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Biomedical subjects

H Neville

Publications and source records attributed to H Neville.

16 recordsLinked to original sources
PubMed2001

Impact of early deafness and early exposure to sign language on the cerebral organization for motion processing.

This functional magnetic resonance imaging study investigated the impact of early auditory deprivation and/or use of a visuospatial language [American sign language (ASL)] on the organization of neural systems important in visual motion processing by comparing hearing controls with deaf and hearing native signers. Participants monitored moving flowfields under different conditions of spatial and featural attention. Recruitment of the motion-selective area MT-MST in hearing controls was observed to be greater when attention was directed centrally and when the task was to detect motion features, confirming previous reports that the motion network is selectively modulated by different aspects of attention. More importantly, we observed marked differences in the recruitment of motion-related areas as a function of early experience. First, the lateralization of MT-MST was found to shift toward the left hemisphere in early signers, suggesting that early exposure to ASL leads to a greater reliance on the left MT-MST. Second, whereas the two hearing populations displayed more MT-MST activation under central than peripheral attention, the opposite pattern was observed in deaf signers, indicating enhanced recruitment of MT-MST during peripheral attention after early deafness. Third, deaf signers, but neither of the hearing populations, displayed increased activation of the posterior parietal cortex, supporting the view that parietal functions are modified after early auditory deprivation. Finally, only in deaf signers did attention to motion result in enhanced recruitment of the posterior superior temporal sulcus, establishing for the first time in humans that this polymodal area is modified after early sensory deprivation. Together these results highlight the functional and regional specificity of neuroplasticity in humans.

Adolescent↗
PubMed2001

Phase III randomized trial of gabapentin in patients with amyotrophic lateral sclerosis.

BACKGROUND: Preclinical and clinical studies of gabapentin in patients with ALS led the authors to undertake a phase III randomized clinical trial. METHODS: Patients were randomly assigned, in a double-blinded fashion, to receive oral gabapentin 3,600 mg or placebo daily for 9 months. The primary outcome measure was the average rate of decline in isometric arm muscle strength for those with two or more evaluations. RESULTS: Two hundred four patients enrolled, 196 had two or more evaluations, and 128 patients completed the study. The mean rate of decline of the arm muscle strength was not significantly different between the groups. Moreover, there was no beneficial effect upon the rate of decline of other secondary measures (vital capacity, survival, ALS functional rating scale, timed walking) nor was there any symptomatic benefit. In fact, analysis of the combined data from the phase II and III trials revealed a significantly more rapid decline of forced vital capacity in patients treated with gabapentin. CONCLUSION: These data provide no evidence of a beneficial effect of gabapentin on disease progression or symptoms in patients with ALS.

Acetates↗
PubMed2000

Visual attention to the periphery is enhanced in congenitally deaf individuals.

We compared normally hearing individuals and congenitally deaf individuals as they monitored moving stimuli either in the periphery or in the center of the visual field. When participants monitored the peripheral visual field, greater recruitment (as measured by functional magnetic resonance imaging) of the motion-selective area MT/MST was observed in deaf than in hearing individuals, whereas the two groups were comparable when attending to the central visual field. This finding indicates an enhancement of visual attention to peripheral visual space in deaf individuals. Structural equation modeling was used to further characterize the nature of this plastic change in the deaf. The effective connectivity between MT/MST and the posterior parietal cortex was stronger in deaf than in hearing individuals during peripheral but not central attention. Thus, enhanced peripheral attention to moving stimuli in the deaf may be mediated by alterations of the connectivity between MT/MST and the parietal cortex, one of the primary centers for spatial representation and attention.

Adolescent↗
PubMed2000

III. Electrophysiological studies of face processing in Williams syndrome.

Williams Syndrome (WMS) is a genetically based disorder characterized by pronounced variability in performance across different domains of cognitive functioning. This study examined brain activity linked to face-processing abilities, which are typically spared in individuals with WMS. Subjects watched photographic pairs of upright or inverted faces and indicated if the second face matched or did not match the first face. Results from a previous study with normal adults showed dramatic differences in the timing and distribution of ERP effects linked to recognition of upright and inverted faces. In normal adults, upright faces elicited ERP differences to matched vs. mismatched faces at approximately 320 msec (N320) after the onset of the second stimulus. This "N320" effect was largest over anterior regions of the right hemisphere. In contrast, the mismatch/match effect for inverted faces consisted of a large positive component between 400 and 1000 msec (P500) that was largest over parietal regions and was symmetrical. In contrast to normal adults, WMS subjects showed an N320-mismatch effect for both upright and inverted faces. Additionally, the WMS subjects did not display the N320 right-hemisphere asymmetry observed in the normal adults. WMS subjects also displayed an abnormally small negativity at 100 msec (N100) and an abnormally large negativity at 200 msec (N200) to both upright and inverted faces. This ERP pattern was observed in all subjects with WMS but was not observed in the normal controls. These results may be linked to increased attention to faces in subjects with WMS and might be specific to the disorder. These results were consistent with our ERP studies of language processing in WMS, which suggested abnormal cerebral specialization for spared cognitive functions in individuals with WMS.

Adolescent↗
PubMed1995

Identification, tissue-specific expression, and subcellular localization of the 80- and 71-kDa forms of myotonic dystrophy kinase protein.

The protein product of the myotonic dystrophy (DM) gene is a putative serine-threonine protein kinase (DM kinase). Previous reports have characterized the DM gene product as various 50-62-kDa proteins. The predicted protein size from DM cDNA sequence is 69 kDa. We therefore expressed a full-length recombinant human DM kinase protein and compared its size and expression to heart, cardiac Purkinje fibers, and skeletal muscle from normal and DM subjects. Recombinantly expressed DM kinase and endogenous DM kinase in human heart, displayed two immunoreactive DM kinase proteins with apparent molecular sizes of 71 and 80 kDa, suggesting that these prior reports are incorrect. In cardiac Purkinje fibers the 71-kDa protein was the major form, and in skeletal muscle the 80-kDa protein was the major form. Immunostaining showed DM kinase localized to neuromuscular junctions in skeletal muscle and intercalated discs in heart and Purkinje fibers. DM subjects showed low abundance of DM kinase in heart and skeletal muscle, suggesting haplotype insufficiency as a potential mechanism for disease expression. These studies describe differential expression of two protein forms of DM kinase, which are localized to specialized cellular structures associated with impulse transmission.

Animals↗
PubMed1988

Isolated vitamin E deficiency in the absence of fat malabsorption--familial and sporadic cases: characterization and investigation of causes.

We observed four young adults, including three siblings, with a progressive neurologic disorder that developed over the first two decades. Electrophysiologic studies revealed mildly delayed nerve conduction, decreased amplitudes of sensory action potentials, and sensory delay in the posterior columns. Known causes of similar neurologic disorders were excluded. Although vitamin E deficiency was well documented, intestinal absorption and plasma lipoprotein transport of vitamin E were normal. Incubation studies in vitro failed to identify a plasma factor causing destruction of circulating vitamin E. There was no clinical or laboratory evidence of steatorrhea caused by gastrointestinal, hepatic, or pancreatic disease. Plasma lipoproteins, apolipoprotein B, and adipose tissue fatty acid composition were normal. Oral vitamin E therapy restored serum levels to normal and caused neurologic improvement in two patients. We postulate that an inherited defect in hepatocyte secretion of vitamin E into lipoproteins may account for this disorder, which occurs in sporadic cases as well as in siblings.

Absorption↗
PubMed1987

Friedreich's disease: V. Variant form with vitamin E deficiency and normal fat absorption.

A 30-year-old woman was thought to have Friedreich's disease because of progressive ataxia, dysarthria, and titubation from age 3 years. Her diet was normal, and there were neither symptoms nor laboratory evidence of liver disease or fat malabsorption. Serum vitamin E content and the ratio of serum vitamin E to total serum lipid were very low, but serum vitamin A, cholylglycine, and lipid levels were normal, as was an oral vitamin E tolerance test. Muscle biopsy showed the lysosomal inclusions of vitamin E deficiency. Mitochondria had normal oxidative phosphorylation using polarographic assays. The cause of her vitamin E deficiency was unknown.

Adult↗
PubMed1982

Event-related brain potentials are different in individuals at high and low risk for developing alcoholism.

Event-related brain potentials (ERPs) from normal drinkers with and without a family history of alcoholism were compared. Three separate groups of 10 subjects each (5 with and 5 without a family history of alcoholism) ingested either a placebo or ethanol at 0.56 or 0.94 g/kg. In each comparison, ERP components elicited in conjunction with subjects' decisions about task-relevant stimuli were of significantly reduced amplitude in individuals with a family history of alcoholism. Additionally, both the latency of the positive component and reaction times to correctly detected targets were significantly later in individuals with a positive history of alcoholism than in those without such a history. These group differences were apparent both with and without a challenge of alcohol. The data suggest that brain functions are different in individuals at high and low risk for the development of alcoholism (i.e., those with and without a family history of alcoholism, respectively).

Alcoholism↗
PubMed1982

Recognition and surprise alter the human visual evoked response.

Event-related brain potentials (ERPs) to colored slides contained a late positive component that was significantly enhanced when adults recognized the person, place, or painting in the photograph. Additionally, two late components change in amplitude, corresponding to the amount of surprise reported. Because subjects received no instructions to differentiate among the slides, these changes in brain potentials reflect natural classifications made according to their perceptions and evaluations of the pictorial material. This may be a useful paradigm with which to assess perception, memory, and orienting capacities in populations such as infants who cannot follow verbal instructions.

Brain↗
PubMed1980

Studies on the retina and the pigment epithelium in hereditary canine ceroid lipofuscinosis. III. Morphologic abnormalities in retinal neurons and retinal pigmented epithelial cells.

Studies of the retina in 6- and 22-month-old English setters with progressive blindness, ataxia, and muscle weakness demonstrated a marked accumulation of abnormal cytosomes within neurons and retinal pigmented epithelial cells. Ganglion cells contained abundant cytosomes with evenly spaced stacks of membranes; bipolar and amacrine cell cytosomes consisted of dense, amorphous material with closely spaced configurations of light and dark lines; cytosomes within photoreceptor cells contained faintly staining curved profiles. All three cytosomes resembled those previously reported in brain neurons of CCL dogs. In retinal pigmented epithelial cells, there were prominent accumulations of lamellar fragments, either free in the cytoplasm or incorporated into melanin granules. These retinal abnormalities are likely to be related to deficiences of peroxidase and defects of lipid peroxidation. The pathologic and biochemical changes seen in these dogs are similar in many respects to those reported in human patients with Batten disease. As such, these dogs provide a convenient model for the study disease mechanisms and for therapeutic approaches to blindness in Batten disease.

Animals↗
PubMed1977

Detection of canine Batten disease with the EEG.

Although it has been suggested that EEG changes appear early in the course of human Batten disease, these observations have been made only after the onset of clinical abnormalities and without immediate pathological correlation. In this brief report we have been able to document for the first time, abnormal EEGs in a strain of dogs proposed as a model for Batten disease. The degree of abnormality in the canine EEG correlated with the degree of clinical involvement and with the presence of pathological inclusions, resembling those seen in human Batten disease. In younger dogs, abnormal EEGs were obtained even before clinical manifestations of the disease. The large amplitude discharges reported with photic stimulation in children with the late infantile form of Batten disease were not elicited in the dog model. However, this dog strain is a model for the juvenile rather than the late infantile form although similarities between dogs and both forms of human Batten disease were seen. It is proposed that the EEG is both a method for early detection of this disease as well as a tool ot measure the degree of involvement. This information may be of use in relation to future therapeutic trials.

Animals↗
PubMed1976

Monitoring of visual function during parasellar surgery.

Damage to the visual system is an unfortunate complication of surgery in the area of the optic chiasm. It is now possible tomonitor the functional status of the visual system intreoperatively at regulat intervals. This is accomplished by recording the Visual Evoked Response to flashes of light from light-emitting-eiodes. These diodes are embedded in a special plastic shell which inserts under the eye lids of each eye. Since the light comes from the diodes in the plastic shell, there is no need to disturb the surgical procedure when a test run is desired. A record is obtained by averaging 100 three-per-second flashes.

Adenoma, Acidophil↗
PubMed1975

Thyroid peroxidase deficiency in Batten-Spielmeyer-Vogt disease.

Thyroid tissue from two patients with Batten-Spielmeyer-Vogt disease (BSV) was studied for peroxidase enzyme activity and for morphological abnormalities by light and electron microscopy. Diagnosis was confirmed by the demonstration of intracytoplasmic material identical to that described in other reported cases of BSV. There was a substantial decrease in peroxidase activity in the thyroid tissue from both patients. An abnormally low level of peroxidase activity had previously been demonstrated in the white blood cells of these patients. Thyroid biopsy offers obvious advantages over brain biopsy, provides adequate tissue for enzyme analysis, and allows the demonstration of the intracytoplasmic structures characteristic of BSV.

Autopsy↗