Improved Motion Perception and Impaired Spatial Suppression following Disruption of Cortical Area MT/V5

Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY 14627, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 01/2011; 31(4):1279-83. DOI: 10.1523/JNEUROSCI.4121-10.2011
Source: PubMed


As stimulus size increases, motion direction of high-contrast patterns becomes increasingly harder to perceive. This counterintuitive behavioral result, termed "spatial suppression," is hypothesized to reflect center-surround antagonism-a receptive field property ubiquitous in sensory systems. Prior research proposed that spatial suppression of motion signals is a direct correlate of center-surround antagonism within cortical area MT. Here, we investigated whether human MT/V5 is indeed causally involved in spatial suppression of motion signals. The key assumption is that a disruption of neural mechanisms that play a critical role in spatial suppression could allow these normally suppressed motion signals to reach perceptual awareness. Thus, our hypothesis was that a disruption of MT/V5 should weaken spatial suppression and, consequently, improve motion perception of large, moving patterns. To disrupt MT/V5, we used offline 1 Hz transcranial magnetic stimulation (TMS)-a method that temporarily attenuates normal functioning of the targeted cortex. Early visual areas were also targeted as a control site. The results supported our hypotheses and showed that disruption of MT/V5 improved motion discrimination of large, moving stimuli, presumably by weakening surround suppression strength. This effect was specific to MT/V5 stimulation and contralaterally presented stimuli. Evidently, the critical neural constraints limiting motion perception of large, high-contrast stimuli involve MT/V5. Additionally, our findings mimic spatial suppression deficits that are observed in several patient populations and implicate impaired MT/V5 processes as likely neural correlates for the reported perceptual abnormalities in the elderly, patients with schizophrenia and those with a history of depression.

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    • "As V1/V2 are not selective areas for global stimulus attributes, such as motion, we do not expect pronounced effects on motion discrimination, but might expect an effect on color detection [10]. On-line [11e16], and off-line [17] TMS have previously been shown to be effective at reducing, or improving [18] motion sensitivity using a range of different stimuli and tasks, stimulation protocols, and brain areas targeted. Here we use a continuous thetaburst stimulation protocol (cTBS) [19], an off-line rTMS protocol, which is relatively novel to vision testing. "
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    ABSTRACT: Background: Psychophysical evidence suggests that the perception of the motion and color of moving stimuli are determined separately in the human brain. Here we aim to determine the role of visual cortical areas hMT+ and V1/V2 in each task by measuring the effect of rTMS of each area using an off-line continuous theta-burst stimulation (cTBS) protocol. Methods: In the motion task, the direction of moving dots was identified using a global motion stimulus that avoids tracking, and in the detection task for the same stimulus, the presence of the dots was detected regardless of motion. Performance was measured using forced-choice methods in 8 subjects, both before and at 4 time-intervals in the 1-hour after brain stimulation. All experiments were done using achromatic and isoluminant, red-green chromatic stimuli. Results: Performance on global motion for both achromatic and chromatic stimuli was significantly impaired following cTBS of visual area hMT+, with a maximum effect occurring 11 min after stimulation. In comparison, there was no effect of cTBS on the motion task for areas V1/V2 or the vertex (control). cTBS did not affect the detection task in either area. Conclusions: Our experiments validate the use of cTBS as an advantageous off-line rTMS protocol for studying visual areas. The results indicate a causal link between neural activity in area hMT+ and perception of motion of isoluminant chromatic stimuli. We conclude that area hMT+ is part of a common pathway processing the global motion of chromatic and achromatic stimuli, but is not involved in their detection.
    Brain Stimulation 11/2014; 8(2). DOI:10.1016/j.brs.2014.11.001 · 4.40 Impact Factor
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    • "Superior global motion perception (relative to controls) has also been shown in certain patient groups such as those suffering from schizophrenia (Tadin et al., 2006) where inhibition is known to be weak. Most recently, Tadin et al. (2011) have shown that applying repetitive transcranial magnetic stimulation (TMS) over area V5/MT can improve motion discrimination for large stimuli, an effect that they attributed to a TMS-induced weakening of surround suppression strength. As such, our findings may, at least in part, reflect reduced center-surround antagonism and hence less spatial suppression in area V5/MT in older adults. "
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    ABSTRACT: Recent evidence suggests that normal aging is typically accompanied by impairment in the ability to perceive the global (overall) motion of visual objects in the world. The purpose of this study was to examine the interplay between age-related changes in the ability to perceive translational global motion (up vs. down) and important factors such as the spatial extent (size) over which movement occurs and how cluttered the moving elements are (density). We used random dot kinematograms (RDKs) and measured motion coherence thresholds (% signal elements required to reliably discriminate global direction) for young and older adults. We did so as a function of the number and density of local signal elements, and the aperture area in which they were displayed. We found that older adults' performance was relatively unaffected by changes in aperture size, the number and density of local elements in the display. In young adults, performance was also insensitive to element number and density but was modulated markedly by display size, such that motion coherence thresholds decreased as aperture area increased (participants required fewer local elements to move coherently to determine the overall image direction). With the smallest apertures tested, young participants' motion coherence thresholds were considerably higher (~1.5 times worse) than those of their older counterparts. Therefore, when RDK size is relatively small, older participants were actually better than young participants at processing global motion. These findings suggest that the normal (disease-free) aging process does not lead to a general decline in perceptual ability and in some cases may be visually advantageous. The results have important implications for the understanding of the consequences of aging on visual function and a number of potential explanations are explored. These include age-related changes in spatial summation, reduced cortical inhibition, neural blur and attentional resource allocation.
    Frontiers in Aging Neuroscience 08/2014; 6:199. DOI:10.3389/fnagi.2014.00199 · 4.00 Impact Factor
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    • "One of the proposed hypotheses for the illusion (Ito, 2012) is that a centre-surround relative-motion (or motion-contrast) detector (Figure 2b) produces an illusory motion component of the centre disc. The centre-surround antagonism for motion in V5/MT cells has been investigated physiologically and psychophysically (Allman, Miezin, & McGuinness, 1957; Born & Tootell, 1992; Born, Groh, Zhao, & Lukasewycz, 2000; Murakami & Shimojo, 1996; Shioiri, Ono, & Sato, 2002; Tadin, Lappin, Gilroy, & Blake, 2003; Tadin, Silvanto, Pascual-Leone, & Battelli, 2011; Takemura, Ashida, Amano, Kitaoka, & Murakami, 2012; van der Smagt, Verstraten, & Paffen, 2010). The typical receptive field of the detector consists of a classical receptive field for motion and the surround inhibitory area as shown in Figure 2b. "
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    ABSTRACT: The pursuit-pursuing illusion is a visual illusion where a circular object placed in the centre of a radial pattern consisting of thin sectors is seen to move in the pursuit eye movement direction. The present study investigates the role of the surrounding texture, replacing the sectors with random dots or stripes in an orientation that was orthogonal, parallel or oblique to the pursuit direction. The experiments demonstrate that the acquired illusory effect was large for the orthogonal stripes. However, each surrounding texture produces a relatively smaller effect than the radial sectors. These results suggest that a hypothesis based on the property of a centre-surround relative-motion detector cannot fully explain the illusion and that the radial stimulus structure itself plays an important role in this illusion.
    Perception 01/2014; 5(1):20-40. DOI:10.1068/i0597 · 0.91 Impact Factor
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