Attentional networks in children and adolescents with autism spectrum disorder.

Individuals diagnosed with autism spectrum disorder (ASD) exhibit early (Elsabbagh et al., 2009; Osterling, Dawson, & Munson, 2002; Swettenham et al., 1998; Zwaigenbaum et al., 2005) and pervasive (see Allen & Courchesne, 2001; Burack, Enns, Stauder, Mottron, & Randolph, 1997, for reviews) abnormalities in the allocation of visual attention. The ubiquitous nature of attentional impairments in ASD has led some authors to hypothesize that early atypical attentional modulation may, in part, act as a significant contributing factor in the development of higher-level sociocommunicative deficits (Belmonte & Yurgelun-Todd, 2003; Dawson & Lewy, 1989; Gold & Gold, 1975; Ornitz, 1988; Pierce, Glad, & Schreibman, 1997). Recently, Posner and Fan (2004) proposed conceptualizing attention as an organ system. This system is comprised of three specialized neurofunctional networks, previously described by Posner and Petersen (1990), which are responsible for a distinct set of cognitive processes: the alerting, orienting, and executive control networks. The authors hypothesize that this conceptualization may assist in elucidating differences in attentional modulation between typically developing (TD) individuals and individuals with atypical attentional processes. Evidence from behavioral, neuropsychological, and neuroimaging investigations now support the theory of separable anatomical networks responsible for unique sets of attentional functions (see Raz & Buhle, 2006, for a review); however, interactions between these networks are also important for successful and efficient attentional modulation in TD adults (Callejas, Lupianez, Funes,T Callejas, Lupianez, & Tudela, 2004; Fan et al., 2009). The alerting network is responsible for achieving and maintaining a state of increased sensitivity to incoming information. Alertness has been divided into tonic and phasic components (see Sturm & Willmes, 2001, for review). Tonic alertness is a state of general wakefulness; endogenously controlled tonic alertness (referred to as vigilance or sustained attention) is the voluntary maintenance of alertness at a certain level. Phasic alertness is a more transient alert state, modulated by a warning that precedes a target stimulus. The orienting network is responsible for the selection of information from sensory input. Orienting visual attention has been defined as disengaging, shifting, and reengaging attention (Posner, Walker, Friedrich, & Rafal, 1984). Finally, the executive control network is a multidimensional attentional system, responsible for inhibition, conflict resolution, planning, and cognitive flexibility. Abnormal function of each attentional network has been demonstrated in ASD. Furthermore, specific deficits in alerting (Gold & Gold, 1975; Dawson & Lewy, 1989), orienting (Ornitz, 1988), and executive control (Ozonoff, Pennington, & Rogers, 1991) have been hypothesized to contribute to the development of ASD. Prior research on alertness/arousal in ASD has been inconsistent; individuals with ASD exhibit intact endogenous tonic (Garretson, Fein, & Waterhouse, 1990; Pascualvaca, Fantie, Papageorgiou, & Mirsky, 1998) and phasic (Raymaekers, van der Meere, & Roeyers, 2006) components of alerting, yet also demonstrate atypical arousal (e.g., Anderson & Colombo, 2009; Hirstein, Iversen, & Ramachandran, 2001) and reduced sensitivity to novel information (e.g., Ciesielski, Courchesne, & Elmasian, 1990; Keehn & Joseph, 2008). Dysfunctional shifting and disengagement of attention has also been reported in ASD. Dawson and colleagues (1998) demonstrated that children with ASD have difficulties orienting to both social and non-social information within their environment. Previous studies using the Posner cueing paradigm (1980) have shown that individuals with ASD have difficulties disengaging (Wainwright- Sharp & Bryson, 1993) and shifting visual attention (Townsend et al., 1999; Townsend, Harris, & Courchesne, 1996), and demonstrate atypical activation of the orienting network (Haist, Adamo, Westerfield, Courchesne, & Townsend, 2005). Furthermore, studies employing the gap-overlap paradigm, a task used to evaluate attentional disengagement by examining the response time (RT) differences to targets appearing with and without a central fixation, have also demonstrated that children with ASD evidence significant impairments in disengaging visual attention (Elsabbagh et al., 2009; Landry & Bryson, 2004). Finally, the extant literature on executive control abilities in ASD suggests intact inhibitory processing (Lopez, Lincoln, Ozonoff, & Lai, 2005; Ozonoff & Strayer, 1997), but impaired cognitive flexibility (Courchesne et al., 1994; Ozonoff, Strayer, McMahon, & Filloux, 1994). Additionally, there appears to be a relationship between IQ and executive abilities in individuals with ASD (Liss et al., 2001; Lopez et al., 2005). Together, these findings indicate that individuals with ASD exhibit impairments in each attentional network; however, no study has attempted to examine each attentional network in the same cohort of children. The Attention Network Test (ANT; Fan et al., 2002), which consists of both a cued reaction time task (Posner, 1980) and a flanker paradigm (Eriksen & Eriksen, 1974), permits investigators to examine each attentional network in the context of a single integrated task. The test, which was designed to be short and simple, has been used in TD children and adults (Fan et al., 2002; Rueda et al., 2004), as well as clinical populations with attentional abnormalities (for example, see Johnson et al., 2008; Urbanek et al., 2009). To date, no study has employed the ANT to investigate attention networks in ASD. Our goal in the current study was to use the ANT to simultaneously examine alerting, orienting, and executive control networks in children and adolescents with ASD. Moreover, because it has been suggested that abnormalities in the modulation of attention may be related to sociocommunicative deficits, we sought to examine the relationship between attentional function and sociocommunicative impairments in children with ASD.