Distinct effects of attention on the neural responses to form and motion processing: A SSVEP source-imaging study

Abstract

We measured neural responses to local and global aspects of form and motion stimuli using frequency-tagged, steady-state visual evoked potentials (SSVEPs) combined with magnetic resonance imaging (MRI) data. Random dot stimuli were used to portray either dynamic Glass patterns (Glass, 1969) or coherent motion displays. SSVEPs were used to estimate neural activity in a set of fMRI-defined visual areas in each subject. To compare activity associated with local versus global processing, we analyzed two frequency components of the SSVEP in each visual area: the high temporal frequency at which the local dots were updated (30 Hz) and the much lower frequency corresponding to updates in the global structure (0.83 Hz). Local and global responses were evaluated in the context of two different behavioral tasks--subjects had to either direct their attention toward or away from the global coherence of the stimuli. The data show that the effect of attention on global and local responses is both stimulus and visual area dependent. When attention was directed away from stimulus coherence, both local and global responses were higher in the coherent motion than Glass pattern condition. Directing attention to coherence in Glass patterns enhanced global activity in areas LOC, hMT+, V4, V3a, and V1, while attention to global motion modulated responses by a smaller amount in a smaller set of areas: V4, hMT+, and LOC. In contrast, directing attention towards stimulus coherence weakly increased local responses to both coherent motion and Glass patterns. These results suggest that visual attention differentially modulates the activity of early visual areas at both local and global levels of structural encoding.

Spatial attention enhances cortical tracking of quasi-rhythmic visual stimuli

“…Our whole-brain analysis, supported by a fine-grained cortical parcellation (Glasser et al 2016), allowed us to investigate the cortical topography of attentional modulation with unprecedented spatial detail. The results support an attentional modulation of SSRs as early as V1 (Lauritzen et al 2010, Palomares et al 2012, Keil et al 2012) and substantiate attentional gain effects in subsequent early visual cortices V2, V3 and V4, as well as in dorsal stream area V6 and ventral stream area V8. In addition to V1 and V4, Lauritzen et al (2010) reported SSR attentional gain in the middle temporal area (hMT+ in their notation, likely a region in the MT+ complex of Glasser et al 2016) and in the intraparietal sulcus (IPS in their notation, possibly IPS1 in Glasser et al 2016), which we did not find.…”

“…Direct enquiries into which visual cortices show attentional modulation of SSRs have been limited. Electrical source imaging has implicated V1 consistently (Andersen & Muller, 2010;Keil et al, 2012;Keitel, Andersen, Quigley, & Müller, 2013, but see Hillyard et al, 1997 and other visual cortices, such as V4, the lateral occipital complex (LOC) and human area MT have been screened for attentional modulation after being pre-selected as regions of interest (Lauritzen, Ales, & Wade, 2010;Palomares, Ales, Wade, Cottereau, & Norcia, 2012). Studies investigating the cortical processing of naturally occurring quasi-rhythmic visual stimuli in low frequency bands (< 7 Hz), such as the tracking of a speaker's lips movements (Hauswald, Lithari, Collignon, Leonardelli, & Weisz, 2018;Park, Kayser, Thut, & Gross, 2016) or hand gestures (Biau, Morís Fernández, Holle, Avila, & Soto-Faraco, 2016), have localized sources in circumscribed visual cortices without looking into detailed mapping of cortical regions and a modulation of the tracking response by visuo-spatial attention along the visual hierarchy.…”

Neurofeedback Therapy for Enhancing Visual Attention: State-of-the-Art and Challenges

“…Another widely used BCI protocol is the SSVEP (Zhang et al, 2010 ; Palomares et al, 2012 ; Lesenfants et al, 2014 ; Wu and Su, 2014 ; Reuter et al, 2015 ). Visual evoked potential (VEP) is the brain responses to a visual stimulus such as light flash or flickering of a checker board at a specific frequency (Punsawad and Wongsawat, 2012 ).…”

Directional Visual Motion Is Represented in the Auditory and Association Cortices of Early Deaf Individuals

“…Unfortunately, due to the spatial scale, such direction-tuning cannot be studied non-invasively in humans, and direction specific representation in humans has thus remained elusive (see Kamitani & Tong, 2006 for a potential exception, but also Beckett et al, 2012; for axis of motion mapping at 7 Tesla, see Zimmermann et al, 2011). Despite this, direction selective areas may be identified in the human brain with functional magnetic resonance imaging (fMRI) with stimulation presentation techniques, such as contrasting directional (i.e., coherent) motion with directionless (i.e., non-coherent) motion or dynamic noise (Beauchamp, Cox & DeYoe, 1997; Braddick et al, 1997; Morrone et al, 2000; in electro/magnetoencephalography: Tyler & Kaitz, 1977; Lam et al, 2000; Nakamura et al, 2003; Ales & Norcia, 2009; Palomares et al, 2012).…”