mPFC catecholamines modulate attentional capture by appetitive distracters and attention to time in a peak-interval procedure in rats

Abstract

The behavioral and neural mechanisms by which distracters delay interval timing behavior are currently unclear. Distracters delay timing in a considerable dynamic range: Some distracters have no effect on timing ("run"), whereas others seem to "stop" timing; some distracters restart ("reset") the entire timing mechanisms at their offset, whereas others seem to capture attentional resources long after their termination ("over-reset"). While the run-reset range of delays is accounted for by the Time-Sharing Hypothesis (Buhusi, 2003, 2012), the behavioral and neural mechanisms of "over-resetting" are currently uncertain. We investigated the role of novelty (novel/familiar) and significance (consequential/inconsequential) in the time-delaying effect of distracters and the role of medial prefrontal cortex (mPFC) catecholamines by local infusion of norepinephrine-dopamine reuptake inhibitor (NDRI) nomifensine in a peak-interval (PI) procedure in rats. Results indicate differences in time delay between groups, suggesting a role for both novelty and significance: inconsequential, familiar distracters "stopped" timing, novel distracters "reset" timing, whereas appetitively conditioned distracters "over-reset" timing. mPFC infusion of nomifensine modulated attentional capture by appetitive distracters in a "U"-shaped fashion, reduced the delay after novel distracters, but had no effects after inconsequential, familiar distracters. These results were not due to nomifensine affecting either timing accuracy, precision, or peak response rate. Results may help elucidate the behavioral and physiological mechanisms underlying interval timing and attention to time and may contribute to developing new treatment strategies for disorders of attention. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Figure 1.

Injection location on coronal plates from (Paxinos & Watson, 1998).

Figure 2.

Normalized timing functions under nomifensine (NOM) in trials without distracters (left panel) and trials with distracters (right panel). Distracter presentations are shown as black rectangles. Dotted vertical lines indicate the timing criterion (40 s, left panel) and the timing of a putative “reset” response after the distracter (right panel).

Figure 3.

Average time delay (± SEM) under mPFC infusion of nomifensine (NOM). Dotted lines indicate behavioral responses “run” (0-s delay), “stop” (8-s delay), and “reset” (32-s delay). FA = Familiar Appetitive; FN = Familiar Neutral; NN = Novel Neutral; * p < 0.05; ** p < 0.01.

Figure 4.

Response rate (± SEM) on the timing (left) and non-timing lever (right) in RPI+N trials under nomifensine in three 8-s time blocks: pre-distracter (8 s before the distracter), during the distracter, and post-distracter (8 s after the distracter). † significant differences between FA rats and both FN and NN rats (see text); †† significant differences between FN rats and both FA and NN rats (see text); * p < 0.05; ** p < 0.01.