The present study investigated the impact of bilingualism on efficiency of alerting, orienting and executive attention by means of the Lateralized Attention Network Test (LANT). Young adult bilinguals who had been exposed to their second language before the age of four years showed a reduced conflict cost and a larger alerting effect in terms of response time (RT), while no difference between bilinguals and monolinguals was observed in overall RT. Bilinguals also outperformed monolinguals on accuracy in both conflict and non-conflict trials, though the effect in the latter condition was very small. Moreover, while a left visual field advantage for accuracy of conflict resolution was present in the monolingual group, bilinguals did not show the asymmetry. The findings suggest that bilingualism enhances the efficiency of executive network while reducing its lateralization. The larger alerting effect in bilinguals is hypothesized to be related to bilinguals’ more efficient executive control, which may support processes of response anticipation or temporal orienting.

Patterns of cerebral asymmetry related to visuospatial functions may change with age. The typical leftward bias on a line bisection task may reflect cerebral asymmetry. With age, such leftward bias decreases. This study demonstrated that the age-related decrease of leftward bias may actually be sex-specific. In addition, previous research suggests that young adults’ deviation in line bisection may reflect asymmetric hemispheric activation of perceptual–attentional “where” spatial systems, rather than motor-intentional “aiming” spatial systems; thus, we specifically fractionated “where” and “aiming” bias of men and women ranging in age from 22 to 93 years old. We observed that older men produced greater rightward line bisection errors, of primarily “where” spatial character. However, women's errors remained leftward biased, and did not significantly change with age. “Where” spatial systems may be linked to cortico-cortical processing networks involving the posterior part of the dorsal visuospatial processing stream. Thus, the current results are consistent with the conclusion that reduced right dorsal spatial activity in aging may occur in the male, but not female, adult spatial system development. (JINS, 2011, 17, 455–462)

To test the hypothesis that activation asymmetries of the most anterior parts of the prefrontal cortex may be related to state-dependent regulation of emotion, spontaneous changes of cortical activation asymmetries from one session to a second one were related to spontaneous mood changes in two large samples (ns = 56 and 128). The interval between sessions was 2 to 4 weeks. Results show that mood changes specifically covary with changes of EEG asymmetry at the frontopolar electrode positions, but not with changes at other locations (dorsolateral frontal, temporal, and parietal). Anxiety, tension, and depression were found to decrease when frontopolar activation asymmetry shifted to the right. Taking the new findings into account may contribute to the refinement and extension of theories on EEG laterality and emotion.

Brain activity was monitored while 36 participants produced facial configurations denoting anger, disgust, fear, joy, and sadness. EEG alpha power was analyzed during each facial pose, with facial conditions grouped according to the approach/withdrawal motivational model of emotion. This model suggests that “approach” emotions are associated with relatively greater left frontal brain activity whereas “withdrawal” emotions are associated with relatively greater right frontal brain activity. In the context of a bilateral decrease in activation, facial poses of emotions in the withdrawal condition resulted in relatively less left frontal activation in the lateral-frontal, midfrontal and frontal-temporal-central region, but not in the parietal region, as predicted. Findings in the approach condition were less consistently supportive of predictions of the approach/withdrawal model. Implications for the approach/withdrawal model and for the emotion eliciting potential of voluntary facial movement are discussed.

Previous studies on aversive learning have suggested a right hemispheric advantage for eliciting autonomic reactions to a masked conditioned facial stimulus (CS) depicting anger. The present study investigated the effects of visual field (VF), stimulus awareness, and emotional valence of the CSs on indicators of conditioning (bilateral SCRs, HR) using a differential conditioning paradigm (N = 41). In Group 1, four different negatively valenced facial expressions (CS+) but not four positively valenced CS− were associated with an unconditioned stimulus (US, aversive vocalization, 97 dB, 3 s) during acquisition. Group 2 received a treatment reversal with positive CS+ associated with the US. In a repeated measures design, CSs were presented with or without awareness during extinction (two weeks interval, order counterbalanced). SOAs were adapted for each subject and condition prior to the experiment so that identification performance was approaching chance level. The results revealed that both negative and positive facial expressions could be aversively conditioned providing evidence for a generalization of learning in the valence dimension. During extinction, preattentive negative CS+ presented to the left VF showed a trend towards greater electrodermal and cardiac reactions. However, no such effect emerged under full awareness of the CSs. These results confirm and further specify the nature of hemispheric asymmetries in emotional associative learning.

Previous research on asymmetric effects of emotional expression and brain-hemispheric asymmetry has supported opposing theories of hemispheric dominance in the control of emotional reactions. In the present study, 32 subjects were exposed to pictures of happy and angry facial stimuli while facial electromyographic (EMG) activity from the zygomatic major and the corrugator supercilii muscle regions was detected from the left and right sides of the face. The subjects reacted spontaneously and rapidly with larger zygomatic EMG activity to happy facial stimuli and larger corrugator EMG activity to angry stimuli. These distinct reactions were significantly larger on the left side of the face. It is concluded that the present results support the hypothesis that the right brain hemisphere is predominantly involved in the control of spontaneously evoked emotional reactions.

The hypothesis of atypical functional hemispheric asymmetry in schizophrenia is tested using the directed global–local paradigm, a lateralizing measure of visual perception. Results indicate low error rates (< 2%) for schizophrenia and normal control groups, but longer response times for the schizophrenia group. In the normal group, detection speed of global and local forms did not differ. In contrast, the schizophrenia group responded significantly faster to local relative to global forms, which supports the asymmetry hypotheses of left hemisphere overactivity–right hemisphere underactivity in schizophrenia. The normal group exhibited a global interference effect (slowed response latency to the local target in the presence of a dissimilar global distractor). When the schizophrenia group was examined according to symptom type and severity, high positive symptom severity was associated with local interference (slowed response latency to the global target in the presence of dissimilar local distractors). Negative symptoms were not associated with interference from the competing local or global forms. Patients with a combination of high positive and low negative symptoms showed significantly greater local interference than patients with high negative and low positive symptoms. Interconnected temporal and frontal systems are postulated to contribute to this pattern of perceptual processing efficiency and distractibility in schizophrenia. (JINS, 1999, 5, 442–451.)

Seventy-four patients with focal brain lesions were compared to a neurologically normal control group on tasks of letter-based and category-based list generation. When patients were divided only by right frontal, left frontal, or nonfrontal lesion sites, the pattern of fluency impairments confirmed prior claims. When more precise lesion sites within the frontal lobes were compared between groups classified based on their fluency performance, much more specific brain–behavior relations were uncovered. Damage to the right dorsolateral cortical or connecting striatal regions, the right posterior area, or the medial inferior frontal lobe of either hemisphere did not significantly affect letter-based fluency performance. Superior medial frontal damage, right or left, resulted in moderate impairment. Patients with left dorsolateral and/or striatal lesions were most impaired. Left parietal damage led to performance relatively equivalent to the superior medial and left dorsolateral groups. The same lesion sites produced impairments in category based fluency, but so did lesions of right dorsolateral and inferior medial regions. Task analysis and correlations with other measures revealed that different cognitive processes related to different brain regions underlie performance on verbal fluency tests. (JINS, 1998, 4, 265–278.)

Sixteen right-handed male students were administered a unilateral lexical decision task in 4 conditions: a baseline condition and three sound conditions. In the sound conditions, the participants listened to noise, to music with a positive emotional valence, and to music with a negative emotional valence, while performing the visual half-field task. In the baseline condition, the noise condition, and the positive music condition, lexical decision latencies were shorter to right than to left visual field presentations. In the negative music condition, there was a selective enhancement of left visual field performance, which cancelled the visual field advantage completely. None of the concurrent sounds affected autonomic arousal as measured by heart rate. The results demonstrated that music with a negative emotional valence can alter the half-field asymmetry of a verbal task. The outcome was discussed in terms of right hemisphere priming due to negative emotional experience. (JINS, 1997, 3, 473–479.)

The incidence of clinically apparent asymmetric profiles of neuropsychological deficits in Alzheimer's disease (AD) patients similar to those reported in the PET literature is currently unclear. This study investigated lateral neuropsychological asymmetry using principal component factor analysis in a sample of 153 patients diagnosed with probable AD. Using factor scores, patients were classified into groups exhibiting asymmetric or symmetric profiles of neuropsychological deficits. In the analysis of lateral asymmetry, 27.5% of patients were classified as asymmetric (10% verbally and 17% visuospatially). Consistent with reports of continued asymmetry beyond the mild dementia stage, asymmetry was exhibited in the mild, moderate, and severely demented groups. These findings of neuropsychological asymmetry across stages of dementia are consistent with the picture of significant neuropsychological heterogeneity in AD that has been emerging in the decade. (JINS, 1997, 3, 420–427.)

In the avian cerebrum and in the spinal cord, sympathetic ganglia, hypothalamico pre-optic area and cerebral cortex of the rat sexually dimorphic' nuclei are clearly recognisable. Similar differences have been described in the human brain. Morphometric analysis has shown a sexually dimorphic nucleus in the pre-optic area. There is continuing controversy over differences in the size and shape of the corpus callosum, but there is accumulating evidence of cerebral asymmetry with more focal representation of language and praxic functions in the left cerebral hemisphere in females. The various sensory modalitites also show gender differences. The significance of these secondary sexual variations in brain structure resides in the developmental and behavioural characteristics of the underlying neural circuits.