Interaction of Numerosity and Time in Prefrontal and Parietal Cortex

Abstract

It has been proposed that numerical and temporal information are processed by partially overlapping magnitude systems. Interactions across different magnitude domains could occur both at the level of perception and decision-making. However, their neural correlates have been elusive. Here, using functional magnetic resonance imaging in humans, we show that the right intraparietal cortex (IPC) and inferior frontal gyrus (IFG) are jointly activated by duration and numerosity discrimination tasks, with a congruency effect in the right IFG. To determine whether the IPC and the IFG are involved in response conflict (or facilitation) or modulation of subjective passage of time by numerical information, we examined their functional roles using transcranial magnetic stimulation (TMS) and two different numerosity-time interaction tasks: duration discrimination and time reproduction tasks. Our results show that TMS of the right IFG impairs categorical duration discrimination, whereas that of the right IPC modulates the degree of influence of numerosity on time perception and impairs precise time estimation. These results indicate that the right IFG is specifically involved at the categorical decision stage, whereas bleeding of numerosity information on perception of time occurs within the IPC. Together, our findings suggest a two-stage model of numerosity-time interactions whereby the interaction at the perceptual level occurs within the parietal region and the interaction at categorical decisions takes place in the prefrontal cortex.

Impaired Numerical Ability Affects Supra-Second Time Estimation

“…We note however, that our control task did not involve a continuous accumulation process, so it is not possible to fully test the accumulation hypothesis. Here we focused on supra-second durations of the order of 12 s that are well within the supra-second domain to ensure that we were not tapping into short sub-second temporal mechanisms (Hayashi et al, 2013a;Poppel, 1997), and are also in the big numerosities range (Agrillo et al, 2012;Butterworth, 2010).…”

“…For example the parietal cortex is activated by both sub-second temporal information and by numeric information (Castelli et al, 2006;Hayashi et al, 2013a), and lesion studies in parietal cortex indicate its involvement in processing both dimensions (Cappelletti et al, 2011b; see also Bueti & Walsh, 2009).…”

“…The parietal cortex has been suggested to be the underlying common magnitude processing region (Cohen Kadosh et al, 2012;Walsh, 2003), especially for smaller quantities, in activation studies (Castelli et al, 2006;Hayashi et al, 2013a), lesion studies (Cappelletti et al, 2011b), and TMS (e.g., Hayashi et al, 2013a), but whether such a 'hub' exists for bigger quantities is still unclear. Furthermore, while bigger numerosities (bigger than 4, see above) might parallel supra-second time range, it is not clear what would be the spatial parallel.…”

“…Although it has been proposed that temporal and numerical processing rely on shared mechanisms (e.g., Cantlon et al, 2009;Cappelletti et al, 2011b;Dehaene & Brannon, 2010;Meck & Church, 1983;Meck et al, 1985;Walsh, 2003; but see Agrillo et al, 2010), most studies investigating these processes focused on very brief temporal durations, usually in the sub-second range (e.g., for reviews see Hayashi et al, 2013a;Walsh, 2003), while investigations in the supra-second time range are very limited (Cappelletti et al, 2009(Cappelletti et al, , 2011bHayashi et al, 2013b). These studies found that numerical information affects supra-second timing performance.…”

Arm and Hand Movement: Current Knowledge and Future Perspective

“…In an opinion article, Moore (10) argues that nerve transfer is increasingly popular and is becoming the best treatment strategy for most brachial plexus damage as well as for patients with spinal cord injury at cervical levels. Vicario (11) provides a personal commentary on a paper from Hayashi et al (12) and, in a review article, Karl and Whishaw (13) summarize the evidence that show that reaching and grasping are from distinct neural and evolutionary origins. Irvine et al (14) contribute a methods article that assesses the reliability of the Irvine, Beatties, and Bresnahan (IBB) forelimb recovery scale.…”