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Results for “Functional Laterality”

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At least 973 records · Page 54Linked to original sources

PubMed2003

[Characteristic changes of acetylcholine receptor in rat lateral pterygoid muscles after functional mandibule advancement].

OBJECTIVE: The purpose of this study was to evaluate the maximum binding(Bmax) and affinity(Kd value) changes of acetylcholine receptor (n-AchR) in rat lateral pterygoid muscles after functional mandibule advancement. METHODS: 40 five-weeks-old male Sprague-Dawley rats were equally divided into experimental and control group. The mimic functional appliances were used in experiment group and the rats were killed after 1, 3, 7, 14 days. Radio-ligand binding assay (RBA) was applied to determine the maximum binding(Bmax) and Kd value of n-AchR of lateral pterygoid muscle. RESULTS: The Bmax of n-AchR in experimental group was higher than that in control group and the Kd value always kept in high level. CONCLUSION: The functional orthopedics can increase the Bmax of n-AchR in rapid growing rat lateral pterygoid muscles.

Animals↗

PubMed2004

The functional locus of the lateralized readiness potential.

The lateralized readiness potential (LRP) is considered to reflect motor activation and has been used extensively as a tool in elucidating cognitive processes. In the present study, we attempted to more precisely determine the origins of the LRP within the cognitive system. The response selection and motor programming stages were selectively manipulated by varying symbolic stimulus response compatibility and the time to peak force of an isometric finger extension response. Stimulus response compatibility and time to peak force affected response latency, as measured in the electromyogram, in a strictly additive fashion. The effects of the experimental manipulations on stimulus- and response-synchronized LRPs indicate that the LRP starts after the completion of response-hand selection and at the beginning of motor programming. These results allow a more rigorous interpretation of LRP findings in basic and applied research.

Adult↗

PubMed1999

Head impulses reveal loss of individual semicircular canal function.

We studied individual semicircular canal responses in three dimensions to high-acceleration head rotations ("head impulses") in subjects with known surgical lesions of the semicircular canals, and compared their results to those of normal subjects. We found that vestibular-ocular reflex (VOR) gains at close to peak head velocity in response to yaw, pitch and roll impulses were reliable indicators of semicircular canal function. When compared to normals, lateral canal function showed a 70-80% decrease in VOR gain at peak of yaw head velocity during ipsilesional yaw impulses. After the loss of one vertical canal function there was a 30-50% decrease in vertical and torsional VOR gain in response to ipsilesional pitch and roll impulses respectively. Bilateral deficits in anterior or posterior canal function resulted in a 80-90% decrease in vertical VOR gain during ipsilesional pitch impulses, while the loss of ipsilateral anterior and posterior canal functions will result in a 80-90% decrease in torsional VOR gain in response to ipsilesional roll impulses. Three-dimensional vector analysis and animation of the VOR responses in a unilateral vestibular deafferented subject to yaw, pitch and roll impulses further demonstrated the deficits in magnitude and direction of the VOR responses following the loss of unilateral lateral, anterior and posterior canal functions.

Adult↗

PubMed1996

Bilateral ptosis and upgaze palsy with right hemispheric lesions.

Bilateral ptosis is reported with unilateral hemispheric lesions, suggesting partial lateralization of the control of the levator palpebrae superioris. There is a tight synkinesis between vertical eye and eyelid movements, but a similar, lateralized control of vertical gaze has not been previously described. We report 3 patients with right hemispheric infarctions, in whom bilateral ptosis was accompanied by impaired upward gaze. We postulate that this lateralization of ocular motor function reflects the special contribution that the nondominant hemisphere makes to attention.

Aged↗

PubMed1987

Ontogeny of 3H-muscimol binding to membranes of chick forebrain.

A potent GABA agonist, 3H-muscimol, was used to investigate the development of GABA receptors in left and right hemispheres of chick forebrain from day 12 in ovo to day 21 post-hatch. Total specific 3H-muscimol binding (p mol mg-1 protein) increases rapidly in ovo, reaching a peak at around day one post-hatch and then showing a slow decline to approximately 50% of the maximal level at day 21 post-hatch. Despite the considerable evidence from previous studies of lateralization of avian brain function, no significant hemispheric differences were found in 3H-muscimol binding (either of p mol hemisphere-1 or p mol mg protein-1) at any of the developmental ages examined.

Animals↗

PubMed1995

Cerebral laterality in homosexual males: preliminary communication using magnetoencephalography.

MEG-based auditory M100 source location in the left and right hemispheres of 8 strictly homosexual and 9 strictly heterosexual males were compared to determine if this measure of interhemispheric laterality varies as a function of sexual orientation. MEG fields evoked by auditory tone pips were recorded from left and right hemispheres in response to contralateral ear stimulation. The source of the 100-msec latency component, generated in the superior temporal gyrus, was estimated using a least squares inverse solution algorithm. Auditory sources in heterosexual men were significantly further anterior in the right hemisphere compared to the left hemisphere. Source locations in the homosexual men did not exhibit significant interhemispheric asymmetry, being similarly located in both hemispheres. Findings suggest an anatomic and/or functional difference in the superior temporal gyrus of at least some homosexual men.

Adult↗

PubMed1992

Non-right sidedness: an association with lower IL-2 production.

Using a laterality questionnaire, 138 normal healthy individuals were classified as right-sided and 25 as non-right sided. Interleukin-2 (IL-2) was generated from whole blood obtained from these subjects using mitogen (PHA) stimulation. IL-2 was quantitated in picograms/ml using an enzyme immunoassay (ELISA). Additionally, sera from these subjects were tested for 7 autoantibodies by standard serological methods. As compared to right sided subjects, non-right sided individuals had significantly lower IL-2 production. Non-right sided individuals with autoantibodies had significantly lower IL-2 production than right sided subjects with or without autoantibodies, but did not differ significantly from their non-right sided counterparts without autoantibodies. These data support the increasing evidence for the differential and lateralized regulation of immune functions by the right and left cerebral regions.

Adult↗

PubMed1984

Lateral specialization and social-verbal development in preschool children.

Forty-two 2 1/2- to 5 1/2-year-old children's social and verbal behaviors were observed during free play in a preschool. A test measuring lateral specialization of verbal function and a standardized psychometric test of verbal ability were also administered. Analysis of variance indicated that the right ear (left hemisphere) is predominant in processing verbal stimuli in children as young as 2 1/2. Multiple regression analyses revealed significant relations between the right ear accuracy score for dichotically presented verbal stimuli and both psychometrically measured verbal ability and a social-verbal factor score derived from play behavior. After the increase related to age was statistically partialled out from both verbal ability and social-verbal scores, verbal expression, length of verbal utterances, time spent in conversation, and peer social interactions increased and parallel play decreased as a function of right ear (left hemisphere) accuracy for verbal stimuli. The relationship between left ear (right hemisphere) accuracy scores for verbal stimuli and social-verbal behavior, however, was not linear. Very high and very low levels of left ear recall predicted an increase in the frequency of parallel play and low social-verbal behavior while moderate levels of left ear accuracy scores predicted the reverse.

Auditory Perception↗

PubMed2006

Training to use voice onset time as a cue to talker identification induces a left-ear/right-hemisphere processing advantage.

We examined the effect of perceptual training on a well-established hemispheric asymmetry in speech processing. Eighteen listeners were trained to use a within-category difference in voice onset time (VOT) to cue talker identity. Successful learners (n=8) showed faster response times for stimuli presented only to the left ear than for those presented only to the right. The development of a left-ear/right-hemisphere advantage for processing a prototypically phonetic cue supports a model of speech perception in which lateralization is driven by functional demands (talker identification vs. phonetic categorization) rather than by acoustic stimulus properties alone.

Adolescent↗

PubMed2004

Effects of chlordiazepoxide on single-unit activity in the septal region of the freely moving rat: aversive vs. non-aversive contexts.

Evidence suggests that stimuli that have the property of inhibiting fear in a Pavlovian fear conditioning paradigm increase cellular activity in the lateral septum, a result consistent with the idea that the lateral septum is actively involved in the inhibition of fear. The experiments reported here were designed to determine if an anxiolytic drug with fear-inhibiting properties would also increase neuronal activity in the lateral septum in a manner that might relate to its mechanism of action as an anxiolytic. An experiment was performed to compare the effects of the benzodiazepine anxiolytic chlordiazepoxide (CDP) upon single-unit activity in the septal region of the rat brain during Pavlovian aversive conditioning with the effects of CDP in a non-aversive context. During Pavlovian conditioning there was a decrease in unit activity in the more lateral regions of the septum, the dorsolateral and ventrolateral nuclei, when a stimulus signaling footshock (CS+) was presented. This conditioned suppression of unit activity was blocked by an intraperitoneal injection of CDP. Additionally, CDP increased baseline unit activity in these regions in the absence of conditioned stimuli. In the more medial regions of the septum, the intermediate lateral septum, we observed few consistent changes either to the conditioned stimuli or to the drug. In a non-aversive context CDP had either no effect at low to moderate doses, or a suppressant effect at a higher dose. The results support a fear-relief hypothesis of lateral septal functioning and suggest the lateral septum as a possible site for the anxiolytic action of benzodiazepines.

Action Potentials↗

PubMed1981

Hemispheric lateralization and aesthetic judgement.

Pairs of slides depicting works of art were presented tachistoscopically to the left or right visual half-fields. Subjects performed an aesthetic judgement task, selecting the better work of art in each pair. Subjects with highly lateralized cerebral organization, as inferred by handedness or sex, performed significantly better in response to slides presented in one visual half-field (VHF) than in response to slides presented in the opposite VHF. Some of these subjects showed a left VHF superiority, while others showed a right RHF superiority. Subjects who were less lateralized showed no significant tendency to perform better in response to slides presented in one VHF or the other. The results are interpreted as an indication that subjects will perform a given task in a lateralized or a non-lateralized manner as a function of the interaction between individual differences in cerebral organization and the cognitive processes used to perform the task.

Adolescent↗

PubMed1999

Neurological soft signs in adolescents with poor performance on the continous performance test: markers of liability for schizophrenia spectrum disorders?

There is much evidence that neurological soft signs (NSS) are highly prevalent in both adults and children with schizophrenia. In addition, they have been detected as early precursors of a schizophrenic outcome in at-risk subjects. Such findings point to the possible value of NSS as neurointegrative markers in schizophrenia which has been hypothesized to be a neurodevelopmental disease. In our study we used a biobehavioral criterion to select the 'at-risk' group, a sustained attentional deficit as measured by the continuous performance test (CPT). We compared 140 normal adolescents with 162 'CPT-linked vulnerable' adolescents (index subjects) on a battery for the assessment of NSS (including laterality), IQ, frontal lobe function and schizotypy. An association was found between NSS and attentional deficit. Furthermore, index subjects with NSS were characterized by lower IQ scores, poorer performance on frontal lobe tests and greater problems with social interaction. There was also a trend for an association between male sex and both left-handedness and NSS.

Adolescent↗

PubMed2000

Nigrostriatal dopamine system and motor lateralization.

The mechanism by which most people favor use of the right hand remains unknown. It has been proposed that asymmetries in the nigrostriatal dopamine system may be related to motor lateralization in humans. We explored this hypothesis in vivo by using [18F]fluorodopa positron emission tomography. Whereas the degree of right hand preference was found to correlate with left putamen dominance as assessed by asymmetry in fluorodopa uptake (K(i)), right caudate dominance was positively correlated with the level of performance during simultaneous bimanual movements in right-handed normal subjects. In addition, right-handed patients with Parkinson's disease with higher right than left caudate K(i) performed much better in bimanual movement tests than those in whom the K(i) value of the left caudate was higher than that of the right. These findings support the notion that the nigrostriatal dopaminergic system may play a role in motor lateralization, and suggest a functional model for bimanual movements. We propose that the skill for performing simultaneous bilateral hand movements in right-handed subjects might depend upon both the activation (through the dominant left putamen circuitry) of the left supplementary motor area (SMA), and the inhibition (through the right caudate circuitry) of motor programs stored in the right SMA.

Adult↗

PubMed1995

Cognitive and neuropsychological characteristics of physically aggressive boys.

Cognitive-neuropsychological tests were given to adolescent boys (N = 177) to investigate processes associated with physical aggression. Factor analysis yielded 4 factors representing verbal learning, incidental spatial learning, tactile-lateral ability, and executive functions. Physical aggression was assessed at ages 6, 10, 11, and 12, and 3 groups were created: stable aggressive, unstable aggressive, and nonaggressive. The authors found main effects for only the executive functions factor even when other factors were used as additional covariates in a step-down analysis; nonaggressive boys performed better than stable and unstable aggressive boys. The covariates family adversity and anxiety were both related only to the verbal learning factor. This study highlights the importance of deficits in executive function in the expression of physical aggression relative to other cognitive-neuropsychological functions.

Aggression↗

PubMed2003

Early and late neurodevelopmental disturbances in schizophrenia and their functional consequences.

OBJECTIVE: The evidence from structural imaging studies supports the notion that schizophrenia arises from an early abnormality in brain development. In this paper we review the timing of structural changes in schizophrenia and argue that schizophrenia is a neuro-developmental disorder with limited progressive brain changes occurring during the evolution and early phase of psychosis. METHOD: The available cross-sectional and longitudinal studies are reviewed, along with data from our own research. RESULTS: The current literature, including our own data, suggests that structural brain changes are apparent premorbidly, consistent with a neurodevelopmental lesion. These are prominent in frontal and cingulate regions, and appear related to premorbid neuropsychological deficits in executive function. However, there appear to be additional brain changes over the transition to illness and beyond. CONCLUSIONS: We propose first, that an early neurodevelopmental insult interacts with either normal or abnormal postpubertal brain maturation to produce further (late neurodevelopmental) brain structural and functional changes; and second, that the effect of such neurodevelopmental lesions will have different consequences for functions that normally develop early in life, such as memory, compared with functions developing later, such as executive functions. A model is presented suggesting that the structural and functional abnormalities in schizophrenia can be understood as a consequence of the neurodevelopmental stage at which brain changes occur.

Brain↗

PubMed1998

Failure of dominant left-hemispheric activation to right-ear stimulation in schizophrenia.

Schizophrenia is associated with an absence of the lateralizations that typify the human brain. Previous evidence emphasized structural changes, particularly reduced asymmetry in extension and surface of the planum temporale, although gross structural deviations occur only in a minority of patients. The present study describes an absence of lateralization on a robust functional measure that characterized schizophrenia patients: healthy subjects but not schizophrenics displayed a contralateral left-hemispheric dominance of the auditory evoked magnetic field to right-ear auditory stimulation. Absence of contralateral dominance in response to auditory stimuli among schizophrenia patients may indicate a failure to establish unequivocal left-hemispheric dominance of the phonological loop as hypothesized by Crow.

Acoustic Stimulation↗

PubMed2004

Cardiovascular regulation and hippocampal sclerosis.

PURPOSE: Cardiovascular dysregulation has been detected in patients with temporal lobe epilepsy (TLE) by using cardiovascular reflex tests and analysis of heart rate variability (HRV). The two methods have not previously been used in the same study to compare them in the assessment of cardioregulatory function. Magnetic resonance imaging (MRI) is considered the best method to reveal structural changes such as hippocampal sclerosis associated with TLE. It is not known whether these structural changes modify cardioregulatory function in patients with TLE. METHODS: Standard cardiovascular reflex tests and analysis of spectral and dynamic measures from 24-h electrocardiogram (ECG) recordings were performed for eight patients with and 31 patients without hippocampal sclerosis and for 72 control subjects. MRI also was performed in each patient to reveal hippocampal sclerosis. RESULTS: Various measures of cardiovascular reflexes and HRV were diminished in patients with TLE compared with the control subjects. No significant differences were found in the measures obtained from the cardiovascular reflex tests or analysis of HRV between those with and without hippocampal sclerosis, although a nonsignificant trend toward reduced values was seen among those with hippocampal sclerosis. The values of cardiovascular reflexes and spectral analysis of HRV correlated with each other. CONCLUSIONS: These results suggest that functional rather than structural changes related to TLE are involved mainly as a mechanism of altered cardioregulatory function. The cardiovascular reflex test and analysis of HRV both appear to be useful in studying cardioregulation in patients with TLE.

Adult↗

PubMed1984

Performance and its measurement.

Performance involves numerous sub-functions, and cannot be treated as a unit. Several attempts have been made to separate functions impaired by different classes of drug: for example, high (monitoring) vs lower (performing) levels of function, early (perceptual) vs later (motor) functions, and strategic vs executive functions. The practical implications are that one cannot predict effects of a drug from a single performance test. One must either simulate the practical situation exactly, or use a battery of analytical tests to form a profile of effects. The latter is the policy urged in this paper.

Amphetamine↗