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Results for “Pattern Recognition, Physiological”

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At least 253 records · Page 14Linked to original sources
PubMed2002

Analyzing the physiological signature of anabolic steroids in cattle urine using pyrolysis/metastable atom bombardment mass spectrometry and pattern recognition.

Pyrolysis coupled to metastable atom bombardment (MAB) and time-of-flight mass spectrometry (TOFMS) is used for generating mass spectra from bovine urine samples obtained from cattle treated with anabolic steroids. These spectra constitute fingerprints, which can be discriminated by multivariate statistical analysis. Four main conclusions can be drawn from this work: (i) The use of different metastable gases, such as Xe*, Kr*, or N2*, as an energy-tunable ionization beamline allows control of the internal energy and the dissociation processes of the produced odd electron molecular ions, thus giving rise to complementary mass spectra fingerprints. (ii) A variable transformation depending on the biofluid matrix suitably contracts the frequency distribution of the generated data for low m/z ratios holding information related to endogenous metabolites encountered in urine. (iii) Coupling variable selection to statistical pattern recognition methods results in low error rates (< 1%) for predicting MAB mass fingerprints, especially using lineardiscriminant analysis (LDA). (iv) LDA discriminates controls from treated animals and also correlates to quantitative physiological responses induced by anabolic steroids. This work shows that Py-MAB-TOFMS could be a suitable method for complementary monitoring anabolic use in sports, medicine, and cattle breeding, as well as monitoring many other long-lasting although weak physiological disruptions.

Anabolic Agents↗
PubMed2003

Models for neurovestibular adaptation.

Dynamic models have played a more prominent role in the vestibular and oculomotor field than in any other branch of physiology. The ease of identification of input and output variables and the challenge of multi-loop, multi-axis adaptive control has attracted numerous modelers from engineering and shaped behavioral and neurophysiological experimental programs. In particular, the adaptive characteristics of the neurovestibular system have generated continuing speculation as to mechanisms. This treatment of adaptation and multi-sensor integration covers the development and application of such models, principally in the author's laboratory. It emphasizes the continuing relevance of both "model reference" and "error pattern recognition" notions of adaptive control.

Adaptation, Physiological↗
PubMed1996

Twenty-four-hour pattern of hunger sensation in obesity complicated by type 2 diabetes mellitus: a pattern recognition by spectral analysis.

Hunger sensation (HS) in humans physiologically shows intraday (circadian) and within-day (ultradian) recursivity. This intrinsic periodicity was investigated by applying the cosinor method and spectral analysis to the 24-hour profile of HS (orexigram) derived by a self-rating score (from 1 to 10 hunger units [HU]) recorded every half-hour. The study of circadian and ultradian recursivity on the orexigram was performed in 30 diabetic obese patients ([DOPs], 14 men and 16 women aged 22 to 62 years; body weight, 77 to 130 kg; body mass index, 31-47). The control group consisted of 30 clinically healthy subjects ([CHS], 15 men and 15 women aged 21 to 60 years; body weight, 65 to 72 kg; body mass index, 23 to 25). DOPs showed two types of orexigrams in which hunger was felt with limitation to the diurnal part of the day or with extension to the night, respectively. The type 1 orexigram was characterized by a normal spectrum and circadian rhythm. The type 2 orexigram was characterized by subsidiary ultradian components associated with an abnormal elevation of the circadian mesor and a significant delay of the circadian phase, as the spectral analysis was indicative of a structural difference in the frequencies that sustain the intraday and within-day recursivity of the HS. Accordingly, DOPs can be recognized by their orexigram as "eurectic" or "hyperrectic" to indicate subjects with a normal or an exaggerated HS, respectively, during the 24-hour span.

Adult↗
PubMed2006

Targeted profiling: quantitative analysis of 1H NMR metabolomics data.

Extracting meaningful information from complex spectroscopic data of metabolite mixtures is an area of active research in the emerging field of "metabolomics", which combines metabolism, spectroscopy, and multivariate statistical analysis (pattern recognition) methods. Chemometric analysis and comparison of 1H NMR1 spectra is commonly hampered by intersample peak position and line width variation due to matrix effects (pH, ionic strength, etc.). Here a novel method for mixture analysis is presented, defined as "targeted profiling". Individual NMR resonances of interest are mathematically modeled from pure compound spectra. This database is then interrogated to identify and quantify metabolites in complex spectra of mixtures, such as biofluids. The technique is validated against a traditional "spectral binning" analysis on the basis of sensitivity to water suppression (presaturation, NOESY-presaturation, WET, and CPMG), relaxation effects, and NMR spectral acquisition times (3, 4, 5, and 6 s/scan) using PCA pattern recognition analysis. In addition, a quantitative validation is performed against various metabolites at physiological concentrations (9 microM-8 mM). "Targeted profiling" is highly stable in PCA-based pattern recognition, insensitive to water suppression, relaxation times (within the ranges examined), and scaling factors; hence, direct comparison of data acquired under varying conditions is made possible. In particular, analysis of metabolites at low concentration and overlapping regions are well suited to this analysis. We discuss how targeted profiling can be applied for mixture analysis and examine the effect of various acquisition parameters on the accuracy of quantification.

Metabolism↗
PubMed1992

Neural mechanisms of tactual form and texture perception.

In the last decade or so, there has been rapid movement toward the use of more complex stimuli in the study of perceptual function related to the hand. This review has focused on the neural mechanisms of form and texture perception. Evidence from neurophysiological and psychophysical studies in which static touch, scanning touch, and the Optacon were used indicate that the spatial acuity of the RA system may be as much as three times poorer than the SAI system, evidence that suggests that form perception is dominated by the SAI system. Pattern recognition behavior in a tactual letter recognition task appears to be directly related to the response properties of SAI afferent fibers. Psychophysical studies of roughness perception show that roughness magnitude is related to surface structure in an orderly manner. Because roughness varies along an intensive continuum, mean impulse rate in one or more of the afferent systems is the most obvious coding possibility. No satisfactory relationship between mean impulse rate and roughness has been observed, however. The strongest hypothesis is that tactual roughness perception is based on spatial variation in the SAI population response. The combined evidence from studies reviewed here suggests complementary roles for each of the afferent systems, which are presented as working hypotheses: The SAI system is the primary spatial system and is responsible for tactual form and roughness perception when the fingers contact a surface directly and for the perception of external events through the distribution of forces across the skin surface. The PC system is responsible for the perception of external events that are manifested through transmitted high-frequency vibrations of the kind that are critical in the use of objects as tools. The RA system is responsible for the detection and representation of localized movement between skin and a surface as well as for surface form and texture when surface variation is too small to activate the SAI afferents effectively.

Animals↗
PubMedDate not supplied

fMRI evidence for separable and lateralized prefrontal memory monitoring processes.

Source memory research suggests that attempting to remember specific contextual aspects surrounding prior stimulus encounters results in greater left prefrontal cortex (PFC) activity than simple item-based old/new recognition judgments. Here, we tested a complementary hypothesis that predicts increases in the right PFC with tasks requiring close monitoring of item familiarity. More specifically, we compared a judgment of frequency (JOF) task to an item memory task, in which the former required estimating the number of previous picture encounters and the latter required discriminating old from new exemplars of previously seen items. In comparison to standard old/new recognition, both source memory and the JOF task examined here require more precise mnemonic judgments. However, in contrast to source memory, cognitive models suggest the JOF task relies heavily upon item familiarity, not specific contextual recollections. Event-related fMRI demonstrated greater recruitment of right, not left, dorsolateral and frontopolar PFC regions during the JOF compared to item memory task. These data suggest a role for right PFC in the close monitoring of the familiarity of objects, which becomes critical when contextual recollection is ineffective in satisfying a memory demand.

Adolescent↗
PubMed1988

The pattern electroretinogram by skin electrodes: effect of spatial frequency and age.

Steady-state (8 Hz) pattern electroretinograms in response to sinusoidal gratings were recorded from 18 elder subjects (mean age 62.7 years) and 22 young subjects (mean age 27 years) by means of skin electrodes. All subjects were free from ocular pathology and their corrected visual acuity was 1.0 or better. In young subjects the second harmonic amplitude as a function of spatial frequency is spatially tuned, with a maximum at around 1.7 c/deg. The response of elder subjects is significantly (P less than 0.05) reduced over the whole range of spatial frequency as compared with that of younger ones. This decrease is more marked (P less than 0.01) at intermediate spatial frequencies, resulting in a shallower tuning. The response phase is not significantly different between young and elder subjects.

Adult↗
PubMed1979

Pattern discrimination and visuomotor behavior following rotation of one or both eyes in kittens and in adult cats.

Sixteen cats, each of which had one or both eyes rotated at the time of natural eye opening (group K), were tested for visuomotor behavior and for learning and interocular transfer of two-choice visual discriminations. Their behavior was compared to that of two cats given monocular rotations in adulthood (group A) and to two normal controls (group N). These animals were all reared in the same colony. All cats, including those with monocular rotations up to 180 degrees and those with binocular rotations up to 80 degrees in each eye, showed good visuomotor behavior when using the rotated eye (i.e., with the normal eye covered). Both the group K and group A animals showed comparable visuomotor adaptation. All animals except those with monocular rotations of 180 degrees were able to learn several oriented pattern discriminations and showed considerable though incomplete interocular transfer of such information. The three animals with 180 degrees rotations were able to learn brightness, but not pattern discriminations. Seven further animals with large rotations were used for histological studies of the retina and primary visual pathways. Areas of reduced ganglion cell density were not observed in whole mounts of the retinae, nor were regions of reduced transport of 3H-proline from the retina to the lateral geniculate nuclei or superior colliculi detectable from autoradiographs.

Animals↗
PubMed1978

Fixation-sensitive areas in the eyes of the walking fly, Calliphora erythrocephala.

In Calliphora erythrocephala the visual fixation behaviour in one-eyed flies and partial blinded flies has been investigated. One-eyed flies show approximately the same stripe and edge fixation response as intact flies. Elimination of the frontal eye parts including the binocular field of vision does not effect the visual stripe fixation. On the other hand, if only the frontal areas of both eyes including the binocular field of vision are left open, no preferential direction can be observed (Fig. 1--3). The results imply the existence of a fixation-sensitive area of the eye located outside the binocular field of vision.

Animals↗
PubMed1978

The angular orientation of the movement detectors acting on the flight lift response in flies.

The lift response of houseflies Musca domestica in fixed flight to periodic gratings movins in 12 different orientations has been measured. Two projectors were arranged symmetrically to the flies stimulating successively 18 circular patches of 50 degrees (25 degrees) diameter (9 for each eye) in their visual field. The shapes of the lift responses measured as a function of the orientation of the moving grating varied when different patches in the visual field were stimulated. A qualitative comparison of these response curves leads to the conclusion that the orientation of the movement detecting substrate acting on the flight lift response varies as a function of the stimulated area in the visual field. A straightforward correlation between the geometry of the ommatidial pattern and the orientation of the movement detecting substrate valid for all stimulated areas of the compound eyes does not seem very likely.

Animals↗
PubMedDate not supplied

Tauberian-prony feature extraction technique for esophageal motility patterns.

For the esophageal contractile activity recorded during swallowing, a feature extraction scheme has been developed. It recognizes the time, duration, and amplitudes of local peaks for each peristaltic wave. The method is based on the Tauberian approximation for modeling waveforms as a sum of identically shaped pulses with different time delays and amplitudes. Initial conditions on the pulse properties are set and an optimal solution is sought. The method is completely automated and can be utilized for characterization and classification purposes.

Algorithms↗
PubMed1990

Honey bee cognition.

The visual memory of honey bees is stored pictorially. Bees will accept a mirror-image reversal of a familiar pattern in the absence of the original, but prefer the original over the reversal; the matching system of bees, therefore, does not incorporate a mirror-image ambiguity. Bees will not accept a rotation of a familiar vertical pattern, but readily recognize any rotation of a horizontal pattern; the context-specific ability to make a mental transformation seems justified by natural contingencies. Bees are able to construct and use cognitive maps of their home area, though it is possible to create conditions under which they lack useful cues. Other experiments suggest that recruits, having attended a dance in the hive specifying the distance and direction of a food source, can evaluate the "plausibility" of the location without leaving the hive; this suggests a kind of imagination.

Animals↗
PubMed1977

Computer interpreted fetal electroencephalogram: sharp wave detection and classification of infants for one year neurological outcome.

The presence of visually discernible sharp waves (SWs) in the fetal electroencephalogram (FEEG) has been found to be associated with abnormal neurological infant outcome, but no method of programmed SW detection for FEEG was available. In order to develop an algorithm for SW detection, the first and second derivatives for visually identified SWs and non-SWs were examined and five random variables chosen for discriminant function analysis (DFA). The resulting equation, incorporated into program logic along with logic for artifact rejection, produced classifications from 85% to 89% consistent with visual identifications, suggesting that the number of SWs/epoch (NSW) corresponds with visually identified SWs. In addition, in 61 cases using a threshold for NSW derived by DFA, computer recognized SWs were found to be significantly related to the overall visual interpretation of the tracings (P less than 0.005). Finally, NSW alone produced correct classification of 65.5% of infants for 1 year neurological outcome. The overall consistency was increased to as high as 80% using additional FEEG and neonatal data. These findings imply that some forms of brain damage are present before birth and can be detected during labor using FEEG.

Brain Diseases↗
PubMed1985

Pattern electroretinogram: use of noncorneal skin electrodes.

Pattern electroretinograms (ERGs) were recorded in three adults by a noncorneal electrode technique: silver-silver chloride skin electrodes attached to the inferior orbit of the left eye while the subject monocularly viewed a high contrast checker-board that reversed in contrast at a rate of 10 Hz. Recordings revealed pattern ERGs with an average amplitude of 1.5 microV. In addition, pattern ERGs were recorded as a function of spatial frequency and contrast of a square-wave grating. The results showed that an increase in spatial frequency or contrast yielded an increase in the amplitude of the pattern ERG. The results demonstrate that the pattern ERG can be recorded with a noncorneal electrode technique and that the noncorneal electrode technique is sensitive to changes in retinal function. Finally, it is demonstrated that the pattern ERG can transfer between the eyes such that the pattern ERG from a viewing eye can be recorded from an electrode placed below an occluded eye.

Adult↗
PubMed1983

Binocular and monocular optokinetic nystagmus in cats to textured visual patterns.

Binocular and monocular optokinetic nystagmus (OKN) to the motion of textured visual patterns have been studied in alert cats. In the temporonasal monocular stimulation at a velocity above 10 deg/sec and in the nasotemporal monocular stimulation, the motion of random noise or a checkerboard elicited larger slow phase eye velocities than the motion of stripes with regularly or randomly arranged vertical bars. To temporonasal stimulation at a velocity below 10 deg/sec, there were no differences in slow phase eye velocities according to the types of the textures. Binocular OKN showed similar texture preferences as temporonasal monocular OKN.

Animals↗
PubMed1987

Minimal spanning tree analysis of biological structures.

A new approach to study order and disorder in biological membranes and more generally in biological structures is developed. It is based on a graph constructed on the set points representing the position of particles. From this graph, which is called the minimal spanning tree, it is possible to deduce two parameters, namely the average length m and the standard deviation sigma which are characteristic of the repartition to be studied. The use of a diagram involving both m and sigma makes it possible to determine the degree of order by taking a simple reading in the (m, sigma) plane.

Cell Membrane↗