Are somatosensory saccades voluntary or reflexive?

Abstract

The present study examines whether the distinction between voluntary (endogenous) and reflexive (stimulus-elicited) saccades made in the visual modality can be applied to the somatosensory modality. The behavioural characteristics of putative reflexive pro-saccades and voluntary anti-saccades made to visual and somatosensory stimuli were examined. Both visual and somatosensory pro-saccades had much shorter latency than voluntary anti-saccades made in the direction opposite to a peripheral stimulus. Furthermore, erroneous pro-saccades were made towards both visual and somatosensory stimuli on approximately 11-13% of anti-saccade trials. The observed difference in pro- and anti-saccade latency and the presence of pro-saccade errors in the anti-saccade task indicates that a somatosensory stimulus can elicit a form of reflexive saccade comparable to pro-saccades made in the visual modality. It is proposed that a peripheral somatosensory stimulus can elicit a form of reflexive saccade and that somatosensory saccades do not depend exclusively on higher level endogenous control processes for their generation. However, a comparison of the underlying latency distributions and of peak-velocity profiles of saccades made to visual and somatosensory stimuli showed that this distinction may be less clearly defined for the somatosensory modality and that modality-specific differences (such as differences in neural conduction rates) in the underlying oculomotor structures involved in saccade target selection also need to be considered. It is further suggested that a broader conceptualisation of saccades and saccade programming beyond the simple voluntary and reflexive dichotomy, that takes into account the control processes involved in saccade generation for both modalities, may be required.

Assessing the effectiveness of “intuitive” vibrotactile warning signals in preventing front-to-rear-end collisions in a driving simulator

“…Our results clearly suggest that the vibrotactile warning signals could intuitively direct the drivers' attention to the appropriate spatial direction and trigger a rapid (and appropriate) braking response. This can also be taken to reflect one of the strengths of the tactile system, as compared to the visual system, in terms of its ability to transmit information rapidly to the brain (see Harrar and Harris, 2005;Mowbray and Gebhard, 1961;Robinson, 1934; see also Amlôt and Walker, 2006;Gilmer, 1960Gilmer, , 1961.…”

Irrelevant auditory and tactile signals, but not visual signals, interact with the target onset and modulate saccade latencies

“…Moreover, depending on the distance to the blowing balloon, the auditory signal 15 might reach the observer either before or after the visual signal. The mechanisms involved in the 16 subjective timing of natural events must then show some degree of flexibility to determine whether 17 each unimodal component originate from the same causal source, before combining them into a 18 single multisensory event (for a detailed review on the causality in perception, refer to Shams & 19 Beierholm, 2010). Furthermore, the observed advantage of the visual modality over other senses for 20 spatial processing does not hold for the temporal domain: the auditory system is more sensitive and 21 reliable than the visual system to process the timing of events (Vidal, 2017).…”

“…The mechanism underlying gaze fixation has been proposed 15 to involve fixation cells in the rostral SC, which inhibit the generation of saccades through the 16 excitation of omnipause neurons in the brainstem (Munoz & Wurtz, 1993). Importantly, SC was also 17 the first structure where audiovisual integration in time and space was observed ( 19 superficial SC layers respond to visual stimuli and neurons in the intermediate and deep SC layers 20 also respond to auditory stimuli, such that auditory and visual sensory maps are connected at a very 21 early processing stage. Audiovisual interactions in monkey SC modulate saccade-related activity, 22 though less than what expected from earlier recordings (Maarten A Frens & Van Opstal, 1998).…”

“…For combined congruent audiovisual targets, the latency decrease was well 13 predicted by independent race models, suggesting that multisensory integration in the target 14 selection is not optimal (Corneil & Munoz, 1996). Finally, inhibiting saccades toward an auditory 15 distractor when the fixation point is already turned off proved more difficult than when the fixation 16 remains visible at the target onset (Munoz & Corneil, 1995), revealing an interaction between 17 disengaging fixation and the target selection in the SC. Importantly, tactile stimulations as well 18 influence saccades, both in the spatial and temporal dimensions (Hans Colonius & Diederich, 2004): 19 latencies are reduced when a touch is delivered before target onset, the facilitation being maximal 20 when the touch and visual target are spatially congruent (Amlôt, Walker, Driver, & Spence, 2003).…”

Cortical and cerebellar activation induced by reflexive and voluntary saccades

“…Saccades are fast rotatory eye movements that serve to move the eyes as quickly as possible, so that an object of interest is projected onto the fovea where it can be visually processed in detail (Schall 1995;Hayakawa et al 2002;Schiller and Tehovnik 2005;Amlot and Walker 2006). Saccades can be classiWed into two broad categories: reXexive and higher-order saccades.…”