The linguistic basis of left hemisphere specialization.

In humans the two cerebral hemispheres of the brain are functionally specialized with the left hemisphere predominantly mediating language skills. The basis of this lateralization has been proposed to be differential localization of the linguistic, the motoric, or the symbolic properties of language. To distinguish among these possibilities, lateralization of spoken language, signed language, and nonlinguistic gesture have been compared in deaf and hearing individuals. This analysis, plus additional clinical findings, support a linguistic basis of left hemisphere specialization.

Asymmetries in intermanual transfer of maze learning in right- and left-handed adults.

This study examined asymmetries in transfer learning on a finger maze as a function of handedness, hand at acquisition and maze orientation at transfer. In both handedness groups, right-hand acquisition enhanced opposite hand performance on an identical and a vertically reversed maze at transfer, relative to a mirror-reversed maze; left-hand acquisition, in turn, enhanced opposite hand transfer on the spatially reversed mazes relative to the identical maze. The findings suggest that different strategies (i.e. verbal versus spatial/motoric) come into play in maze learning depending on the hand used at acquisition (right versus left, respectively) rather than on overall hand dominance.

Asymmetries in the perception of facial affect: is there an influence of reading habits?

Perceptions of happy facial affect from asymmetric composite faces presented in free vision were compared in four groups: left-to-right readers (Hindi), right-to-left readers (Arabic), left-to-right and right-to-left readers (Hindi/Urdu) and illiterates (Hindi/Urdu). Right- and left-handed users of Hindi and Urdu were studied. The analysis of asymmetry scores revealed a significant effect of Group, such that a left hemifield preference was present only in the left-to-right (Hindi) group. There were no reliable differences between right- and left-handers. Furthermore, the leftward bias was present in a significantly larger proportion of Hindi than Urdu or Arabic readers. These results are taken to reflect an interaction between a cerebral laterality effect and a directional scanning effect in facial affect judgment.

Hand dominance for signing: clues to brain lateralization of language.

Virtually all right-handed individuals are left hemisphere dominant for language. Sign languages of the deaf provide an unusual vehicle for exploring the link between handedness and hemispheric specialization for language since in sign language the hands themselves are the language articulators. Performance of the right and left hand was examined in deaf native users of American Sign Language (ASL) for speeded production of one-handed signs and for shadowing of signed discourse. Opposite patterns of asymmetries in hand performance were found in right- and left-handers. However, left-handers were more flexible than right-handers in signing with their non-preferred hand. Furthermore, unusual patterns of hand use for sign were found in a deaf signer with a left hemisphere lesion, possibly indexing increased mediation of the intact hemisphere. Implications for brain organization of language in a visual-gestural mode are discussed.

Erythrocyte glutathione and its metabolizing enzymes in bovine urinary bladder cancer.

Glutathione and its metabolizing enzymes were studied in erythrocytes of cattle suffering from urinary bladder cancer and associated hematuria. The concentration of glutathione (GSH) and GSH peroxidase activity were subnormal in the affected animals, whereas activities of GSH reductase and GSH S-transferase were not altered. Decreased GSH and GSH peroxidase are likely to make erythrocytes of the affected animals more susceptible to oxygen-induced injury and the radiomimetic effect of bracken fern.

Visual field asymmetries for rhyme and syntactic category judgments in monolinguals and fluent early and late bilinguals.

A tachistoscopic study investigated hemispheric specialization among monolingual and fluent French-English bilingual adults for speeded rhyme and syntactic category matching. A right visual field superiority was obtained for both types of verbal judgments. This effect was more pronounced in late bilinguals than in early bilinguals or monolinguals. In addition, bilingual subgroup differences in response latency and strategy were found, suggesting a preference for semantic processing among early bilinguals and for surface processing among late bilinguals, consistent with previous findings. Possible theoretical implications of these differences are outlined.

Visual field asymmetries in numerical size comparisons of digits, words, and signs.

Visual field asymmetries were examined in American Sign Language-English bilinguals for speeded numerical size judgments of pairs of digits, number words, and number signs. Physical size of the number pairs was either congruent or incongruent with their numerical size. The results revealed a greater left visual field (LVF) interference for numbers represented as digits and a greater right visual field (RVF) interference for numbers represented as words or signs. Subjects' performance on number words and signs was also influenced by their skill in English and ASL: interference was greater in the RVF in the subjects' better language but was greater in the LVF for the less skilled language. These findings suggest that lateralization of numerical size judgments is moderated by the mode of number presentation and by prior language experience.

Hemispheric asymmetries in reading Korean: task matters.

Native Korean readers were studied in a visual half-field paradigm. Subjects were to make speeded judgments on Hangul (syllabic) and Hanzza (logographic) scripts based on phonetic or visual properties of the stimuli. A task by visual field interaction was obtained indicating that, for both scripts, responses on the phonetic task were faster in the right visual field, whereas no visual field differences were found on the visual task. Script type did not interact with visual field. The results support a task-based account of hemispheric differences in verbal processing.

Sentence interpretation in normal and aphasic Hindi speakers.

In interpreting a sentence, listeners rely on a variety of linguistic cues to assign grammatical roles such as agent and patient. The present study considered the relative ranking of three cues to agenthood (word order, noun animacy, and subject-verb agreement) in normal and aphasic speakers of Hindi. Because animacy plays a grammatical role in Hindi (determining the nature and acceptability of sentences without accusative marking), this language is relevant to the claim that Broca's aphasia involves a dissociation between grammar and semantics. Results of Study 1 with normal Hindi-dominant speakers showed that animacy is the strongest cue in this language, while agreement is the weakest cue. In Study 2, Hindi-English bilinguals were tested in both their languages. Most showed the normal animacy-dominant monolingual pattern in Hindi, with a mixture of strategies from both languages in their interpretation of English. A substantial minority showed mixed strategies in both languages. Only 5 of 48 subjects displayed a complete separation between languages, with animacy dominance in Hindi and word order dominance in English. In Study 3, two Hindi-English bilinguals with Broca's aphasia were tested in both languages. Results indicate (a) greater use of animacy in Hindi than in English and (b) greater use of word order in English than in Hindi. The strategies displayed by these patients fall well within the range observed among bilingual normals. We conclude that the use of animacy in sentence interpretation by these aphasic patients reflects preservation of normal, language-specific processing strategies; it cannot be interpreted as a nonlinguistic strategy developed to compensate for receptive agrammatism. Results are discussed in light of other cross-linguistic evidence on sentence comprehension in monolingual and bilingual aphasics.

Mirror writing: an advantage for the left-handed?

It has been claimed that left-handed individuals are better than right-handers at writing in a mirror script (R. Tankle & K. Heilman, 1983, Brain and Language, 19, 115-123). We tested this claim by comparing the mirror writing ability of normal right- and left-handed adults as a function of hand used and hand use order. Our results do not support the notion of a left-hander superiority in mirror writing since, in two different experiments, right-handed individuals were found to be as good as left-handers. Instead, we obtained evidence for an order effect such that in both experiments, mirror writing was faster in those who started the task with their right hand.

Hemispheric involvement in shadowing vs. interpretation: a time-sharing study of simultaneous interpreters with matched bilingual and monolingual controls.

A time-sharing study used shadowing and interpretation/paraphrasing tasks to evaluate lateralization in professional interpreters individually matched to bilingual and monolingual controls. A two-step multivariate general linear model procedure was used to determine lateralized effects and extent of disruption produced by the tasks. Results revealed the monolingual group to be left lateralized for both tasks, but the two bilingual groups were lateralized in the LH only for shadowing. The monolingual group was significantly different from the bilingual groups in the pattern of hand asymmetry for interpretation/paraphrasing. The findings replicate outcomes of prior repeated measures analysis of variance procedures on percentage of change scores. However, new information is added by the more refined analysis. The findings are also discussed in terms of previous laterality studies using similar tasks and subject samples.

Comparative evaluation of agar gel precipitation, counterimmunoelectrophoresis and passive haemagglutination tests for the diagnosis of Dicrocoelium dendriticum infection in sheep and goats.

The sensitivity and specificity of the agar gel precipitation test (AGPT), counter immunoelectrophoresis (CIEP) and passive haemagglutination test (PHT) were evaluated for the diagnosis of Dicrocoelium dendriticum infection in naturally infected sheep and goats. Two hundred and forty five sheep and goat sera samples were tested using phosphate buffered saline, pH 7.2 extracted adult fluke antigen. CIEP detected 69.8% of the infected animals and was found to be the most sensitive, followed by PHT which detected 50.0% of the infected sheep and goats. AGPT was found to be the least sensitive, detecting only 23.8% of the infected animals. The specificity of

Bacteraemia in man and animals: an overview.

Bacteraemia signifies invasion of the bloodstream by bacteria. In most systemic infections in man and animals, bacteria enter the blood at some stage during the infection and are rapidly distributed throughout the body. A wide variety of organisms have been associated with bacteraemia. Prompt detection of the aetiological agents of bacteraemia is of prime importance in clinical microbiology. There are no defined recommendations for blood cultures in animals but both conventional and improved methods are available for detection of bacteraemia in man. The consequences of bacteraemia are as diverse as the potential aetiological agents. Monoclonal antibodies to the core glycolipid (lipid A) seems very promising for the treatment of bacteraemia and septic shock caused by Gram-negative bacteria in man and animals.

The enzymatic profile of urine and plasma in bovine urinary bladder cancer (enzootic bovine haematuria).

The enzymatic profile of urine and plasma in field cases of bovine bladder cancer was studied. Urinary lactate dehydrogenase activity was significantly altered along with the isoenzyme pattern. Activity of alkaline phosphatase and beta-glucuronidase was decreased in the affected animals. No significant changes were observed in acid phosphatase, or arylsulphatase A and B activity. In plasma, lactate dehydrogenase activity was elevated without any change in the isoenzyme pattern. No significant changes were observed in the other plasma enzymes studied or in the sialic acid concentration.

Asymmetries in tachistoscopic word recognition: scanning effects re-examined.

To investigate the role of scanning biases in visual half field studies, native readers of Hindi (a language written and read from left-to-right) and Urdu (a language written and read from right to left) were tested in a language analogue of the Stroop paradigm. Subjects had to identify the script (Hindi vs. Urdu) in which the words referring to the two languages Hindi and Urdu were presented. Greater RVF than LVF interference was obtained in both groups, indicating a left hemisphere specialization for lexical functioning independent of scanning biases.

Methodological issues in the use of the concurrent activities paradigm.

This paper presents a critical analysis of one type of dual-task procedure, the lateralized concurrent activities paradigm. Extrinsic and intrinsic factors that may influence the interpretation of results obtained with this paradigm are isolated and methodological refinements in experimental design and analysis are suggested.