Parietal Influence on Temporal Encoding Indexed by Simultaneous Transcranial Magnetic Stimulation and Electroencephalography

Abstract

Previous studies have suggested that contingent negative variation (CNV), as recorded by electroencaphalography (EEG), may serve as an index of temporal encoding. The interpretation of these studies is complicated by the fact that in a majority of studies the CNV signal was obtained at a time when subjects were not only registering stimulus duration but also making decisions and preparing to act. Previously, we demonstrated that repetitive transcranial magnetic stimulation (rTMS) of the right supramarginal gyrus (rSMG) in humans lengthened the perceived duration of a visual stimulus (Wiener, et al. 2010a), suggesting the rSMG is involved in basic encoding processes. Here, we report a replication of this effect with simultaneous EEG recordings during the encoding of stimulus duration. Stimulation of the rSMG led to an increase in perceived duration and the amplitude of N1 and CNV components recorded from frontocentral sites. Furthermore, the size of the CNV amplitude, but not N1, positively correlated with the size of the rTMS effect but negatively correlated with bias (the baseline tendency to report a comparison stimulus as shorter), suggesting that the CNV indexes stimulus duration. These results suggest that a feed-forward mechanism from parietal to prefrontal regions mediates temporal encoding, and demonstrate a dissociation between early and late phases of encoding processes.

Duration adaptation modulates EEG correlates of subsequent temporal encoding

“…These patterns were unexpected considering memory or decision-making processes. In contrast, these findings are consistent with previous studies, which suggests that the amplitude of the CNV component reflects the temporal encoding process (Macar et al, 1999;Wiener et al, 2012). Our results offer further evidence that the CNV amplitude constitutes an "on-line index of timing" (Macar and Vidal, 2004).…”

“…Among several ERPs reflecting timing mechanisms, the contingent negative variation (CNV), a fronto-central scalp EEG measurement of slow cortical potential, provides an interesting "on-line index of timing" (Macar and Vidal, 2004;Ng and Penney, 2014). The CNV amplitude was assumed to directly reflect a temporal accumulation process in the Supplementary Motor Area (SMA), with larger CNV amplitude associated with longer subjective duration (Macar et al, 1999;Wiener et al, 2012). Consequently, the CNV activity allowed us to investigate the neural signatures of temporal encoding when subsequent stimuli were presented following duration adaptation.…”

Dedicated Clock/Timing-Circuit Theories of Time Perception and Timed Performance

“…The main observation supporting this notion was that the amplitude of a slow electrophysiological wave (the contingent negative variation, CNV) that is supposed to originate from the (pre-) SMA appears to covary as a function of the event duration that was estimated, e.g., CNV magnitude effect [104][105][106]. However, more recent work questions this interpretation because the CNV magnitude effect has proven difficult to replicate [73] and more recent electrophysiological data fails to align with the assumption that the CNV represents the accumulation process proposed by Scalar Timing Theory [69], but see also [107]. As a consequence, the interpretation of the original CNV results and its specificity of this slow wave potential to interval timing remains uncertain [74,108].…”

Neuroelectromagnetic signatures of the reproduction of supra-second durations

“…In these studies, participants were asked to perceive non-filled supra-second intervals of different durations presented in random order, and to reproduce the durations after perceiving them. This design allows for the assessment of the role of slow electromagnetic waves during the pure perceptual stage and the reproduction stage (see Wiener et al (2012)), and thus for assessing which neuronal populations contribute to the slowly evolving activity in the various stages of the interval timing task. Moreover, by presenting participants with different durations, we can address whether the observed field power is a function of the reproduced duration.…”

“…Moreover, by presenting participants with different durations, we can address whether the observed field power is a function of the reproduced duration. This issue, which will be more extensively addressed in the discussion, is central to the functional role of climbing neuronal activity in interval timing Van Rijn, 2011, 2014;Macar et al, 1999;Ng et al, 2011;Van Rijn et al, 2011;Wiener et al, 2012), and to the role of the SMA in decision making (e.g., Boehm et al, 2014).…”