Neurophysiological signature of effective anticipatory task‐set control: a task‐switching investigation

Abstract

Changing between cognitive tasks requires a reorganization of cognitive processes. Behavioural evidence suggests this can occur in advance of the stimulus. However, the existence or detectability of an anticipatory task-set reconfiguration process remains controversial, in part because several neuroimaging studies have not detected extra brain activity during preparation for a task switch relative to a task repeat. In contrast, electrophysiological studies have identified potential correlates of preparation for a task switch, but their interpretation is hindered by the scarcity of evidence on their relationship to performance. We aimed to: (i) identify the brain potential(s) reflecting effective preparation for a task-switch in a task-cuing paradigm that shows clear behavioural evidence for advance preparation, and (ii) characterize this activity by means of temporal segmentation and source analysis. Our results show that when advance preparation was effective (as indicated by fast responses), a protracted switchrelated component, manifesting itself as widespread posterior positivity and concurrent right anterior negativity, preceded stimulus onset for 300 ms, with sources primarily in the left lateral frontal, right inferior frontal and temporal cortices. When advance preparation was ineffective (as implied by slow responses), or made impossible by a short cue-stimulus interval (CSI), a similar component, with lateral prefrontal generators, peaked 300 ms poststimulus. The protracted prestimulus component (which we show to be distinct from P3 or contingent negative variation, CNV) also correlated over subjects with a behavioural measure of preparation. Furthermore, its differential lateralization for word and picture cues was consistent with a role for verbal self-instruction in preparatory task-set reconfiguration.

Proceedings of the 9th Conference of the Australasian Society for Cognitive Science

“…With long preparation intervals, D-Pos fully resolves prior to stimulus onset, whereas with short preparation intervals, it continues after stimulus onset (Karayanidis et al, 2003). The amplitude of D-Pos has been found to be related to behavioral indices of preparation (Kieffaber & Hetrick, 1995;Lavric, Mizon, & Monsell, 2008). There is continuing disagreement regarding the electrophysiological origins of D-Pos.…”

“…Using a cued-trials task-switching paradigm with task-specific cues, Lavric et al (2008) recorded a D-Pos emerging around 500ms post-cue. LORETA analyses indicated sources in the left superior prefrontal cortex (PFC), left mid-temporal and posterior parietal cortices (PPC) over 500-600 ms, followed by sources in left sensorimotor cortex, and superior and inferior temporal gyri over 600-800 ms. Brass, Ullsperger, Knoesche, von Cramon & Phillips (2005) used fMRI results from an earlier study with the same paradigm (Brass & von Cramon 2004) to constrain ERP dipole placement so as to model differential switch activity in a 400-520 ms post-cue window.…”

“…In addition, most of the above studies have focused on cue-locked effects only. Lavric et al (2008) computed LORETA for stimulus-locked waveforms, but focused primarily on the carryover of the switch-positivity in the short-CSI condition. Rushworth et al (2002) was unable to model a post-target dipole source for intentional set-shifting whereas Rushworth et al (2005) modelled a single dipole in the medial occipital cortex for the later part of the stimulus-locked epoch only.…”

Detection of experimental ERP effects in combined EEG–fMRI: Evaluating the benefits of interleaved acquisition and Independent Component Analysis

“…Because EEG is a complex mixture of signals of cerebral and non-cerebral origin, statistical identification and separation of ERP components has been a central challenge in the ERP field. The most widely employed statistical procedures are Principal Components Analysis (PCA, Donchin and Heffley, 1976;Lavric et al, 2008;Weber and Lavric, 2008;Wills et al, 2007) and Independent Component Analysis (ICA, Bell and Sejnovski, 1995;Makeig et al, 1997).…”

“Smart inhibition”: electrophysiological evidence for the suppression of conflict-generating task rules during task switching

“…This positivity was interpreted by some authors as P3b modulation (Barceló, Periáñez, & Knight, 2002;Kieffaber & Hetrick, 2005;Nicholson, Karayanidis, Poboka, Heathcote, & Michie, 2005;Tieges, Snel, Kok, Plat, & Ridderinkhof, 2007) and by others as a reduction in CNV (Hsieh & Chen, 2006;Lorist et al, 2000). The posterior positivity is sometimes preceded by an early (100 to 300-ms) or moderately early (300 to 500-ms) anterior positivity (Astle, Jackson, & Swainson, 2008;Rushworth et al, 2002) or followed by a late (500 to 1,000-ms) anterior negativity (Astle et al, 2008;Lavric, Mizon, & Monsell, 2008;Moulden et al, 1998). In other studies, the posterior positivity was preceded by an early anterior negativity (Poulsen, Luu, Davey, & Tucker, 2005).…”