Simple Reaction Time: Evidence for Focal Impairment From Lesions of the Right Hemisphere

Abstract

Simple reaction time is significantly increased in patients with unilateral lesions of either cerebral hemisphere responding with the hand ipsilateral to the lesion, but the effect is much greater when the lesion is in the non-dominant hemisphere. This difference cannot be attributed to asymmetries in the size or type of lesion. It applies over the complete distribution of reaction times as well as to the means, and is not diminished by practice. Neither the classical conduction model of reaction time nor the mass-action hypothesis proposed by De Renzi and Faglioni (1965) can account for the findings. Although the increase of about 100 ms observed with lesions of the dominant hemisphere probably represents a non-specific effect of brain disease, the much larger increases resulting from lesions of the non-dominant hemisphere appear to be of focal origin. The critical areas cannot yet be specified with certainty, but maps of the brain scans for patients with the highest reaction times suggest that structures in or near the basal ganglia and the posterior parietal region of the non-dominant hemisphere are involved, and other studies show that the focal effect is not found when patients with contralateral motor involvement are excluded.

Orienting of attention in left unilateral neglect

“…Neglect patients' attention for right targets seemed thus enhanced with respect to RBD control patients, consistent with the opponent processor model. As La Ádavas et al [95] pointed out, according to this model neglect patients should be faster for right-sided stimuli even with respect to normal individuals without brain damage; this, however, would be an unlikely result, given that right brain lesions cause a de®cit in arousal [96]. Indeed, subsequent RT studies [97±101] invariably found that left neglect patients were slower than normal controls when responding to right (ipsilesional) stimuli (Fig.…”

“…Another component of attention, arousal, might be disrupted more by right than by left-hemisphere lesions [96,141]. Since, as we have seen, an arousal de®cit seems to contribute to neglect behavior [75,102,139], this could be another basis for the asymmetry of occurrence of neglect after unilateral brain lesions [56,142].…”

“…Right brain damage slows down RTs more than left-hemispheric lesions [96], which can be interpreted as an arousal de®cit [141]. The preferential occurrence of a de®cit of arousal after right, rather than left, brain damage might be one of the bases of the predominance in frequency and severity of contralesional neglect after right, as opposed to left, hemispheric lesions [56,142].…”

Dependence of reaction times on movement patterns in patients with Parkinson's disease and those with cerebellar degeneration.

“…Recently, Howes and Boller (1975), examining maps of the brain scan for patients with the slow reaction times to simple auditory stimulus, have suggested that structures in or near the basal ganglia and the posterior parietal region of the right hemisphere are critical for the lengthened reaction time. In the present study, however, there was no significant difference of PMTs between the normal and the Parkinsonian subjects.…”

Cerebral Laterality, Emotion, and Cardiopulmonary Functions: An Investigation of Left and Right Cva Patients

“…Such emotional dominance logically follows from the right hemisphere dominance for regulating bilateral cortical arousal levels (Howes & Boller, 1975;Green & Hamilton, 1976;Heilman, Schwartz, & Watson, 1978;Heilman & Van Den Abel, 1979;Heller, 1993), as any intense emotion requires arousal or activation. Sympathetic reactions to emotional events are also associated with right hemisphere activation (Wittling, 1990;1997), which is said to be the primary anatomical location for emotional comprehension and emotional expression (Heilman, 1997).…”