Relation between palm and finger cortical representations in primary somatosensory cortex: A 7T fMRI study. Issue 7 (23rd February 2021)

• Record Type: Journal Article
• Authors: Akselrod, Michel; Martuzzi, Roberto; van der Zwaag, Wietske; Blanke, Olaf; Serino, Andrea
• Is Part Of: Human brain mapping. Volume 42:Issue 7(2021)
• Page Start: 2262
• Page End: 2277
• Publication Date: 2021-02-23
• Subjects: 7T fMRI -- palm and finger cortical representations -- primary somatosensory cortex; Brain mapping -- Periodicals; 611.81
• DOI: 10.1002/hbm.25365
• Languages: English
• ISSNs: 1065-9471

Abstract

Abstract: Many studies focused on the cortical representations of fingers, while the palm is relatively neglected despite its importance for hand function. Here, we investigated palm representation (PR) and its relationship with finger representations (FRs) in primary somatosensory cortex (S1). Few studies in humans suggested that PR is located medially with respect to FRs in S1, yet to date, no study directly quantified the somatotopic organization of PR and the five FRs. Importantly, the link between the somatotopic organization of PR and FRs and their activation properties remains largely unexplored. Using 7T fMRI, we mapped PR and the five FRs at the single subject level. First, we analyzed the cortical distance between PR and FRs to determine their somatotopic organization. Results show that PR was located medially with respect to D5. Second, we tested whether the observed cortical distances would predict the relationship between PR and FRs activations. Using three complementary measures (cross‐activations, pattern similarity and resting‐state connectivity), we show that the relationship between PR and FRs activations were not determined by their somatotopic organization, that is, there was no gradient moving from D5 to D1, except for resting‐state connectivity, which was predicted by the somatotopy. Instead, we show that the representational geometry of PR and FRs activations reflected the physical structure of the hand. Collectively, our findings suggest that the spatial proximity between topographically organized neuronal populations do not necessarily predicts their functional properties, rather the structure of the sensory space (e.g., the hand shape) better describes the observed results. Abstract : Using 7T fMRI, we mapped the somatosensory representations of the palm and the five fingers to investigate their somatotopic and functional organizations. We showed that the activation properties and representational geometry of palm and finger representations do not follow their somatotopy, but are rather related to the physical shape of the hand.