Dialectal differences in hemispheric specialization for Japanese lexical pitch accent

Language experience can alter perceptual abilities and the neural specialization for phonological contrasts. Here we investigated whether dialectal differences in the lexical use of pitch information lead to differences in functional lateralization for pitch processing. We measured cortical hemodynamic responses to pitch pattern changes in native speakers of Standard (Tokyo) Japanese, which has a lexical pitch accent system, and native speakers of ‘accentless’ dialects, which do not have any lexical tonal phenomena. While the Standard Japanese speakers showed left-dominant responses in temporal regions to pitch pattern changes within words, the accentless dialects speakers did not show such left-dominance. Pitch pattern changes within harmonic-complex tones also elicited different brain activation patterns between the two groups. These results indicate that the neural processing of pitch information differs depending on the listener’s native dialect, and that listeners’ linguistic experiences may further affect the processing of pitch changes even for non-linguistic sounds.     

Anomalous global effects induced by ‘blind’ distractors in visual hemifield defects

Previous research has revealed that a stimulus presented in the blind visual field of participants with visual hemifield defects can evoke oculomotor competition, in the absence of awareness. Here we studied three cases to determine whether a distractor in a blind hemifield would be capable of inducing a global effect, a shift of saccade endpoint when target and distractor are close to each other, in participants with lesions of the optic radiations or striate cortex. We found that blind field distractors significantly shifted saccadic endpoints in two of three participants with lesions of either the striate cortex or distal optic radiations. The direction of the effect was paradoxical, however, in that saccadic endpoints shifted away from blind field distractors, whereas endpoints shifted towards distractors in the visible hemifields, which is the normal global effect. These results provide further evidence that elements presented in the blind visual field can generate modulatory interactions in the oculomotor system, which may differ from interactions in normal vision.     

Right–left approach and reaching arm movements of 4-month infants in free and constrained conditions

Recent theories on the evolution of language (e.g. Corballis, 2009) emphazise the interest of early manifestations of manual laterality and manual specialization in human infants. In the present study, left- and right-hand movements towards a midline object were observed in 24 infants aged 4 months in a constrained condition, in which the hands were maintained closed, and in a free condition. A left-hand dominance for approach movements without contact with the object, and a right-hand dominance for reaching movements with object contact was observed in the free condition. In the constrained condition reaching movements of the right hand decreased dramatically. These results are interpreted as strong evidence of manual specialization in 4-month olds, with approach movements having a localization role and reaching movements announcing future right-hand dominance for prehension and object manipulation.     

Consciousness wanted,attention found: Reasons for the advantage of the left visual field in identifying T2 among rapidly presented series

Everyday experience suggests that people are equally aware of events in both hemi-fields. However, when two streams of stimuli are rapidly presented left and right containing two targets, the second target is better identified in the left than in the right visual field.This might be considered evidence for a right-hemisphere advantage in generating conscious percepts. However, this putative asymmetry of conscious perception cannot be measured independently of participants’ access to their conscious percepts, and there is actually evidence from split-brain patients for the reverse, left-hemisphere advantage in having access to conscious percepts. Several other topics were studied in search of the responsible mechanism, among others: Mutual inhibition of hemispheres, cooperation of hemispheres in perceiving midline stimuli, and asymmetries in processing various perceptual inputs. Directing attention by salient cues turned out to be one of the few mechanisms capable of modifying the left visual-field advantage in this paradigm. Thus, this left visual-field advantage is best explained by the notion of a right-hemisphere advantage in directing attention to salient events. Dovetailing with the pathological asymmetries of attention after right-hemisphere lesions and with asymmetries of brain activation when healthy participants shift their attention, the present results extend that body of evidence by demonstrating unusually large and reliable behavioral asymmetries for attention-directing processes in healthy participants.     

Gender characteristics of cerebral hemodynamics during complex cognitive functioning

Functional Transcranial Doppler sonography (fTCD) has been applied to assess peak mean cerebral blood flow velocity (MFV) with a high temporal resolution during cognitive activation. Yet, little attention has been devoted to gender-related alterations of MFV, including spectral analysis. In healthy subjects, fTCD was used to investigate a series of cerebral hemodynamic parameters in the middle cerebral arteries (MCA) during the Trail Making Tests (TMT), a means of selective attention and complex cognitive functioning. In females, there was a frequency peak at 0.375 Hz in both MCA, and we observed a dynamic shift in hemispheric dominance during that condition. Further, after the start phase, there was an MFV decline during complex functioning for the entire sample. These novel results suggest condition-specific features of cerebral hemodynamics in females, and it adds to the notion that gender is a fundamental confounder of brain physiology.     

Hemispheric asymmetries in the split-fovea model of semantic processing

We report a series of neural network models of semantic processing of single English words in the left and the right hemispheres of the brain. We implement the foveal splitting of the visual field and assess the influence of this splitting on a mapping from orthography to semantic representations in single word reading. The models were trained on English four-letter words, presented according to their frequency in all positions encountered during normal reading. The architecture of the model interacted with the training set to produce processing asymmetries comparable to those found in behavioral studies. First, the cueing effects of dominant and subordinate meanings of ambiguous words were different for words presented to the left or to the right of the input layer. Second, priming effects of groups of related words were stronger in the left input than the right input of the model. These effects were caused by coarser-coding in the right half compared with the left half of the model, an emergent effect of the split model interacting with informational asymmetries in the left and right parts of words in the lexicon of English. Some or all of the behavioral data for reading single words in English may have a similar origin.     

Bimanual circle drawing in children with spastic hemiparesis: effect of coupling modes on the performance of the impaired and unimpaired arms

The present study examined the effect of interlimb coupling on the performance of the impaired and unimpaired arm in children with spastic hemiparesis during bimanual circle drawing. The following questions were addressed: (1) does coupling positively influence the performance of the impaired arm compared to single-hand performance and (2) is such an effect dependent on mode of coordination (i.e., symmetric versus asymmetric). Twelve children with spastic hemiparesis produced circle drawings on a digitizer under different task conditions. Spatiotemporal characteristics and quality of movement of pen trajectories of the individual limbs as well as interlimb relative phase were analysed. Coupling in a symmetric coordination mode resulted in a decrease of temporal variability and an increase of smoothness of circle drawing movements in the impaired arm compared to single-handed performance. Coupling in an asymmetric coordination mode resulted in an increase of spatial and temporal variability in the unimpaired arm. It is concluded that coupling may enhance the performance of the impaired arm in children with spastic hemiparesis, but only during symmetric bimanual coordination. A possible underlying neural mechanism that might explain these findings is discussed.     

From cybernetics to brain theory,and more: A memoir

While structured as an autobiography, this memoir exemplifies ways in which classic contributions to cybernetics (e.g., by Wiener, McCulloch & Pitts, and von Neumann) have fed into a diversity of current research areas, including the mathematical theory of systems and computation, artificial intelligence and robotics, computational neuroscience, linguistics, and cognitive science. The challenges of brain theory receive special emphasis. Action-oriented perception and schema theory complement neural network modeling in analyzing cerebral cortex, cerebellum, hippocampus, and basal ganglia. Comparative studies of frog, rat, monkey, ape and human not only deepen insights into the human brain but also ground an EvoDevoSocio view of “how the brain got language.” The rapprochement between neuroscience and architecture provides a recent challenge. The essay also assesses some of the social and theological implications of this broad perspective.     

Hands Support and Postural Oscillation During Sit-to-Stand Movement in Children With Cerebral Palsy and Typical Children

The authors aimed to compare the weight bearing on hands during sit-to-stand (STS) movement in children with cerebral palsy (CP) and typical children (TC), verify its effect on postural oscillation, and analyze the relationship between weight bearing on hands and postural oscillation. Twenty children with CP (Gross Motor Function Classification System levels I and II) and 35 TC performed STS with and without anterior hands support. Mann-Whitney test compared weight bearing between groups. Wilcoxon test investigated differences in postural oscillation between the conditions with and without anterior hand support for both groups. The Spearman correlation tested the relationship between weight-bearing and postural oscillation during the hand support condition. Children with CP bore more weight on hands than TC to perform STS. The hand support reduced postural oscillation during the second phase of STS in both groups. In the CP group, greater weight bearing was related with lower postural oscillation in the beginning of STS. Although children with CP were able to perform STS without support, they bore more weight on their hands to perform the task than TC. Moreover, children with CP and TC use mechanical and somatosensory information to modulate their postural control during STS in different ways.     

Colateralization of Broca's area and the visual word form area in left-handers: fMRI evidence

Language production has been found to be lateralized in the left hemisphere (LH) for 95% of right-handed people and about 75% of left-handers. The prevalence of atypical right hemispheric (RH) or bilateral lateralization for reading and colateralization of production with word reading laterality has never been tested in a large sample. In this study, we scanned 57 left-handers who had previously been identified as being clearly left (N = 30), bilateral (N = 7) or clearly right (N = 20) dominant for speech on the basis of fMRI activity in the inferior frontal gyrus (pars opercularis/pars triangularis) during a silent word generation task. They were asked to perform a lexical decision task, in which words were contrasted against checkerboards, to test the lateralization of reading in the ventral occipitotemporal region. Lateralization indices for both tasks correlated significantly (r = 0.59). The majority of subjects showed most activity during lexical decision in the hemisphere that was identified as their word production dominant hemisphere. However, more than half of the sample (N = 31) had bilateral activity for the lexical decision task without a clear dominant role for either the LH or RH, and three showed a crossed frontotemporal lateralization pattern. These findings have consequences for neurobiological models relating phonological and orthographic processes, and for lateralization measurements for clinical purposes.