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PubMed1986

Hemispheric lateralization of functions related to emotion.

We have reviewed the evidence that processes and functions related to perception and expression of emotions are represented asymmetrically in the cerebral hemispheres. The literature describes three possible aspects of emotional lateralization: that emotions are better recognized by the right hemisphere; that control of emotional expression and related behaviors takes place principally in the right hemisphere; and that the right hemisphere is specialized for dealing with negative emotions, while the left is specialized for dealing with positive emotions. Evidence for the three hypotheses derives from methodologically diverse studies in unimpaired, brain-lesioned, and mood-disordered populations. Relatively little of the work has been precisely replicated, and conclusions rest on parallel lines of evidence from diverse sources. The present level of knowledge suggests a model of emotional control based on interactive inhibition between a right negatively biased and left positively biased hemisphere. However, the details of such a model, including the precise conditions under which emotion-related functions are lateralized, and the mechanisms of such lateralization have yet to be elucidated.

Brain↗
PubMed1990

Hypnosis and lateralized brain functions.

Bilateral EEG measures were obtained on 16 high hypnotizable Ss (scores of greater than 8 on the Harvard Group Scale of Hypnotic Susceptibility, Form A, Shor & E. Orne, 1962), while performing hemisphere-specific tasks during hypnosis and a no-hypnosis control condition. Conditions and tasks were presented in counterbalanced order, and Ss served as their own controls. The data call into question the right hemisphere activation interpretation of lateralized brain function during hypnosis; rather, the data suggest a lack of task appropriate activity during hypnosis. The failure to attend to baseline activity measurements and the use of ratios to evaluate interhemispheric lateralization may contribute to potential misinterpretations of data. It is critical that activity changes of the separate hemispheres be taken into account in the interpretative process.

Cerebral Cortex↗
PubMed1992

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

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

Acceleration↗
PubMedDate not supplied

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

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

Adult↗
PubMed1987

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

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

Animals↗
PubMed1988

New evidence for distinct patterns of brain organization in rats differentiated on the basis of inherent laterality.

The purpose of the present study was to search for possible relationships among diverse measures of behavioral laterality in a non-human species or to identify an index of laterality that was predictive of other non-lateralized functions. Several indices of behavioral laterality and open field activity were assessed in male and female rats before and after asymmetric neocortical ablations. Plasma adrenocorticotropin, corticosterone, and prolactin were measured following stress at sacrifice. Sex-dependent population-level lateral biases were observed preoperatively in the choice of arms in a T-maze and initial direction out of a corner of an open field. Unilateral left neocortical ablation induced a leftward bias in the T-maze in both male and female rats. The direction of rotation following the peripheral administration of amphetamine was correlated with: (a) the degree of sensitization to amphetamine; (b) preoperative open field activity in females; (c) the induction of hyperactivity following right neocortical ablation in males; (d) rotational responses to amphetamine in male rats sustaining bilateral ablations; and (e) the effect of left neocortical ablation on prolactin levels in males. We propose that these data provide new evidence for distinct patterns of brain organization in rats differentiated by a measure of inherent cerebral laterality.

Amphetamine↗
PubMed1979

Nature and severity of hydrocephalus and its relation to later intellectual function.

In 102 cases of infantile hydrocephalus, treated within 365 days of birth, the possibilities of predicting later intelligence were investigated, largely by means of multiple regression methods. No significant effect of aetiology, date of shunting or severity (measured in various ways) could be demonstrated. Within the spina bifida group however the 3 cases of encephalocele had considerably lower IQ's. There was no effect of lesion level in the rest of this group. Educational level of the parents had a significant, but not very marked impact on the IQ's of their children. Most outstanding was the difference between non-communicating and communicating hydrocephalus: nearly 50% of the non-communicating cases were mentally retarded, while this percentage was 22 for the communicating ones.

Adolescent↗
PubMed1978

Sensitivity to laterality as a function of handedness.

This study tested the hypothesis that left-handed individuals are more aware than right-handed individuals of others' handedness. 18 left-handed and 18 right-handed college students were shown a drawing of 8 children at a party. Seven children held objects in the left hand, while one held an object in the right hand. After 2 1/2 min. the drawing was removed and subjects answered 15 questions about its contents. Included were 2 questions asking how many children were holding something in the right or left hand. Compared with right-handed subjects, left-handed subjects reported significantly more children holding something in the left hand and significantly fewer holding something in the right hand. The two groups did not differ on any other questions.

Awareness↗
PubMed1991

Prospective analysis of masticatory function following lateral mandibulotomy.

Based on clinical impressions and subjective reports by patients, it is generally accepted that a loss of mandibular continuity will result in decreased masticatory function while preserving continuity will result in maintenance of masticatory function. Surprisingly, there is a paucity of well controlled studies objectively evaluating masticatory function to support these statements. The purpose of this study was to objectively evaluate masticatory function in a patient who underwent surgical resection for cure of a tonsillar carcinoma where a lateral mandibulotomy was used. Masticatory performance and swallowing threshold were assessed using a 0.5 gm frito as the test food substance and a sieve analysis. The subject was evaluated pre and post surgery and post prosthetic rehabilitation. When compared with pre surgery function, masticatory function and swallowing threshold were maintained and enhanced with prosthetic treatment 1 year post surgery. Maintenance of mandibular continuity did have functional merit for the subject studied.

Denture, Complete, Upper↗
PubMed1988

Modest decrements in plasma glucose concentration cause early impairment in cognitive function and later activation of glucose counterregulation in the absence of hypoglycemic symptoms in normal man.

To establish the glycemic threshold for onset of neuroglycopenia (impaired cognitive function, measured by the latency of the P300 wave), activation of hormonal counterregulation and hypoglycemic symptoms, 12 normal subjects were studied either under conditions of insulin-induced, glucose-controlled plasma glucose decrements, or during maintenance of euglycemia. A decrement in plasma glucose concentration from 88 +/- 3 to 80 +/- 1 mg/dl for 150 min did not result in changes in the latency of the P300 wave nor in an activation of counterregulatory hormonal response. In contrast, a greater decrement in plasma glucose concentration from 87 +/- 3 to 72 +/- 1 mg/dl for 120 min caused an increase in the latency of the P300 wave (from 301 +/- 12 to 348 +/- 20 ms, P less than 0.01), a subsequent increase in all counterregulatory hormones but no hypoglycemic symptoms. Finally, when plasma glucose concentration was decreased in a stepwise manner from 88 +/- 2 to 50 +/- 1 mg/dl within 75 min, the increase in the latency of the P300 wave was correlated with the corresponding plasma glucose concentration (r = -0.76, P less than 0.001). The glycemic threshold for hypoglycemic symptoms was 49 +/- 2 mg/dl. Thus, in normal man the glycemic threshold for neuroglycopenia (72 +/- 1 mg/dl) is greater than currently thought; the hormonal counterregulation follows the onset of neuroglycopenia; the hypoglycemic symptoms are a late indicator of advanced neuroglycopenia.

3-Hydroxybutyric Acid↗
PubMed1989

Crossed aphasia in a dextral.

A case of crossed aphasia in a monolingual dextral with detailed clinical, neuropsychological and language assessment is described. The presence of Gerstmann-syndrome suggested cross-over of even dominant parietal lobe functions. Lateralization and localization of various language functions in relation to crossed aphasia are discussed.

Adult↗
PubMed1977

Function of lateral reticular nucleus in central cardiovascular regulation in the cat.

The role of the lateral reticular nucleus (LRN) in central cardiovascular regulation was investigated in cats. In 15 cerebellectomized and nine intact chloralosed cats stimulation of 115 histologically verified sites in the LRN elicited increases in arterial pressure and heart rate; the latter was abolished by propranolol but not by bilateral cervical vagotomy. The pressor response was significantly greater in intact animals. Electrical activity was recorded from the right inferior cardiac nerve (ICN) during stimulation fo the LRN and of a vasomotor region in the posteromedial hypothalamus (PMH). Stimulation of sites in the LRN and in the PMH, on both sides, elicited a response in the right ICN that was consistently abolished during baroreceptor excitation. Medullary transection 3 mm rostral to the LRN did not abolish the ICN response to LRN stimulation. The conclusions are drawn that stimulation of the LRN elicits cardiovascular responses probably due to excitation of groups of neurons in this nucleus located in a descending sympathetic pathway originating in the PMH and that these responses can be inhibited by excitation of baroreceptors. In view of the known functional connections of the LRN with the somatomotor system it is suggested that this nucleus may play a major role in somatosympathetic reflexes.

Animals↗
PubMed1990

Urinoma formation in posterior urethral valves: relationship to later renal function.

A retrospective analysis of radiologically determined individual renal function was performed in five boys who presented in the neonatal period with posterior urethral valves, vesicoureteral reflux and documented urinoma formation. Renal function was evaluated with scintigraphy. There was reflux in eight of ten ureters. Six of these ureters had an associated urinoma and compromised renal function in the neonatal period. In two of the boys the kidney with urinoma functioned better than the contralateral kidney with reflux alone. In two other boys with unilateral urinoma the contralateral ureter did not reflux and the affected kidney functioned less well. In follow up (20 to 36 months) seven of the ten kidneys have a near normal appearance or function. Those kidneys which are now abnormal were noted to be abnormal in the neonatal period.

Follow-Up Studies↗
PubMed1988

Detection of cerebral lateralization of function using EEG alpha-contingent visual stimulation II.

The replicative reliability of durations of alpha-blocking following visual stimulation over different cortical sites was assessed with the method of alpha-contingent stimulation. Fourteen right-handed undergraduates were tested in a randomized factorial design. Words or geometric designs of equal luminance were presented by computer to randomly selected visual half-fields contingent on the occurrence of alpha at one of 4 placements (left and right occipital and left and right temporal). The control (mean/s) of alpha-blocking durations was significantly greater for contralateral visual half-field stimulation compared to ipsilateral visual half-field stimulation. This and other results were interpreted in terms of the concept of replicative reliability of retinal-cortical connections to occipital and temporal lobes and affirm the validity and sensitivity of the method.

Adolescent↗