![]() The first influential theory that accounted for selective attention was proposed by Broadbent ( 1958) and later updated by Treisman ( 1969). Researchers have long been interested in detecting how behaviorally relevant information is selected within the course of attentional processing. Perceptual load and the locus of selection In the present study, we used pupil size measures of tonic and phasic LC-NE activity to predict performance in an attentional task. On the contrary, high tonic activity correlated with poorer performance (higher rate of false-positive responses to non-target stimuli) and diminished LC-NE phasic responses.Īlthough accumulating evidence links noradrenergic activity with attention and cognitive processes, the role of LC-NE activity within attentional selection mechanisms is not yet understood. Most of this evidence comes from electrophysiological studies in monkeys performing go/no-go tasks, in which epochs of low LC tonic activity correlated with better attentional performance (reflected by lower rates of false-positive responses to non-target stimuli) and pronounced phasic spike bursts after the perceptual detection of the targets. The LC-NE system can have periods of higher or lower tonic (basal) activity, which have been associated with shifts in attentional performance (Usher, 1999 Gilzenrat et al., 2010). When a target is detected, the LC produces a phasic activation that is subsequently accompanied by a task-evoked pupil response (Usher, 1999 Aston-Jones et al., 1994 Privitera et al., 2010). Among other functions, the LC-NE system seems to be highly involved in the detection of behaviorally relevant stimuli. In fact, a recent neuroimaging study showed that LC-NE activity improves the precision of cortical representations of perceptual signals (Warren et al., 2016). Norepinephrine release on these target areas is believed to act by increasing neural gain (Aston-Jones & Cohen, 2005), which enhances the signal-to-noise ratio in the processing of sensory input (Sara & Bouret, 2012b Mather et al., 2016a Arnsten & Rubia, 2012). The LC sends inputs to different prefrontal brain areas involved in control functions and attentional processing (Foote et al., 1991 Joshi et al., 2016). This relationship arises because under isoluminance conditions, pupil dilation is largely caused by norepinephrine (NE) release from the locus coeruleus (LC) (Joshi et al., 2016). This suggests that the degree with which LC-NE influences behavioral performance is related to the perceptual load of the task at hand.įluctuations in pupil size have been associated with the time course of perceptual processing (de Gee et al., 2014) and decision-making (Einhäuser et al., 2010 Oliva & Anikin, 2018). Because pupil baseline predicted attentional performance in low load but not in high load, this suggests that different attentional mechanisms are involved, one in which the LC-NE system plays a key role (low load) and one in which it is less relevant (high load). Thus, this study relates attentional selection mechanisms, as defined by the perceptual-load theory, with pupil-related LC-NE activity. In addition, pupil dilation was linked to the time course of perceptual processing and predicted response times in both perceptual load conditions, an association that was enhanced in high load. The results showed that pupil baseline size, measured prior trial onset, significantly predicted the upcoming search efficiency only in low perceptual load, when-according to the perceptual-load hypothesis-all perceptual information receives attentional resources. Participants were asked to search for a target in conditions of high and low perceptual load, while ignoring irrelevant stimuli. ![]() Here, we assessed pupil baseline (and pupil dilation) as predictors of load-related early and late selection performance. Additionally, evidence shows that pupil size serves as proxy of locus coeruleus-norepinephrine (LC-NE) activity, a system associated with cognitive and attentional mediation. The perceptual-load hypothesis argues that the occurrence of early or late selection mechanisms is determined by task-relevant perceptual load. The ability to focus on a task while disregarding irrelevant information is an example of selective attention. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |