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Results for “Functional Laterality”

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PubMed1992

Physiological characterization of lateral line function in the Antarctic fish Trematomus bernacchii.

The Antarctic notothenioids are a monophyletic radiation of fishes that have evolved under conditions of low light and cold, where non-visual sensory systems, such as the mechanosensory lateral line system, would be of importance. As part of a study of the structure and function of the mechanosensory lateral line system in these fishes we systematically characterized the function of the anterior lateral line system in one of the common benthic species, Trematomus bernacchii. Frequency-response and threshold-tuning curve methods yield similar functional characterizations of single afferent fibre responses to vibrational stimulation. Curve fitting of generalized transfer function to frequency-response curves allows an objective splitting of responses into velocity and acceleration sensitive populations thought to correspond to superficial and canal neuromasts, respectively. Both response types are characterized by a low-pass frequency-response curve, with a relatively low upper frequency cut-off when compared with data from temperate species. The sensitivity of the lateral line system of T. bernacchii is comparable to that of the mottled sculpin Cottus bairdi.

Acceleration↗

PubMed1980

Lateralization of functions in the vertebrate brain: a review.

That the human left and right cerebral hemispheres perform different functions is widely accepted; but there is little evidence of whether or not similar functional asymmetries exist in non-human vertebrates. In this paper, neuro-anatomical similarities between human and other vertebrate brains are considered, and data concerning physical asymmetries reviewed. The defining features of human lateralization are taken to be right-handedness, as a skewed but continuous distribution of preferences, and a greater involvement of the left hemisphere in species-specific vocalization, with right-hemisphere superiority in spatial perception and emotionality less well-marked characteristics. Rodents, cats, at least one species of marsupial, and macaque monkeys have consistent hand preferences for food reaching. These may result from constitutional factors, but in every species studied the distribution of preferences is unskewed. Canaries appear to have left-hemisphere dominance of vocal production, and there is limited support for the conjecture that macaque monkeys have left-hemisphere dominance for reception of species-specific cries, and/or for short-term auditory memory. Left and right unilateral hemispheric damage may have appreciably different effects on emotionality in rats, sound localization in cats, and tactile discrimination in monkeys, although the available evidence is equivocal. It seems possible that asymmetries of cerebral function are widespread in vertebrates. In particular, left hemisphere dominance of species-specific communication might be common in birds and primates: left-hemisphere dominance of human speech may be an example of a general vertebrate tendency towards unilateral control of vocalization.

Animals↗

PubMed2002

[Predominant occlusal function during lateral mandibular movements in the black African patient].

The research of the predominant occlusal function during mandibular movements of laterality at the topic African melanoderme, drove authors of this survey to: select 52 healthy topics (11 women and 41 men), aged of 22 to 33 years old observe and note at every topic the presence and the nature of contacts or their possible absence of the working side during the movement of deduction. Observations done as well directly in mouth, that on models put in semi-adaptable articulators, permitted to note that the function of posterior group is more the recovered so much at women that at men, at the young adults and at adults.

Adult↗

PubMed1998

Assessment of functional cerebral laterality for language using magnetoencephalography.

The purpose of the study was to examine the feasibility of using magnetoencephalography (MEG), a noninvasive functional brain imaging technique, to assess cerebral laterality for language. The magnetic flux normal to the scalp surface was measured with a whole-head neuromagnetometer while subjects (n = 16) were engaged in a word-matching and a tone-matching task. The effect of hemisphere and task on the number of satisfactory equivalent current dipole (ECD) solutions obtained during the late portion of the responses to the word and tone stimuli was examined. An interhemispheric ECD laterality index was also computed. Satisfactory ECD solutions were localized in perisylvian cortices during both tasks. A greater number of ECDs was found in the left hemisphere in 14 (87%) of 16 of the subjects in the word-matching task, a proportion that approaches the reported incidence of left-hemisphere dominance among right-handers. A similar proportion of subjects also showed a clear asymmetry in the number of ECDs favoring the left hemisphere in the language task as compared to the nonlanguage task. These findings suggest that MEG is a promising tool for laterality assessment. Magnetoencephalography-based functional asymmetry data are currently being compared against invasive presurgical procedures (i.e., intracarotid amobarbital procedure).

Adult↗

PubMed2002

Functional and postural lateral preferences in humans: interrelations and life-span age differences.

This study aimed to provide data on lateral preferences among older subjects, to analyze age differences, and to determine interrelations between lateral preferences. Four functional preferences (handedness, footedness, eyedness, earedness) and three postural lateral preferences (hand-clasping, arm-folding, leg-crossing) were assessed in 628 Germans (252 men, 376 women) aged between 19 and 90 years. Sex differences, age differences, and associations between lateralities were analyzed applying chi-square tests. Logistic regression analyses considering age, sex, and interactions between variables were applied to analyze combined effects on laterality measures. Right-sided preference for handedness, footedness, eyedness, earedness, and leg-crossing characterized 86.8%, 77.1%, 70.9%, 67.8%, and 56.6%, respectively, of subjects, while a left-sided preference for hand-clasping and arm-folding characterized 56.4% and 60.2%, respectively, of all participants. Results are within the range of other populations. Only footedness differed between the sexes: there were more left-footed men. Older cohorts showed a rightward shift in handedness, eyedness, earedness, and leg-crossing, the opposite for arm-folding. No age-related differences exist in footedness or hand-clasping. Logistic regression models indicate no interaction between age and sex for each laterality measure. The four functional lateralities are significantly interrelated. All also are positively associated with leg-crossing. Conversely, the postural lateralities generally are not correlated, although leg-crossing and arm-folding are, inversely. The observed relationships among lateralities support the hypothesis that handedness, footedness, leg-crossing, and earedness might be aspects of a larger phenotype that is independent of hand-clasping and arm-folding.

Adult↗

PubMed1981

Lateralization of functions in the animal brain.

The study was performed on mice, rats, and cats. The techniques used were those of conditional reflexes and evoked potentials. The results obtained give proof of the existence of hemisphere specialization of the brain in animals, and some of its properties are described. Motor control is shown to be mainly connected with the left hemisphere. Spatial analysis is mainly lateralized in the right hemisphere, and time analysis in the left one. It has been found that differentiation of absolute characteristics is mainly determined by the right hemisphere, and of relative ones by the left hemisphere. In males the brain has been shown to be more asymmetrical than in females. Proof is given of genetic determination of interhemispheric asymmetry magnitude. It is suggested that interhemispheric asymmetry arose not under the influence of speech and right-handedness but is determined by some more fundamental factors.

Animals↗

PubMedDate not supplied

Headache lateralization and functional cerebral asymmetry: a task-related EEG power spectrum analysis.

Clinical evidence shows that pain, particularly without organic lesions, tends to be more frequent on the left side of the body. Concomitantly, experimental data indicate that differential sensitivity for the right and left side, the pain threshold and tolerance being usually higher in the dominant than in the non-dominant side of the body. Headache laterality was investigated in 188 consecutive chronic headache patients. Headache was lateralized in approximately 50% of the cases, with an overall right predominance (59%). However, when descriptive diagnosis was taken into consideration, lateralized pain was predominant on the left side in psychogenic headache (p less than .01), whereas somatogenic headache was more often right-sited. Since pain lateralization can hardly be explained by peripheral factors, we assumed that reduced efficiency of the non-dominant side in processing several perceptual and cognitive activities could reflect asymmetry in cerebral organization. As differential engagement of the two hemispheres by appropriate tasks can be demonstrated with the EEG, we have studied 13 chronic headache patients with quantitative EEG analysis, compared with a control group of normal subjects (n = 7). The analysis of alpha-asymmetry, during analytical and spatial tasks, revealed that chronic headache patients showed a trend toward a relative activation of the right hemisphere during both tasks, independently of descriptive diagnosis, suggesting that chronic headache might be considered a "psychosomatic continuum". We postulate that pain perception may be biased by the reduced efficiency of the right hemisphere in sensory processing, so that the sensory message may be misinterpreted or amplified as painful by higher centers, even in absence of nociceptive stimuli.

Adult↗

PubMed1984

Visual experience, unilateral cortical lesions, and lateralization of function in rats.

The effects of early visual experience and later unilateral neocortical lesions on the behavior of male hooded rats were measured on an open-field, 17-arm spatial maze, and a visual field or perimetry test. The comparison of behavior observed in the open field revealed that light-reared (LR) rats that suffered a right hemispheric lesion were more active and reared more than any of their dark-reared (DR) counterparts as well as LR animals that had left hemispheric or sham operations. On the radial maze task in which 8 of 17 arms were baited, the rats with unilateral lesions performed less effectively than did the sham-operated animals. The effect of the lesions was significantly greater for LR rats than their DR counterparts. The perimetry testing revealed that although the operated animals did react to stimuli throughout their visual field, some contralateral neglect was evident in the case of both LR and DR rats. The lesions did have a much greater impact on orientational behavior of operated LR rats. However, as was the case with respect to performance on the radial maze, no evidence emerged of any functional asymmetry following the unilateral cortical lesions. The results are discussed in terms of Denenberg's (1981) hypothesis about cerebral and functional asymmetry in the rat.

Animals↗

PubMed1994

Patterns of recovery and change in verbal and nonverbal functions in a case of crossed aphasia: implications for models of functional brain lateralization and localization.

We present a 2-year verbal and nonverbal follow-up of a crossed aphasic patient. The patient had suffered from widespread ischemic damage in the area of right middle cerebral artery, with a parieto-temporal lesion. Three months postonset he showed classical Wernicke's aphasia associated with oral, limb and constructional apraxia and left hemineglect. However, follow-up findings showed a complex, dynamic pattern entirely consistent with cognitive models of language and nonlanguage abilities. Current models of functional brain lateralizations could not satisfactorily account for such longitudinal, fine-grain observations.

Agraphia↗

PubMed2004

Prenatal exposure to testosterone and functional cerebral lateralization: a study in same-sex and opposite-sex twin girls.

In animals it has been shown that exposure to sex hormones is influenced by intrauterine position. Thus fetuses located between two male fetuses are exposed to higher levels of testosterone (T) than fetuses situated between two female fetuses or one female and one male fetus. In a group of opposite-sex (OS) twin girls and same-sex (SS) twin girls a potential effect of prenatal exposure to testosterone (T) on functional cerebral lateralization was investigated. We hypothesized that prenatal exposure to T would result in a more masculine, i.e. a more lateralized pattern of cerebral lateralization in OS twin girls than in SS twin girls. An auditory-verbal dichotic listening task (DLT) was used as an indirect method to study hemispheric specialization. Firstly, we established a sex difference on the DLT. Compared with SS girls, OS twin boys showed a more lateralized pattern of processing verbal stimuli. Secondly, as predicted OS girls had a more masculine pattern of cerebral lateralization, than SS girls. These findings support the notion of an influence of prenatal T on early brain organization in girls.

Acoustic Stimulation↗

PubMed1997

Handedness and speech: a critical reappraisal of the role of genetic and environmental factors in the cerebral lateralization of function.

Functional predominance of the left cerebral hemisphere with regard to both handedness and speech has usually been assumed to be due to some underlying neural specialization that is predetermined and inborn. However, data from left-handed individuals and animal experiments, together with a consideration of the effects of natural selection on brain and behaviour during hominid evolution, are incompatible with such an explanation. A critical reexamination of the relevant nonhuman and human evidence suggests that although the development of a cerebral lateralization for speech and handedness is dependent on both genetic and environmental factors, the specific role of inborn and postnatal influences is very different. This has significant implications for a fundamental revision of current theory and research orientation.

Animals↗

PubMed2006

Haptic orientation perception: sex differences and lateralization of functions.

The present study examined sex differences in haptic orientation representation using three tasks: a bimanual parallel-setting task comprising haptic orientation perception and motor matching action, and two unimanual tasks focusing on the perception and action elements separately. A verbal judgment task focused on haptic orientation perception: participants were to assign a number of minutes to a felt orientation. An orientation production task required the rotation of a bar to match a verbally presented number of minutes. Although both male and female performance was systematically biased we found that males are more accurate in parallel-setting and verbal judgment of orientation, suggesting differences in haptic orientation perception, in particular. Increasing allocentric reference frame involvement by delaying the action in the parallel-setting task did not affect the sex difference found. In addition to a male advantage over tasks, performance on both unimanual tasks suggests sex differences in lateralization of haptic orientation processing; a dependence on hand orientation was found only for right hand performance in males.

Adolescent↗

PubMed1987

The function of lateral hypothalamic catecholamine and endorphin systems in the control of motor performance.

Morphine (1 or 10 micrograms in 1 microliter) or beta-endorphin (1 microgram in 1 microliter) were injected bilaterally into the posterior lateral hypothalamus of Sprague-Dawley rats to determine what effect they may have on motor performance. Severe reductions in open field performance and motor reflex control were observed after the injection of 1 microgram of beta-endorphin or morphine into this area. The injection of 10 micrograms of morphine into the same area was less effective in causing motor impairment. The central (32.7 micrograms in 1 microliter) and peripheral (2 mg/kg) injection of naloxone did not prevent the motor impairment observed after the injection of beta-endorphin or morphine. Pretreatment with 6-hydroxydopamine into the lateral hypothalamus in a multistage regime did not prevent the motor impairment observed after beta-endorphin or morphine injection. These results indicate that lateral hypothalamic participation in the control of motor function may not involve the ascending nigrostriatal and mesocortical dopamine systems and that endogenous opiate systems may function independently to influence motor performance.

Animals↗

PubMed2001

Quality of life self-assessment as a function of lateralization of lesion in candidates for epilepsy surgery.

PURPOSE: This prospective study aimed to investigate the relationship(s) of the laterality of the epileptogenic lesion to personality factors, emotional processing, and the subjective experience of quality-of-life (QOL) self-assessment in candidates for epilepsy surgery. METHODS: Patients who were candidates for epilepsy surgery were studied. Eighteen of them (aged 19-61 years) had localization-related epilepsy in the right temporal lobe (RTLE), 18 (aged 21-50 years) had localization-related epilepsy in the left temporal lobe (LTLE), and 20 were demographically matched normal subjects. The Spielberger Trait/State Anxiety questionnaire and the QOLIE-31 questionnaire for self-assessment of quality of life were used. One-way analysis of variance, Pearson correlations, and linear regression analyses were performed on group and anxiety levels and QOLIE variables. RESULTS: LTLE patients systematically showed higher levels of anxiety and lower self-estimates of the quality of their lives when compared with RTLE patients. All anxiety measures were highly correlated with Total QOL in LTLE (p < 0.05) but not in RTLE patients; however, different parameters of QOL showed different relationships with measures of anxiety. Results of multiple regression analyses suggested that the level of anxiety was relatively stable and less affected by QOL factors in LTLE as compared with RTLE patients (p = 0.03). CONCLUSIONS: A high level of anxiety shown by LTLE patients may represent a personality trait and cause a response bias in overreporting of negative symptoms and a decreased self-assessment of QOL. It may also present a presurgical risk factor, particularly for patients with LTLE lesions. Appropriate patient counseling is advised.

Adult↗

PubMed1996

Cellular, morphometric, ontogenetic and connectional substrates of anatomical asymmetry.

Although anatomical cerebral asymmetry appears in all animals that have been examined, its link to functional lateralization is not clear. In an attempt to further elucidate this relationship between structure and function, we have compared, in rats and humans, brains that have asymmetric architectonic areas to those that are symmetric. We have found that (1) asymmetry is the result of the production of a small side rather than the production of a large side; (2) architectonic asymmetry is the result of changes in the total numbers of neurons rather than cell-packing density; (3) events occurring early in corticogenesis--specifically during the period of progenitor cell proliferation and/or death--are important for the formation of asymmetric cortical areas; and (4) symmetric brains have relatively greater numbers of callosal fibers and more patches of termination than their asymmetric counterparts. These results, taken together, suggest that if anatomic asymmetry underlies functional lateralization, it may have more to do with the different organization of symmetric and asymmetric brains, rather than simply which hemisphere (or brain region) is larger.

Animals↗

PubMed2006

Hemispheric interactions are different in left-handed individuals.

In a previous study, N. Cherbuin and C. Brinkman (2006) showed that in right-handed participants, interhemispheric transfer time (measured with A. T. Poffenberger's, 1912, paradigm) was a significant predictor of the efficiency of hemispheric interactions (measured with a split visual field, letter-matching task). No effect was found for degree of handedness in this study. This was surprising because handedness has been shown to be associated with differences in the morphology and the structure of the corpus callosum, and cerebral anatomical lateralization, as well as functional lateralization both in behavioral and scanning studies. Because these findings were found in a large sample, but one limited to right-handed participants, the aim of the present study was to determine whether a similar relationship was present between interhemispheric transfer time and hemispheric interaction in left-handed participants (using identical measures) and to assess whether the analysis of a larger sample that comprised both left- and right-handed participants might reveal an effect of handedness. Results demonstrate significant handedness effects, suggesting that left-handed individuals tend to have more efficient hemispheric interactions.

Adolescent↗

PubMed1983

Lateralization of function in rats.

Research findings during the past several years have shown that the rat's brain is lateralized for a number of behavioral functions. Neurochemical and anatomical asymmetries have also been found and, in some instances, have been associated with the behavioral asymmetries. It has also been found that extra stimulation in early life can enhance existing asymmetries or can induce asymmetries where none previously existed.

Aggression↗

PubMed2001

Functional asymmetry in schizophrenic patients during auditory speech processing.

In two experiments, functional laterality and interhemispheric transfer was investigated in schizophrenic patients (n=14) and healthy controls (n=17). In Experiment 1, words and pseudowords were presented either to the left or right ear (monaural condition) or simultaneously to both ears (binaural condition). In Experiment 2, subjects had to discriminate two tones differing in frequency during monaural and binaural stimulation. Healthy controls showed a right ear advantage (REA) for word stimuli, indicating left-hemispheric superiority for word processing. The same lateralization pattern was found in schizophrenic patients, indicating unimpaired functional lateralization of auditory language processing. In both groups, no REA was found for pseudowords resulting in significant WordnessxEar interactions. When presented binaurally, auditory processing of words and pseudowords did not differ significantly from any of the two monaural conditions. Tone discrimination did not lead to any ear asymmetry. The results show normal patterns of functional asymmetry during auditory language processing and tone discrimination in schizophrenic patients.

Adult↗