Overlapping representations of numerical magnitude and motion direction in the posterior parietal cortex: A TMS-adaptation study

Chiara Renzi, Tomaso Vecchi, Juha Silvanto, Zaira Cattaneo

Research output: Contribution to journalArticlepeer-review

Abstract

The human posterior parietal cortex (PPC) is involved in the encoding of both visual motion and numerical magnitude. In non human primates, neurons have been found in PPC that are selective for both motion direction and magnitude. Whether such neurons also exist in human PPC is not known. Here we investigated this hypothesis using state-dependent transcranial magnetic stimulation (TMS). Participants were adapted to a specific motion direction (either leftward or rightward), after which they performed a magnitude comparison task, with TMS applied at the onset of each trial. Our hypothesis was that neurons tuned to leftward motion may also be sensitive to small magnitudes and neurons tuned to rightward motion may also be sensitive to large magnitudes, a mapping that may have developed via spatial attentional mechanisms. Our results supported this view by showing that the effect of PPC TMS on small and large numbers depended on the motion direction being adapted, thus suggesting that there may be a functional overlap in neuronal representations of motion direction and numerical magnitude in human PPC.

Original languageEnglish
Pages (from-to)145-149
Number of pages5
JournalNeuroscience Letters
Volume490
Issue number2
DOIs
Publication statusPublished - Feb 25 2011

Keywords

  • Adaptation
  • Motion processing
  • Number processing
  • Parietal cortex
  • State-dependency
  • TMS

ASJC Scopus subject areas

  • Neuroscience(all)

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