Pro- and antisaccades in children elicited by visual and acoustic targets - does modality matter?

Peer reviewedPublisher PD

Medio-Frontal and Anterior Temporal abnormalities in children with attention deficit hyperactivity disorder (ADHD) during an acoustic antisaccade task as revealed by electro-cortical source reconstruction

<p>Abstract</p> <p>Background</p> <p>Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent disorders in children and adolescence. Impulsivity is one of three core symptoms and likely associated with inhibition difficulties. To date the neural correlate of the antisaccade task, a test of response inhibition, has not been studied in children with (or without) ADHD.</p> <p>Methods</p> <p>Antisaccade responses to visual and acoustic cues were examined in nine unmedicated boys with ADHD (mean age 122.44 ± 20.81 months) and 14 healthy control children (mean age 115.64 ± 22.87 months, three girls) while an electroencephalogram (EEG) was recorded. Brain activity before saccade onset was reconstructed using a 23-source-montage.</p> <p>Results</p> <p>When cues were acoustic, children with ADHD had a higher source activity than control children in Medio-Frontal Cortex (MFC) between -230 and -120 ms and in the left-hemispheric Temporal Anterior Cortex (TAC) between -112 and 0 ms before saccade onset, despite both groups performing similarly behaviourally (antisaccades errors and saccade latency). When visual cues were used EEG-activity preceding antisaccades did not differ between groups.</p> <p>Conclusion</p> <p>Children with ADHD exhibit altered functioning of the TAC and MFC during an antisaccade task elicited by acoustic cues. Children with ADHD need more source activation to reach the same behavioural level as control children.</p

Antisaccades elicited by visual and acoustic cues – an investigation of children with and without attention deficit hyperactivity disorder

Impulsivity and with it deficient inhibition control is one of the core symptoms of attention deficit hyperactivity disorder (ADHD) – one of the most prevalent chronic psychiatric disorders in childhood and adolescence. One possibility to investigate inhibitory mechanisms is the antisaccade task – a task, in which a subject is required to suppress a saccade towards a suddenly appearing cue (prosaccade) and to generate a voluntary saccade of equal size towards the opposite direction instead. Aim of the present thesis was to investigate if children with ADHD are constricted in their inhibition of not only suddenly arising visual but also suddenly arising acoustic cues in order to establish a basis for a better differential diagnostic. Study I – an eye tracker pilot study – investigated control children in a random anti-/prosaccade task and revealed similar inhibition performance in visual and acoustic conditions: more errors in the anti- compared to the prosaccade condition. Additionally, modality dependant differences were found: the “grasp-reflex” was weaker for acoustically elicited saccades and they seemed less prone to be influenced by impulsivity as their latency was longer which in turn resulted in fewer antisaccade errors. During Study II the same paradigm was tested with children with and without ADHD in an Electroencephalography (EEG) experiment. On the behavioural level no group differences were found but in a 23-source-model analysis group differences were observable in acoustically elicited and correct performed antisaccades: children with ADHD showed more activity in the anterior temporal lobe and medio-frontal cortex (structures important for inhibition) to achieve the same behavioural output than children without ADHD. The heightened activation could possibly be seen as a compensatory mechanism. In Study III children with and without ADHD were compared during a blocked saccade task in an EEG experiment. In the visual condition children with ADHD were impaired on the behavioural level (more errors and elongated latency in the antisaccade condition) as well as on the physiological level. The findings suggest a frontal hypoactivation and a parietal-cerebellar compensatory network in ADHD. During the acoustic experiment children with ADHD seemed to have greater difficulties generating saccades but not inhibiting. Finally, it is to assume that children with ADHD are probably impaired quite differently concerning inhibition control. This seems to depend on task complexity and not on cue modality per se

Make EU trade with Brazil sustainable

Brazil, home to one of the planet's last great forests, is currently in trade negotiations with its second largest trading partner, the European Union (EU). We urge the EU to seize this critical opportunity to ensure that Brazil protects human rights and the environment