Images of Illusory Motion in Primary Visual Cortex

ArticleinJournal of Cognitive Neuroscience 18(7):1174-80 · August 2006with15 Reads
DOI: 10.1162/jocn.2006.18.7.1174 · Source: PubMed
Illusory motion can be generated by successively flashing a stationary visual stimulus in two spatial locations separated by several degrees of visual angle. In appropriate conditions, the apparent motion is indistinguishable from real motion: The observer experiences a luminous object traversing a continuous path from one stimulus location to the other through intervening positions where no physical stimuli exist. The phenomenon has been extensively investigated for nearly a century but little is known about its neurophysiological foundation. Here we present images of activations in the primary visual cortex in response to real and apparent motion. The images show that during apparent motion, a path connecting the cortical representations of the stimulus locations is filled in by activation. The activation along the path of apparent motion is similar to the activation found when a stimulus is presented in real motion between the two locations.
    • "The retina and early visual areas (including V1 and V5) are retinotopic. V1 by means of reentrant processing in a mere 20 ms after the activation of V5 (Muckli et al. 2005 ; Larsen et al. 2006 ; Wibral et al. 2009 ), there is ample time for us to perceive (apparent) motion before the processing related to the perception of the second stimulus is completed. It is worth emphasizing that this explanation rests upon the idea that we perceive motion and the second stimulus once the reentrant processing related to them terminate in V1. "
    [Show abstract] [Hide abstract] ABSTRACT: Philosophers have usually approached the concept of timing of experiences by addressing the question how the experiences of temporal phenomena can be explained. As a result, the issue of timing has been addressed in two different ways. The first, similar to the questions posed in sciences, concerns the relationship between the experienced time of events and the objective time of events. The second approach is more specific to philosophers’ debates, and concerns the phenomenology of experiences: how is the apparent temporal structure of experiences constituted? In regard to both questions, this article shows why and how philosophers’ views differ from those held by most scientists. To conclude, I present a combination of views that is not only compatible with that of scientists, but also addresses the problems that engage philosophers.
    Full-text · Chapter · Jan 2016 · Cerebral Cortex
    • "This suggests that, in the apparent motion experiments, the cortical motion processing can begin even before the sensory signals resulting in the perception of the second stimulus reach the cortex. Given that the apparent motion stimuli can induce V5 activation, which in turn activates the primary visual cortex by means of local reentrant processing in a mere 20 ms after the activation of V5 (Larsen et al., 2006; Muckli, Kohler, Kriegeskorte, & Singer, 2005; Wibral et al., 2009), there is ample time to perceive (apparent) motion before the processing related to the perception of the second stimulus is completed. Although the non-linear latency difference view can therefore account for apparent motion, and do so in a way that is well substantiated by the empirical evidence, it may appear to be in disagreement with results showing how apparent motion results from two computationally distinct systems. "
    [Show abstract] [Hide abstract] ABSTRACT: Postdiction effects are phenomena in which a stimulus influences the appearance of events taking place before it. In metacontrast masking, for instance, a masking stimulus can render a target stimulus shown before the mask invisible. This and other postdiction effects have been considered incompatible with a simple explanation according to which (i) our perceptual experiences are delayed for only the time it takes for a distal stimulus to reach our sensory receptors and for our neural mechanisms to process it, and (ii) the order in which the processing of stimuli is completed corresponds with the apparent temporal order of stimuli. As a result, the theories that account for more than a single postdiction effect reject at least one of these theses. This paper presents a new framework for the timing of experiences-the non-linear latency difference view-in which the three most discussed postdiction effects-apparent motion, the flash-lag effect, and metacontrast masking-can be accounted for while simultaneously holding theses (i) and (ii). This view is grounded in the local reentrant processes, which are known to have a crucial role in perception. Accordingly, the non-linear latency difference view is both more parsimonious and more empirically plausible than the competing theories, all of which remain largely silent about the neural implementation of the mechanisms they postulate.
    Full-text · Article · Nov 2015
    • "Using brain imaging, we demonstrated that V1 neurons retinotopically responsive to the apparent motion trace are activated during apparent motion as if real motion was present, despite the absence of actual feed-forward stimulation (Muckli et al. 2005). This effect may be explained by visual motion area V5/ human motion complex, human medial temporal complex (hMT) communicating the prediction of a moving token to V1 via feedback connections (Goebel et al. 1998; Muckli et al. 2002; Silvanto et al. 2005; Larsen et al. 2006; Sterzer et al. 2006; Ahmed et al. 2008; Wibral et al. 2009; Frégnac et al. 2010 ). Furthermore , we showed that the creation of a predictive signal on the apparent motion trace is spatio-temporally specific: Targets flashed on the apparent motion trace in-time with the illusory motion token are detected better than that flashed out-of-time (Schwiedrzik et al. 2007; Vetter et al. 2012). "
    [Show abstract] [Hide abstract] ABSTRACT: Given the vast amount of sensory information the brain has to deal with, predicting some of this information based on the current context is a resource-efficient strategy. The framework of predictive coding states that higher-level brain areas generate a predictive model to be communicated via feedback connections to early sensory areas. Here, we directly tested the necessity of a higher-level visual area, V5, in this predictive processing in the context of an apparent motion paradigm. We flashed targets on the apparent motion trace in-time or out-of-time with the predicted illusory motion token. As in previous studies, we found that predictable in-time targets were better detected than unpredictable out-of-time targets. However, when we applied functional magnetic resonance imaging-guided, double-pulse transcranial magnetic stimulation (TMS) over left V5 at 13–53 ms before target onset, the detection advantage of in-time targets was eliminated; this was not the case when TMS was applied over the vertex. Our results are causal evidence that V5 is necessary for a prediction effect, which has been shown to modulate V1 activity (Alink et al. 2010). Thus, our findings suggest that information processing between V5 and V1 is crucial for visual motion prediction, providing experimental support for the predictive coding framework.
    Full-text · Article · Apr 2015
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