Exp Brain Res (2005) 166: 287–288 DOI 10.1007/s00221-005-2369-8
INTROD U CTIO N
Salvador Soto-Faraco Æ John J. Foxe Æ Mark T. Wallace
Multisensory processes
Published online: 14 July 2005 Ó Springer-Verlag 2005
Introduction Research on the brain processes responsible for combining information from different sensory systems has experienced a spectacular growth in recent years. Yet, rather than evolving into a (yet another) sub-discipline in the brain sciences, multisensory research thrives from within a wide variety of different research areas and approaches, naturally embracing the interdisciplinary spirit of contemporary neuroscience. Such diversity makes for an ideal environment in which to begin to unravel the mysteries of multisensory processes, and sets the stage for unique opportunities for interaction. The International Multisensory Research Forum (IMRF), through its annual meetings, represents the principal vehicle for formalizing these interactions. The first meeting of the IMRF was held in Oxford in 1999, and by 2006 (where the meeting will be held in Dublin, Ireland) will have traveled to seven different countries. This special issue on Multisensory Processes stems from the fifth annual meeting of the IMRF, held in Barcelona (Spain) on June 2–5, 2004. Although most of the contributions arise from papers presented at the meeting, this volume is the result of an open call for submissions not restricted to IMRF speakers or attendees, with each submission being subjected to a peer review process. The S. Soto-Faraco (&) Cognitive Neuroscience Group, Departament de Psicologia Pa`sica, Universitat de Barcelona, Pg. Vall d’Hebron, 171, 08035 Barcelona, Spain E-mail:
[email protected] J. J. Foxe The Cognitive Neurophysiology Laboratory, Program in Cognitive Neuroscience and Schizophrenia, The Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA M. T. Wallace Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA
end product showcases current research efforts focusing on multisensory interactions, but is in no way meant to be an exhaustive representation of the state-of-the-field. The issue begins by highlighting several of the current methodological issues in multisensory research. In the first contribution, Laurienti et al. caution about the possible interpretational difficulties associated with extrapolating the results from single neuron studies of multisensory mechanisms in animal models to measures based on metabolic changes in the human brain, such as fMRI. In the second paper, Gonzalez et al. report on a novel analysis procedure for human electrophysiological data based on individual trials, and illustrate both its potential power and applicability to multisensory research. A second section comprises articles that concentrate largely on the mechanisms of multisensory integration. Two of the articles focus on the superior colliculus (SC), one of the pre-eminent models for examining multisensory processes. The first of these examines the development and plasticity of multisensory SC neurons and their interactions as a function of cortical influences, which have been shown to play a critical role for gating integrated multisensory responses (Stein). The second article looks at the intrinsic connectivity of the human SC (Tardiff et al.). Two additional articles in this section look at higher-order multisensory interactions, focusing on the cross-modal and cross-temporal associative properties of neurons in the prefrontal cortex (Deco et al.), and the nature of representations in sensory memory (Besle et al.). This section ends with a review paper addressing the psychophysics and brain mechanisms involved in the integration of odor and taste that gives rise to flavor perception (Prescott and Small). The third section of this special issue comprises papers that focus on crossmodal attention. Several of the contributions in this section make use of electrophysiological measures of brain activity to address the mechanisms subserving crossmodal shifts of attention (Foxe et al. and Green et al.), and the consequences that such shifts have for sensory processing (Eimer and van Velzen; Foxe and Simpson; Senkowski et al.). The
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final two papers in this section illustrate the effects of crossmodal attention on both involuntary (Rolfs et al.) and voluntary eye movements (Kirchner et al.). The temporal aspects of multisensory integration, which have recently generated a great deal of interest, represent the fourth section of this special issue. Three of these papers address the question of what is simultaneity when it comes to events occurring in different sensory modalities. This question is approached as a function of the type of event (first versus second order changes, Alais and Burr), the spatial location of the different stimuli (Harrar and Harris), and the frequency at which stimulation is received (Fujisaki and Nishida). Each of these contributions agrees that differences in neural transmission times are not the sole contributing factor to the perception of simultaneity. The last paper of this section provides evidence for alterations in the temporal window for multisensory integration in patients suffering from a prevalent reading disability—dyslexia (Hairston et al.). Following from the temporal issues, the next section focuses on the spatial aspects of multisensory integration. Three of the contributions target the potential interactions between proprioception, touch, and vision, and examine the consequences of posture change (Holmes et al. and Zampini et al.) and movement (Newell et al.) on tactile performance. The contribution of Kitagawa et al. also addresses tactile processing, but examines performance as a function of the location of auditory events (instead of visual events), and stresses the importance of these events taking place in close proximity to the body. Two other papers in this section look at tactile processing as a function of (top–down) influences enabled by vision in terms of its informational content; either as its validity as a spatial cue for touch (Shore and Simic), or for posture (in the form of a shadow cast by the body, Galfano and Pavani). The last two papers of this section examine multisensory interactions in motion processing. The first deals with audiovisual signals (Meyer et al.), and the second assesses the effects of concurrent visual and tactile motion information on auditory performance (Sanabria et al.). The final section of the issue is made up of articles dealing with multisensory form and object recognition, starting with a review paper on functional imaging studies on this topic (Amedi et al.). The next contribution deals with the consequences of short-term visual deprivation (i.e. blindfolding) on tactile form processing as measured with functional imaging techniques (Weisser et al.), whereas the final paper focuses
on how previous visual and tactile experience (i.e. familiarization) influences haptic face recognition (Casey and Newell). Our goal as guest editors of this special issue was to provide the reader with a glimpse into the burgeoning field of multisensory research, and to give a taste of the multitude of research opportunities that characterize this emerging and exciting area of inquiry. The intention was not to provide a comprehensive picture of the conference proceedings—this would be well beyond the scope of a single issue (and well beyond our energy!). Nonetheless, we hope that we have been able to preserve some essence of the spirit that makes the IMRF meetings so enjoyable and informative. For those who have an interest in exploring further, we would like to invite you to visit the IMRF web site (http://www.multisense.info). If your interest is truly aroused, then we encourage you to come join us at one of our upcoming meetings (Rovereto, Italy, in 2005, and Dublin, Ireland, in 2006). In closing this foreword, we would like to express our sincere gratitude to all of the authors who contributed to this special issue—it is your work that has been chosen as a snapshot of the current state of multisensory research, and apologize to those whose papers could not be considered for publication. We also want to extend our warmest thanks to the reviewers for their altruistic and exceedingly valuable contributions, as well as to Carlo Marzi (section editor of Experimental Brain Research) and Springer-Verlag for their enthusiastic support for this volume from the beginning of the process. Finally, we want to acknowledge the following companies and institutions for their financial support to the fifth IMRF meeting, from which this special issue has been derived: Brain Products Gbh (http://www.brainproducts.com), Electrical Geodesics Inc. (http://www.egi.com), BioSemi (http://www.biosemi.com by way of StarLab; http:// www.starlab.es), Firmenich (http://www.firmenich.com), Compumedics/Neuroscan (http://www.neuro.com by way of Intelimed Ibe´rica; http://www.intelimed.es), Unilever (http://www.unilever.com), The MIT Press (http:// www.mitpress.mit.edu), Oxford University Press (http:// www.oup.co.uk), Departament de Psicologia Ba`sica (Universitat de Barcelona; http://www.ub.edu), Sociedad Espan˜ola de Psicologı´ a Experimental (SEPEX), Parc Cientı´ fic de Barcelona (http://www.pcb.ub.es), Ministerio de Ciencia y Tecnologı´ a (Accio´n Especial BSO200212816-E), and DURSI—Generalitat de Catalunya (2004ARCS100001).
