Activity patterns in human motion-sensitive areas depend on the interpretation of global motion

Abstract

Numerous imaging studies have contributed to the localization of motion-sensitive areas in the human brain. It is, however, still unclear how these areas contribute to global motion perception. Here, we investigate with functional MRI whether the motionsensitive area hMT ؉ ͞V5 is involved in perceptual segmentation and integration of motion signals. Stimuli were overlapping moving gratings that can be perceived either as two independently moving, transparent surfaces or as a single surface moving in an intermediate direction. We examined whether motion-sensitive area hMT ؉ ͞V5 is involved in mediating the switches between the two percepts. The data show differential activation of hMT ؉ ͞V5 with perceptual switches, suggesting that these are associated with a reconfiguration of cell assemblies in this area.

Neuromagnetic brain responses during 3D object perception from 2D optic flow

“…The change in the activation in the occipito-temporal motion-sensitive area in conjunction with the perception of global motion is also reported in the previous fMRI studies [11,12], and the intra-parietal region were reported to be activated during the mental imagery processing [13,14], which suggests that the perception of moving 3D object from 2D random-dot motion includes both perception of global motion and 3D mental image processing, that are accomplished by the cooperative activation in the ventral and dorsal visual pathways.…”

A neural basis for inference in perceptual ambiguity

“…There is ample evidence to suggest that perceived changes in motion direction, no matter whether they are spontaneous or stimulus-driven, are reflected by eventrelated hMTϩ/V5 activations (16,(23)(24)(25)(26)(27)(28). We hypothesized that if the inferior frontal cortex was causally involved in inducing switches during bistable perception, then frontal activations in association with spontaneous perceptual switches should precede those in hMTϩ/V5.…”

“…According to evidence from neurophysiological studies in nonhuman primates (30,31) and human fMRI studies (32), subjective fluctuations in perception are reflected by relative activity levels of neuronal populations representing either perceptual content. The finding of switch-related hMTϩ/V5 activations in bistable motion perception (16,(24)(25)(26)28) has led to the suggestion that separate direction-selective neuronal populations coding for different directions of motion might be in rivalry and that, at perceptual switches, one of these populations displays a transient rise in activity. This interpretation is supported by the electrophysiological observation in monkeys that responses of directionally selective cells in MT signal the perceived direction of motion in ambiguous motion stimuli (27).…”

The hierarchy of directional interactions in visual motion processing

“…In the case of direction repulsion, a number of authors have proposed that the mechanism driving it occurs at the early local motion-processing stages (Marshak & Sekuler 1979;Hiris & Blake 1996;Grunewald 2004;Wiese & Wenderoth 2007), while others have proposed it occurs at the later global motion processing stages ( Wilson & Kim 1994;Kim & Wilson 1996, 1997Benton & Curran 2003). These two stages of motion processing have been identified as occurring in area V1 and the human homologue of macaque MT/V5, respectively (Snowden 1994;Castelo-Branco et al 2002;Huk & Heeger 2002). Again, in the case of the DAE, there is evidence supporting both a local (Kohn & Movshon 2004;Curran et al 2006a) and global motion processing (Kohn & Movshon 2004;Wiese & Wenderoth 2007) account.…”