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Results for “Functional Laterality”

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At least 451 records · Page 25Linked to original sources

PubMed1999

Superior temporal gyral volumes and laterality correlates of auditory hallucinations in schizophrenia.

BACKGROUND: Previous studies have reported significant correlations, indicating an emerging relationship, between severity of auditory hallucinations and reduced size of temporal lobe cortical regions implicated in language processing. The present study used high-resolution magnetic resonance imaging (MRI) scanning, along with assessment of functional lateralization via a dichotic listening task (DLT), to extend these findings. METHODS: Thirty patients with schizophrenia and a history of auditory hallucinations participated in the study. All were completely right-handed. Eleven subjects were currently hallucinating at the time of the study. Volumetric T1-weighted MRI scans were obtained and regions of interest were manually traced using the BRAINS package (Andreasen et al 1993). Whole brain, bilateral temporal lobe, and anterior superior temporal gyrus volumes were calculated. Subjects completed a binaural consonant-vowel DLT. RESULTS: Increased severity of hallucinatory experience was significantly associated with smaller left anterior superior temporal gyrus volumes. Current hallucinators demonstrated a reduction in right ear advantage on the DLT. CONCLUSIONS: The results suggest that auditory hallucinations are subserved by a trait-like dysfunction in language-related neural networks, of which the superior temporal cortex forms one component. The findings are also consistent with theories proposing abnormal lateralization in the etiology of auditory hallucinations.

Adult↗

PubMed2003

Uniformity in dynamic baroreflex regulation of left and right cardiac sympathetic nerve activities.

Functional laterality of cardiac sympathetic nerve stimulation in chronotropic and inotropic effects is well known. Whether left (LSNA) and right (RSNA) cardiac sympathetic nerve activities show laterality during dynamic baroreflex activation remains to be determined. In nine anesthetized, vagotomized, and aortic-denervated rabbits, we randomly perturbed intracarotid sinus pressure (CSP) in both carotid sinus regions while simultaneously recording LSNA and RSNA. The baroreflex neural arc transfer function from CSP to LSNA and from CSP to RSNA revealed derivative characteristics, i.e., the magnitude of LSNA and RSNA responses became greater as the input frequency of CSP perturbation increased. The average slope of increasing gain in the frequencies between 0.03 and 0.3 Hz showed no difference between LSNA and RSNA responses (9.7 +/- 2.9 vs. 9.7 +/- 3.1 dB/decade, means +/- SD). The amplitude ratio and phase difference between LSNA and RSNA approximated unity and zero radians, respectively, in the frequencies from 0.01 to 1 Hz. In addition, the LSNA-RSNA relationship during stepwise CSP perturbation from 40 to 160 mmHg showed a straight line (r(2) ranged from 0.969 to 0.999). These findings indicate no laterality in the dynamic as well as static baroreflex regulation of LSNA and RSNA as far as grouped axonal activity is concerned.

Adrenergic Fibers↗

PubMed2000

Influence of pre- and post-pubertal grazing regimes on adult testicular morphology in extensively reared corriedale rams.

The aim of the present study was to determine whether pre- and post-pubertal young rams on different grazing regimes, resulting in differences in live weight (LW), would show corresponding differences in testicular growth or testicular morphometry that could influence the reproductive traits of these rams upon reaching adulthood. Forty-one spring-born Corriedale rams were reared on either native pasture (low feeding level, Group L, n=22) or improved pasture (higher feeding level, Group H, n=19) from 1 to 7 months of age. Thereafter, half the animals in the native-pasture group were placed on improved pasture and vice versa, thus creating an additional four differential-grazing treatment groups (Groups LL, n=11; LH, n=11; HL, n=10; and HH, n=9). Animals were managed in this way until 18 months of age. Half the animals from each group were then castrated and their testes were subjected to morphometric analysis. The remaining animals (Groups LL, n=6; LH, n=6; HL, n=5; and HH, n=4) were managed together until 30 months of age (from 18 to 27 months on native pastures and from 27 to 30 months of age on improved pastures, at a stocking rate of two to three rams per hectare), whereupon they were also castrated for testicular morphometry. LW and scrotal circumference (SC) were recorded every 60 days. The stereological analysis of testicular parenchyma included counts of elongated spermatids and Sertoli cells. Differences (P<0.001) in LW were observed between feeding levels, even at 30 months of age. Differences (P<0.001) in SC existing at the end of the differential treatment (18 months of age) disappeared (n.s.) soon after. Most differences (P<0.05) in testicular morphometry existing at the end of the differential treatments were no longer significant 1 year later. It is concluded that changes in grazing management during pre- and post-pubertal periods can induce short-lived differences in testicular post-natal growth in Corriedale rams but do not influence testicular morphology or function later in life.

Animal Feed↗

PubMed2003

Accuracy, information, and response time in a saccadic decision task.

Reaction times generally follow a simple law economically described by the LATER model, in which a decision signal rises linearly in response to information about a target to a threshold at which a response is initiated, at a rate that varies from trial to trial with a Gaussian distribution. Functionally, LATER may be regarded as an ideal decision mechanism incorporating prior probability, information, and criterion level or urgency; this can be tested quantitatively by seeing whether LATER accurately predicts the effects on latency distributions of manipulating these variables: in this case, information and urgency. We presented subjects with random-dot kinematograms while fixating a central LED. The information content of the display was varied by altering the proportion of the dots moving coherently together either left or right rather than randomly. As soon as subjects detected the direction of coherent movement, they made a saccade in the same direction to one of a pair of LEDs on each side of the fixation target. Subjects responded either carefully, taking time to ensure an accurate judgement, or more hastily and with less regard for accuracy. The distributions of latencies under the different combinations of conditions were found to conform to LATER's predictions. Providing more information or increasing urgency both reduce latency; but they alter the observed distributions in different ways, equivalent to increasing the mean rate of rise on the one hand or reducing the criterion level on the other. Making only simple assumptions about the underlying mechanisms, the observed changes can be accounted for quantitatively.

Decision Making↗

PubMed1982

Self-stimulation and circling reveal functional differences between medial and lateral substantia nigra.

Functional differences between medial and lateral substantia nigra (SN) sites mediating intracranial self-stimulation (ICSS) and circling behaviours were explored. It was found that, for medial SN stimulation sites, D- and L-amphetamine (1 mg/kg) had equipotent, slightly facilitatory effects on ICSS rates while for lateral SN stimulation sites, D-amphetamine increased and L-amphetamine decreased ICSS rates. It is suggested that these effects may be due to medial and lateral dopamine cells having different sensitivities to amphetamine isomers. Imposed continuous stimulation of the ICSS sites induced contralateral circling from the medial SN placements and ipsilateral circling from the lateral SN placements. In rats receiving lesions through the ICSS electrode, D-amphetamine (2 mg/kg) induced ipsilateral circling following medial SN damage and contralateral circling after lateral SN damage. These results suggest that lateral and medial SN mechanisms of ICSS and circling differ, and that the lateral SN may be antagonistic to medial SN mechanisms involved in circling behaviour.

Amphetamine↗

PubMed2001

Neurobehavioral symptoms in childhood closed-head injuries: changes in prevalence and correlates during the first year postinjury.

OBJECTIVE: To examine changes in the prevalence and correlates of neurobehavioral symptoms during the first year following childhood closed-head injuries (CHIs). METHODS: Participants included 31 children with severe CHIs, 38 with moderate CHIs, and 53 with orthopedic injuries (OIs). Children and their families were assessed shortly after injury and at 6- and 12-month follow-ups. Parents rated 15 symptoms classified as either cognitive/somatic (C/S) or emotional/behavioral (E/B). RESULTS: Both kinds of symptoms were more common in the CHI groups than in the OI group. C/S symptoms declined in the CHI groups over time, whereas E/B symptoms became relatively more common. Measures of injury severity, children's premorbid behavioral adjustment, and concurrent cognitive functioning predicted C/S symptoms. E/B symptoms were predicted by injury severity, concurrent cognitive functioning soon after the injury, and concurrent parent and family functioning later in time. Both types of symptoms contributed to the prediction of perceived family burden, with the relationships strengthening over time. CONCLUSIONS: The findings indicate that the prevalence and correlates of neurobehavioral symptoms in childhood CHIs vary as a function of symptom type and time since injury.

Child↗

PubMed1984

Voluntary control of two lateralized conscious states: validation by electrical and behavioral studies.

A subject is described who can voluntarily select and hold either of two qualitatively different states of consciousness. Evidence is presented which confirmed differential left or right hemisphere dominance in each state. Asymmetries of EEG alpha and task performance scores indicated a state-dependent shift in functional lateralization. Evoked response studies showed directional changes in rate of interhemispheric transmission correlated with state-related hemisphere dominance. These findings demonstrated that capability for voluntary endogenous control of cerebral dominance under natural conditions.

Adult↗

PubMed2000

The aurora-related kinase AIR-2 recruits ZEN-4/CeMKLP1 to the mitotic spindle at metaphase and is required for cytokinesis.

BACKGROUND: The Aurora/Ipl1p-related kinase AIR-2 is required for mitotic chromosome segregation and cytokinesis in early Caenorhabditis elegans embryos. Previous studies have relied on non-conditional mutations or RNA-mediated interference (RNAi) to inactivate AIR-2. It has therefore not been possible to determine whether AIR-2 functions directly in cytokinesis or if the cleavage defect results indirectly from the failure to segregate DNA. One intriguing hypothesis is that AIR-2 acts to localize the mitotic kinesin-like protein ZEN-4 (also known as CeMKLP1), which later functions in cytokinesis. RESULTS: Using conditional alleles, we established that AIR-2 is required at metaphase or early anaphase for normal segregation of chromosomes, localization of ZEN-4, and cytokinesis. ZEN-4 is first required late in cytokinesis, and also functions to maintain cell separation through much of the subsequent interphase. DNA segregation defects alone were not sufficient to disrupt cytokinesis in other mutants, suggesting that AIR-2 acts specifically during cytokinesis through ZEN-4. AIR-2 and ZEN-4 shared similar genetic interactions with the formin homology (FH) protein CYK-1, suggesting that AIR-2 and ZEN-4 function in a single pathway, in parallel to a contractile ring pathway that includes CYK-1. Using in vitro co-immunoprecipitation experiments, we found that AIR-2 and ZEN-4 interact directly. CONCLUSIONS: AIR-2 has two functions during mitosis: one in chromosome segregation, and a second, independent function in cytokinesis through ZEN-4. AIR-2 and ZEN-4 may act in parallel to a second pathway that includes CYK-1.

Animals↗

PubMed1999

Evidence for the function of an exonic splicing enhancer after the first catalytic step of pre-mRNA splicing.

Exonic splicing enhancers (ESEs) activate pre-mRNA splicing by promoting the use of the flanking splice sites. They are recognized by members of the serine/arginine-rich (SR) family of proteins, such as splicing factor 2/alternative splicing factor (SF2/ASF), which recruit basal splicing factors to form the initial complexes during spliceosome assembly. The in vitro splicing kinetics of an ESE-dependent IgM pre-mRNA suggested that an SF2/ASF-specific ESE has additional functions later in the splicing reaction, after the completion of the first catalytic step. A bimolecular exon ligation assay, which physically uncouples the first and second catalytic steps of splicing in a trans-splicing reaction, was adapted to test the function of the ESE after the first step. A 3' exon containing the SF2/ASF-specific ESE underwent bimolecular exon ligation, whereas 3' exons without the ESE or with control sequences did not. The ESE-dependent trans-splicing reaction occurred after inactivation of U1 or U2 small nuclear ribonucleoprotein particles, compatible with a functional assay for events after the first step of splicing. The ESE-dependent step appears to take place before the ATP-independent part of the second catalytic step. Bimolecular exon ligation also occurred in an S100 cytosolic extract, requiring both the SF2/ASF-dependent ESE and complementation with SF2/ASF. These data suggest that some ESEs can act late in the splicing reaction, together with appropriate SR proteins, to enhance the second catalytic step of splicing.

Adenosine Triphosphate↗

PubMed1999

Vasopressin and oxytocin neurons of the human supraoptic and paraventricular nucleus: size changes in relation to age and sex.

The hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei consist of arginine vasopressin (AVP)- and oxytocin (OT)-synthesizing neurons that send projections to the neurohypophysis, whereas the PVN also projects to other brain areas. A growing body of evidence in animals suggests the presence of sex differences in the vasopressinergic and oxytocinergic systems. The present study was aimed at determining whether the sizes of AVP and OT neurons in the human SON and PVN show sex differences, as earlier studies demonstrated that a change in neuronal size is a sensitive parameter for activity. The minimal and maximal diameters were determined to estimate the volumes of cell somata and cell nuclei in AVP and OT neurons stained with an antibody against human glycoprotein-(22-39), a part of the AVP precursor, and a monoclonal anti-OT antibody in 15 men and 17 women ranging in age from 29-94 yr. The AVP neurons appeared to be larger in young men than in young women (< or =50 yr old). In elderly women (>50 yr old) AVP cell size considerably exceeded that in young women. In elderly men AVP neurons were larger than in young men and elderly women, although these differences were not significant. In addition, AVP cell size correlated positively with age in women but not in men. No significant differences were found in the AVP cell nucleus volumes among all four groups studied. Sex differences in the size of the PVN vasopressin neurons were pronounced at the left side (P = 0.048) and absent at the right side (P = 0.368), indicating the presence of functional lateralization in this nucleus. No difference was found in any morphometric parameter of OT neurons in the PVN among the 4 groups studied. Thus, our data demonstrate sex differences in the size of the AVP neurons, and thus in their function, that are age and probably also side dependent and the absence of such changes in OT neurons in the PVN. These data provide a basis for the reported higher AVP plasma levels in men compared to women.

Adult↗

PubMed2006

Nitric oxide and endoplasmic reticulum stress.

Nitric oxide (NO) is a multifunctional biomolecule involved in a variety of physiological and pathological processes, including regulation of blood vessel dilatation and anti-arteriosclerotic effects. However, a large amount of NO is toxic to the host and causes several diseases such as apoptosis, septic shock, and diabetes mellitus. Inducible-form NO synthase is induced in inflammatory diseases, including insulitis and arteriosclerosis. Endoplasmic reticulum (ER) stress pathway was first identified as a cellular response pathway induced by the accumulation of unfolded proteins in ER to preserve ER functions. Later it was found that ER stress pathway is also activated by various cellular stresses to protect cells, but when stresses are severe, apoptosis is induced to remove damaged cells. It is reported that NO and reactive oxygen species disturb ER functions, then ER stress-mediated apoptosis pathway is activated. CHOP/GADD153, which belongs to C/EBP transcription factor family, is induced in this process and mediates apoptosis. ER stress pathway induced by NO can be involved in the pathogenesis of various vascular diseases.

Animals↗

PubMed1994

Ages of onset of psychiatric disorders in a community population of older adolescents.

OBJECTIVE: Ages of onset of psychiatric disorders, as well as the link between early onset and later psychosocial functioning, were examined in a community population of older adolescents. METHOD: Subjects were 386 adolescents who were participants in an ongoing 14-year longitudinal study. At age 18, lifetime diagnoses and ages of onset of major depression, phobias, post-traumatic stress disorder, and substance disorders were assessed using the NIMH Diagnostic Interview Schedule, Revised Version. Behavioral, emotional, and academic functioning in later adolescence were evaluated through self-report measures and school records. RESULTS: Almost one fourth of the adolescents met criteria for at least one disorder by age 14. Simple phobias emerged earliest (by early childhood), whereas for major depression and substance disorders the peak risk periods for onset were midadolescence. The early onset (by age 14) of disorders was associated with continued impairments in behavioral and emotional functioning in late adolescence (at age 18). Furthermore, the early onset of disorders, compared to later onset (ages 15 through 18), increased the risk for additional co-occurring disorders. CONCLUSIONS: The striking levels of early psychopathology and associated long-term deficits in functioning found in this community population underscore the need for programs of early intervention.

Adaptation, Psychological↗

PubMed2006

Conditional (loxP-flanked) allele for the gene encoding the retinoic acid-synthesizing enzyme retinaldehyde dehydrogenase 2 (RALDH2).

Retinoic acid, the active vitamin A derivative, has pleiotropic functions during vertebrate development and postnatal life. Retinaldehyde dehydrogenase 2 (RALDH2) acts as the main retinoic acid-synthesizing enzyme during development. Mouse Raldh2 germline null mutants are early embryonic lethal and exhibit complex abnormalities that include defective heart looping morphogenesis. To investigate later functions of this enzyme, we have engineered a "floxed" (loxP-flanked) allele allowing Cre-mediated somatic gene inactivations. Mice heterozygous or homozygous for the floxed Raldh2 allele are viable and fertile. We tested whether the novel Raldh2 allele behaves as a null mutation after Cre-mediated in vivo excision by crossing the conditional mutants with CMV-Cre transgenic mice. An embryonic lethal phenotype indistinguishable from that of germline mutants was obtained. The conditional allele described herein is a genetic tool for studying tissue-specific, RALDH2-dependent functions of retinoic acid during development and in adult life.

Aldehyde Oxidoreductases↗

PubMed1992

Lateralized deficits in visual attention in males with developmental dopamine depletion.

Children with early treated phenylketonuria (ETPKU), a disorder associated with developmental dopamine depletion, were tested with a visual orienting paradigm to determine the existence of lateralized deficits in specific attentional operations. Male ETPKU subjects showed a right visual field impairment in disengaging attention, indicating left hemisphere dysfunction, and overall slowed reaction times. Female ETPKU and normal subjects did not differ. The results suggest that for males, dopamine depletion disrupts left hemisphere function. This finding has important implications for disorders with suspected developmental dopamine abnormalities, and may also illustrate how sex differences in functional lateralization develop in the normal brain.

Attention↗

PubMed1998

Lack of lateral inhibitory interactions in visual cortex of monocularly deprived cats.

To gain new insight into the effects of monocular deprivation, we studied the visual cortex of adult cats deprived of vision in one eye. Local field potentials were recorded in response to contrast reversal of square-wave gratings modulated in time either by pseudorandom, m-sequences or periodically. We have found that: (1) stimulation of the retinotopic locus of the recording site elicits responses with abnormal waveforms and long latencies from the deprived eye; (2) stimulation of a remote, non-retinotopic locus elicits responses from the non-deprived eye but not from the deprived eye; (3) the monocularly deprived cortex lacks lateral inhibitory interactions which are characteristic of the normal cortex; and (4) steady-state responses showed little difference in spatial-frequency tuning and contrast sensitivity between the deprived and non-deprived eye, mostly conforming to earlier field-potential data in monocular deprivation. Functional lateral interactions appear to be greatly reduced in monocularly deprived cortex.

Animals↗

PubMed1986

Modulation of ethanol-induced central nervous system depression by ibuprofen.

We investigated the effect of pretreatment with a prostaglandin synthetase inhibitor, ibuprofen, on the pharmacokinetics and pharmacodynamics of ethanol in six fasting subjects. Ibuprofen caused a 10% decrease in the maximum rate of elimination of ethanol. Visual memory, which is a function primarily mediated by the right cerebral hemisphere, was measured by the Benton Visual Retention test and was more impaired during combined ibuprofen and ethanol dosing than during ethanol dosing alone (P = 0.05). The auditory-verbal memory of the subjects, which is primarily a function of the left cerebral hemisphere, was assessed by the Selective Reminding Test and showed decreased impairment during combined ibuprofen and ethanol dosing as compared with ethanol dosing alone (P = 0.04). The opposite effect of ibuprofen on ethanol-induced cognitive impairment as measured by two lateralized functions is consistent with the reports in tissue and animal models that central nervous system effects of ethanol may be mediated at least in part by prostaglandins.

Adult↗

PubMed1995

Isolated posterior fossa hypertension and brainstem compression caused by entrapped Dandy-Walker cyst: a case report.

Lateral ventricular shunting alone is often considered to be adequate treatment for hydrocephalus caused by Dandy-Walker syndrome. A patient is presented in whom progressive spastic tetraparesis and signs of severe brainstem compression developed due to an entrapped posterior fossa cysts, in spite of an adequately functioning lateral ventricular shunt. Addition of a cystoperitoneal shunt resulted in rapid resolution of symptoms and deficits. This case illustrates that potentially fatal brainstem compression and dangerous posterior fossa hypertension may develop if the posterior fossa cyst does not communicate with the lateral ventricles, where the shunt is placed.

Brain Diseases↗

PubMed2005

Functional status and quality of life after emergency revascularization for cardiogenic shock complicating acute myocardial infarction.

OBJECTIVES: Our goal was to describe the functional status of cardiogenic shock survivors, identify the correlates of cardiogenic shock, and compare global quality of life and functional status of patients randomly assigned to treatment with emergency revascularization (ERV) versus initial medical stabilization (IMS). BACKGROUND: Historically, the hospital survival rate of patients with cardiogenic shock complicating acute myocardial infarction (MI) has been very low. Shock survivors are salvaged from a critically ill state, and their later functional status is not well documented. The SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK (SHOCK) trial showed significantly improved one-year survival after ERV compared with IMS. METHODS: The SHOCK trial survivors completed interviews at 2 weeks after discharge and at 6 and 12 months after MI. Functional status assessment included the Multidimensional Index of Life Quality and New York Heart Association (NYHA) congestive heart failure functional class. RESULTS: Eighty-seven percent of one-year survivors of the SHOCK trial were in NYHA functional class I or II. Between two weeks after discharge and one year after MI, improvement was similar in the two treatment groups (18% overall), but fewer patients remained stable (44% vs. 71%), and more patients worsened or died (34% vs. 15%) in the IMS group compared with those assigned to ERV. Assignment to ERV was the only independent predictor of outcome at one year. CONCLUSIONS: Although one-year mortality after ERV is still high (54%), most survivors have good functional status. The ERV patients have a lower rate of deterioration than IMS patients. The level of recovery for shock patients undergoing ERV is similar to that of historical controls not in cardiogenic shock undergoing elective revascularization.

Angioplasty, Balloon, Coronary↗