Images of Illusory Motion in Primary Visual Cortex

Department of Psychology, University of Copenhagen, Denmark.
Journal of Cognitive Neuroscience (Impact Factor: 4.09). 08/2006; 18(7):1174-80. 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.

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    • "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). "
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    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.
    Cerebral Cortex 04/2015; 25:1052-1059. DOI:10.1093/cercor/bht297 · 8.67 Impact Factor
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    • "The sensation of motion typically coincides with neural activations in specialised motion-sensitive areas of the visual cortex, most prominently the MT+ complex [1]. Imaging studies have shown that activation in MT+ is not limited to situations involving real motion, but can also be elicited by static images that induce the percept of motion, such as the Enigma illusion [2], the Rotating Snake illusion [2], [3], moving illusory contours [4], [5], or other types of apparent motion [6], [7], [8], [9], [10], [11], [12]. "
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    ABSTRACT: Illusory line motion (ILM) refers to a motion illusion in which a flash at one end of a bar prior to the bar's instantaneous presentation or removal results in the percept of motion. While some theories attribute the origin of ILM to attention or early perceptual mechanisms, others have proposed that ILM results from impletion mechanisms that reinterpret the static bar as one in motion. The current functional magnetic resonance imaging study examined participants while they made decisions about the direction of motion in which a bar appeared to be removed. Preceding the instantaneous removal of the bar with a flash at one end resulted in a motion percept away from the flash. If this flash and the bar's removal overlapped in time, it appeared that the bar was removed towards the flash (reverse ILM). Independent of the motion type, brain responses indicated activations in areas associated with motion (MT+), endogenous and exogenous attention (intraparietal sulcus, frontal eye fields, and ventral frontal cortex), and response selection (ACC). ILM was associated with lower percept scores and higher activations in ACC relative to real motion, but no differences in shape-selective areas emerged. This pattern of brain activation is consistent with the attentional gradient model or bottom-up accounts of ILM in preference to impletion.
    PLoS ONE 01/2014; 9(1):e87595. DOI:10.1371/journal.pone.0087595 · 3.23 Impact Factor
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    • "Apparent motion is an illusion of motion induced by two stationary stimuli that blink on and off alternately. It gives rise to an illusory object moving between the inducing stimuli along the shortest path, but avoiding obstacles (Kolers, 1963; Attneave and Block, 1974; Shepard and Zare, 1983; Goebel et al., 1998; Muckli et al., 2002, 2005; Liu et al., 2004; Larsen et al., 2006). Long distance apparent motion is a particularly suitable paradigm as higher visual areas have larger receptive fields which enable them to process the spatio-temporal dynamics of the illusion, thus creating a prediction with regard to where the illusory motion token is at a certain time (Alink et al., 2010). "
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    ABSTRACT: Predicting visual information facilitates efficient processing of visual signals. Higher visual areas can support the processing of incoming visual information by generating predictive models that are fed back to lower visual areas. Functional brain imaging has previously shown that predictions interact with visual input already at the level of the primary visual cortex (V1; Harrison et al., 2007; Alink et al., 2010). Given that fixation changes up to four times a second in natural viewing conditions, cortical predictions are effective in V1 only if they are fed back in time for the processing of the next stimulus and at the corresponding new retinotopic position. Here, we tested whether spatio-temporal predictions are updated before, during, or shortly after an inter-hemifield saccade is executed, and thus, whether the predictive signal is transferred swiftly across hemifields. Using an apparent motion illusion, we induced an internal motion model that is known to produce a spatio-temporal prediction signal along the apparent motion trace in V1 (Muckli et al., 2005; Alink et al., 2010). We presented participants with both visually predictable and unpredictable targets on the apparent motion trace. During the task, participants saccaded across the illusion whilst detecting the target. As found previously, predictable stimuli were detected more frequently than unpredictable stimuli. Furthermore, we found that the detection advantage of predictable targets is detectable as early as 50-100 ms after saccade offset. This result demonstrates the rapid nature of the transfer of a spatio-temporally precise predictive signal across hemifields, in a paradigm previously shown to modulate V1.
    Frontiers in Psychology 06/2012; 3:176. DOI:10.3389/fpsyg.2012.00176 · 2.80 Impact Factor
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