Tool Manipulation Knowledge is Retrieved by way of the Ventral Visual Object Processing Pathway J Almeida1, A Fintzi2, B Mahon2 |
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1Faculty of Psychology - PROACTION Lab, University of Coimbra, Portugal |
| Visual object processing is organized into two functionally independent visual pathways. The dorsal visual stream subserves object-directed action, and the ventral visual stream subserves visual object recognition. The neural representation of manipulable objects offers an unique window into interactions between the ventral and dorsal visual streams. Here we show, using fMRI, that object manipulation knowledge is accessed by way of the ventral object processing pathway. We exploit the fact that parvocellular channels project to the ventral but not the dorsal stream, and find that increased neural responses for tool stimuli are observed in the inferior parietal lobule when those stimuli are visible only to the ventral object processing stream. For stimuli titrated so as to be visible by the dorsal visual pathway (through koniocellular inputs), tool-preferences were observed in superior and posterior parietal regions. Functional connectivity analyses confirm the dissociation between sub-regions of parietal cortex according to whether their principal afferent input is via the ventral or dorsal visual pathway. These results challenge the embodied hypothesis of tool recognition, as they show that activation of parietal regions that process object manipulation is contingent on processing within the ventral pathway. |
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