title: Moving sounds within the peripersonal space modulate the motor system.
abstract: Interactions between ourselves and the external world are mediated by a multisensory representation of the space surrounding the body, i.e. the peripersonal space (PPS). In particular, a special interplay is observed among tactile stimuli delivered on a body part, e.g. the hand, and visual or auditory external inputs presented close, but not far, from the same body part, e.g. within hand PPS. This coding of multisensory stimuli as a function of their distance from the hand has a role in upper limb actions. However, it remains unclear whether PPS representation affects the motor system only when stimuli occur specifically at the hand location or when they move within a continuous portion of space where the hand can potentially act. Here, in order to study these two alternatively hypotheses, we assessed the critical distance at which moving sounds have a direct effect on hand corticospinal excitability by using Transcranial Magnetic Stimulation (TMS). Specifically, TMS single pulses were delivered when a sound source was perceived at six different positions in space: from very close to subjects' hand (15 cm) to far away (90 cm). Moreover, sound direction was manipulated to test if stimuli approaching and receding from the hand might have the same relevance for the motor system. MEPs amplitude was enhanced when sounds were delivered within a limited distance from the hand (around 60 cm) as compared to when the sounds were beyond this space. This effect captures the spatial boundaries within which PPS representation modulates hand cortico-motor excitability. This spatially-dependent modulation of corticospinal activity was not further affected by the sound direction. Such findings support a strict link between the multisensory representation of the space around the body and the motor representation of potential approaching or defensive acts within that space.
authors.affiliation: Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Finisguerra
authors.affiliation: Laboratory of Cognitive Neuroscience, Center for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Elisa
authors.initials: E
authors.lastname: Canzoneri
authors.affiliation: Laboratory of Cognitive Neuroscience, Center for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Department of Psychology, University of Bologna, 40127 Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Serino
authors.affiliation: Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genova 16163, Italy; IUF, INSERM U1093 Cognition, Action et Plasticité Sensorimotrice, Université de Bourgogne, Dijon 21078, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Pozzo
authors.affiliation: Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genova 16163, Italy. Electronic address: michela.bassolino@epfl.ch.
authors.forename: Michela
authors.initials: M
authors.lastname: Bassolino
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006225:Hand; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology; D010550:Personal Space; D013017:Sound Localization / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Action; Looming sound; Motor cortex; Peripersonal space; Transcranial Magnetic Stimulation