title: Transfer of tactile perceptual learning to untrained neighboring fingers reflects natural use relationships.
abstract: Tactile learning transfers from trained to untrained fingers in a pattern that reflects overlap between the representations of fingers in the somatosensory system (e.g., neurons with multifinger receptive fields). While physical proximity on the body is known to determine the topography of somatosensory representations, tactile coactivation is also an established organizing principle of somatosensory topography. In this study we investigated whether tactile coactivation, induced by habitual inter-finger cooperative use (use pattern), shapes inter-finger overlap. To this end, we used psychophysics to compare the transfer of tactile learning from the middle finger to its adjacent fingers. This allowed us to compare transfer to two fingers that are both physically and cortically adjacent to the middle finger but have differing use patterns. Specifically, the middle finger is used more frequently with the ring than with the index finger. We predicted this should lead to greater representational overlap between the former than the latter pair. Furthermore, this difference in overlap should be reflected in differential learning transfer from the middle to index vs. ring fingers. Subsequently, we predicted temporary learning-related changes in the middle finger's representation (e.g., cortical magnification) would cause transient interference in perceptual thresholds of the ring, but not the index, finger. Supporting this, longitudinal analysis revealed a divergence where learning transfer was fast to the index finger but relatively delayed to the ring finger. Our results support the theory that tactile coactivation patterns between digits affect their topographic relationships. Our findings emphasize how action shapes perception and somatosensory organization.
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; School of Psychology, University of Queensland, Brisbane, Australia;
authors.forename: Harriet
authors.identifier: http://orcid.org/0000-0002-9360-7842
authors.initials: H
authors.lastname: Dempsey-Jones
authors.affiliation: School of Optometry, University of Montreal, Montreal, Quebec, Canada; and Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Harrar
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Oliver
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom;
authors.forename: Heidi
authors.initials: H
authors.lastname: Johansen-Berg
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
authors.forename: Charles
authors.initials: C
authors.lastname: Spence
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; tamar.makin@ndcn.ox.ac.uk.
authors.forename: Tamar R
authors.initials: TR
authors.lastname: Makin
mesh_terms: D000328:Adult; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology*; D006801:Humans; D007858:Learning; D008297:Male; D013003:Somatosensory Cortex / Q000502:physiology; D055698:Touch Perception
keywords: co-activation; generalization; perceptual learning; primary somatosensory cortex; topography