Prismatic adaptation effects on spatial representation of time in neglect patients

Department of Psychology, University of Palermo, Palermo, Italy
Cortex (Impact Factor: 5.13). 11/2011; 49(1). DOI: 10.1016/j.cortex.2011.11.010
Source: PubMed


Processing of temporal information may require the use of spatial attention to represent time along a mental time line. We used prismatic adaptation (PA) to explore the contribution of spatial attention to the spatial representation of time in right brain damaged patients with and without neglect of left space and in age-matched healthy controls. Right brain damaged patients presented time underestimation deficits, that were significantly greater in patients with neglect than in patients without neglect. PA inducing leftward attentional deviation reduced time underestimation deficit in patients with neglect. The results support the hypothesis that a right hemispheric network has a role, per se, in time perception. Moreover, they suggest that right hemisphere is important in time perception for its control of spatial attention, engaged in spatial representation of time. Procedures that ameliorate left spatial deficits could also be useful for modulating temporal deficits in right brain damaged patients with neglect.

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Available from: Stefano Avanzi
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    • "From the observation of interactions between duration and space processing, it has been proposed that the representation of durations could rely on a spatial medium oriented from left-to-right, namely a MTL mirroring the MNL. However, studies on neglect have shown some contradictory results that did not fit completely with the idea that duration is underlied by a spatial representation oriented from left to right (Basso et al., 1996; Calabria et al., 2011; Danckert et al., 2007; Oliveri et al., 2013). To test the possible existence of such a MTL, the present study aimed at comparing the performance of neglect patients in a non-symbolic numerical and duration comparison tasks. "
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    ABSTRACT: Previous studies have shown that left neglect patients are impaired when they have to orient their attention leftward relative to a standard in numerical comparison tasks. This finding has been accounted for by the idea that numerical magnitudes are represented along a spatial continuum oriented from left to right with small magnitudes on the left and large magnitudes on the right. Similarly, it has been proposed that duration could be represented along a mental time line that shares the properties of the number continuum. By comparing directly duration and numerosity processing, this study investigates whether or not the performance of neglect patients supports the hypothesis of a mental time line. Twenty-two right brain-damaged patients (11 with and 11 without left neglect), as well as 11 age-matched healthy controls, had to judge whether a single dot presented visually lasted shorter or longer than 500 ms and whether a sequence of flashed dots was smaller or larger than 5. Digit spans were also assessed to measure verbal working memory capacities. In duration comparison, no spatial-duration bias was found in neglect patients. Moreover, a significant correlation between verbal working memory and duration performance was observed in right brain-damaged patients, irrespective of the presence or absence of neglect. In numerical comparison, only neglect patients showed an enhanced distance effect for numerical magnitude smaller than the standard. These results do not support the hypothesis of the existence of a mental continuum oriented from left to right for duration. We discuss an alternative account to explain the duration impairment observed in right brain-damaged patients.
    Full-text · Article · Sep 2015 · British Journal of Psychology
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    • "Patients with left hemispatial neglect showed a specific deficit when remembering and attributing items to the past, whereas this " distortion " was absent in right brain damaged patients without neglect and in healthy controls. By using prismatic adaptation Oliveri et al. (2013) crucially demonstrated that the disturbances in the time domain shown by neglect patients result from their impaired spatial processing rather than by other, more general, cognitive impairments (Bonato et al., 2012b). "

    Full-text · Article · Jun 2014 · Frontiers in Psychology
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    • "The procedure for prismatic adaptation was similar to that adopted in previous studies (Frassinetti et al., 2009; Magnani et al., 2011; Oliveri et al., 2013) and was administered outside the scanner (see paradigm below). "
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    ABSTRACT: Prismatic Adaptation (PA) has been shown to affect left-to-right spatial representations of temporal durations. A leftward aftereffect usually distorts time representation toward an underestimation, while rightward aftereffect usually results in an overestimation of temporal durations. Here, we used functional magnetic resonance imaging (fMRI) to study the neural mechanisms that underlie PA effects on time perception. Additionally, we investigated whether the effect of PA on time is transient or stable and, in the case of stability, which cortical areas are responsible of its maintenance. Functional brain images were acquired while participants (n=17) performed a time reproduction task and a control task before, immediately after and 30 minutes after PA inducing a leftward aftereffect, administered outside the scanner. The leftward aftereffect induced an underestimation of time intervals that lasted for at least 30 minutes. The left anterior insula and the left superior frontal gyrus showed increased functional activation immediately after versus before PA in the time versus the control task, suggesting these brain areas to be involved in the executive spatial manipulation of the representation of time. The left middle frontal gyrus showed an increase of activation after 30 minutes with respect to before PA. This suggests that this brain region may play a key role in the maintenance of the PA effect over time.
    Full-text · Article · Jan 2014 · NeuroImage
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