Attention deficit and impulsivity: Selecting, shifting, and stopping

Abstract

The present selective review addresses attention, inhibition, and their underlying brain mechanisms, especially in relation to attention deficit/hyperactivity disorders (AD/HD), and the effects of methylphenidate. In particular, event-related potential (ERP) studies suggest a deficit in the early-filtering aspect of selective attention in children with AD/HD. Results from stop tasks are consistent with impairments in stopping performance in AD/HD, but in children (as opposed to adults) these effects cannot be easily dissociated from more general impairments in attention to the task, and therefore an interpretation in terms of inhibitory control is not straightforward. On the other hand, the beneficial effects of methylphenidate are more specific to stopping, and there are no clearcut effects of methylphenidate on measures of selective attention. Even when group differences pertain specifically to stopping performance (as with adults with AD/HD), ERP evidence suggests at least a partial contribution of differences in switching attention to the stop signal, as revealed in measures of sensory cortex activation. ERP evidence from cued go/nogo tasks underlines the importance of taking into account the contribution of higher order control processes involved in anticipation of and preparation for task stimuli. It suggests that in certain conditions, expectancy, rather than response bias, contributes to increased behavioral response tendencies, and that a presumed index of response inhibition, the nogo N2, may rather reflect conflict monitoring. In sum, direct reflections of brain activity suggest that mechanisms of expectation and attention, rather than of response bias or inhibitory control, govern behavioral manifestations of impulsivity.

International Society for the Study of Fatty Acids and Lipids 2018 Symposium: Arachidonic and Docosahexaenoic Acids in Infant Development

“…Similarly, the greater amplitude observed in response to the no-go part of the test could be construed as reflecting more mature forms of inhibition control. These responses are consistent with those reported by others [41,42]. The authors suggest that their results from the ERP analyses are consistent with previous data from the same cohort in which LCPUFA-supplemented children outperformed controls in executive function tasks involving learning rules and inhibition tasks [31].…”

Heritability of anterior and posterior visual N1

“…It is possible that more consistent effects may be found in the 'processing negativity', which is the negative shift seen in a selective attention task by comparing ERPs of stimuli from the attended to those of the unattended channel, appearing in a time range covering the N1, P1 and N2 (Altenmüller and Gerloff, 1999). Recently, it has indeed been reported that ADHD patients have a reduced processing negativity in an auditory selective attention task (Jonkman et al, 1997;Kenemans et al, 2005).…”

How Human Electrophysiology Informs Psychopharmacology: from Bottom-up Driven Processing to Top-Down Control

“…Thus, two substances with opposing effects on general information processing have identical effects on selectivity of attention. We have previously proposed a solution of this apparent contradiction (Kenemans et al, 2005), resting on two assumptions: clonidine (NE reduction) mainly reduces attentional control, therefore reduces the validity effect; nicotine (ACh enhancement) mainly facilitates disengagement, therefore reduces the validity effect. For a true test for this hypothesis however, it is necessary to use separate ERP correlates for attentional control and disengagement, respectively, which have indeed been described, eg, cuelocked attention-directing negativity and positivity (van der Lubbe et al, 2006) and the late-positive deflection that is larger to invalid than to valid targets (Mangun and Hillyard, 1991).…”