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PubMed1990

Detection of binding sites for biotinylated neoglycoproteins and heparin (endogenous lectins) during cerebellar ontogenesis in the rat.

Endogenous carbohydrate-binding sites were studied during rat cerebellar development on sections of fixed tissue using synthetic tools, biotinylated neoglycoproteins, in conjunction with subsequent avidinperoxidase staining. Neoglycoproteins were constructed by chemically coupling the histochemically pivotal carbohydrate moieties to an inert carrier protein. The sugar part of the neoglycoproteins included common constituents of the carbohydrate part of cellular glycoconjugates, namely mannose, galactose, fucose, N-acetyl-glucosamine, N-acetylgalactosamine and N-acetyl-neuraminic acid to probe for the presence of respective endogenous receptors. Heparin was biotinylated after mild cyanogen bromide activation and aminoalkylation. Specific positive reactions were obtained for all neoglycoproteins and heparin. The staining pattern with the individual probes disclosed variable developmental regulation. Consequently, these results suggest that recognition processes during cerebellar development may include several types of carbohydrate determinants. In two instances, the binding of neoglycoproteins could be compared to endogenous lectin-specific antibodies. Despite a significant extent of accordance the comparison revealed notable differences. These differences were attributed primarily to fixation and the presence of physiological ligands that can mask the active endogenous carbohydrate-binding proteins. In any case, histochemical application of labeled neoglycoproteins is valuable to discern the presence, localization and developmental pattern of binding sites for the carbohydrate part of glycoconjugates, on which further biochemical and cell biological studies can consequently be based.

Acetylgalactosamine↗
PubMedDate not supplied

Constancy of adenine methylation in Tetrahymena macronuclear DNA.

Macronuclear DNA from Tetrahymena was examined in order to determine whether the pattern of adenine methylation changed with the transcriptional activity of nearby genes. The DNA from growing, starved and conjugating cells was digested with six restriction enzymes which are sensitive to methylation of adenine within their recognition site. Southern blots of the restricted DNAs were probed with seven cDNA clones and one genomic clone which are homologous to polyA+ RNAs, whose transcriptional activity varies with the physiological state of the cell. One of the cDNA clones, BC11, had not been described previously. It hybridized to a 1.3 kb transcript which was present in populations of starved and conjugating, but not in growing cells. On Southern blots of genomic DNA it hybridized to a complex pattern of bands which was highly polymorphic between the DNAs of closely related strains. It was estimated that between 137 and 272 sites were assayed for changes in methylation, including at least 27 sites which were known to be methylated. No differences were seen in the size of restriction fragments from cells in different physiological states. The data suggested that the methylation pattern, which is determined during macronuclear development, does not vary with the physiological state of the cell.

Adenine↗
PubMed1992

Temporal and spatial integration in dynamic random-dot stimuli.

Random-dot cinematograms comprising many different, spatially intermingled local motion vectors can produce a percept of global coherent motion in a single direction. Thresholds for discriminating the direction of global motion were measured under various conditions. Discrimination thresholds increased with the width of the distribution of directions in the cinematogram. Thresholds decreased as the duration of area of the cinematogram increased. Temporal integration for global direction discrimination extends over about 465 msec (9.3 frames) while the spatial integration limit is at least as large as 63 deg2 (circular aperture diameter = 9 deg). The large spatial integration area is consistent with the physiology of higher visual areas such as MT and MST.

Discrimination, Psychological↗
PubMed1995

A comparison of varieties of "second-order" motion.

Bistable apparent-movement displays were created using four different kinds of "second-order" stimuli in which figures were defined by binocular disparity, spatial phase shifts of periodic luminance distributions, relative motion, and texture-element orientation differences. For each display, characteristics of the local structure of the figures, backgrounds, or both were varied. For each experimental condition, the type of apparent movement seen as a function of interstimulus interval was measured, and it was found that the relationship between perceived apparent movement and interstimulus interval differed across the types of displays viewed. The results suggest that the transformations between first-order stimulus properties and second-order motion may be too complex to imply a single uniform class of second-order motion detectors. Alternative physiological accounts of the results are discussed.

Adolescent↗
PubMed1998

Visual evoked cortical magnetic responses to checkerboard pattern reversal stimulation: a study on the neural generators of N75, P100 and N145.

In an attempt to elucidate the neural generators of pattern reversal visual evoked potentials (PR-VEPs), we measured the visual evoked magnetic fields (PR-VEFs) using a 37-channel magnetoencephalography in six healthy young adults. A half-field checkerboard pattern was phase-reversed at a rate of 1 Hz to stimulate the right or left visual half-field, thus yielding 12 PR-VEFs in total from the six subjects. The simultaneously recorded scalp PR-VEPs showed three distinct components of N75, P100 and N145. Three corresponding components were also identified in the PR-VEFs with similar peak latencies (N75m, P100m and N145m). P100m and N145m were clearly identified in all 12 PR-VEFs, whereas N75m was observed in only nine of 12 PR-VEFs. The equivalent current dipoles (ECDs) of N75m, P100m and N145m were located closely to each other in the occipital cortex around the calcarine fissure contralateral to the stimulated visual field, when they were overlaid on the MRI. The reliability of dipole estimation was highest in P100m, followed by N145m while N75m showed the least reliability. The direction of the current flow of ECDs of N75m and N145m was from the medial to the lateral in the occipital cortex when viewed in a coronal section, whereas that for P100m was toward the medial. The ECD location of P100m changed according to the retinotopic organization when the upper or lower quadrant of the visual field was stimulated, with the ECDs being located in the lower or upper part, respectively, of the visual cortex. Our results therefore indicate that the neural origins of N75m, P100m and N145m of PR-VEFs are in the primary visual cortex on the contralateral side of the stimulated visual half-field, while the three components are physiologically distinct.

Adult↗
PubMed1977

Heart rate and cardiac phase influences on visual perception.

Twenty-six subjects were tested with a tachistoscopic recognition task while heart rate and several other autonomic indexes were monitored. In Experiment 1, heart rate was employed as an independent variable, and stimulus presentation was contingent upon the presence of individually determined low, middle, and high heart rates. The results indicated that low heart rate facilitated performance especially for stimuli presented at the fastest exposure. In Experiment 2, stimulus presentation was dependent upon cardiac phase. The findings indicated that stimulus recognition was enhanced during the cardiac P wave, but the effect was apparent only during the fastest exposure. Multiple regression analyses of the individual subject's data during both experiments indicated that highly idiosyncratic patterns of physiological responses predicted perceptual performance. The results were interpreted as being consistent with the formulations of the Laceys and also suggested that cerebral perfusion be considered as a relevant determinant of behavior.

Adult↗
PubMed1990

A left to right hemisphere callosal transfer deficit of nonlinguistic information in alexithymia.

Schalling-Sifneos and MMPI Alexithymia Scales were used to screen 730 Japanese subjects. The 27 subjects scoring highest and the 26 scoring lowest on both scales were designated high and low alexithymic respectively. The two groups were tested by tachistoscopically presenting them with a lateralized visual matching task, which incorporated both linguistic and nonlinguistic stimuli. Differences in ipsilateral and contralateral hand reaction times were used as an indicator of callosal transfer speed. The results indicated that the two groups did not differ in the callosal transfer of linguistic information. They differed significantly, however, in the right to left hemisphere transfer of nonlinguistic information. This result is suggestive of a physiological basis in alexithymia.

Adult↗
PubMed2004

Touchscreen-enhanced visual learning in rats.

The efficiency of traditional levers and of modern touchscreen technology for training rats on a computerized visual discrimination was studied in a series of observations. When compared with a lever-based discrimination procedure, the use of touchscreens supported the faster development of signal tracking behavior and acquisition of a two-stimulus simultaneous visual discrimination. It did not affect the final level of accuracy. Factors related to spatial proximity of the responses with the stimuli, sign-tracking, and increased ease of touchscreen motor responses were suggested as possible reasons for the touchscreen training advantage. This increased efficiency allows large numbers of animals to be tested quickly, a necessary requirement for studies involving genetic and physiological interventions.

Animals↗
PubMed1999

An approach to primary prevention from the aspect of applied physiology.

The main reason for our decreasing population number--a most remarkable indicator of the inadequacy of our health culture--is the high rate of overall mortality. In its background one finds a number of risk factors of high prevalence, such as hypertension disease, addiction pathology, reduced stress tolerance as well as physical and psychic inactivity. Patterns of life that are positive are scarce and as yet not attractive or efficient. The spirit of primary prevention is yet far from permeating medicine; the most the clinical side did realize has been a recognition of the population's need for regular medical screenings. A completely new approach that involves prevention programs embracing the whole of society, and an elaboration of new strategies are badly needed to achieve a desirable change in the present set of values. One of the already available remedies is to give full and science-based support to the positive life patterns in our culture, for instance by demonstrating how physiology can be applied to human life, by putting the latter within a broader scope, namely that of psychophysiology and social psychology. In this framework the elements to be discussed are such aspects of culture as dietary habits, physical exercise, and mental and sexual hygiene. Placing greater emphasis on sports and intense habitual physical exercise can promote a healthier lifestyle, above all in our youth.

Electrocardiography↗
PubMed2004

Are avoidance and numbing distinct PTSD symptom clusters?

We present the conceptual basis and empirical evidence for considering avoidance and numbing as distinct posttraumatic stress disorder (PTSD) symptom clusters. The majority of data from factor analytic studies supports the position that avoidance and numbing are distinct symptom clusters. As well, the available data suggest that (a) different treatment modalities have differential effects on reducing avoidance but not numbing, (b) patients with more severe pretreatment numbing have poorer treatment outcomes, (c) avoidance and numbing have different patterns of correlation with depression, and (d) they have different correlations with physiological indices of attention. We conclude that avoidance and numbing are distinct PTSD symptom clusters. This distinction has implications for revising current diagnostic criteria. The recognition of this distinction may lead to advances in understanding and treating PTSD.

Adaptation, Psychological↗
PubMed2004

Theory of networked minority games based on strategy pattern dynamics.

We formulate a theory of agent-based models in which agents compete to be in a winning group. The agents may be part of a network or not, and the winning group may be a minority group or not. An important feature of the present formalism is its focus on the dynamical pattern of strategy rankings, and its careful treatment of the strategy ties which arise during the system's temporal evolution. We apply it to the minority game with connected populations. Expressions for the mean success rate among the agents and for the mean success rate for agents with k neighbors are derived. We also use the theory to estimate the value of connectivity p above which the binary-agent-resource system with high resource levels makes the transition into the high-connectivity state.

Adaptation, Physiological↗
PubMed2003

Short, 12 mer fluorescently labeled methylphosphonated oligonucleotides to visualize beta-actin MRNA in vivo.

A pair of fluorescently labeled antisense ( complementary to beta-actin mRNA) or control methylphosphonated DNA 12-mers were introduced into live cells. After fixation their distribution throughout the cell was compared to the localization pattern for the pair of control oligos.The distribution of the two sets of oligos differed in that there was a distinct pool of antisense probes that were detected at elevated levels in the leading edge of fibroblast and cortical underlining. The resulting fluorescence patterns of antisense probes colocalized and were analogous to labeling pattern already described and produced by in situ hybridization. The length of each of the probe destabilized binding to mismatched sequences at physiological temperature, while the overall length of the pair gave a unique, highly sequence specific recognition of a target sequence. Simultaneous, in vivo application of multiple probes let include internal controls into the experimental setup, in order to distinguish different distributions of antisense and control probes in the same specimen.

3T3 Cells↗
PubMed1997

What represents a face? A computational approach for the integration of physiological and psychological data.

Empirical studies of face recognition suggest that faces might be stored in memory by means of a few canonical representations. The nature of these canonical representations is, however, unclear. Although psychological data show a three-quarter-view advantage, physiological studies suggest profile and frontal views are stored in memory. A computational approach to reconcile these findings is proposed. The pattern of results obtained when different views, or combinations of views, are used as the internal representation of a two-stage identification network consisting of an autoassociative memory followed by a radial-basis-function network are compared. Results show that (i) a frontal and a profile view are sufficient to reach the optimal network performance; and (ii) all the different representations produce a three-quarter view advantage, similar to that generally described for human subjects. These results indicate that although three-quarter views yield better recognition than other views, they need not be stored in memory to show this advantage.

Computer Simulation↗
PubMed1978

Storage of spatially specific threshold elevation.

The decay of several visual aftereffects may be prolonged by interposing a period of light-free or pattern-free viewing between adaptation and testing. We demonstrate that this storage phenomenon can be observed using the threshold elevation aftereffect that follows inspection of a high-contrast grating pattern. Control experiments comparing thresholds for vertical and horizontal gratings after adaptation to a vertical grating reveal that the stored aftereffect, like its unstored counterpart, is pattern-selective. Storage is equally pronounced with stimuli that are detected by pattern-analyzing or movement-analyzing visual channels. Unlike other aftereffects, the threshold-elevation aftereffect requires that the storage period be light-free; no storage is seen if a blank field is inspected between adaptation and testing. The results are discussed with respect to the nature of visual aftereffects, and possible cognitive or physiological models of storage.

Figural Aftereffect↗
PubMed2006

Transient receptor potential ion channels as participants in thermosensation and thermoregulation.

Living organisms must evaluate changes in environmental and internal temperatures to mount appropriate physiological and behavioral responses conducive to survival. Classical physiology has provided a wealth of information regarding the specialization of thermosensory functions among subclasses of peripheral sensory neurons and intrinsically thermosensitive neurons within the hypothalamus. However, until recently, the molecular mechanisms by which these cells carry out thermometry have remained poorly understood. The demonstration that certain ion channels of the transient receptor potential (TRP) family can be activated by increases or decreases in ambient temperature, along with the recognition of their heterogeneous expression patterns and heterogeneous temperature sensitivities, has led investigators to evaluate these proteins as candidate endogenous thermosensors. Much of this work has involved one specific channel, TRP vanilloid 1 (TRPV1), which is both a receptor for capsaicin and related pungent vanilloid compounds and a "heat receptor," capable of directly depolarizing neurons in response to temperatures >42 degrees C. Evidence for a contribution of TRPV1 to peripheral thermosensation has come from pharmacological, physiological, and genetic approaches. In contrast, although capsaicin-sensitive mechanisms clearly influence core body temperature regulation, the specific contribution of TRPV1 to this process remains a matter of debate. Besides TRPV1, at least six additional thermally sensitive TRP channels have been identified in mammals, and many of these also appear to participate in thermosensation. Moreover, the identification of invertebrate TRP channels, whose genetic ablation alters thermally driven behaviors, makes it clear that thermosensation represents an evolutionarily conserved role of this ion channel family.

Animals↗
PubMed1984

Syntactic pattern recognition of fetal stress.

At present, units designed to diagnose the state of the foetus during labour base their decisions on relatively short segments of the monitored foetal heart rate and uterine pressure signals. This article describes a new method which takes a sequence of such local diagnoses of individual contractions, extracts the most relevant pathological features and predicts the neuro-physiological performance of the child at birth.

Biomedical Engineering↗
PubMed1972

On the existence in human auditory pathways of channels selectively tuned to the modulation present in frequency-modulated tones.

1. The sensitivity of detecting modulation in a test tone sinusoidally frequency-modulated at a rate varphi(test) is diminished after exposure to a conditioning tone more deeply frequency-modulated at a rate varphi(cond) provided that varphi(cond) is not very different from varphi(test), the sound amplitude being kept constant for each tone at a comfortable hearing level 40-45 dB above threshold.2. When varphi(cond) = varphi(test) the frequency deviation in the modulated test tone must be increased to about three times the unconditioned threshold magnitude to be detectable immediately after exposure to the conditioning tone. Detection sensitivity returns to normal in about one minute.3. At low modulation frequencies the conditioning effects are tuned, being much diminished when varphi(cond) differs from varphi(test) by a few cycles per second.4. Comparing monaural with contra-aural conditioning demonstrates a considerable interaural transfer of about 60-80% of the effect, indicating that the conditioning and its selectivity are predominantly central phenomena.5. The magnitude of the deterioration in detection sensitivity after conditioning is about 3 x at modulation frequencies between about 3/sec and 30/sec. It diminishes at lower and higher modulation frequencies and is effectively absent at 100/sec modulation. The bandwidth of the effect increases from a few cycles per second at the lower end of this range, to some tens of cycles per second at the upper end.6. For the same modulation frequency, the conditioning is relatively insensitive to the mean ;carrier' audiofrequency, f(0). The band width in terms of carrier frequency is at least as wide as ;critical bands'. With a test signal f(0) = 250 Hz, varphi(test) = 8/sec, conditioning is still appreciable for a conditioning tone of varphi(cond) = 8/sec but centred upon f(0) = 150 Hz or = 350 Hz. Conditioning is thus not explicable in terms of coincidences between particular spectral components in the conditioning and test tones.7. Whereas the sensitivity of detecting 8/sec amplitude modulation in a tone is conditioned by prior exposure to either amplitude- or frequency-modulated tones, in contrast the detectability of 8/sec frequency-modulated signals is conditioned only by prior exposure to frequency-modulated tones and not by amplitude-modulated conditioning tones. This underlines the special place of frequency modulation in human audition and emphasizes that the operative stimulus cannot be some aspect common to amplitude modulation and frequency modulation, like identical periodicity or coincident positioning of bands in the integrated spectra of the tones, but points to the instantaneous frequency-modulated wave form as the adequate stimulus.8. These findings strongly suggest that the human auditory pathways contain ;channels' in their organization which determine a final response selectively tuned to particular frequency-modulations. Periodicity coding alone cannot adequately explain this effect which may well only be understood in terms of a ;place' theory of frequency selectivity.9. This organization is well suited to subserve the recognition of frequency-modulation patterns in acoustic signals rather independently of the mean audiofrequency that carries the frequency modulation.

Acoustic Stimulation↗