The role of the human extrastriate visual cortex in mirror symmetry discrimination: A TMS-adaptation study

Zaira Cattaneo*, Giulia Mattavelli, Costanza Papagno, Andrew Herbert, Juha Silvanto

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    36 Citations (Scopus)

    Abstract

    The human visual system is able to efficiently extract symmetry information from the visual environment. Prior neuroimaging evidence has revealed symmetry-preferring neuronal representations in the dorsolateral extrastriate visual cortex; the objective of the present study was to investigate the necessity of these representations in symmetry discrimination. This was accomplished by the use of state-dependent transcranial magnetic stimulation, which combines the fine resolution of adaptation paradigms with the assessment of causality. Subjects were presented with adapters and targets consisting of dot configurations that could be symmetric along either the vertical or horizontal axis (or they could be non-symmetric), and they were asked to perform a symmetry discrimination task on the targets while fixating the center of the screen. TMS was applied during the delay between the adapter and the test stimulus over one of four different sites: Left or Right V1/V2, or left or right dorsolateral extrastriate cortex (DLO). TMS over both Left and Right DLO reduced the adaptation effect in detecting vertical and horizontal symmetry, although the Left DLO effect on horizontal symmetry and the Right DLO effect on both vertical and horizontal symmetry were present only when considering subjects who showed a behavioral adaptation effect in the baseline No-TMS condition. Application of TMS over the Left or Right V1/V2 did not modulate the adaptation effect. Overall, these data suggest that both the Left and Right DLO contain neuronal representations tuned to mirror symmetry which play a causal role in symmetry discrimination.

    Original languageEnglish
    Pages (from-to)120-127
    Number of pages8
    JournalBrain and Cognition
    Volume77
    Issue number1
    DOIs
    Publication statusPublished - Oct 2011
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Extrastriate cortex
    • Transcranial magnetic stimulation
    • Visual cortex
    • Visual symmetry

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