Neural Processes Involved in Directing Attention

Abstract

Neural processes associated with two aspects of visual-spatial attention were investigated with event-related potential (ERPs): those that direct spatial attention to a given point in space and those that modulate the processing of sensory input after attention has been directed. The subjects were 6- to 9-year-old children (51 boys and 35 girls). An arrow cue directed attention from the central to peripheral visual field; targets were then flashed in the attended or ignored visual field 600 msec after the cue. The directing of attention to the left vs. right visual field was associated with hemispheric differences in slow potentials prior to the presentation of the targets. The earliest potential, which started about 200 msec after the cue and was negative over the hemisphere contralateral to the direction of attention, was greatest over the parietal area and appeared to reflect processes directing attention per se. The last potential, which peaked 60 msec after the target and was positive over the hemisphere contralateral to the direction of attention, was greatest over the occipital-parietal region. It appeared to reflect the modulation of cortical excitability in the regions receiving input from the relevant and irrelevant visual fields. The effects of spatial attention on P1, N1, and P3 ERP components following the targets replicated previous results. Boys appeared more aroused (as indicated by CNVs) and reflected faster and greater selective processing (as indicated by reaction time, and N1-P1 latency and amplitude) than girls.

ERP correlates of tactile spatial attention differ under intra- and intermodal conditions

“…Thus, the ADAN appears to be sensitive to the anatomical identity of the cued hand (and not the attentional shift in external space) and has therefore been suggested to reflect attentional control processes based on somatotopically defined coordinates (see also Eimer et al, 2004). In contrast, the LDAP component does not appear to be sensitive to crossed hand postural changes, instead it has been found to be absent in blind people and in sighted people in complete darkness suggesting that this component is based on representations of visually mediated external space (Van Velzen et al, 2006; see also Harter et al, 1989). Furthermore, this suggests that the availability of visual spatial information influences mechanisms of endogenous spatial orienting.…”

Effects of hand posture on preparatory control processes and sensory modulations in tactile-spatial attention

“…1 These effects were similar to the results found in earlier studies which have measured ERPs elicited during covert shifts of visual attention. For example, Harter et al (1989) measured ERPs triggered by a central arrow cue indicating the side of an upcoming visual event. An early negative deflection at posterior electrodes contralateral to the direction of the induced attentional shift ('Early Directing Attention Negativity', EDAN) was followed by a contralateral positivity at posterior electrodes (LDAP; see also Yamaguchi et al, 1994;Hopf and Mangun, 2000;Nobre et al, 2000).…”

“…First, we have shown that the posterior EDAN component reported in several earlier studies (cf. Harter et al, 1989;Hopf and Mangun, 2000) is not directly linked to the control of attentional shifts, but appears to reflect a lateralized visual response triggered by non-symmetrical visual cue stimulus (such as left-pointing and right-pointing arrows; see Van Velzen and Eimer, 2003, for more details). This component is absent in response to auditory attention cues , and when symmetrical visual cues are used , and the present experiment).…”

“…This component is absent in response to auditory attention cues , and when symmetrical visual cues are used , and the present experiment). Second, the fact that LDAP components can be observed during shifts attention towards the expected location of tactile and auditory events calls into question the hypothesis that this component reflects the anticipatory preparation of sensory-specific extrastriate visual areas (Harter et al, 1989). Based on these findings, we have previously argued that both ADAN and LDAP components reflect sensory-unspecific preparatory processes operating within a multimodal attentional control system (see ; for more detailed discussion).…”

“…Since all previous studies in this field (starting with Harter et al, 1989) have described the polarity of these effects with reference to the contralateral hemisphere, this convention is also adopted here.…”