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PubMed2001

Tooth eruption symmetry in functional lateralities.

Dental casts and oral photographs from a cross-sectional sample of 2092 young North Americans with detailed information on functional lateralities (eyedness, handedness and footedness) were examined to compare the proportions of symmetrical and asymmetrical eruption of the antimeric (left-right, contralateral pair) permanent teeth using a four-grade eruption scale. The proportion of symmetrically erupting antimeric teeth was higher for some teeth in those with non-right-sidedness of the feet and eyes, but not significantly so in the case of handedness. Left-footedness was significantly (95% confidence interval) associated with an increased proportion of symmetrical pairs of the maxillary first molar and mandibular lateral incisor, and non-right-eyedness with an increased proportion of symmetrical eruption and left/right non-balanced proportions of asymmetrical eruption in maxillary central incisors. True right-sidedness (hand, foot and eye) was significantly (P< or =0.05) associated with advanced eruption of the left mandibular first molar. It is suggested that while the timing of antimeric tooth emergence and clinical eruption is primarily programmed before crown mineralization, starting approximately at the 30th gestational week in the case of first permanent molars, symmetrical/asymmetrical tooth emergence and eruption may provide information a posteriori on prenatal and early postnatal growth and development.

Body Patterning↗
PubMed1997

Measurement of plantar pressure distribution during gait for diagnosis of functional lateral ankle instability.

INTRODUCTION:: Chronic functional instability of the lateral ankle may be difficult to distinguish from mechanical instability when radiological stress tests reveal only small ligamentous defects. For decision making whether to surgically reconstruct the ligaments or not, it can be helpful to use additional information on joint and foot function. Therefore, the aim of a prospective study of patients with longstanding chronic ankle instability was to demonstrate that the dynamic measurement of plantar pressure distribution can identify patients with functional ankle instability. [Table: see text] MATERIALS AND METHODS:: Sixty five patients (mean age 24 (4.6 years)) were included. After clinical examination and radiological stress views, plantar pressure patterns were measured during gait using a capacitive platform, the EMED-SF 2-system. Five trials of each foot were documented and the maximum impulses in eight points of the foot (central heel, lateral and medial heel, midfoot, 1st, 2nd, 5th metatarsal head and hallux) were calculated intraindividually and compared with a group of 100 healthy subjects. The medio-lateral loading factor (MLF) as the quotient of the medial and lateral relative impulses indicated the tendency to walk on the lateral edge of the foot. RESULTS:: Based on clinical criteria alone, two comparable groups of patients were separated, 35 with functional instability and 30 with mechanical instability. After collective analyses of the results, the patients with functional instability showed a significantly increased lateral loading of the unstable foot (p=0 0 1), whereas the mechanically unstable group tended to walk more on the medial side of the unstable foot (Table 1). DISCUSSION:: Dynamic measurement of plantar pressure can identify a group of patients walking on the lateral side of the unstable foot when compared with the stable foot. This finding is explained by a deficit of peroneal strength during stance phase based on a proprioceptive defect after trauma. The new application of the EMED-system provides additional information which helps to make decisions about the individual patient with chronic instability.

Journal Article↗
PubMed2005

Exposure of postnatal rats to a static magnetic field of 0.14 T influences functional laterality of the hippocampal high-affinity choline uptake system in adulthood; in vitro test with magnetic nanoparticles.

Our previous experiments indicated an age- and sex-dependent functional lateralization of a high-affinity choline uptake system in hippocampi of Wistar rats. The system is connected with acetylcholine synthesis and also plays a role in spatial navigation. The current study demonstrates that a single in vivo exposure of 7- or 14-day-old males to a static magnetic field of 0.14 T for 60-120 min evokes asymmetric alterations in the activity of carriers in adulthood. Namely, the negative field (antiparallel orientation with a vertical component of the geomagnetic field) mediated a more marked decrease in the right hippocampus. The positive field (parallel orientation) was ineffective. Moreover, differences between the carriers from the right and the left hippocampi were observed on synaptosomes pretreated with superparamagnetic nanoparticles and exposed for 30 min in vitro. The positive field enhanced more markedly the activity of carriers from the right hippocampus, the negative that from the left hippocampus, on the contrary. Our results demonstrate functionally teratogenic risks of the alterations in the orientation of the strong static magnetic field for postnatal brain development and suggest functional specialization of both hippocampi in rats. Choline carriers could be involved as secondary receptors in magnetoreception through direct effects of geomagnetic field on intracellular magnetite crystals and nanoparticles applied in vivo should be a useful tool to evaluate magnetoreception in future research.

Aging↗
PubMed1987

Lateralized functional relationship between the preoptic area and lateral hypothalamic reinforcement.

Electrical self-stimulation in the lateral hypothalamus of both hemispheres was recorded in 14 rats before and after administration of a unilateral ibotenic acid lesion of the cell bodies in the region of the lateral preoptic area. A significant decrease in the rate of self-stimulation at each of two stimulation intensities was found when the electrode was placed in the hemisphere in which the ibotenic acid lesion was made. This decrease remained constant over 21 days of testing. No changes were detected in rate of self-stimulation in the intact contralateral hemisphere. These results provide evidence for a role in lateral hypothalamic self-stimulation of intrinsic neurons located in the region of the lateral preoptic area.

Animals↗
PubMed2004

Unilateral Angle II in functional lateralities.

The aim of this study was to explore unilateral Angle II-type malocclusion prevalences in functionally true right-sided (TRS) and non-right-sided (NRS) children having one or more left-sided functions (eye, hand, foot). A half cusp sagittal relationship of the upper and lower M1 and Dm2 was determined on dental casts of 1423 young American black and white children in a cross-sectional sample with the mean age of 8.5 years (range 6-12 years). Hand, foot and eye preferences were recorded at the age of 4 years during the Collaborative Perinatal Study. The prevalences of symmetric bilateral Angle I and II and asymmetric unilateral Angle II right and Angle II left cases were compared between TRS and NRS children using Chi-square analysis. In general, unilateral Angle II right occurred in 9 per cent of the population and Angle II left in 6.5 per cent. In moderate non-right sideness (two-thirds of left dominant functions), these proportions were 17 and 3 per cent, respectively, and in true right sidedness 8 and 6 per cent, respectively. TRS subjects were more symmetric (bilateral Angle I or II in 85 per cent of cases) than NRS children (80 per cent), and the differences were statistically significant (P < 0.02). These results highlight the anatomical relationships of structures supporting the occlusion and the symmetry/asymmetry of the neurocranium, cranial base, masticatory apparatus, and probably also the sidedness and the growth-stimulating effect of lateralized jaw function. Based on the results and considering earlier observations on brain asymmetry in functional lateralities, it can be hypothesized that a normal symmetric sagittal occlusal relationship is based on unilateral sagittal compensatory growth to maintain optimal bite, challenging early preventive orthodontic treatment in suspect unilateral Angle II cases.

Black People↗
PubMed1997

Differential contributions of the two visual pathways to functional lateralization in chicks.

The contribution of the two visual pathways to lateralization of visual behaviour in chicks was assessed using unilateral injections of 0.5 microliters of 100 mM monosodium glutamate into localized regions of the forebrain. Chicks treated with glutamate in the left visual hyperstriatum made more errors in a visual discrimination task (pebble-floor test) than did chicks treated in the right visual hyperstriatum. Glutamate injection into the left visual hyperstriatum also elevated attack and copulation scores, but this did not occur following injection of the right visual hyperstriatum. The performance of chicks treated in the right visual hyperstriatum did not differ from that of sham-operated controls. Thus, only the left visual hyperstriatum is involved in the control of these three visually guided behaviours. By contrast, glutamate injections of the left ectostriatum affected only the attack behavior and not performance in the pebble-floor test or copulation responses. Glutamate treatment of the right ectostriatum had no affect on any of the behaviours tested and this was also the case for glutamate treatment of both the left and right neostriata. Although injecting glutamate in a larger volume that allows glutamate to spread over a wide area of the left hemisphere is known to retard auditory habituation, localized injection of glutamate in the areas chosen for this study had no effect on auditory habituation. The results suggest that the tectofugal and thalamofugal pathways have different roles in the lateralization of visual functions. The forebrain region which receives input from the thalamofugal visual system has a lateralized role in categorising pebbles as different from food grains, and also a role in controlling attack and copulation responses. The forebrain region which receives input from the tectofugal visual system is involved in the control of attack responses only.

Agonistic Behavior↗
PubMed1990

Light input and the reversal of functional lateralization in the chicken brain.

During its later stages of development, the chicken embryo is oriented in the egg so that it occludes its left eye with its body and the right eye is positioned so that it can receive light input. This lateralized light input has been shown to play a decisive role in determining the direction of brain lateralization for two behavioural functions, copulation and performance of a visual discrimination task known as the 'pebble floor test', since the direction of lateralization for these functions can be reversed by occluding the right eye of the embryo on day 19/20 of incubation and at the same time exposing the left eye to light. The sensitive period during which this role of lateralized light input influences the lateralization for copulation extends to day 1 posthatching if the eggs are incubated and hatched in darkness, but it is over by day 3. For the pebble floor test the sensitive period is already over by day 1 posthatching. By exposing eggs to light for various times on day 19 of incubation, it was possible to determine that between 2.5 and 6 h of lateralized light exposure is necessary to stabilise the normal direction of lateralization so that it can no longer be reversed by occlusion of the right eye. Thus, in the developing chicken embryo substantial neural reorganization must occur in response to a brief period of lateralized light input.

Animals↗
PubMed1999

Human taste cortical areas studied with functional magnetic resonance imaging: evidence of functional lateralization related to handedness.

Whole-brain functional magnetic resonance imaging was used to detect local hemodynamic changes reflecting cortical activation in five left handed and five right handed human subjects during bilateral stimulation of the tongue with various tastes. Activation was found bilaterally in the insula and the perisylvian region. These regions correspond to the primary taste cortical areas identified with electrophysiological recordings in monkeys and suggested from former clinical observations in human subjects. Moreover, a unilateral projection was described for the first time in the inferior part of the insula of the dominant hemisphere, according to the subject's handedness.

Adult↗
PubMed1980

Functional lateralization of the chicken forebrain revealed by use of intracranial glutamate.

By injecting monosodium L-glutamate into either one of the forebrain hemispheres of the developing chicken brain and examining the behavioural effects which ensue, it has been possible to demonstrate that there is functional lateralization for control of a number of behaviours. Glutamate treatment of the left hemisphere retards visual discrimination learning and auditory habituation, as does glutamate treatment of both hemispheres, but treatment of the right hemisphere is without effect on these behaviours. An imbalance generated by administering glutamate to the left hemisphere causes a marked increase in aggressive and sexual behaviour, which does not occur either after treatment of both hemispheres or treatment of the right hemisphere. A preliminary study on the distribution of radioactive glutamate is also reported.

Aggression↗
PubMed2006

Lateralized functional components of spatial cognition in the avian hippocampal formation: evidence from single-unit recordings in freely moving homing pigeons.

Previous research has revealed that the functional components of spatial cognition are lateralized in the forebrain of birds, including the hippocampal formation (HF). To investigate how HF cells in the left and right avian brain may differentially participate in representations of space, we recorded single-units from the HF of homing pigeons as they ran a plus maze for food. The rate maps of left HF cells often displayed elongated regions of increased activity in the center of the maze and along the maze corridors, whereas right HF cells tended to display patches at the ends of maze arms at/near goal locations. Left HF cells displayed a higher degree of spatial-specificity compared with right HF cells, including higher patch-specificity, higher reliability, and a higher incidence of location-correlated activity. Analysis of speed-correlated and trajectory-dependent activity also revealed significant HF-lateralized differences. Right HF cells tended to display significant negative correlations between spike rate and speed, although speed-dependent rate maps indicate that this relationship did not explain their space-specific activity. Left HF cells displayed a significantly higher incidence of trajectory-dependent space-specific activity than was observed in the right HF, suggesting that left HF cells may participate in navigating among goal locations. Differences in the correlates of left and right pigeon HF cells are consistent with unilateral HF-lesion data suggesting that the functional components of spatial cognition are lateralized in the avian brain, and furthermore, provide a basis for hypotheses regarding how the left and right HF support different aspects of spatial cognition.

Animals↗
PubMed2003

Lateral functional shift of the mandible: Part II. Effects on gene expression in condylar cartilage.

There is considerable evidence that proliferation and growth in the mandibular condylar cartilage (MCC) might be altered after a change in the postural position of the mandible. However, almost nothing is known about the molecular basis of this response. Using semiquantitative reverse-transcription polymerase chain reaction, we examined the expression of insulin-like growth factor-1 (Igf-1), fibroblast growth factor-2 (Fgf-2), and their receptors (Igf-1r, Fgfr1, Fgfr2, and Fgfr3) in the MCC of 28 day-old rats at 3, 7, and 14 days after placing intraoral appliances designed to produce a lateral functional shift of the mandible. This shift resulted in a transverse rotation of the mandible so that the condyle on the side away from the shift was distracted anteriorly (ie, protruded) from the glenoid fossa, while the contralateral condyle remained in place or moved slightly posteriorly (ie, nonprotruded). Gene expression for 5 of the 6 genes studied was significantly different (P <.05) between the protruded and the nonprotruded sides. In nearly every instance at the 3- and 7-day intervals, mRNA expression on the protruded side compared with age-matched controls was altered in the opposite direction from the nonprotruded side. Especially on the protruded side, the most pronounced differences from the control were evident at 3 and 7 days. In general, the changes in gene expression preceded the alterations in proliferative activity documented previously. These data suggest that alterations in the mRNA expression of Igf-1, Fgf-2, and their receptors might underlie in part changes in MCC proliferative activity after alteration in mandibular posture.

Animals↗
PubMed2006

Positive symptoms and duration of illness predict functional laterality and attention modulation in schizophrenia.

OBJECTIVE: Dichotic listening (DL) performance in schizophrenia, reflecting hemispheric asymmetry and the functional integrity of the left temporal lobe, can vary with clinical characteristics. Previous studies have not taken the co-linearity of clinical variables into account. The aim of the present study was to evaluate the roles of positive symptoms and duration of illness in DL through Structural Equation Modeling (SEM), thus allowing for complex relationships between the variables. METHOD: We pooled patients from four previous DL studies to create a heterogeneous group of 129 schizophrenic patients, all tested with a consonant-vowel syllables DL procedure that included attentional instructions. RESULTS: A model where positive symptoms predicted a laterality component and duration of illness predicted an attention component in DL was confirmed. CONCLUSION: Positive symptoms predicted reduced functional laterality, suggesting involvement of left temporal lobe language processing. Duration of illness predicted impaired attention modulation, possibly reflecting the involvement of frontotemporal networks.

Adolescent↗
PubMedDate not supplied

Primary dentition unilateral crossbite in relation to functional lateralities.

PURPOSE: The aim of this study was to explore primary dentition unilateral crossbite malocclusion prevalences in functionally true right-sided and nonright-sided children, with the latter having 1 or more left-sided or indeterminate functions (eye, hand, foot). METHODS: The transversal relationship of the primary teeth was determined from dental casts of 1,835 young African American (60%) and Caucasian (40%) children in a cross-sectional sample at a mean age of 8.5 years. Hand, foot, and eye preferences (right, left, or indeterminate) were recorded at the age of 4 years during the same collaborative perinatal study. The prevalences of left and right crossbites were compared between true right-sided and mixed or completely nonright-sided children using chi-square analysis. RESULTS: Unilateral crossbite occurred in 140 cases with a complete set of laterality tests: 65 were right-sided and 75 left-sided. True right-sided children had more bilaterally symmetric occlusions and less crossbite on the right side than those having nonright-sidedness in their functions, with the differences being statistically significant (P<.01). CONCLUSIONS: These results point to anatomical relationships between the structures supporting the occlusion, the asymmetric neurocranium, and the cranial base. This suggests variable unilateral compensatory growth after unbalanced fetal asymmetry, modified by sidedness and the growth-stimulating effects of early lateralized functions and oral habits.

Adolescent↗
PubMed1998

Functional lateralization of human gustatory cortex related to handedness disclosed by fMRI study.

Ten healthy subjects aged 20-25 including five right-handed and five left-handed according to the Dellatolas test participated in this functional magnetic resonance imaging (fMRI) study. A 3 Tesla whole-body MR scanner allowed echo planar imaging (EPI)-64 x 64 pixels, repetition time (TR) = 6 s, field of view (FOV) = 20 x 20 cm2--associated to acute anatomical localization of activated foci (256 x 256 pixels). Subjects were bilaterally stimulated with NaCl 85 mM, aspartame 2 mM, quinine hydrochloride 1 mM, glycyrrhizic acid 0.5 mM, guanosine monophosphate 1 mM and D-threonine 250 mM alternating with water. Stimuli and rinse were continuously pushed as bolus of 50 microliters every 3 s to the subject's mouth through microsyringes. We detected brain activated areas by correlation of the MR signal to an on-line perception profile recorded for each experiment and each subject with the finger-span method. We found most activations in the insula and the perisylvian region in agreement with previous electrophysiological studies on monkeys and clinical reports in humans. The superior part of the insula was bilaterally activated, in accordance with a whole-mouth stimulation. A striking lateralization related to handedness was found in a lower part of the insula. This projection in the dominant hemisphere, located in the same coronal plane as the upper insular activation, is the first evidence of a functional lateralization of brain processing involved in taste perception.

Adult↗
PubMed1997

Abnormal functional lateralization of the sensorimotor cortex in patients with schizophrenia.

Previous neuroimaging studies have suggested that patients with schizophrenia fail to recruit appropriate focal patterns of cortical responses to cognitive tasks. We investigated whether patients with schizophrenia show a normal focal response to a simple motor task. Seven strongly right-handed patients with schizophrenia and seven strongly right-handed normal subjects performed motor tasks of increasing complexity. Patients were unable to recruit as focal a response even to a simple, automatic sequential finger movement task. They showed greater ipsilateral activation in the primary sensorimotor and lateral premotor regions and had a significantly lower laterality quotient than normal subjects. These phenomena increased with the complexity of the task. These results demonstrate a functional disturbance in the cortical motor circuitry of patients with schizophrenia.

Adult↗
PubMed2004

Functional lateralization of the sensorimotor cortex in patients with schizophrenia: effects of treatment with olanzapine.

BACKGROUND: Earlier cross-sectional studies with functional magnetic resonance imaging (fMRI) in treated patients with schizophrenia have reported abnormalities of cortical motor processing, including reduced lateralization of primary sensory motor cortex. The objective of the present longitudinal study was to evaluate whether such cortical abnormalities represent state or trait phenomena of the disorder. METHODS: Seventeen acutely ill, previously untreated patients were studied after 4 weeks and after 8 weeks of olanzapine therapy. Seventeen matched healthy subjects served as control subjects. All subjects underwent two fMRI scans 4 weeks apart during a visually paced motor task using a simple periodic block design. Functional magnetic resonance imaging data were analyzed in Statistical Parametric Mapping (SPM99). Region of interest analyses were used to determine a laterality quotient (an index of lateralization) of motor cortical regions. RESULTS: The fMRI data indicated that patients had reduced activation of the primary sensory motor cortex at 4 weeks but not at 8 weeks; however, the laterality quotient in the primary sensory motor cortex was reduced in patients at both time points. CONCLUSIONS: These results suggest that some cortical abnormalities during motor processing represent state phenomena, whereas reduced functional lateralization of the primary sensory motor cortex represents an enduring trait of schizophrenia.

Adolescent↗