Cortex; a journal devoted to the study of the nervous system and behavior
-
Attention Deficit Hyperactivity Disorder (ADHD) has long been associated with abnormalities in frontal brain regions. In this paper we review the current structural and functional imaging evidence for abnormalities in children and adults with ADHD in fronto-striatal, fronto-parieto-temporal, fronto-cerebellar and fronto-limbic regions and networks. While the imaging studies in children with ADHD are more numerous and consistent, an increasing number of studies suggests that these structural and functional abnormalities in fronto-cortical and fronto-subcortical networks persist into adulthood, despite a relative symptomatic improvement in the adult form of the disorder. ⋯ The ventromedial orbitofrontal deficits, however, were associated with comorbid conduct disorder (CD), highlighting the potential confound of comorbid antisocial conditions on paralimbic brain deficits in ADHD. Our review supported by the new data therefore suggest that both adult and childhood ADHD are associated with brain abnormalities in fronto-cortical and fronto-subcortical systems that mediate the control of cognition and motivation. The brain deficits in ADHD therefore appear to be multi-systemic and to persist throughout the lifespan.
-
Patients with Huntington's Disease (HD) are impaired in the recognition of emotional signals. However, the nature and extent of the impairment is controversial: it has variously been argued to disproportionately affect disgust (e.g., Sprengelmeyer et al., 1996), to be general for negative emotions (Snowden et al., 2008), or to be a consequence of item difficulty (Milders et al., 2003). Yet no study to date has included more than one positive stimulus category in emotion recognition tasks, and most studies have focused on the recognition of emotions from facial stimuli. ⋯ We present a study of 14 Huntington's patients and 15 controls performing a forced-choice task with a previously validated set of negative and positive non-verbal emotional vocalizations (Sauter and Scott, 2007). Although HD patients performed above chance for each emotion, they were found to be impaired in both positive and negative emotions, including pleasure, fear and anger. These findings complement previous work by demonstrating that impairments in emotion recognition in HD extend to positive and negative emotions, which may imply a general deficit.
-
Homonymous visual field defects are a frequent consequence of brain damage occurring in some 20-40% of stroke patients. They are often accompanied by a peculiar spatial bias termed "Hemianopic Line Bisection Error" (HLBE). Although known for more than 100 years the explanations for the HLBE put forward remain controversial. ⋯ In the present article we summarize the main arguments of both theoretical positions and argue that although both accounts are valid, they are incomplete and several important issues remain unresolved. These include the potential contribution of eccentric fixation to the HLBE, the question of multimodal impairments, the role of (visuo)-motor processes, the relation between the HLBE and visual field recovery, and the exact clinical significance of the HLBE. Thus, far from concluding the research on the line-bisection error in hemianopia, the recent series of publications on this topic serve as a welcome reminder of how much more research is needed.
-
The contralesional line bisection error in unilateral homonymous hemianopia is a frequent but neglected clinical phenomenon. Our knowledge about this bisection error is based on small samples of hemianopic patients. Moreover, horizontal line bisection has never been investigated in other unilateral visual field defects. ⋯ It is frequently associated with any unilateral homonymous visual field defect, i.e., hemianopia, upper/lower quadranopia, paracentral scotoma. Moreover, our results further support the recent finding that the contralesional bisection error is not a direct consequence of the visual field defect. Yet, they also suggest that, although the visual field defect does not seem to be the primary cause of the contralesional bisection error, it may nevertheless contribute to it.