Hemisphere Dominance For Attention Research Articles

Hemispheric asymmetry in the efficiency of attentional networks

Despite the fact that hemispheric asymmetry of attention has been widely studied, a clear picture of this complex phenomenon is still lacking. The aim of the present study was to provide an efficient and reliable measurement of potential hemispheric asymmetries of three attentional networks, i.e. alerting, orienting and executive attention. Participants (N=125) were tested with the Lateralized Attention Network Test (LANT) that allowed us to investigate the efficiency of the networks in both visual fields (VF). We found a LVF advantage when a target occurred in an unattended location, which seems to reflect right hemisphere superiority in control of the reorienting of attention. Furthermore, a LVF advantage in conflict resolution was observed, which may indicate hemispheric asymmetry of the executive network. No VF effect for alerting was found. The results, consistent with the common notion of general right hemisphere dominance for attention, provide a more detailed account of hemispheric asymmetries of the attentional networks than previous studies using the LANT task.

Temperament profiles of children with vein of Galen malformations.

Unlike many brain injured children who are often rather difficult, toddlers and school-aged children with congenital vein of Galen malformations (n = 20; age range, 4 months to 12 years with a mean of 4 years) evidence a relatively positive temperament profile (based on the Temperament Scales of Carey, McDevitt, Fullard, Hegvik, Medoff-Cooper). They do not, however, differ from normal children with regard to the frequency of easy, difficult, slow to warm up, and intermediate temperament clusters. The temperament profile of children with vein of Galen malformations appears unaffected by additional neurologic abnormalities (hydrocephalus, abnormal developmental quotient, seizure disorder, focal cortical lesions) or other factors including age at testing, sex, or socioeconomic status. Contrary to the findings in adults of right hemisphere dominance for attention, presence of additional right-sided focal cortical pathology was not associated with greater activity level, distractibility, or impersistence. In contrast to the findings in adults and children of right hemisphere dominance for emotions in general, children with vein of Galen malformations and additional right hemisphere cortical damage are not more difficult than those with additional left cortical pathology or no additional focal cortical pathology. The fact that the pathology in vein of Galen malformations is subcortical may explain their relatively easier temperament and the absence of lateralization effects.

Stimulus Effects in Unilateral Neglect?

Unilaterally brain-damaged subjects and normal controls were administered parallel verbal and nonverbal forms of a visual cancellation task. The attentional theory of unilateral neglect, which predicts less manifest neglect on tasks that preferentially engage the damaged hemisphere, was not supported. Subjects who exhibited neglect did so to a comparable degree on both verbal and nonverbal tasks. The data are consistent with a model of right hemisphere dominance for attention across the visual field.

Right hemisphere dominance for attention: the mechanism underlying hemispheric asymmetries of inattention (neglect).

Because hemiinattention is most commonly caused by right parietal lesions, it is possible that the left hemisphere attends to contralateral stimuli whereas the right attends to both contralateral and ipsilateral stimuli. We gave lateralized visual stimuli to 12 normal subjects and recorded the electroencephalograms. Desynchronization was determined by comparing the alpha power 1 second before and 1 second after a lateralized visual stimulus. Although the left parietal lobe desynchronized most after right-sided stimuli, the right parietal lobe desynchronized equally after right or left stimuli. These findings support the hypothesis that the right hemisphere is dominant for attention.