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At least 973 records · Page 54Linked to original sources
PubMed2002

Selective attention regulates spatial and intensity information processing in the human primary somatosensory cortex.

Attention-related cognitive processes in the primary somatosensory cortex (SI) were studied by measuring somatosensory evoked magnetic fields (SEFs). Twenty-one normal adult human subjects participated in this study for investigating effects of attention and stimulus intensity on cortical finger representation in the SI cortex. Electric stimuli at low and high intensity were delivered to the index or middle finger in finger discrimination and non-discrimination task. For the low intensity stimulation at 1.25 times sensory threshold, an early component (M50) showed clear segregation of the sources for the two fingers and an increase of the amplitude specific to the finger discrimination task. Such an attentional effect on the SI cortex was masked by the high intensity stimulation (2.5 times sensory threshold); the M50 source separation by the fingers was induced irrespective of the discrimination or non-discrimination task. The results suggest that a conscious regulation of stimulus intensity coding in the SI cortex underlies the attention-dependent enhancement of spatial finger information processing.

Adult↗
PubMed2005

How chemical information processing interferes with face processing: a magnetoencephalographic study.

Magnetic field changes related to face encoding were recorded in 20 healthy young participants. Faces had to be deeply encoded under four kinds of simultaneous nasal chemical stimulation. Neutral room air, phenyl ethyl alcohol (PEA, rose flavor), carbon dioxide (CO2, pain), and hydrogen sulfide (H2S, rotten eggs flavor) were used as chemical stimuli. PEA and H2S represented odor stimuli, whereas CO2 was used for trigeminal stimulation (pain sensation). After the encoding of faces, the respective recognition performances were tested focusing on recognition effects related to specific chemical stimulation during encoding. The number of correctly recognized faces (hits) varied between chemical conditions. PEA stimulation during face encoding significantly increased the number of hits compared to the control condition. H2S also led to an increased mean number of hits, whereas simultaneous CO2 administration during face encoding resulted in a reduction. Analysis of the physiological data revealed two latency regions of interest. Compared to the control condition, both olfactory stimulus conditions resulted in reduced activity components peaking at about 260 ms after stimulus onset, whereas CO2 produced a strongly pronounced enhanced activity component peaking at about 700 ms after stimulus onset. Both olfactory conditions elicited only weak enhanced activities at about 700 ms, and CO2 did not show any difference activity at 260 ms after stimulus onset compared to the control condition. It is concluded that the early activity differences represent subconscious olfactory information processing leading to enhanced memory performances irrespective of the hedonic value, at least if they are only subconsciously processed. The later activity is suggested to reflect conscious CO2 perception negatively affecting face encoding and therefore leading to reduced subsequent face recognition. We interpret that conscious processing of nasal chemical stimulation competes with deep face encoding with respect to cortical resources, whereas subconscious processing of nasal chemical stimulation does not.

Adult↗
PubMed2005

Experimental hand pain delays recognition of the contralateral hand--evidence that acute and chronic pain have opposite effects on information processing?

Recognising the laterality of a pictured hand involves making an initial decision and confirming that choice by mentally moving one's own hand to match the picture. This depends on an intact body schema. Because patients with complex regional pain syndrome type 1 (CRPS1) take longer to recognise a hand's laterality when it corresponds to their affected hand, it has been proposed that nociceptive input disrupts the body schema. However, chronic pain is associated with physiological and psychosocial complexities that may also explain the results. In three studies, we investigated whether the effect is simply due to nociceptive input. Study one evaluated the temporal and perceptual characteristics of acute hand pain elicited by intramuscular injection of hypertonic saline into the thenar eminence. In studies two and three, subjects performed a hand laterality recognition task before, during, and after acute experimental hand pain, and experimental elbow pain, respectively. During hand pain and during elbow pain, when the laterality of the pictured hand corresponded to the painful side, there was no effect on response time (RT). That suggests that nociceptive input alone is not sufficient to disrupt the working body schema. Conversely to patients with CRPS1, when the laterality of the pictured hand corresponded to the non-painful hand, RT increased approximately 380 ms (95% confidence interval 190 ms-590 ms). The results highlight the differences between acute and chronic pain and may reflect a bias in information processing in acute pain toward the affected part.

Arm↗
PubMed1995

Acute effects of the anxiolytics suriclone and alprazolam on cognitive information processing utilizing topographic mapping of event-related brain potentials (P300) in healthy subjects.

In a double-blind, placebo-controlled, cross-over study, acute effects of suriclone--a cyclopyrrolone derivative--were investigated by means of topographic mapping of event-related potentials (ERPs). Fifteen normal volunteers, aged 22-35 years, received randomized, oral single doses of placebo, 0.1 mg, 0.2 mg and 0.4 mg suriclone and 1 mg alprazolam as a reference compound. ERPs were investigated in an auditory oddball paradigm before and 3 h after intake of each drug. In addition to 17 EEG leads, vertical and horizontal electro-oculograms (EOGs) were recorded. After EOG minimization and artifact identification, the peak latencies of the spatial average were determined by an automatic procedure. Compared to placebo, no significant effects of the low and middle doses of suriclone on N1 amplitude were observed; the highest dosage reduced N1 amplitude, as did 1 mg alprazolam to an even greater extent. While no consistent effects on P2 amplitude were observed after suriclone, alprazolam reduced P2 amplitude. P300 amplitude was reduced only after the highest dosage of suriclone, but much more so after alprazolam. P300 latency was not affected significantly by suriclone, but a marked prolongation of P300 latency was observed after 1 mg alprazolam. Concerning N1 and P2 effects, alprazolam, but not suriclone, may have an inhibitory influence on stimulus-induced cortical arousal. Concerning P300 effects, the used doses of suriclone were superior to 1 mg alprazolam, which seemed to have reduced cognitive information processing capacity and prolonged stimulus evaluation time. Self-rated well-being (adjective checklist) showed subtle beneficial effects after 0.1 mg and 0.2 mg, but marked sedative effects after both 0.4 mg suriclone and 1 mg alprazolam.

Adult↗
PubMed2002

Effects of a low dose of transdermal nicotine on information processing.

The objective of this research was to assess the effect of a low dose of nicotine (7 mg/24 h), administered through a transdermal device, on the cognitive processes of subjects who were slightly dependent smokers. Sixteen smokers were chosen as subjects using a French version of Fagerström's Test of Nicotine Dependence. Under suboptimal alertness conditions the subjects were faced with a choice reaction time (CRT) task. Two conditions of signal quality (intact or degraded) and two conditions of fore period (FP) (short or long) were used during two different experimental sessions (nicotine or placebo). At the same time, the subjects filled in a mood questionnaire and took part in a critical flicker fusion (CFF) determination test. The results obtained suggest that nicotine improves the subjective state of alertness of the subjects and enables them, despite the suboptimal state, to maintain a constant performance level during a CRT task. Neither an effect of nicotine on the CFF nor any interaction between the nicotine, the signal quality or the duration of the FP were observed. The conclusion to be drawn from the results is that nicotine has an enabling effect, but the results do not allow the determination of the precise site of this effect among the different stages of information processing.

Administration, Cutaneous↗
PubMed2005

An integrated spinal cord-hindlimbs preparation for studying the role of intrinsic properties in somatosensory information processing.

Several studies performed using the slice in vitro technique have shown that spinal cord neurons display specialized intrinsic electrophysiological properties. However, the actual role of intrinsic properties in somatosensory processing remains unclear, mainly due to the impossibility to generate natural sensory inputs in spinal cord slices. Here, we show an integrated spinal cord-hindlimbs preparation of juvenile turtles that has the advantages of in vitro approaches and still enables natural stimulation. By making patch-clamp whole-cell recordings of both superficial and deep dorsal horn neurons in the integrated preparation, we found similar electrophysiological phenotypes as those observed in slices. Most of the cells responded to natural stimuli, had large receptive fields and were classified as wide-dynamic range neurons. Both low-threshold spikes and plateau potentials interacted with naturally evoked sensory inputs, generating complex dynamics. Furthermore, we found that the activity of the spinal cord network induced by natural stimulation modulated the excitability of plateau-generating cells. This effect was mimicked by bath application of cis-(+/-)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD), a group I glutamate metabotropic receptor agonist. Our results show that the spinal cord-hindlimbs preparation represents a valuable model to study the contribution of intrinsic properties to early stages of somatosensory information processing.

Animals↗
PubMed1996

The information processing organisms.

In spite of the tremendous progress in recent decades of biological science, many aspects of the behaviour of organisms in general and of humans in particular remain still somewhat obscure. A new approach towards the study of the behaviour of man was presented by Heisenberg when he emphasized that a Cartesian view of nature as an object "out there" is an illusion in so far as "the observer is always part of the formula, the man viewing nature must be figured in, the experimenter into his experiment and the artist in the scene he paints." (Heisenberg, 1969). The present study is an attempt to make a step forward in this direction by focusing on the ways and means of involvement of the observer which make him an indelible part of the observation. To get a fresh start let us have a look at the physical universe. Although showing an immense variety, all objects, living and non-living, have some characteristics in common. They all obey the physical laws and they all are engaged in perpetual interactions. How do we tell then the difference between living and non-living objects? According to the traditional concept it is the capacity for reproduction that distinguishes living from non-living objects. (Luria et al., 1981). The non-traditional concept presented in this study stresses the way in which objects interact as the crucial point of difference between living and non-living objects. This concept claims that living objects assert themselves as such only when and while interacting in terms of information processing. Under such conditions only, living objects are able to display relative independence of the physical laws, for instance active movement. This display of relative independence is governed by biological laws and defines the behaviour of the living objects as active in principle. All objects who share these characteristics are called living, they behave as wholes assessing themselves as individuals. The definition suggests that they all share the same internal organization which is principally dynamic.

Animals↗
PubMedDate not supplied

Recurrent fractal neural networks: a strategy for the exchange of local and global information processing in the brain.

The regulation of biological networks relies significantly on convergent feedback signaling loops that render a global output locally accessible. Ideally, the recurrent connectivity within these systems is self-organized by a time-dependent phase-locking mechanism. This study analyzes recurrent fractal neural networks (RFNNs), which utilize a self-similar or fractal branching structure of dendrites and downstream networks for phase-locking of reciprocal feedback loops: output from outer branch nodes of the network tree enters inner branch nodes of the dendritic tree in single neurons. This structural organization enables RFNNs to amplify re-entrant input by over-the-threshold signal summation from feedback loops with equivalent signal traveling times. The columnar organization of pyramidal neurons in the neocortical layers V and III is discussed as the structural substrate for this network architecture. RFNNs self-organize spike trains and render the entire neural network output accessible to the dendritic tree of each neuron within this network. As the result of a contraction mapping operation, the local dendritic input pattern contains a downscaled version of the network output coding structure. RFNNs perform robust, fractal data compression, thus coping with a limited number of feedback loops for signal transport in convergent neural networks. This property is discussed as a significant step toward the solution of a fundamental problem in neuroscience: how is neuronal computation in separate neurons and remote brain areas unified as an instance of experience in consciousness? RFNNs are promising candidates for engaging neural networks into a coherent activity and provide a strategy for the exchange of global and local information processing in the human brain, thereby ensuring the completeness of a transformation from neuronal computation into conscious experience.

Brain↗
PubMed1989

Effects of uncertainty on melodic information processing.

In three experiments, musically trained and untrained adults listened to three repetitions of a 5-note melodic sequence followed by a final melody with either the same tune as those preceding it or differing in one position by one semitone. In Experiment 1, ability to recognize the final sequence was examined as a function of redundancy at the levels of musical structure in a sequence, contour complexity of transpositions in a trial, and trial context in a session. Within a sequence, tones were related as the major or augmented triad; within a trial, the four sequences began on successively higher notes (simple macrocontour) or on randomly selected notes (complex macrocontour); and within a session, trials were either blocked (all major or all augmented) or mixed (major and augmented randomly selected). Performance was superior for major melodies, for systematic transpositions within a trial (simple macrocontours), for blocked trials, and for musically trained listeners. In Experiment 2, we examined further the effect of macrocontour. Performance on simple macrocontours exceeded that on complex, and excluded the possibility that repetition of the 20-note sequences provided the entire benefit of systematic transposition in Experiment 1. The effect of musical structure (major/augmented) was also replicated. In Experiment 3, listeners provided structure ratings of ascending 20-note sequences from Experiment 2. Ratings on same trials were higher than those on corresponding different trials, in contrast to performance scores for augmented same and different trials in previous experiments. The concept of functional uncertainty was proposed to account for recognition difficulties on augmented same trials. The significant effects of redundancy on all the levels examined confirm the utility of the information-processing framework for the study of melodic sequence perception.

Adolescent↗
PubMed1994

The effect of D-amphetamine, clonidine, and yohimbine on human information processing.

Twelve subjects were tested with D-amphetamine, yohimbine, clonidine, and a placebo on a task with two levels of stimulus and two levels of response complexity. The purpose of this study was to test the hypothesis that noradrenergic drugs affect early stimulus processes. D-amphetamine speeded reaction time (RT), clonidine slowed it, and yohimbine had no effect. D-amphetamine and yohimbine decreased N1 latency and clonidine increased it. D-amphetamine and yohimbine decreased P3 latency and clonidine increased it but, in each case, only when latency estimates were based on single trials, not on averages. D-amphetamine's effect on RT, not P3, as measured by the average, is consistent with previous results. Single trial measures appear more sensitive. Speeding of N1 and single-trial P3 data indicate that noradrenergic drugs affect processing of early (visual) information. D-amphetamine's speeding of single-trial P3 estimates was attributed to its noradrenergic actions. Yohimbine's speeding of P3 without changing RT is consistent with neural net (parallel) simulations but not with a serial model. These findings support the assumption that different neurotransmitters modulate specific cognitive processes.

Adult↗
PubMed1996

Central mechanisms of pheromone information processing.

An advantage of using pheromones in olfactory studies is that they are chemical signals for which receptor neurons are evolved and thus elicit biologically relevant odour-information to be processed in the brain. In many vertebrate and insect species, the olfactory system is separated into a 'main' and an 'accessory' division, the latter mediating pheromone information. In moths, the pheromone information is first processed in the brain in a large and sexually dimorphic structure, the macroglomerular complex (MGC) of the antennal lobe (AL). Also in vertebrates the pheromone information is processed in specific or modified glomerular complexes. One principle question is whether individual olfactory glomeruli are functional units, processing specific information concerning both the chemical quality and spatiotemporal features of the stimulus, like the pheromone plume. Indeed it has been shown that the axons of different pheromone-selective receptor neurons project into different MGC-glomeruli. Intracellular recordings from the AL projection (output) neurons also show that information about single components of the pheromone blend is preserved in some output pathways, whereas other output neurons respond in a unique fashion to the blend. The information about interspecific signals, which interrupts pheromone attraction, is processed in a specific MGC-glomerulus and is to a large extent kept separate from the pheromone information throughout the AL. Many of the output neurons accurately encode changes in the temporal characteristics of the stimulus.

Animals↗
PubMed2001

Cultural and linguistic considerations in psychodiagnosis with Hispanics: the need for an empirically informed process model.

It is estimated that in the next century nearly half of the clientele seeking mental health services will be members of ethnic minority groups. Hispanics are the most rapidly growing population in the United States, and epidemiological evidence suggests that they present higher levels of psychiatric symptomatology and prevalence rates of disorder compared with other ethnic groups. Despite the unprecedented recognition of cultural considerations found in DSM-IV for rendering a psychiatric diagnosis, there is still surprisingly little empirical research examining cultural and linguistic factors influencing the diagnostic process. This article critically reviews this research and considers process variables that can inform social workers' culturally sensitive diagnosis of Hispanics.

Communication Barriers↗
PubMed1993

Is the selective information processing of food and body words specific to patients with eating disorders?

The selective processing of food- and body size-related information was investigated using a modified version of the Stroop task. Anorexic and bulimic patients and matched female controls were compared on the basis of categorical (diagnosis), dimensional (restraint and drive for thinness) criteria, or both. The findings suggest that the phenomenon assessed by the Stroop paradigm is not exclusive to patients with a clinical eating disorder, but patients and those control subjects who are restrained eaters with a high drive for thinness share a selective processing of information related to shape and eating. The discussion focuses on the implications of these findings.

Anorexia Nervosa↗
PubMed2000

Contributions of postrhinal and perirhinal cortex to contextual information processing.

The role of the postrhinal cortex (POR) and the perirhinal cortex (PER) in processing relational or contextual information was examined with Pavlovian fear conditioning. Rats with electrolytic or neurotoxic lesions of the POR or PER were tested in 2 contextual fear conditioning paradigms. In Experiment 1, electrolytic lesions of the POR or PER produced impairments in contextual fear conditioning but not in conditioning to a phasic auditory conditioned stimulus. Neurotoxic lesions of the POR or PER likewise resulted in anterograde (Experiment 2) and retrograde (Experiment 3) deficits in fear conditioning to the training context in an unsignaled shock paradigm. The results suggest that operations performed on sensory information by the POR and PER are necessary to support contextual learning.

Animals↗
PubMed1985

Compound-stimulus information processing by 3-month-old infants.

According to Cohen's (1973) component-compound developmental hypothesis, before 20 weeks of age, infants do not process compound-stimulus information when presented with simple colored forms. This hypothesis was examined in the present study. Eighty 3-month-old infants were presented with novel and familiar simple colored forms (e.g., red square vs. green square). Conditions were controlled so that novelty discriminations based on component- or compound-stimulus information could be separated. Contrary to the component-compound developmental hypothesis, the results indicate that by 12 weeks of age infants encode compound-stimulus information when presented with simple colored forms. These results are discussed in terms of the property-set model of stimulus recognition (Hayes-Roth & Hayes-Roth, 1977).

Child Development↗
PubMed1992

Keyless data capture: emerging technologies in health information processing.

As middle managers, medical record practitioners will be involved in justification of auto ID technology to upper management. To prepare a good justification, one must have a thorough knowledge of the technology and its advantages and disadvantages. One must also be familiar with the payback period and the installation process. This article has attempted to introduce the reader to some emerging technologies in health care, and answer some of the questions that are key to justifying their acquisition. By most estimates, these technologies are finding their way into health care, however slowly, and hold much promise for improvement in productivity and accuracy in data collection.

Computer Communication Networks↗