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PubMed2004

Choosing sides: lateralization in line trisection and quadrisection as a function of reading direction and handedness.

It might be intuited that a person's reading direction will impact linguistic and/or oculomotor tasks. Whether it also influences nonlanguage tasks, and by what means, is less clear. A novel technique to probe this effect is introduced in this paper, and the affirmative results are presented. The line bisection task has been a standard bedside diagnostic technique for assessing hemifield spatial neglect for many years. In recent years, numerous studies have also examined how normal subjects perform on this task. A recent line of study has focused on the reading habits of the subjects and the effect it has on line bisection. Most European languages are read from left to right, and it is thus postulated that readers of those languages will scan a line from left to right. On the other hand, Hebrew is read from right to left. These previous studies have yielded intriguing results about the role that reading direction plays in nonlanguage tasks. The present study utilized two other line partition tasks, line trisection and line quadrisection, and subjects whose principal reading language was either right-to-left or left-to-right. These tasks are ambiguous when used without instructing the subject on which side to perform the line transection. It was found that principal language was correlated with the side on which the subject chose to trisect or quadrisect the line. However, there was no correlation between preferred side and writing hand and there was no significant difference in accuracy between the preferred side and the secondary side. Thus, the preferred side in this nonlanguage task does not seem to be influenced by writing hand or accuracy but rather would seem to depend exclusively upon the earliest legitimate point, as determined by reading direction.

Adult↗
PubMed1990

Laterality of cerebral controls on somatic and autonomic functions.

The mode of cerebral representation for each half of the body is various according to the functions that are represented; contralateral, ipsilateral and bilateral. We reviewed, and discussed the meaning of, such different patterns of cerebral representation for somatic and autonomic functions.

Autonomic Nervous System↗
PubMed1992

Compound functioning free muscle flap transplantation (lateral half of soleus, fibula, and skin flap).

The functioning free-muscle transfer is a microneurovascular technique that has proven effective for patients who have a major muscle or muscle group loss for which no other less complicated procedures are available. A new functioning muscle (lateral half of the soleus) transfer was used for forearm reconstruction. This functioning muscle can be transferred alone, or it can be used with overlying skin or nearby fibular bone or both. It was used in a selective complicated case in which not only were major functional muscles lost, but a bone deficiency and skin loss also were seen. The operation was done in one stage with the composite flap (muscle plus bone plus skin). The recovered transferred muscle provided adequate strength and excursion for a functional hand and forearm.

Adolescent↗
PubMed2002

Models of functional organization of the lateral prefrontal cortex in verbal working memory: evidence in favor of the process model.

Research on the functional organization of the lateral prefrontal cortex (PFC) in working memory continues to be fairly equivocal between two major frameworks: organization-by-process or organization-by-material. Although there is fairly strong evidence for organization-by-process models from event-related fMRI studies, some investigators argue that the nature of the stimulus material better defines the functional organization of the lateral PFC, particularly in more ventral regions (BA 47/45/44). Specifically, the anterior region of the ventrolateral PFC (BA 47/45) is hypothesized to subserve semantic processing while the posterior region (BA 44) may subserve phonological processing. In the current event-related fMRI study, we directly compared process-related versus material-related organizational principles in a verbal working memory task. Subjects performed a modified delayed response task in which they (1) retained a list of five words or five nonwords during the delay period ("maintenance"), or (2) performed a semantic (size reordering) or phonological (alphabetical reordering) task on the word or nonword lists, respectively ("manipulation"). We did not find evidence during the delay period of our task to support claims of anterior-posterior specializations in the ventrolateral PFC for semantic versus phonological processing. Subjects did, however, display greater neuronal activity during the delay period of manipulation trials than maintenance trials in both the dorsolateral PFC and posterior ventrolateral regions. These data are more consistent with the process model of the organization of lateral PFC in verbal working memory.

Adolescent↗
PubMed1990

Functional compensation in the lateral suprasylvian visual area following bilateral visual cortex damage in kittens.

Previous studies have shown that functional compensation is present in the cat's posteromedial lateral suprasylvian (PMLS) area of cortex after damage to areas 17, 18, and 19 (visual cortex) early in life but not after damage in adults. These studies all have investigated animals with a unilateral visual cortex lesion, whereas all behavioral studies of compensation for early visual cortex damage have investigated animals with a bilateral lesion. In the present experiment, we investigated whether functional compensation also is present in PMLS cortex after a bilateral visual cortex lesion early in life. We recorded from single neurons in the PMLS cortex of adult cats that had received a bilateral lesion of areas 17, 18, and 19 on the day of birth or at 8 weeks of age. We found that PMLS cells in both groups of cats had functional compensation (normal direction selectivity and ocular dominance) similar to that seen after a unilateral lesion at the same ages. These results are consistent with the hypothesis that PMLS cortex is involved in the behavioral compensation seen after early visual cortex damage. In addition, the results indicate that inputs from contralateral visual cortex are not necessary for the development of functional compensation seen in PMLS cortex.

Age Factors↗
PubMed1990

[Vertical changes in the lateral teleroentgenographic image after functional orthodontic therapy].

We looked for vertical changes in lateral cephalometric X-rays of patients who had been treated with Andresen and Häupl appliances to correct distal occlusion. Thus, a therapy using functional appliances for orthodontic correction has the following effects on the vertical proportions of the visceral cranium. 1. The alveolar processes show additional vertical growth in the area of the incisors of the upper jaw and the molars of the lower jaw. 2. In conjunction with 1, increased vertical growth of the anterior facial heights compared to the posterior facial height causes an opening of the bite which, however, is not significant in terms of the Jarabak ratio. 3. Functional therapy has an effect on the spina plane, and, in addition, causes active vertical growth in the area of both upper facial heights, i.e., of the entire nasomaxillary complex. This additional growth is a little bit more pronounced anteriorly than posteriorly. Therefore the effect of functional orthodontic appliances on the nasomaxillary complex seems to be more complex than previously believed. 4. We did not observe any additional growth in the area of the ascending rami and/or condyles of the lower jaw during activator treatment. Our studies showed that the influence of functional orthodontic therapy on the vertical growth of the lower jaw is rather insignificant; the significant vertical changes were seen in the area of the mandibular molars and of the anterior facial heights. 5. Our findings thus support the assumption that the main vertical effect of the activator can be described as a relative inhibition of the development of the nasomaxillary complex with simultaneous normal progression of mandibular growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Activator Appliances↗
PubMed2003

Motor-related functional subdivisions of human lateral premotor cortex: epicortical recording in conditional visuomotor task.

OBJECTIVE: To clarify the functional subdivisions of the human lateral premotor cortex (PM) in the visuomotor control. METHODS: Event-related potentials (ERPs) were epicortically recorded from PM in 5 epilepsy patients. S1-Go/NoGo choice delayed reaction time (RT), S1-warned S2-Go simple RT and control fixation paradigms were compared using paired visual stimuli (S1, S2). RESULTS: Signal-related activity peaked at 176-194 ms after S1 in the ventrorostral PM (PMvr) in all 3 paradigms, indicating its role in signal perception. Early set-related activity was recorded with its peak <810 ms after S1 in the dorsorostral PM (PMdr) and was larger in the choice than in the simple RT paradigm, suggesting its role in signal selection. Its cognitive component was recorded as surface-positive transients at PMdr, while its motoric aspect, seen as negative transients, extended to the caudal PM. Late sustained set-related activity was observed in preparation for hand movement in the caudal PM at the hand and face positive motor areas. After presentation of S2, movement-related activity was observed at the hand sensorimotor area for motor execution, following the signal-related activity at PMvr. CONCLUSIONS: The present ERP study suggests the temporally sequential representation of predominantly 'cognitive' function in the rostral PM and 'motor' function in the caudal PM. SIGNIFICANCE: The rostrocaudal cognitive-motor gradient was demonstrated in the lateral premotor cortex in humans by means of an epicortical ERP approach.

Adolescent↗
PubMed1989

Octopamine modulates photoreceptor function in the Limulus lateral eye.

Activity at night in efferent nerve fibers from a central circadian clock produces changes in photoreceptor function in the lateral compound eye of Limulus: the response to light is increased; membrane potential fluctuations (bumps) occurring in the dark are suppressed; and the duration of bumps occurring both in the dark and under dim illumination is increased (Barlow et al., 1977; Kaplan & Barlow, 1980; Barlow, 1983; Barlow et al., 1985). Efferent nerve terminals release octopamine when activated (Battelle et al., 1982; Battelle & Evans, 1984, 1986); exogenous octopamine in vitro produces some of the changes resulting from efferent nerve activity in vivo (Kass et al., 1988). We report here that the increase in both on-transient and steady-state response to light induced by octopamine in the lateral eye in vitro are concentration dependent with threshold at or below 100 nM, saturation at or above 100 microM, and half-maximal increase in the range 1-10 microM. Octopamine also reduces bump activity in the dark in a concentration-dependent way. Unlike the increase in light response, the dependence of this effect on octopamine concentration is extremely variable from specimen to specimen. The effects of exogenous octopamine on light response and bump activity can sometimes be reversed by removing octopamine from the medium bathing the in vitro preparation. Octopamine also increases bump duration, apparently in a concentration-dependent manner. We have not succeeded in reversing this increase in bump duration. The concentration dependence of changes in photoreceptor response described here agrees qualitatively with the dependence of cAMP levels on octopamine in Limulus photoreceptors (Kaupp et al., 1982), lending further support to the idea that cAMP acts as a second messenger in the circadian control of photoreceptor function. Our results also suggest that the changes induced in the transient and steady-state response to light by both efferent nerve activity and exogenous octopamine have a common origin, which may differ from that responsible for the modulation of bump activity.

Animals↗
PubMed2003

Lateralization of auditory-cortex functions.

In the present review, we summarize the most recent findings and current views about the structural and functional basis of human brain lateralization in the auditory modality. Main emphasis is given to hemodynamic and electromagnetic data of healthy adult participants with regard to music- vs. speech-sound encoding. Moreover, a selective set of behavioral dichotic-listening (DL) results and clinical findings (e.g., schizophrenia, dyslexia) are included. It is shown that human brain has a strong predisposition to process speech sounds in the left and music sounds in the right auditory cortex in the temporal lobe. Up to great extent, an auditory area located at the posterior end of the temporal lobe (called planum temporale [PT]) underlies this functional asymmetry. However, the predisposition is not bound to informational sound content but to rapid temporal information more common in speech than in music sounds. Finally, we obtain evidence for the vulnerability of the functional specialization of sound processing. These altered forms of lateralization may be caused by top-down and bottom-up effects inter- and intraindividually In other words, relatively small changes in acoustic sound features or in their familiarity may modify the degree in which the left vs. right auditory areas contribute to sound encoding.

Acoustic Stimulation↗
PubMed2003

Robust localization and lateralization of human language function: an optimized clinical functional magnetic resonance imaging protocol.

An optimized clinical functional magnetic resonance imaging (fMRI) protocol with a total scanning time of 8 min is presented that localizes Broca's and Wernicke's areas robustly and determines hemispheric dominance. Language function was visualized using two different sentence generation (SG) and word generation (WG) tasks. Block designed blood oxygenation level dependent (BOLD) fMRI was applied in 14 right-handed volunteers at 1.5 T during visual stimulation. BOLD-clusters were assessed individually for anatomical localization. Reference data are provided for the maximum correlation of the measured BOLD-signal time course to the applied reference function (r(max)), for the maximum relative signal change (dS%), cluster size and Euklidian coordinates of Broca and Wernicke activation and of the anatomical homologues in the right hemispheres. Statistical means and a lateralization index (LI) were calculated. Broca activation focussed on the inferior frontal gyrus, and Wernicke activation on the superior temporal, supramarginal or middle temporal gyri. Mean BOLD-signals for Broca ranged from 1.53% (SG) to 2.56% (WG), and for Wernicke from 1.47% (SG) to 1.80% (WG). LI indicated left language dominance. The data provided further evidence for the high anatomical variability of language areas, which underlined the relevance of an individual language localization and lateralization prior to brain surgery.

Adult↗
PubMed1983

The cholinergic influence on the function of the cat dorsal lateral geniculate nucleus (dLGN).

The functional influence of the cholinergic input to cat dLGN has been examined by assessing the action of iontophoretically applied acetylcholine (ACh) on the visual responses of cells in layers A and A1. Iontophoretically applied pulses of ACh exerted a strong excitatory action on all 113 cells studied within these layers. In the presence of a sustained application of ACh, the excitatory responses to an optimal stimulus such as a spot of light located within the receptive field centre were greatly facilitated, but at the same time stimulus-specific inhibitory influences were also enhanced. The action of ACh on the stimulus-specific inhibitory influences had the consequence that the responses to non-optimal stimuli were not facilitated to the same extent as those to optimal stimuli and in some cases even diminished. The stimulus-specific inhibitory effects seen in the presence of ACh were very powerful and frequently resulted in complete suppression of the elevated background discharge. We suggest that the ACh directly excites both the relay cells and the Golgi type II inhibitory interneurones within the dLGN. The facilitation of the stimulus-specific inhibition may follow from a direct action on the presynaptic dendrites of the Golgi type II cells which arborize within the dendritic field of the relay cell. Supplementary observations on cells in the perigeniculate nucleus confirm previous findings showing that ACh has an inhibitory effect on these cells. We suggest a tripartite action for the cholinergic influence on the dLGN, involving direct facilitation of relay cells, enhancement of stimulus-specific inhibition via the Golgi type II cells, and disinhibition of the non-specific inhibitory influence form the perigeniculate nucleus.

Acetylcholine↗
PubMedDate not supplied

Dual response modes in lateral geniculate neurons: mechanisms and functions.

Relay cells of the lateral geniculate nucleus, like those of other thalamic nuclei, manifest two distinct response modes, and these represent two very different forms of relay of information to cortex. When relatively hyperpolarized, these relay cells respond with a low threshold Ca2+ spike that triggers a brief burst of conventional action potentials. These cells switch to tonic mode when depolarized, since the low threshold Ca2+ spike, being voltage dependent, is inactivated at depolarized levels. In this mode they relay information with much more fidelity. This switch can occur under the influence of afferents from the visual cortex or parabrachial region of the brain stem. It has been previously suggested that the tonic mode is characteristic of the waking state while the burst mode signals an interruption of the geniculate relay during sleep. This review surveys the key properties of these two response modes and discusses the implications of new evidence that the burst mode may also occur in the waking animal.

Action Potentials↗
PubMed1998

The effects of the lateral position on cardiopulmonary function during laparoscopic urological surgery.

UNLABELLED: Laparoscopic urological surgery is usually performed transperitoneally with retroperitoneal insufflation of carbon dioxide (CO2) in the lateral position. We studied whether a difference in the side of lateral position affected hemodynamic and pulmonary functions during pneumoperitoneum. Fifteen patients (eight in the right and seven in the left lateral position) undergoing elective laparoscopic urological surgery were studied under general anesthesia. Hemodynamic variables and blood gas data were recorded. Before insufflation, mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), central venous pressure (CVP), and pulmonary capillary wedge pressure (PCWP) in the right lateral position were higher than those in the left lateral position. Pneumoperitoneum increased MAP, MPAP, CVP, PCWP, and cardiac index but decreased systemic vascular resistance in the right lateral position. Similar changes occurred during pneumoperitoneum in the left lateral position, but the changes were less than those in the right lateral position. The respiratory index (PaO2/PAO2), intrapulmonary shunt, and SpO2 did not change during pneumoperitoneum in either lateral position. Changing the side of the lateral position affected hemodynamic function but did not affect pulmonary oxygenation during pneumoperitoneum. IMPLICATIONS: The right and left lateral positions produced different hemodynamic changes during laparoscopic urological surgery. The increases in preload and cardiac index and the decrease in systemic vascular resistance were greater in the right than in the left lateral position. Respiratory changes were not affected differently between the right and left lateral positions.

Anesthesia, General↗
PubMed1990

The predictability of infant visual-evoked response testing on future visual acuity.

We reviewed the records of 27 infants with abnormal eye examinations and visual-evoked response (VER) testing (mean age, 10.5 months) who subsequently underwent a long-term follow-up ophthalmology examination (mean duration, 41 months). The infants were initially diagnosed with various ocular disorders including cortical blindness (eight), optic nerve hypoplasia (six), congenital cataract (two), and retinopathy of prematurity (one). Standard optotype visual-acuity determinations were available in the follow-up records of 11 children (21 eyes), and fixation behavior was obtained in the remaining 16 children (32 eyes). Results revealed that pattern-reversal VER P1 latency was predictive (87%) of whether visual acuity was equal to (or better than) or worse than 20/100 and whether a patient would have good fixation behavior (fix and follow, FF) or poor fixation (no FF) (86%) (P less than .001). Although flash VER P1 latency was also predictive of later visual acuity or good fixation (73%), it was not statistically significant. Pattern VER P1 amplitude and flash VER P1 amplitude were not predictive of later visual function. The predictive power of pattern VER P1 latency for later visual function probably relates to its reflection of macular function and low variability. An analysis of the variability of each of the four VER factors in normal infants (n = 50) indicated that pattern VER P1 latency was the least variable, and consequently most sensitive, VER factor for detecting and quantifying pathology. Overall, the results of this retrospective study suggest that pattern VER P1 latency may have important predictive power for later visual function in infants with an initially abnormal ophthalmologic examination.

Evoked Potentials, Visual↗
PubMed2002

Immobilisation and functional treatment for acute lateral ankle ligament injuries in adults.

BACKGROUND: Acute lateral ankle ligament injuries (ankle sprains) are common problems in acute medical care. The treatment variation observed for the acutely injured lateral ankle ligament complex suggests a lack of evidence-based management strategies for this problem. OBJECTIVES: The objective of this review was to assess the effectiveness of methods of immobilisation for acute lateral ankle ligament injuries and to compare immobilisation with functional treatment methods. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group specialised register (December 2001); the Cochrane Controlled Trials Register (The Cochrane Library, Issue 4, 2001), MEDLINE (1966-May 2000), EMBASE (1988-May 2000), reference lists of articles, and contacted organisations and researchers in the field. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials comparing either different types of immobilisation or immobilisation versus functional treatments for injuries to the lateral ligament complex of the ankle in adults were included. Trials which investigated the treatment of chronic instability or post-surgical treatment were excluded. DATA COLLECTION AND ANALYSIS: Data were independently extracted by two authors. Where appropriate, results of comparable studies were pooled using fixed effects models. Individual and pooled statistics were reported as relative risks with 95% confidence intervals for dichotomous outcomes and weighted (WMD) or standardised (SMD) mean differences and 95% confidence intervals for continuous outcome measures. Heterogeneity between trials was tested using a standard chi-squared test. MAIN RESULTS: Twenty-one trials involving 2184 participants were included. The mean validity score of the included trials increased from 9.1 (SD 3.0) to 10 (SD 2.9) after retrieving further information (maximum 18 points). Statistically significant differences in favour of functional treatment when compared with immobilisation were found for seven outcome measures: more patients returned to sport in the long term (relative risk (RR) 1.86, 95% confidence interval (CI) 1.22 to 2.86); the time taken to return to sport was shorter (WMD 4.88 (days), 95% CI 1.50 to 8.25); more patients had returned to work at short term follow-up (RR 5.75, 95% CI 1.01 to 32.71); the time taken to return to work was shorter (WMD 8.23 days, 95% CI 6.31 to 10.16); fewer patients suffered from persistent swelling at short term follow-up (RR 1.74, 95% CI 1.17 to 2.59); fewer patients suffered from objective instability as tested by stress X-ray (WMD 2.60, 95% CI 1.24 to 3.96); and patients treated functionally were more satisfied with their treatment (RR 1.83, 95% CI 1.09 to 3.07). A separate analysis of trials that scored 50 per cent or more in quality assessment found a similar result for time to return to work only (WMD (days) 12.89, 95% CI 7.10 to 18.67). No significant differences between varying types of immobilisation, immobilisation and physiotherapy or no treatment were found, apart from one trial where patients returned to work sooner after treatment with a soft cast. In all analyses performed, no results were significantly in favour of immobilisation. REVIEWER'S CONCLUSIONS: Functional treatment appears to be the favourable strategy for treating acute ankle sprains when compared with immobilisation. However, these results should be interpreted with caution, as most of the differences are not significant after exclusion of the low quality trials. Many trials were poorly reported and there was variety amongst the functional treatments evaluated.

Humans↗
PubMed1987

Relationship of laterality of stroke to emotional and functional outcome.

The role of hemispheric laterality and emotion in the stroke population has been studied less than in other brain-damaged populations. Neuroscience nurses caring for stroke patients need knowledge about the anatomical placement of ischemic deficits and the relationship of emotions to that placement to understand observed affect and behavior. Knowing how to assess negative affect and behavior will help nurses design interventions to produce optimal recovery.

Aged↗
PubMed2000

Lateralized tinnitus studied with functional magnetic resonance imaging: abnormal inferior colliculus activation.

Tinnitus, the perception of sound in the absence of external stimuli, is a common and often disturbing symptom that is not understood physiologically. This paper presents an approach for using functional magnetic resonance imaging (fMRI) to investigate the physiology of tinnitus and demonstrates that the approach is effective in revealing tinnitus-related abnormalities in brain function. Our approach as applied here included 1) using a masking noise stimulus to change tinnitus loudness and examining the inferior colliculus (IC) for corresponding changes in activity, 2) separately considering subpopulations with particular tinnitus characteristics, in this case tinnitus lateralized to one ear, 3) controlling for intersubject differences in hearing loss by considering only subjects with normal or near-normal audiograms, and 4) tailoring the experimental design to the characteristics of the tinnitus subpopulation under study. For lateralized tinnitus subjects, we hypothesized that sound-evoked activation would be abnormally asymmetric because of the asymmetry of the tinnitus percept. This was tested using two reference groups for comparison: nontinnitus subjects and nonlateralized tinnitus subjects. Binaural noise produced abnormally asymmetric IC activation in every lateralized tinnitus subject (n = 4). In reference subjects (n = 9), activation (i.e., percent change in image signal) in the right versus left IC did not differ significantly. Compared with reference subjects, lateralized tinnitus subjects showed abnormally low percent signal change in the IC contralateral, but not ipsilateral, to the tinnitus percept. Consequently, activation asymmetry (i.e., the ratio of percent signal change in the IC ipsilateral versus contralateral to the tinnitus percept) was significantly greater in lateralized tinnitus subjects as compared with reference subjects. Monaural noise also produced abnormally asymmetric IC activation in lateralized tinnitus subjects. Two possible models are presented to explain why IC activation was abnormally low contralateral to the tinnitus percept in lateralized tinnitus subjects. Both assume that the percept is associated with abnormally high ("tinnitus-related") neural activity in the contralateral IC. Additionally, they assume that either 1) additional activity evoked by sound was limited by saturation or 2) sound stimulation reduced the level of tinnitus-related activity as it reduced the loudness of (i.e., masked) the tinnitus percept. In summary, this work demonstrates that fMRI can provide objective measures of lateralized tinnitus and tinnitus-related activation can be interpreted at a neural level.

Acoustic Stimulation↗