The Contribution of Primary and Secondary Somatosensory Cortices to the Representation of Body Parts and Body Sides: An fMRI Adaptation Study

Tamè, Luigi and Braun, Christoph and Lingnau, Angelika and Schwarzbach, Jens and Demarchi, Gianpaolo and Li Hegner, Yiwen and Farnè, Alessandro and Pavani, Francesco (2012) The Contribution of Primary and Secondary Somatosensory Cortices to the Representation of Body Parts and Body Sides: An fMRI Adaptation Study. Journal of Cognitive Neuroscience, 24 (12). pp. 2306-2320. ISSN 0898-929X. (doi:https://doi.org/10.1162/jocn_a_00272) (Full text available)

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Abstract

While the somatosensory homunculus is a classically used description of the way somatosensory inputs are processed in the brain, the actual contribution of primary (SI) and secondary (SII) somatosensory cortices to the spatial coding of touch remains poorly understood. We studied adaptation of the fMRI BOLD response in the somatosensory cortex by delivering pairs of vibrotactile stimuli to the finger tips of the index and middle fingers. The second stimulus (test) was always administered to the left index finger, while the first stimulus (adaptor) was delivered either to the same or to a different (middle) finger of the right or left hand. The overall BOLD response evoked by the stimulation was primarily contralateral in SI and was more bilateral in SII. However, our fMRI adaptation approach also revealed that both somatosensory cortices were sensitive to ipsilateral as well as to contralateral inputs. SI and SII adapted more when the stimulation repeated over homologous than non-homologous fingers, showing a distinction between different fingers. Most importantly, for both somatosensory cortices this finger-specific adaptation occurred irrespective of whether the tactile stimulus was delivered to the same or to different hands. This result implies integration of contralateral and ipsilateral somatosensory inputs in SI, as well as in SII. These findings suggest that SI is more than simply a relay for sensory information, and that both SI and SII contribute to the spatial coding of touch by discriminating between body parts (fingers) and by integrating the somatosensory input from the two sides of the body (hands).

Item Type: Article
Subjects: B Philosophy. Psychology. Religion
Divisions: Faculties > Social Sciences > School of Psychology
Faculties > Social Sciences > School of Psychology > Cognitive Psychology
Depositing User: Luigi Tame
Date Deposited: 24 Jan 2019 18:25 UTC
Last Modified: 25 Jan 2019 16:02 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/71600 (The current URI for this page, for reference purposes)
Tamè, Luigi: https://orcid.org/0000-0002-9172-2281
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