Mental maze solving: Directional fMRI tuning and population coding in the superior parietal lobule

Pavlos Gourtzelidis, Haris Tzagarakis, Scott M. Lewis, David A. Crowe, Edward J Auerbach, Trenton A. Jerde, Kamil Ugurbil, Apostolos P Georgopoulos

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The superior parietal lobule (SPL) of six human subjects was imaged at 4 T during mental traversing of a directed maze path. Here we demonstrate the orderly involvement of the SPL in this function, as follows. Forty-two percent of the voxels were tuned with respect to the direction of the maze path. This suggests a coherent tuning of local neuronal populations contributing to the change of the single-voxel BOLD signal. Preferred directions ranged throughout the directional continuum of 360°. Voxels with similar preferred directions tended to cluster together: on average there were seven same-direction clusters per slice, with an average cluster membership of five voxels/cluster and an average nearest-neighbor same-direction intercluster distance of 13.1 mm. On the other hand, the average nearest-neighbor intercluster distance between a given direction and all other directions was 3.1 mm. This suggests a patchy arrangement such that patches of directionally tuned voxels, containing voxels with different preferred directions, alternate with patches of non-tuned voxels. Finally, the population vector predicted accurately the direction of the maze path (with an error of 12.7°), and provided good estimates (with an error of 29°) when calculated within parts of the SPL. Altogether, these findings document a new, orderly functional organization of the SPL with respect to mental tracing.

Original languageEnglish (US)
Pages (from-to)273-282
Number of pages10
JournalExperimental Brain Research
Volume165
Issue number3
DOIs
StatePublished - Aug 2005

Keywords

  • Directional tuning
  • Mental tracing
  • Spatial cognition
  • Superior parietal lobule
  • fMRI

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