Browsing by Author "Karadeniz, Sami"

Aims of the present study: Attention-deficit/hyperactivity disorder (ADHD), beginning in childhood and often continuing into adulthood, is a neurodevelopmental condition that impairs an individual’s functioning in everyday life. The disorder is characterized by impairments in attention regulation or impulse control, or both. Many of the symptoms are related to disturbances in attention, the ability to select behaviorally relevant stimuli and to filter out irrelevant information among the overwhelming amount of sensory data. Neural mechanisms of attention have been linked to oscillations in electophysiological brain activity at alpha frequencies (8–13 Hz), but information on alpha oscillations in adult ADHD has remained scarce. The aim of the present study was to examine differences in attention and distractibility related alpha oscillations between adult ADHD patients and neurotypical controls. Methods: Participants were instructed to attend moving spherical objects and to report color changes in the objects. Number of attended objects varied from one (in right or left visual hemifield) to two (one in both hemifields). In addition to the attended objects, participants were at times presented with distractors which they were instructed to ignore. Brain activity during task performance was measured with magnetoencephalography (MEG). Results and discussion: Behavioral performance was similar between the groups. However, alpha oscillations related to distractor processing differed in a statistically significant manner between ADHD patients and controls. Main differences were related to inter-hemispheric interactions, suggesting that attentional deficits in ADHD might be related to abnormalities between inter-hemispheric communication.