show the regression analyses between the gray-matter density (hippocampus and caudate nucleus) and the errors made by the entire group of participants while performing the probe trial. The right side of the figure shows the results superimposed onto an anatomical MRI and displayed in the sagittal plane. Gray-matter density in the right hippocampus at the peak (x = 24, y = −13, z = −20; t = 3.55) was correlated with spatial memory strategies (r = 0.56; p < 0.005; top), whereas the density in the head of the caudate nucleus at the peak (x = −14, y = 28, z = 4; t = −4.33) was correlated with response learning strategies (r = −0.63; p < 0.005; bottom). Other than a negative correlation between probe errors and the tail of the caudate nucleus (x = −26, y = −32, z = 3; t = −4.07; correlation coefficient r = 0.56; p < 0.005), no other region of the brain crossed the threshold for significance corrected for multiple comparisons. The color bars illustrate the range of t statistical values.

Figure 3.

Figure 3.

Inverse correlation (r = −0.43; p < 0.05) between gray-matter density in hippocampus (x = 24, y = −13, z = −20) and the head of the caudate nucleus (x = −14, y = 28, z = 4) at the peaks resulting from the first VBM analysis in all 30 participants (Fig. 2).

Figure 4.

Figure 4.

Regions of the brain that covaried with hippocampal gray matter extracted at the coordinates resulting from the first VBM analysis (x = 24, y = −13, z = −20). The coronal section (top left) is displayed at the coordinate y = −14, the sagittal section is displayed at x = 25, and the axial section is displayed at z = −14. A, Amygdala; H, hippocampus; EC, entorhinal cortex; PR, perirhinal cortex; PH, parahippocampal cortex; OF, orbitofrontal cortex. The color bar illustrates the range of t statistical values.

References

    1. Adams MM, Smith TD, Moga D, Gallagher M, Wang Y, Wolfe BB, Rapp PR, Morrison JH. Hippocampal dependent learning ability correlates with N-methyl-d-aspartate (NMDA) receptor levels in CA3 neurons of young and aged rats. J Comp Neurol. 2001;432:230–243. -PubMed
    1. Ashburner J, Friston KJ. Voxel-based morphometry—the methods. NeuroImage. 2000;11:805–821. -PubMed
    1. Bohbot VD, Iaria G, Petrides M. Hippocampal function and spatial memory: evidence from functional neuroimaging in healthy participants and performance of patients with medial temporal lobe resections. Neuropsychology. 2004;18:418–425. -PubMed
    1. Bueller JA, Aftab M, Sen S, Gomez-Hassan D, Burmeister M, Zubieta JK. BDNF Val66Met allele is associated with reduced hippocampal volume in healthy subjects. Biol Psychiatry. 2006;59:812–815. -PubMed
    1. Clayton NS. The neuroethological development of food-storing memory: a case of use it, or lose it! Behav Brain Res. 1995;70:95–102. -PubMed

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