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At least 109 records · Page 6Linked to original sources
PubMed1999

Expanding the neurological examination using functional neurologic assessment: part II neurologic basis of applied kinesiology.

Functional Neurologic Assessment and treatment methods common to the practice of applied kinesiology are presented. These methods are proposed to enhance neurological examination and treatment procedures toward more effective assessment and care of functional impairment. A neurologic model for these procedures is proposed. Manual assessment of muscular function is used to identify changes associated with facilitation and inhibition, in response to the introduction of sensory receptor-based stimuli. Muscle testing responses to sensory stimulation of known value are compared with usually predictable patterns based on known neuroanatomy and neurophysiology, guiding the clinician to an understanding of the functional status of the patient's nervous system. These assessment procedures are used in addition to other standard diagnostic measures to augment rather than replace the existing diagnostic armamentarium. The proper understanding of the neurophysiologic basis of muscle testing procedures will assist in the design of further investigations into applied kinesiology. Accordingly, the neurophysiologic basis and proposed mechanisms of these methods are reviewed.

Gait↗
PubMed1984

Behavioral disorders in multiple sclerosis, temporal lobe epilepsy, and amyotrophic lateral sclerosis. An epidemiologic study.

Certain CNS diseases can produce specific behavioral abnormalities. We used a computer search technique to identify all inpatients at Strong Memorial Hospital, Rochester, NY, who had received diagnoses of multiple sclerosis (MS), temporal lobe epilepsy (TLE), and amyotrophic lateral sclerosis (ALS) between 1965 and 1978. We found 368 patients with MS, 402 patients with TLE, and 124 patients with ALS. These groups were matched against the Monroe County (New York) Psychiatric Register to determine patterns of behavioral pathology. Prevalence rates for psychiatric contact were not significantly different between MS and TLE (19.3% v 22.9%), but both were higher than the prevalence rate for ALS (4.8%). When behavioral patterns were assessed, patients with MS demonstrated a significantly higher rate of depressed affective disorders (61.97% of register matches) than patients with the other two diseases. Multiple sclerosis may present a neurologic model for mood disturbance.

Amyotrophic Lateral Sclerosis↗
PubMed1987

Computer simulations of neural information processing and the schizophrenia-mania dichotomy.

Recent developments in artificial intelligence use computer simulations of complex neural systems to model associative memory and gestalt-seeking during cognition. Perturbations imposed on such computer simulations caused catastrophic breakdowns of neural functioning. The resulting cognitive disturbances assumed two forms, one "schizophreniclike" and the other "maniclike." The former was induced by memory overload and resulted in misperceptions, loose associations, and also parasitic processing states that pathologically controlled the flow of associations. The latter was caused by increased randomness of neural activity, which induced "jumps" from one gestalt to another. The relationship between this differential model of psychotic disturbances and other studies of schizophrenia and mania were explored.

Arousal↗
PubMed1995

Symptoms of schizophrenia. Methods, meanings, and mechanisms.

BACKGROUND: The "group of schizophrenias," normally referred to with a single nominative, is phenomenologically heterogeneous. Its symptoms represent multiple psychological domains, including perception, inferential thinking, language, attention, social interaction, emotion expression, and volition. Studies of psychopathology have simplified this complex array in several ways, one of which is a subdivision into positive and negative symptoms. METHODS: This study examined the positive vs negative distinction in a sample of 243 patients with schizophrenia or schizophreniform disorder who were evaluated with the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms. A two-stage factor analysis was applied, beginning with a principal components analysis applying varimax rotation, followed by an extension analysis. The purpose of these analyses was to evaluate the correlational relationships of the various symptoms of schizophrenia. RESULTS: The results confirmed previous reports by our group and others suggesting that the symptoms of schizophrenia fall into three natural dimensions, as assessed by the correlational interrelationships: positive symptoms subdivide into psychotic and disorganized dimensions, while a third negative dimension also emerges. CONCLUSION: Because these dimensions have impressive consistency across studies, future work must examine their relationship to clinically relevant concepts such as prognosis or etiology and examine four different aspects: longitudinal course, neural mechanisms, relationship to treatment, and interrelationships in other pathological conditions.

Age of Onset↗
PubMed1995

A longitudinal study of symptom dimensions in schizophrenia. Prediction and patterns of change.

BACKGROUND: Factor analytic studies have suggested that the symptoms of schizophrenia may be divided into three uncorrelated dimensions. This study examines the longitudinal course of the symptoms of schizophrenia using this three-dimensional perspective. METHODS: The sample was composed primarily of neuroleptic-naive patients suffering from schizophrenia. Subjects were studied in a prospective longitudinal design, with comprehensive structured assessments at index, discharge, and 6-month intervals after discharge over a 2-year period. RESULTS: Negative symptoms were already relatively prominent at the time of index evaluation; they tended to remain stable throughout the follow-up period. The two dimensions of positive symptoms, psychoticism and disorganization, although prominent at index evaluation, declined over the course of the follow-up period and tended to be less stable. A longitudinal factor analysis was conducted to determine whether the changes in symptoms followed any consistent pattern. We observed that all three groups of symptoms tended to change in unison and independently from one another. CONCLUSIONS: These results suggest that these three dimensions of psychopathology show different patterns of exacerbation and remission during the course of schizophrenia. This independent pattern of evolution suggests that these three dimensions should be studied further with respect to response to treatment, cognitive mechanisms, psychosocial correlates, and neural substrates.

Adult↗
PubMed1999

A unitary model of schizophrenia: Bleuler's "fragmented phrene" as schizencephaly.

inding a unifying concept behind the diversity of signs and symptoms in schizophrenia is a central challenge to contemporary research. A neo-Bleulerian unitary model is described, which defines the illness as a neurodevelopmentally derived "misconnection syndrome," involving connections between cortical regions and the cerebellum mediated through the thalamus (the cortico-cerebellar-thalamic-cortical circuit [CCTCC]). An abnormality in this circuitry, normally used to coordinate both motor and mental activity, leads to misconnections in many aspects of mental activity, or "cognitive dysmetria." As Bleuler originally proposed, "thought disorder" is the primary defining feature of schizophrenia, rather than the more obvious signs and symptoms such as delusions and hallucinations. Cognitive dysmetria, or a disorder in the CCTCC, may provide a heuristic theoretical framework for strategies to explore etiology, pathophysiology, intervention, or prevention.

Animals↗
PubMed1997

Uniqueness of the S-cone pedicle in the human retina and consequences for color processing.

The purpose of this study was to investigate more fully the shape and content of ribbons and synapses to second-order neurons in the short-wavelength cone (S-cone, blue cone) pedicle and to learn more concerning the uniqueness of the S-cone system in the primate retina. A piece of well-fixed peripheral human retina (10 mm, 35 degrees nasal to the fovea) was serially thick sectioned in the tangential plane from the level of the outer segments to the tops of the cone pedicles. Then serial electron microscope (EM) sections were collected through the whole depth of the pedicle-occupying region into the neuropil of the outer plexiform layer (OPL). The resultant EM micrograph montages of a large field of cone pedicles were perused, and S-cone pedicles were identified. Serial micrographs of a single S-cone pedicle, picked out of the montages, were digitized and reconstructed by computer three-dimensional methods. The S-cone pedicle arose from a slightly oblique axon and projected 0.5-1 microm more vitread in the OPL than other cone pedicles. It was bilobed in shape, with synaptic invaginations and ribbons in both lobes. No cone-contacting telodendria projected from the S-cone pedicle itself, but a small number of neighboring cones sent telodendria to its surface to make small gap junctions. Neighboring rod spherules also made small gap junctions. Four robust bipolar cell dendrites, most likely from S-cone-specific bipolar cells, made synapses at ribbons and basal (distal) junctions. A small number of other bipolar cell dendrites made narrow-cleft basal junction only. The majority of lateral elements were thought to be from HII horizontal cells, and a minority from HI horizontal cells. We conclude that the S-cone pedicle has a unique morphology and connectivity to second-order neurons that makes it quite different from the other two longer wavelength cone systems, and we speculate on the consequences for color processing in the visual system in general.

Adult↗
PubMed1998

Influence of skull anisotropy for the forward and inverse problem in EEG: simulation studies using FEM on realistic head models.

For the sake of realism in the description of conduction from primary neural currents to scalp potentials, we investigated the influence of skull anisotropy on the forward and inverse problems in brain functional imaging with EEG. At present, all methods available for cortical imaging assume a spherical geometry, or when using realistic head shapes do not consider the anisotropy of head tissues. However, to our knowledge, no study relates the implication of this simplifying hypothesis on the spatial resolution of EEG for source imaging. In this paper, a method using finite elements in a realistic head geometry is implemented and validated. The influence of erroneous conductivity values for the head tissues is presented, and results show that the conductivities of the brain and the skull in the radial orientation are the most critical ones. In the inverse problem, this influence has been evaluated with simulations using a distributed source model with a comparison of two regularization techniques, with the isotropic model working on data sets produced by a nonisotropic model. Regularization with minimum norm priors produces source images with spurious activity, meaning that the errors in the head model totally annihilate any localization ability. But nonlinear regularization allows the accurate recovery of simultaneous spots of activity, while the restoration of very close active regions is profoundly disabled by errors in the head model. We conclude that for robust cortical source imaging with EEG, a realistic head model taking anisotropy of tissues into account should be used.

Anisotropy↗
PubMed1998

Modeling hemodynamic response for analysis of functional MRI time-series.

The standard Gaussian function is proposed for the hemodynamic modulation function (HDMF) of functional magnetic resonance imaging (fMRI) time-series. Unlike previously proposed parametric models, the Gaussian model accounts independently for the delay and dispersion of the hemodynamic responses and provides a more flexible and mathematically convenient model. A suboptimal noniterative scheme to estimate the hemodynamic parameters is presented. The ability of the Gaussian function to represent the HDMF of brain activation is compared with Poisson and Gamma models. The proposed model seems valid because the lag and dispersion values of hemodynamic responses rendered by the Gaussian model are in the ranges of their previously reported values in recent optical and fMR imaging studies. An extension of multiple regression analysis to incorporate the HDMF is presented. The detected activity patterns exhibit improvements with hemodynamic correction. The proposed model and efficient parameter estimation scheme facilitated the investigation of variability of hemodynamic parameters of human brain activation. The hemodynamic parameters estimated over different brain regions and across different stimuli showed significant differences. Measurement of hemodynamic parameters over the brain during sensory or cognitive stimulation may reveal vital information on physiological events accompanying neuronal activation and functional variability of the human brain, and should lead to the investigation of more accurate and complex models.

Brain↗
PubMed2000

Mathematical/computational challenges in creating deformable and probabilistic atlases of the human brain.

Striking variations in brain structure, especially in the gyral patterns of the human cortex, present fundamental challenges in human brain mapping. Probabilistic brain atlases, which encode information on structural and functional variability in large human populations, are powerful research tools with broad applications. Knowledge-based imaging algorithms can also leverage atlased information on anatomic variation. Applications include automated image labeling, pathology detection in individuals or groups, and investigating how regional anatomy is altered in disease, and with age, gender, handedness and other clinical or genetic factors. In this report, we illustrate some of the mathematical challenges involved in constructing population-based brain atlases. A disease-specific atlas is constructed to represent the human brain in Alzheimer's disease (AD). Specialized strategies are developed for population-based averaging of anatomy. Sets of high-dimensional elastic mappings, based on the principles of continuum mechanics, reconfigure the anatomy of a large number of subjects in an anatomic image database. These mappings generate a local encoding of anatomic variability and are used to create a crisp anatomical image template with highly resolved structures in their mean spatial location. Specialized approaches are also developed to average cortical topography. Since cortical patterns are altered in a variety of diseases, gyral pattern matching is used to encode the magnitude and principal directions of local cortical variation. In the resulting cortical templates, subtle features emerge. Regional asymmetries appear that are not apparent in individual anatomies. Population-based maps of cortical variation reveal a mosaic of variability patterns that segregate sharply according to functional specialization and cytoarchitectonic boundaries.

Aged↗
PubMed1997

Motor unit number estimation by spatial-temporal summation of single motor unit potentials.

Current techniques for motor unit number estimation (MUNE) rely on the amplitude of the compound muscle action potential (CMAP) evoked by supramaximal stimulation and mean amplitude of single motor unit potentials (SMUPs). The phase cancellation during summation is not considered. We developed a technique to address this issue. Slow and fast types of motor unit potentials were collected from 5 normal subjects from their abductor pollicis brevis muscles by low-level voluntary contractions, and near-threshold nerve stimulation, respectively. Two of each type of SMUPs were used as templates for reconstructing the best fitted CMAP using a feed-forward neural network. The total number of SMUPs simulated from the four templates during the reconstruction served as MUNE. The mean MUNE was 222 +/- 98. The technique is simple and noninvasive, and may be applied in the future for MUNE in patients.

Action Potentials↗