Differential bilingual laterality: mythical monster found in Wales

Can bilingualism increase neuroplasticity of language networks in epilepsy?

Individuals with left temporal lobe epilepsy (TLE) have a higher rate of atypical (i.e., bilateral or right hemisphere) language lateralization compared to healthy controls. In addition, bilinguals have been observed to have a less left-lateralized pattern of language representation. We examined the combined influence of bilingual language experience and side of seizure focus on language lateralization profiles in TLE to determine whether bilingualism promotes re-organization of language networks. Seventy-two monolingual speakers of English (21 left TLE; LTLE, 22 right TLE; RTLE, 29 age-matched healthy controls; HC) and 24 English-dominant bilinguals (6 LTLE, 7 RTLE, 11 HC) completed a lexical-semantic functional MRI task and standardized measures of language in English. Language lateralization was determined using laterality indices based on activations in left vs right homologous perisylvian regions-of-interest (ROIs). In a fronto-temporal ROI, LTLE showed the expected pattern of weaker left language lateralization relative to HC, and monolinguals showed a trend of weaker left language lateralization relative to bilinguals. Importantly, these effects were qualified by a significant group by language status interaction, revealing that bilinguals with LTLE had greater rightward language lateralization relative to monolingual LTLE, with a large effect size particularly in the lateral temporal region. Rightward language lateralization was associated with better language scores in bilingual LTLE. These preliminary findings suggest a combined effect of bilingual language experience and a left hemisphere neurologic insult, which may together increase the likelihood of language re-organization to the right hemisphere. Our data underscore the need to consider bilingualism as an important factor contributing to language laterality in patients with TLE. Bilingualism may be neuroprotective pre-surgically and may mitigate post-surgical language decline following left anterior temporal lobectomy, which will be important to test in larger samples.

Hand preference in referential gestures: Relationships to accessing words for speaking in monolingual and bilingual children

INTRODUCTION

Infants' right-hand preference for pointing is associated with higher vocabulary. It is not clear whether the link between right-hand preference for gesturing and language persists into the preschool years. The primary purpose of the present study was to test whether preschool children's hand preference for referential gestures was associated with their language abilities. Secondarily, we predicted that the children's right-hand preference would be negatively associated with their visuospatial abilities. We also predicted that monolingual children would show a strong right-hand preference while bilinguals might show a reduced right-hand preference.

METHODS

Monolingual and bilingual children between the ages of four and six years did a storytelling task. Their referential gestures were coded for hand use (right, left, both). We measured language skills (receptive vocabulary, semantic fluency).

RESULTS

We found no difference between bilinguals and monolinguals on hand preference. Semantic fluency was a positive predictor and vocabulary a negative predictor of right-hand preference. Children's visuospatial abilities were not a predictor of right-hand preference.

CONCLUSION

These results suggest that right-hand preference may help children select semantically appropriate words out of their existing vocabulary. In other words, this preference may be related to children's construction of the message that they would like to produce. The association between hand preference and language skills persists into the preschool years.

Inhibitory Control in Speech Comprehension among Dai-Han Bilingual Children

We aimed to investigate differences in inhibitory control ability between proficient and non-proficient Dai–Han bilinguals. Two experiments used a combined stimulus–stimulus and stimulus–response compatibility paradigm for this purpose. Participants were Dai–Han bilingual primary-school students selected from a Dai-speaking town in Yunnan province, China. In Dai language interference condition, participants were asked to complete a picture category task. Results showed that the effect of attentional control for non-proficient bilinguals (NPBs) was significantly greater than that for proficient bilinguals (PBs), while the effect of response inhibition was not. This implied that a difference in inhibitory control between PBs and NPBs appeared at the attention control stage when interference by the Dai lexicon emerged. In Han language interference condition, however, participants were also asked to complete the same task. Results showed that the effect of response inhibition for NPBs was significantly greater than that for PBs, but the effect of attentional control was not. This demonstrated that a difference in inhibitory control emerged at the response inhibition stage when interference by the Han lexicon emerged. This pattern of results is opposite to previous researches, which indicated that the difference between PBs and NPBs occurred at the response inhibition stage under first language condition, whereas at the attentional control stage under second language (L2) condition. Based on these, this study suggests that Dai–Han bilinguals showed a remarkable L2 advantage. In addition, results showed that response times (RTs) of PBs were faster than RTs of NPBs while confounding variables (e.g., intelligence, etc.) were under control. This indicates that the inhibitory control ability of the PBs is superior to that of NPBs in this study.

Estimates of functional cerebral hemispheric differences in monolingual and bilingual people who stutter: Visual hemifield paradigm

The relationship between stuttering and bilingualism to functional cerebral hemispheric processing was examined using a visual hemifield paradigm. Eighty native German speakers, half of whom were also proficient speakers of English as a second language (L2), were recruited. The participants were organised into four different groups according to speech status and language ability: 20 monolinguals who stutter, 20 bilinguals who stutter, 20 monolinguals who do not stutter, and 20 bilinguals who do not stutter. All participants completed a task involving selective identification of common objects simultaneously presented to both visual fields. Overall, an LVF advantage was observed across all groups with no significant group differences in regard to hemispheric asymmetry. However, both bilingual groups showed faster reaction times and fewer identification errors than the two monolingual groups. A prevailing finding was that bilingualism seems to offset deficits in executive functioning associated with stuttering. Hence, the results lend support to previous findings implicating the benefits of bilingualism.

Hemispheric asymmetries in bilinguals: tongue similarity affects lateralization of second language

It is known that the left hemisphere of the human brain is critical in understanding and producing spoken language, but it remains a topic of great interest determining the cerebral lateralization of multiple languages. The aim of this study is to examine the effects of similarity between languages on hemispheric asymmetry of bilingual brains. The involvement degree of left and right hemisphere was examined during the processing of the first (L1) and second (L2) language in two different groups of bilinguals with English as L2. The first group consisted of German native speakers and the second group of Italian native speakers. Subjects from the two groups acquired L2 later in life (after the age of six) and had a comparable level of proficiency in second language comprehension. The functional lateralization was tested by a classical dichotic test with words in L1 and L2. Dependent variables were number of responses associated to words presented at the left vs. right ear and reaction time. Results showed a significant right ear advantage (REA) for number of responses in both languages and in both groups. However, the REA for L2 (English) processing was stronger in the German group. Reaction times were significantly lower during L1 processing and showed a trend towards the results obtained with the number of response variable. This study provides neuropsychological evidence pointing to a different lateralization pattern in the elaboration of a same L2 if L1 comes from different linguistic roots.

Accessing newly learned names and meanings in the native language

Ten healthy adults encountered pictures of unfamiliar archaic tools and successfully learned either their name, verbal definition of their usage, or both. Neural representation of the newly acquired information was probed with magnetoencephalography in an overt picture-naming task before and after learning, and in two categorization tasks after learning. Within 400 ms, activation proceeded from occipital through parietal to left temporal cortex, inferior frontal cortex (naming) and right temporal cortex (categorization). Comparison of naming of newly learned versus familiar pictures indicated that acquisition and maintenance of word forms are supported by the same neural network. Explicit access to newly learned phonology when such information was known strongly enhanced left temporal activation. By contrast, access to newly learned semantics had no comparable, direct neural effects. Both the behavioral learning pattern and neurophysiological results point to fundamentally different implementation of and access to phonological versus semantic features in processing pictured objects.

Visual laterality effects in readers of a deep and a shallow orthography

Using a tachistoscopic split-field paradigm, hemifield asymmetry for single word recognition was examined in monolingual English speakers and in fluent bilingual English-Welsh speakers. A robust right hemifield advantage was found for both groups and both languages. Among bilinguals, the laterality index was significantly greater for Welsh than for English, supporting previous findings. The magnitude of the laterality index was unaffected by which language was learned first (Welsh or English) and by the age of acquisition (before or after 5-6years old) of the second language. However, among bilinguals there was a significant difference in the laterality index for Welsh words compared with English words for those participants brought up in a predominantly Welsh-speaking environment, but not for those brought up in a predominantly English-speaking or dual-language environment. We attribute our results to the difference in orthographic depth between Welsh and English. and argue that the transparency of Welsh favours adoption of a left-hemisphere based phonological decoding strategy in reading. Such a strategy is not necessarily used exclusively by readers of Welsh, but is encouraged by regular exposure to the Welsh language on a day-to-day basis.

The bilingual Loch Ness Monster raises its non-asymmetric head again-or, why bother with such cumbersome notions as validity and reliability? Comments on Evans et al. (2000)

All of the experimental studies of the past 25 years combined and the meta-analyses of their findings have not advanced our knowledge of the lateralization of language in bilingual speakers one bit. We are left with a clutter of inherently uninterpretable contradictory results. Successive studies do not contribute a single brick to the edifice or a single piece to the puzzle-only more confusion. study is no exception. So far, there has been no demonstration of the validity of any experimental paradigm claiming to measure degree of language laterality in bilingual speakers. Experimentation is pointless unless the nature of what is alleged to be lateralized is clearly defined and the validity of the measures employed has been established. Because of the lack of validity of the paradigms used in bilingual laterality studies, experiments and meta-analyses of their findings cannot have any scientific significance. Like their predecessors, Evans et al. pay lip service to a number of methodological problems, but ignore their implications and simply carry on anyway. The authors ought to demonstrate, rather than assume, that degree of visual half-field advantage for single words corresponds to degree of lateralization of any component of language (even if only of words).