Left insular cortex and left SFG underlie prismatic adaptation effects on time perception: Evidence from fMRI Barbara Magnani a, ⁎, Francesca Frassinetti b,c , Thomas Ditye d , Massimiliano Oliveri a,e , Marcello Costantini f,g , Vincent Walsh d a Fondazione “Santa Lucia”, IRCCS, 00179 Roma, Italy b Department of Psychology, University of Bologna, 40127 Bologna, Italy c Fondazione Salvatore Maugeri, Clinica del Lavoro e della Riabilitazione, IRCCS, Istituto Scientifico di Castel Goffredo, 46042 Mantova, Italy d Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, UK e Department of Psychology, University of Palermo, 90100 Palermo, Italy f Laboratory of Neuropsychology and Cognitive Neuroscience, Department of Neuroscience and Imaging, University G. d'Annunzio, 66013 Chieti, Italy g Institute for Advanced Biomedical Technologies — ITAB, Foundation University G. d'Annunzio, 66013 Chieti, Italy abstract article info Article history: Accepted 19 January 2014 Available online 24 January 2014 Keywords: Spatial representation of time Prismatic adaptation Left frontal lobe 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 respon- sible 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 min 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 min. The left an- terior 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 min 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. © 2014 Published by Elsevier Inc. Introduction Recent empirical data and theoretical models suggest that space and time representations share common cognitive resources. For instance, Xuan et al. (2007) showed that spatial features of a stimulus (size, in this case) affect judgments of time duration of the same stimulus; that is, larger stimuli are judged to last longer than smaller stimuli. In the same vein, neuropsychological observations suggest that following a se- lective parietal brain lesion patients show both spatial and temporal deficits (Basso et al., 1996; Critchley, 1953; Danckert et al., 2007). At the neuronal level, Leon and Shadlen (2003), demonstrated that parietal neurons in monkeys encode both time and space. A recent theory unifies the present evidence on these interactions between space and time in the brain (“A Theory Of Magnitude — ATOM”; Walsh, 2003; Bueti and Walsh, 2009). This theory assumes that space, time and also other kinds of quantity, such as number, are part of a generalized mag- nitude system. In other words, networks of similar brain regions are en- gaged whenever a quantity needs to be measured, regardless of the particular domain of quantity (i.e. temporal, spatial, or numerical). In order to facilitate the quantification process, the same metrical map used to measure all quantities would have a spatial nature, with the aim to give a spatial shape and a spatial order to the dimension being measured. Numerous studies support this theory and provide results suggesting that time intervals are represented via a spatial Mental Time Line (MTL), with shorter time durations represented to the left of longer durations. For example, it has been shown that the duration of a temporal stimulus primes a motor response that is spatially orga- nized according to the direction of the MTL: subjects are significantly faster and more accurate in responding to short periods with their left hand, and in responding to long periods with their right hand (Ishihara et al., 2008; Vallesi et al., 2008). This priming of a spatial motor response by means of temporal stimuli has not only been found for time durations, but also for temporal metaphor concepts: words with meaning referring to past events prime left responses, while NeuroImage 92 (2014) 340–348 ⁎ Corresponding author at: Laboratorio di Neurologia Clinica e Comportamentale, Fondazione S. Lucia, IRCCS, Via Ardeatina, 306-00143 Rome, Italy. E-mail address: barbara.magnani2@unibo.its (B. Magnani). 1053-8119/$ – see front matter © 2014 Published by Elsevier Inc. http://dx.doi.org/10.1016/j.neuroimage.2014.01.028 Contents lists available at ScienceDirect NeuroImage journal homepage: www.elsevier.com/locate/ynimg