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Results for “Functional Laterality”

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At least 19 recordsLinked to original sources
PubMed1995

Differential recovery of volitional motor function, lateralized cognitive function, dopamine agonist-induced rotation and dopaminergic parameters in monkeys made hemi-parkinsonian by intracarotid MPTP infusion.

There is still controversy regarding the frequency and extent of spontaneous functional recovery in primate models of parkinsonism, perhaps in part stemming from the variety of ways in which recovery has been assessed. The present study examined functional recovery in monkeys made unilaterally parkinsonian by intracarotid infusion of MPTP. Monkeys were evaluated prior to lesioning and for at least 1 year after lesioning on a battery of tests including a rating of spontaneous behaviors, a learned reaction time/movement time task, tests of lateralized neglect or inattention (i.e. lateralized reward retrieval task, extinction with double simultaneous stimulation, and response to a target moving from one hemispace to the other), and rotational asymmetry in response to a dopamine agonist. Some animals also received 6-[18F]Fluoro-L-Dopa (F-DOPA) position emission tomography (PET) scans before MPTP, when symptomatic, and when showing signs of functional recovery. These animals were sacrificed for post mortem neurochemical assessment following the last PET scan. Results showed that estimates of functional recovery in hemi-parkinsonian monkeys may depend upon the behavioral assay used. Even in behavioral tasks that were sensitive to recovery effects, the degree of functional recovery shown by an animal on one such task did not predict recovery on another. This may in part be due to the inherent difficulty in designing behavioral tests to assess basal ganglia functioning, when there is no consensus concerning which aspects of behavior the normal basal ganglia actually control.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2006

Functional lateral deviation of the mandible and its positional recovery on the rat condylar cartilage during the growth period.

The objective was to examine the effects of a lateral functional shift of the rat mandible and the effects of a shift release on the condylar cartilage during the growth period. Fifty 5-week-old male Wistar rats were initially divided into three groups: shift, recovery, and control. At 5 weeks of age, each animal in the shift and recovery groups received an appliance designed to produce a lateral functional shift of the mandible to the left side. For the recovery group, the appliance was removed after 2 weeks. For the shift group, the appliance was used for 4 weeks. Total cartilage thickness, 5-bromo-2'-deoxyuridine-labeling index, and toluidine blue and tartrate-resistant acid phosphatase-positive cell number in the condylar cartilage at 1, 2, 3, and 4 weeks were compared with those in age-matched controls that had no appliances. In the shift group at 2 weeks, the cartilage thickness and labeling index increased in the central region on the contralateral side, whereas these decreased in the lateral region on the ipsilateral side. However, in the recovery group, 1 to 2 weeks after appliance removal, the cartilage thickness and labeling index in both investigated regions became similar to the control groups. These results emphasize the importance of early treatment to normalize occlusion and create appropriate conditions for normal occlusal development.

Acid Phosphatase↗
PubMed1986

Asymmetrical head-turning of preterm infants: some effects on later postural and functional lateralities.

Asymmetrical head-turning and its effects on subsequent functional lateralities and postural asymmetries were examined in 44 relatively low-risk preterm and 53 fullterm infants. Persisting head-turning to the right was observed more often among preterm infants, as was an asymmetrical skull with flattened right occiput and head-turning to the right. Asymmetrical trunk posture was present in 20 preterm and four fullterm infants. At nine months right-hand preference was more marked in preterm infants, and hand preference was well coincident with head-turning. Changes in hand preference occurred more often among fullterm infants. Asymmetrical gait seemed to correlate with head-turning in preterm infants.

Functional Laterality↗
PubMed1987

Effect of body position on later postural and functional lateralities of preterm infants.

The effects of body position during the neonatal period on subsequent functional and postural behaviours were examined in relatively low-risk preterm infants. 44 infants were nursed in the supine position and 37 in a prone position throughout their admission period. Persistent head-turning to the right was observed more often and continued longer in the infants lying in supine. Asymmetrical postures, e.g. of skull and trunk, were more often seen in infants lying in supine than in prone. The prone position was thought to help prevent infantile scoliosis. At nine months, preference for the right hand was more marked in infants lying in supine, whereas infants lying in prone used their hands bilaterally, a tendency that persisted at 18 months. Asymmetrical gait pattern with mild gait disturbance was found more often in infants lying in supine than in prone. The prone position was thought to prevent asymmetrical posture and excessive functional asymmetries.

Child Development↗
PubMed1996

On the magnitude of laterality effects and sex differences in functional lateralities.

In the last 20 years, the hypothesis that men and women differ in functional lateralities has been used to account for sex-related differences in verbal and spatial skills. However, this hypothesis has not been clearly supported, with some reviewers confirming it (McGlone, 1980 for example), and others rejecting it (Fairweather, 1982 for example). The purpose of the present study was to provide a definite test of this hypothesis and to estimate the magnitude of overall laterality effects by means of a meta-analytic procedure. A total of 396 significance levels from a variety of studies on functional asymmetries utilising auditory, visual, or tactile presentation of verbal or nonverbal stimuli were sampled. Results showed that laterality effects tend to be large and significant but that they are heterogeneous in the visual modality. Homogeneity was generally achieved by a partition of the studies in terms of the specific task used. The results also showed sex differences to be significant in two modalities (visual and auditory). The data indicated the presence of sex differences in favour of men in functional asymmetries. However, it appears that the findings are not resistant to the file drawer problem. The results are discussed with regard to their implications for explanations of individual differences in cognitive abilities. The relation between functional lateralities and anatomical asymmetries is also discussed.

Journal Article↗
PubMed2006

White matter pathway asymmetry underlies functional lateralization.

Structural and functional asymmetry of the human brain has been well documented using techniques such as magnetic resonance imaging (MRI). However, asymmetry of underlying white matter connections is less well understood. We applied an MRI technique known as diffusion tensor tractography to reveal the morphology of the white matter in vivo by mapping directions of maximum water diffusion in brain tissue. White matter pathway asymmetry was investigated in a normalized image data set of 30 right-handed young healthy individuals. We identified, for the first time, a rightwardly asymmetric pathway connecting the posterior temporal lobe to the superior parietal lobule. This pathway may be related to auditory spatial attention and working memory for which there is evidence for a rightward laterality from functional imaging studies. Additional leftward asymmetries connecting the parietal and frontal lobes to the temporal lobe may be more closely related to laterality of language.

Adult↗
PubMed1992

Anatomical asymmetries and functional laterality.

Anatomical and functional asymmetries were measured using MRI and dichotic, visual field and hand performance laterality tasks in 104 normal right- and left-handed male and female adults. Comprehensive linear and area measures showed consistently larger brains when handedness and language laterality were in the same direction. Right-handers with left cerebral dominance for dichotic listening and left-handers with right cerebral dominance had larger structures. Hand performance was the strongest functional laterality related to anatomical asymmetries. Left hemisphere dominance on this task was associated with larger right frontal and left occipital widths. Dichotic listening or visual field laterality alone was not associated with contralaterally larger temporal, parietal or occipital measurements. Left visual field dominance for reading, interacting with right-handedness, was associated with wider left parietal width. The complex associations between anatomical and functional asymmetries contribute to individual differences in cerebral organization. The demonstrated association of coincident hand performance and language laterality measures with larger anatomical structures may confer biological advantage. Morphometric analysis in vivo may have increasing importance in interpreting behaviour.

Adult↗
PubMed2007

Minimally invasive video-assisted functional lateral neck dissection for metastatic papillary thyroid carcinoma.

Functional lateral neck dissection requires a large incision providing adequate exposure of the surgical field. We evaluated the feasibility of minimally invasive video-assisted functional lateral neck dissection (VALNED) in patients with papillary thyroid carcinoma (PTC). Low-risk PTC patients with lateral neck metastases <2 cm, in absence of any evidence of great vessels involvement, were considered eligible. After accomplishing total thyroidectomy and central neck clearance, dissection was performed under endoscopic vision by using a technique very similar to conventional surgery through the single 4-cm skin incision used for thyroidectomy. Two patients were selected: 1 underwent bilateral and 1 unilateral VALNED. The mean number of the removed nodes was 25 per side. Both patients experienced transient postoperative hypocalcemia. No other complication occurred. No evidence of residual or recurrent disease was found at follow-up. VALNED is feasible, and the results are encouraging. For definitive conclusions, larger series and comparative studies are necessary.

Adenocarcinoma, Papillary↗
PubMed1996

Functional lateralization of speech production at primary motor cortex: a fMRI study.

To evaluate lateralization of speech production at the level of the Rolandic cortex, functional magnetic resonance imaging (1.5 Tesla, 27 parallel axial slices, EPI-technique) was performed during a speech task (continuous silent recitation of the names of the months of the year). As control conditions, non-speech tongue movements and silent singing of a well-known melody with the syllable 'la' as its carrier were considered. Tongue movements produced symmetrical activation at the lower primary motor cortex. During automatic speech a strong functional lateralization to the left hemisphere emerged within the same area. In contrast, singing yielded a predominant right-sided activation of the Rolandic region. Functional lateralization of speech production therefore seems to include the precentral gyrus as well as Broca's area.

Adult↗
PubMed2003

Lateral functional shift of the mandible: Part I. Effects on condylar cartilage thickness and proliferation.

Lateral functional shift of the mandible is characterized by transverse rotation of the entire mandible about a vertical axis toward 1 side of the head. The effect of this shift is that the condyle on the side opposite the direction of the shift is displaced anteriorly, or protruded, while the condyle on the side toward the shift is more stable positionally and is likely to be slightly retruded. According to the view that growth of the mandibular condylar cartilage (MCC) adapts to its local functional-biomechanical environment, differential changes in metabolic activity of the MCC would be expected on the nonprotruded and the protruded sides. To evaluate this hypothesis, 21 rats (28 days old) were fitted with intraoral positioners designed to shift the mandibular postural position asymmetrically. Cartilage thickness and BrdU labeling index in the MCC 3, 7, and 14 days after placement of the positioners were compared with those in age-matched controls that received no positioners. Cartilage thickness in the MCC on the protruded side was significantly greater than that in the controls at each time interval, with the difference increasing slightly with time. The labeling index for the protruded MCC was significantly greater than the controls at both 7 and 14 days after positioner placement. Trends on the nonprotruded side were generally opposite, culminating in reduced thickness and proliferation after 14 days. Thickness and labeling index were greater on the protruded side at every time interval except 3 days (labeling index). These trends in cartilage thickness and proliferation are consistent with previous studies of MCC changes after bilateral functional protrusion or retrusion. These data suggest that changes in MCC thickness and proliferative activity might accompany a lateral functional shift of the mandible in growing persons.

Analysis of Variance↗
PubMed1996

Functional lateralization of the prefrontal cortex during traditional frontal lobe tasks.

We attempted to identify brain regions functionally lateralized during cognitive tasks traditionally linked to the prefrontal cortex (PFC) by measuring regional cerebral blood flow with H2(15)O positron emission tomography (PET). Fourteen normal subjects were scanned six times while performing six different cognitive conditions comprising three task paradigms putatively sensitive to PFC integrity: the Wisconsin Card Sort (WCS), Delayed Response Alternation (DA), and the Spatial Delayed Response (SDR) Tasks, and three matched sensorimotor control tasks. Multivariate and repeated measures analyses indicated that for all three cognitive paradigms there were no significant hemisphere, hemisphere-by-condition, or hemisphere-by-region effects. However, with more liberal statistical comparison (paired t tests), the superior frontal gyrus showed lateralization during both the WCS and SDR tasks (both R > L). These results suggest that, although some asymmetries may be found using liberal analyses, there is less evidence of lateralized brain function during performance of these tasks of PFC function, than in language and motor systems. Implications for testing PFC function in neuropsychiatric groups are discussed.

Adult↗
PubMed2006

Sex influences on material-sensitive functional lateralization in working and episodic memory: men and women are not all that different.

Research investigating the effects of sex on the lateralization of language functions has produced mixed results to date, with some studies finding sex differences and others not [Shaywitz, B.A., Shaywitz, S.E., Pugh, K.R., Constable, R.T., Skudlarski, P., Fulbright, R.K., Bronen, R.A., Fletcher, J.M., Shankweiler, D.P., Katz, L., et al., 1995. Sex differences in the functional organization of the brain for language. Nature 373 607-609.; Frost, J.A., Binder, J.R., Springer, J.A., Hammeke, T.A., Bellgowan, P.S., Rao, S.M., Cox, R.W., 1999. Language processing is strongly left lateralized in both sexes. Evidence from functional MRI. Brain 122 (Pt 2) 199-208.]. Further, few studies have evaluated how any such sex effects extend to tasks involving cognitive functions that may utilize language processes such as working and episodic memory. This study examined sex difference in material-sensitive functional activation (using fMRI) in working memory and episodic memory that included either words and faces. We performed these analyses on two large groups of healthy subjects with the goal of attempting to replicate results across two independent data sets. The results indicated that both males and females showed strong and consistent evidence for material-sensitive lateralization for both working and episodic memory, such that word tasks resulted in greater left-sided activation and face tasks resulted in greater right-sided activation. Further, few of the sex differences in regions showing material specificity effects in at least one gender replicated across studies, providing little evidence for any differences in lateralization patterns between the sexes. In conclusion, our data suggest that males and females show a similar pattern of lateralized activation to material type during working memory and recognition tasks.

Adult↗
PubMed1993

Functional lateralization of the perception of Norwegian word tones--evidence from a dichotic listening experiment.

The present paper addresses the question of the functional lateralization of the ability to perceive the tonal distinctions in tone languages. Dichotic listening experiments and investigations of the brain-damaged population have indicated that the left hemisphere is more active than the right in the perception of tone in East Asian tone languages like Mandarin Chinese and Thai. Two dichotic listening experiments involving speakers of Norwegian, a language with an opposition of two tones, have demonstrated a right-ear superiority in the perception of the tonal distinction, indicating left-hemisphere lateralization of the ability to perceive tonal distinctions in Norwegian as well as in the East Asian tone languages that have been previously investigated.

Brain↗