August 2023
Volume 23, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2023
Cortical quantity representations of visual numerosity and timing overlap increasingly but remain distinct
Author Affiliations & Notes
  • Evi Hendrikx
    Utrecht University
  • Jacob M. Paul
    University of Melbourne
  • Martijn van Ackooij
    Utrecht University
  • Nathan van der Stoep
    Utrecht University
  • Ben M. Harvey
    Utrecht University
  • Footnotes
    Acknowledgements  This work was supported by the Netherlands Organization for Scientific Research (452.17.012 to B.M.H.) and the Helmholtz Institute (PhD funding to E.H. & B.M.H.).
Journal of Vision August 2023, Vol.23, 4819. doi:
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      Evi Hendrikx, Jacob M. Paul, Martijn van Ackooij, Nathan van der Stoep, Ben M. Harvey; Cortical quantity representations of visual numerosity and timing overlap increasingly but remain distinct. Journal of Vision 2023;23(9):4819.

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      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements

Numerical and temporal quantity estimations show behavioral commonalities, like adhering to Weber’s law. They also portray behavioral interactions, such that the duration of relatively low or high numerical values are perceived to be shorter or longer than they actually are, respectively. This is striking, as numerosity and timing are unrelated in natural scenes, for example, more numerous events do not consistently last longer. A predominant theory ascribes such behavioral interactions to a generalized magnitude system with shared neural responses across quantities, allowing shared action planning. Recently, 7T fMRI and neural model-based analyses have revealed largely overlapping networks of cortical maps with tuned responses to both visual numerosity and visual event timing (duration and period). These maps are topographically organized, with quantity preferences gradually changing across the cortical surface. They also show hierarchical relationships between maps, with anterior and superior maps showing more specific responses that are more closely linked to behavior. Here we asked whether numerosity and event timing are also hierarchically transformed into a common representation that might underlie their behavioral interactions. We found that there is no significant overlap between the earliest, most posterior numerosity and timing maps. Thereafter, overlap increases from inferior to superior maps. Around the intraparietal sulcus we find consistent but low correlations between numerosity and timing preferences, and relationships between their topographic progressions. Therefore, responses to different quantities are initially derived separately then progressively brought together in the same brain areas, without being transformed into a common representation. This suggests that perceptual and behavioral interactions result from interactions between distinct neural populations responding to different quantities within shared brain areas. We speculate that superior parietal and frontal brain areas may bring responses to different quantities together to access shared comparison and action planning systems nearby.


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