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Results for “Functional Laterality”

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PubMed1997

The intracarotid amobarbital procedure: an historical perspective.

The intracarotid sodium amobarbital procedure (IAP) is currently regarded as the best method of the determination of hemispheric specialization for speech, and it is universally relied on as a prognostic test for patients with medically refractory epilepsy who are candidates for neurosurgical intervention. Since its initial development, the IAP also has been adapted for assessing lateralized mesiotemporal contributions to memory functioning in this patient population, and it is now in wide use for both basic and applied research in behavioral neuroscience on language, memory, visuospatial functions, emotion, attention, and consciousness. Despite the IAP's wide range of applications, little has been said about its history and development. This essay recounts and discusses this history.

Amobarbital↗

PubMed2002

Sex differences, laterality, and hormonal regulation of androgen receptor immunoreactivity in rat hippocampus.

Sex differences, laterality, and hormonal regulation of androgen receptor (AR) immunoreactivity in rat hippocampal CA1 pyramidal cells were examined using the PG21 antibody. Adult male rats were either castrated or sham-operated at least 2 weeks prior to sacrifice. Gonadally intact females were sacrificed on the day of proestrus. Animals received an injection of either testosterone propionate (TP) or vehicle 2 h prior to sacrifice. Within CA1, both the intensity of staining and the number of AR+ cells were assessed. AR immunostaining was detected in all the groups with marked variation among them. The overall ranking of staining intensity was: gonadally intact males > females given TP > castrated males given TP > females > castrated males given vehicle. The number of AR+cells within subregions of CA1 showed the same basic pattern: among control-treated animals, gonadally intact males have more than females, but castrated males have the least, and acute TP treatment increases the number in both sexes. The increased level of AR immunoreactivity in CA1 of castrated males following acute TP treatment suggests that testicular androgens in adulthood normally increase AR immunoreactivity there, producing a sex difference favoring males in gonadally intact animals. We also found a higher number of AR+ CA1 cells on the left than on the right, but only in gonadally intact males and in females given TP. These results suggest that a laterality of AR distribution in the rat hippocampus may lead to lateralities in hippocampal structure and function.

Animals↗

PubMed1989

Handedness and language among the mentally retarded: implications for the model of pathological left-handedness and gender differences in hemispheric specialization.

The relationship between handedness and language was examined among 238 mentally retarded subjects representing the four DSM III classification ranges of mental retardation. Language ability was found to be significantly related to handedness, with an increased prevalence of left-handedness among those individuals with language deficits. In addition, both expressive and receptive language ability interacted with gender, with the main effects of each language variable being stronger for females than males. Although no main effects were found for severity of retardation, a significant interaction was found between severity and gender. Results support the model of pathological left-handedness and are discussed within the context of this theory, as well as with regard to gender differences in cerebral lateralization of language and cognitive functioning.

Adolescent↗

PubMed1986

Subject variable effects in correlations between auditory and visual language processing asymmetries.

The cross-modal correlations between auditory and visual language lateralization were examined as a function of the subject variables of handedness, sex, familial sinistrality, and handwriting posture. In this study, left-handers showed a significantly greater correlation between visual and auditory language processing asymmetries than right-handers, contradicting previous reports.

Adult↗

PubMed1984

Variations in patterns of lateral asymmetry among dextrals.

Evidence supporting individual variations in patterns of hemispheric involvement in the recognition of visuo-spatial and verbal stimuli among dextrals is reported. In Experiment 1, subjects' asymmetry scores on a task that was nonlateralized for the group as a whole were significantly correlated with their asymmetry scores on right-hemisphere-specialized tasks, including face recognition. In Experiment 2, subjects' asymmetry scores on a task that was nonlateralized for the group as a whole were significantly correlated with their asymmetry scores on a left-hemisphere-specialized word recognition task. These results suggest that individual dextrals' asymmetry scores on lateralized tasks are a joint function of a subject's underlying hemispheric specialization for that task and stable individual variations in asymmetric hemispheric reliance.

Arousal↗

PubMed1999

Excess of non-right handedness among individuals with intellectual disability: experimental evidence and possible explanations.

Seventy-three subjects with mild and moderate intellectual disability (ID) of an unknown/idiopathic nature, who had no record of specific deficits in motor control, and 73 normal controls, matched for chronological age and sex, underwent evaluation of handedness. The results confirmed the previously reported excess of non-right handedness among subjects with ID, and suggested that this finding might be indicative of a deviant cerebral organization or atypical lateralization of cerebral representation of function in this group. However, it was noted that further research is needed to clarify how far this is a function of level of motor skill and how far is a syndrome-specific pathological phenomenon.

Adolescent↗

PubMed2002

Memory traces for inflectional affixes as shown by mismatch negativity.

Mismatch negativity (MMN), an index of experience-dependent memory traces, was used to investigate the processing of grammatical affixes in the human brain. The MMN was elicited by either a verb stem or an inflected verb form, phonetic contrasts being identical in both conditions. The topography of the mismatch responses showed clear left-hemispheric laterality in both conditions. However, the MMN to the inflected form occurred later than that for the stem. Furthermore, the inflected stimulus produced MMN maximal in centroparietal sites, whereas stem-elicited MMN was more profound at more frontal sites. We suggest that these features of the MMN to inflected form indicate delayed activation of left-lateralized perisylvian cell assemblies that function as cortical memory traces of inflectional affixes.

Acoustic Stimulation↗

PubMed1970

Inference from inadequate and inaccurate data, I.

Having measured D numerical properties of a physical object E which requires many more than D parameters for its complete specification, an observer seeks to estimate P other numerical properties of E. This paper describes how he can proceed when E is adequately described by one member m(E) of a Hilbert space [unk] of possible models of E, when he believes that the Hilbert norm of m(E) is very likely rather smaller than some known number M, and (except for section 6) when all the observed and sought-after properties of E are continuous linear functionals on [unk]. Section 6 treats Frechet-differentiable non-linear functionals. A later paper will reduce unbounded functionals on arbitrary topological linear spaces to the present case.

Journal Article↗

PubMed2000

Performance on a mirror-drawing task by non-right-handers.

Left-, mixed-, and right-handed (each n = 10, N = 30) adolescent boys who were classified on the basis of a hand preference inventory performed a mirror-drawing task with a bilateral transfer of a skill paradigm. Participants' hand preference and the magnitude of bilateral transfer of skill were assessed in terms of errors committed and time taken to complete the mirror-drawing task. Mixed-handed participants exhibited significantly less habit interference for mirror drawing, and they performed the task significantly faster than the left-handers did; the group difference was not significant for the frequency of errors committed. These groups did not differ in terms of the magnitude of bilateral transfer of skill; the trend, however, showed that the transfer of skill was minimum in mixed-handers. These findings extend the theory that mixed-handed participants' inability to transfer motor skill from one hand to the other could be attributable to their lack of a clear pattern of lateralization. Their ability to perform well either at initial or later trials may be a function of less interference from their normal motor habits.

Adolescent↗

PubMed2002

Effects of musical training on speech-induced modulation in corticospinal excitability.

We investigated the effect of previous musical training on lateralization of language as indexed by the effects of reading aloud on the modulation of motor evoked potentials (MEPs) induced in the first dorsal interosseus muscles (FDI) by transcranial magnetic stimulation (TMS) of the primary motor cortex. We studied 13 right-handed subjects, seven musicians who had been playing a musical instrument for >10 years and six controls who had never studied a musical instrument. In all subjects, the amplitude of MEPs in the right FDI was facilitated by reading aloud. However, the musicians also showed significant facilitation in the left FDI, while controls did not. These results illustrate striking effects of musical training on lateralization of motor and language functions.

Adult↗

PubMed1993

Wada memory testing and hippocampal volume measurements in the evaluation for temporal lobectomy.

We examined the relationship of Wada memory performance and MRI hippocampal volume measurements to laterality of ultimate seizure localization in 20 patients with complex partial seizures who later underwent temporal lobectomy. Discriminant function analysis employing both Wada memory test asymmetries and hippocampal volume asymmetries correctly classified 100% of the patients into left and right temporal lobe groups. Wada memory asymmetries alone correctly classified 90% of the sample (80% of the sample when the discriminant function included all patients except the one being classified), and hippocampal volume asymmetries alone correctly classified 90% of the patients. A significant correlation was present between Wada memory asymmetries and hippocampal volume asymmetries (r = 0.78), indicating that structural evidence of reduced hippocampal volume has a functional correlate reflected by Wada memory performance. These data suggest that the combination of functional and structural measures is of value in the preoperative evaluation for epilepsy surgery.

Adult↗

PubMed2003

Evidence of hemispheric specialization in marmosets (Callithrix penicillata) using tympanic membrane thermometry.

Recent studies have employed tympanic thermometry to assess lateralization of cognitive and emotional functions in primates. However, no studies using this technique have investigated the possibility of hemispheric specialization in New World monkeys. Therefore, the aim of the present study was to investigate tympanic membrane (TM) temperature asymmetries and their possible correlation with stress responses in marmosets (Callithrix penicillata). Infrared TM thermometry was completed bilaterally in 24 animals (14 males and 10 females) during a stressful situation of capture and restraint. There were no significant differences between gender. A significant negative correlation was observed between TM temperature of the right ear and the number of captures (r = -0.633; P<0.001). Subjects with a more frequent previous history of captures (5 to 9 captures; N = 11) showed lower TM temperature when compared to those with fewer previous captures (1 to 4 captures; N = 13). No differences were observed for the left TM temperature. These results suggest that under intense emotional challenge (capture and restraint) there is a stronger activation of the neural structures situated in the right brain hemisphere. Taken together, the data reveal for the first time evidence of hemispheric specialization in emotional physiological processing in a New World monkey.

Animals↗

PubMed1989

The Hoffmann reflex from the flexor pollicis longus of the thumb in left-handed subjects: spinal motor asymmetry and supraspinal facilitation to Cattell's intelligence test.

The spinal motor asymmetry was studied in left-handers. Hand preference was assessed by Geschwind scores (GS), and hand skill by peg moving task, the reflex responses were recorded from the long flexor muscle of the thumb. The H-reflex could be elicited by averaging during cortico-spinal facilitation (voluntary isometric force). The Cattell's Culture Fair Intelligence Test was used to assess the individual differences in mental abilities. H-reflexes were found to be significantly larger on the left than the right side. The amplitude of H-reflex increased linearly with force applied to transducer by the thumb. This facilitation was more pronounced for the left than the right reflexes. Removal of the visual visual input caused facilitation in H-reflex (supraspinal disinhibition). Post-activation potentiation was also observed in H-reflex. There was a positive linear correlation between the degree of left-hand preference (-GSs) and left-hand skill. The correlation for the right-hand skill was not significant. There was a linear correlation between the degree of left-hand preference and the right minus left hand skill. There was an inverse correlation between left-hand skill and H-reflex from left. The correlation for the right side did not reach the 5% significance level. The force-reflex relation did not show any significant change to IQ for the right H-reflex. The left H-reflexes were significantly larger in subjects with high IQ than those with low IQ. The regression line and its slope for the force-reflex relation on the left was found to be higher in subjects with high IQ than those with low IQs. There was a positive linear relationship between IQ and H reflex from left. The correlation for the right side was not as pronounced as that for the left side. The left minus right H reflex was also positive linearly correlated with IQ. These results provide further evidence for the psycho-motor hypothesis (Tan. 1988b) as well as the spinal motor asymmetry to handedness. It was suggested that lateralization of cognitive and motor functions would be essential to create subjects with high psychomotor capacity.

Adolescent↗

PubMed2005

Adolescence. Alcohol sensitivity, tolerance, and intake.

Research conducted in laboratory animals has shown adolescents to be less sensitive to numerous ethanol effects that may serve as cues to limit intake, including effects evident during intoxication (e.g., ethanol-induced motor impairment, anxiolysis, social impairment, and sedation), as well as during the post-intoxication period (e.g., "hangover"-associated anxiogenesis). Conversely, adolescents are more sensitive than adults to a few ethanol effects, including ethanol-induced social facilitation and impairments in hippocampal long-term-potentiation. These age-specific ethanol sensitivities are not simply related to developmental differences in ethanol pharmacokinetics. Instead, they appear related in part to an ontogenetic decline in expression of within session (acute) tolerance and to differential rates of development of neural systems underlying different actions of ethanol. Relatively high levels of ethanol intake often seen in adolescent rodents and their human counterparts may be related not only to an attenuated sensitivity of adolescents to negative cues that normally serve to limit drinking, but also their greater sensitivity to both the facilitation of social behavior by ethanol and the stimulation of ethanol intake by social experiences. Although data are sparse, studies in laboratory animals hint that under some circumstances chronic adolescent exposure to ethanol may influence ongoing neural maturation and later neural, cognitive, and behavioral functioning, including later sensitivity to and propensity to use ethanol. Recommendations for further research are discussed.

Adolescent↗

PubMed1981

[Radionuclide methods in evaluating the sequelae of gastrectomy for cancer].

The fat, protein and B12 absorption by the liver, kidney and small intestine was studied by radionuclide methods in gastric cancer patients during the preoperative period as well as within 15-30 days, 3-12 months and for more than a year following gastrectomy. It was observed that the function of the kidney, liver and B12 absorption was disturbed during the preoperative period. Gastrectomy caused a marked depression of the renal, hepatic and small intestinal function. During later periods following gastrectomy, these functions improved but were not restored to normal.

Follow-Up Studies↗

PubMed2006

Asymmetries of cortical shape: Effects of handedness, sex and schizophrenia.

Some evidence suggests that sex, handedness and disease processes associated with schizophrenia affect the magnitude and/or direction of structural brain asymmetries. There are mixed findings, however, on how these factors influence cerebral torque, when torque is assessed with linear or volumetric measurements. We obtained MRI data from 67 healthy (30 males, 10 non-dextrals) and 84 schizophrenia subjects (60 males; 16 non-dextrals) and applied cortical pattern matching to spatially relate and compare differences in the surface morphology of the two cerebral hemispheres at high spatial resolution. Asymmetry indices, computed at thousands of matched hemispheric locations, were used to examine effects of sex, handedness and schizophrenia on hemispheric shape asymmetries while controlling for age and the other factors. Highly significant and discriminative right-frontal and left parietal-occipital surface expansions and protrusions (petalias) were mapped within groups. Although hemispheric shape asymmetries appeared less pronounced within female non-dextrals, asymmetry indices were not shown to differ significantly across sex, hand preference or diagnosis, or to reveal interactions of handedness with sex or diagnosis. Our 3D maps of spatially detailed anterior and posterior hemispheric shape asymmetries reflect subtle geometric distortions in hemispheric surface morphology that cannot be characterized with 2D or volumetric methods. Inter-individual variations in hemispheric torque appear minimally influenced by sex, dextrality or disease status. Biological factors driving language dominance or other lateralized brain functions dissociable from handedness, may more closely relate to hemispheric shape asymmetries, while the lateralization of other discrete brain regions may be more influenced by sexually dimorphic factors or by schizophrenia pathophysiology.

Cerebral Cortex↗

PubMed2005

Interaction in the perceptual processing of interaural time and level differences.

Phillips and Hall [Psychophysical evidence for adaptation of central auditory processors for interaural differences in time and level, Hear. Res., 202 (2005) 188-199.] recently described the frequency-specific, selective adaptation of perceptual channels for interaural differences in level (ILD) and time (ITD). Psychometric functions for laterality based on ITD or ILD were obtained before and after exposure to adaptor tones of two frequencies presented alternately and highly lateralized to opposite sides. Following adaptation, points of perceived centrality (PPCs) were displaced towards the sides of the adaptor tones, and in opposite directions for the two frequencies. That is, laterality judgements showed a shift away from the adapted side, particularly for test cue values near the middle of the range. These data were congruent with a two-channel, opponent-process model of sound laterality coding. The present study used the same general paradigm to explore the independence of perceptual ITD and ILD processing. Psychometric functions for laterality based on ITD or ILD were obtained for each of two frequencies concurrently, before and after exposure to adaptor tones lateralized using the complementary cue. Once again, PPCs derived from the psychometric functions were displaced towards the sides of the adaptor tones, consistent with an opponent-process account of sound laterality coding. The size of the adaptation effect was at least as great as that described in the earlier study. Thus, a quarter cycle ITD adapting stimulus effected a 3 dB shift in the mean ILD-based PPC, and a 12 dB ILD adapting stimulus effected a 100 micros shift in the mean ITD-based PPC. These data offer new evidence concerning interaction in the processing of ITDs and ILDs.

Adaptation, Physiological↗

PubMed2002

Palate re-repair revisited.

OBJECTIVE: To analyze the results of a consecutive series of palate re-repairs performed using the operating microscope and identify predictive factors for outcome. DESIGN: Prospective data collection, with blind assessment of randomized recordings of speech and velar function on lateral videofluoroscopy and nasendoscopy. PATIENTS: One hundred twenty-nine consecutive patients with previously repaired cleft palates and symptomatic velopharyngeal incompetence (VPI) and evidence of anterior insertion of the levator veli palatini underwent palate re-repairs by a single surgeon from 1992 to 1998. Syndromic patients, those who had significant additional surgical procedures at the time of re-repair (23 patients), and all patients with inadequate pre- or postoperative speech recordings were excluded, leaving a total of 85 patients in the study. INTERVENTIONS: Palate re-repairs, with radical dissection and retropositioning of the velar muscles, were performed using the operating microscope with intraoperative grading of anatomical and surgical findings. MAIN OUTCOME MEASURES: Pre- and postoperative perceptual speech assessments using the Cleft Audit Protocol for Speech (CAPS) score, measurement of velar function on lateral videofluoroscopy, and assessment of nasendoscopy recordings. RESULTS: There were significant improvements in hypernasality, nasal emission, and nasal turbulence and measures of velar function on lateral videofluoroscopy, with improvement in the closure ratio, velopharyngeal gap at closure, velar excursion, velar movement angle, and velar velocity. CONCLUSIONS: Palate re-repair has been shown to be effective in treating VPI following cleft palate repair, both in patients who have not had an intravelar veloplasty and those who have had a previous attempt at muscle dissection and retropositioning. Palate re-repair has a lower morbidity and is more physiological than a pharyngoplasty or pharyngeal flap.

Adolescent↗