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PubMedDate not supplied

Multimodal information processing in neurons.

Advances in neuroscience research have led to substantial expansion and even revision of many concepts of neuronal structure and function. The essence of this progress is contained in the knowledge that there are multiple modes of information processing in neurons and even subneuronal elements such as the dendrite. The challenge and opportunity of the new findings lies in understanding how the various modes are integrated in complex brain function. Progress in this area should offer new insights into the pathophysiology of neurological disease.

Action Potentials↗
PubMed1992

Information processing in the separated hemispheres of callosotomy patients: does the analytic-holistic dichotomy hold?

The characterization of the left and right cerebral hemispheres as analytic and holistic, respectively, was evaluated with callosotomy patients. This distinction was operationalized by reference to the work of Garner, Kemler Nelson, and their colleagues on separable (analytic) and integral (holistic) dimensions of cognition. In one experiment, patients were asked to make similarity judgments when faced with triads of stimuli such that one pair matched on a criterial attribute (analytic) and another pair showed a family resemblance (holistic). The right hemisphere showed a stronger bias to judge on the basis of the criterial attribute. In a second experiment, each hemisphere was engaged separately in a concept formation task. Depending on the exemplars in a particular set, analytic or holistic processing was seen in either hemisphere. However, the left hemisphere was more likely to engage in analytic processing. The results suggest that both hemispheres are capable of either type of processing and may use either mode, depending on the nature of the task and stimulus material. Thus, the analytic/holistic distinction may not provide a simple, generalizable description of information processing differences between the two hemispheres.

Adult↗
PubMed1996

A solution to the binding problem? Information processing.

The brain effortlessly recombines information about the shape, colour, motion and so on of objects in the visual scene, but how it does so is not known. Synchronous neuronal firing has seemed an attractive solution to this problem, but new results and theoretical insights cast doubt on its functional role.

Evoked Potentials, Visual↗
PubMed2006

Role of inhibitory feedback for information processing in thalamocortical circuits.

The information transfer in the thalamus is blocked dynamically during sleep, in conjunction with the occurrence of spindle waves. In order to describe the dynamic mechanisms which control the sensory transfer of information, it is necessary to have a qualitative model for the response properties of thalamic neurons. As the theoretical understanding of the mechanism remains incomplete, we analyze two modeling approaches for a recent experiment by Le Masson et al. [Nature (London) 417, 854 (2002)] on the thalamocortical loop. We use a conductance based model in order to motivate an extension of the Hindmarsh-Rose model, which mimics experimental observations of Le Masson et al. Typically, thalamic neurons possess two different firing modes, depending on their membrane potential. At depolarized potentials, the cells fire in a single spike mode and relay synaptic inputs in a one-to-one manner to the cortex. If the cell gets hyperpolarized, T-type calcium currents generate burst-mode firing which leads to a decrease in the spike transfer. In thalamocortical circuits, the cell membrane gets hyperpolarized by recurrent inhibitory feedback loops. In the case of reciprocally coupled excitatory and inhibitory neurons, inhibitory feedback leads to metastable self-sustained oscillations, which mask the incoming input, and thereby reduce the information transfer significantly.

Action Potentials↗
PubMed1998

Neurogastroenterology--information processing from the viscera to the brain in humans.

With the many new investigational possibilities allowing access to the gut-brain axis in humans, new techniques, mainly from neurology, as well as interdisciplinary approaches, have produced insights into afferent information processing from the gut to the brain. They have become research tools in recent years, but will eventually become clinical tools for diagnostic purposes in the future. Gut-brain interactions may be seen at different levels: rather simple research models such as recordable perception and pain, on the one hand, can be contrasted and/or supplemented with neurological stimulation and imaging techniques, and clinical models such as spinal cord injury. All have contributed to the development of a new subspecialty in medicine, neurogastroenterology.

Brain↗
PubMed2001

Information processing deficits in withdrawing alcoholics.

Prepulse inhibition (PPI) of the acoustic startle response (a reduction in response to an intense, startling stimulus (the pulse) if preceded by 30-150 ms by a weaker, non-startling stimulus) is an established model to index information processing deficits in thought-disordered schizophrenic patients. The present study aimed to investigate the influence of alcohol withdrawal on the PPI effect. Eight withdrawing alcoholic patients underwent testing for PPI of the acoustic startle response (defined as percentage reduction of the response over pulse-alone stimulus; prepulses 15 dB above the background) on three occasions (1, 3 and 7 days following the last drink). The results demonstrated remarkably low levels of PPI on days 1 and 3, with this being very robust in three patients who had a history of delirium tremens; there was a trend towards normalization of PPI on day 7. This study, although preliminary, suggests strongly that there is a deficit in the filtering of sensory information in alcohol-dependent patients undergoing alcohol withdrawal. This was most apparent in those with a history of delirium tremens. Further studies are needed to define the cause and chronicity of these deficits.

Journal Article↗
PubMed2005

Rapid visual information processing in schizophrenic patients: the impact of cognitive load and duration of stimulus presentation. A pilot study.

The inability to sustain attention has been proposed as a core deficit in schizophrenia. The Continuous Performance Task (AX-CPT) and the Rapid Visual Information Processing Task (RVP) are widely used neuropsychological tasks to measure sustained attention. The RVP displays numbers as stimuli, whereas the AX-CPT uses letters. Ten patients with chronic schizophrenia and 18 healthy control subjects were studied using four different versions of the RVP. The versions differed with regard to stimulus presentation time (600 vs. 1,200 ms) and the number of target sequences to be memorized: either one sequence (low cognitive load) or two sequences (high cognitive load). Schizophrenic patients showed a reduced number of hits only on the task version with 600 ms stimulus duration coupled with high cognitive load. The combination of high cognitive load and short stimulus duration created a critical performance breaking point for schizophrenic patients. This finding supports the hypothesis that patients have an impaired ability to coactivate different cognitive performances; thus the results favor the theory of impaired functional connectivity in schizophrenia.

Adult↗
PubMed1979

Consciousness, information processing and schizophrenia.

The symptoms of schizophrenia can be interpreted as the result of a defect in the mechanism that controls and limits the contents of consciousness. This defect can be understood as excessive self-awareness. Normally most of the complex information processing which is continuously required by even simple acts of perception, language and thought goes on below the level of awareness; whereas in schizophrenic patients some of this processing, or the results of this processing, not in themselves abnormal, become conscious. This excessive awareness can account for the typical symptoms of schizophrenia and explains many of the specific cognitive abnormalities found in schizophrenic patients.

Cognition Disorders↗
PubMed1988

Differential effect of low and conventional doses of fluphenazine on schizophrenic outpatients with good or poor information-processing abilities.

Thirty-six stabilized schizophrenic outpatients were randomly assigned to receive either 5 or 25 mg of fluphenazine decanoate biweekly and were followed up for two years. The best and worst outcomes were found in groups with good or poor information-processing abilities (as measured by a partial-report span-of-apprehension task) given the same 25-mg dose of fluphenazine decanoate. The 86% two-year survival rate of the patients with poor span performance was considerably better, while the 44% one-year and the 21% two-year survival rates of patients with good span performance were considerably lower than previously reported survival rates for schizophrenic patients receiving a conventional dose of fluphenazine. The significant correlations in a patient's span performance for periods up to one year were consistent with the hypothesis that this task taps processes associated with vulnerability to schizophrenic disorder.

Adult↗
PubMed1993

The roles of non-temporal information processing load and temporal expectations in children's prospective time estimation.

Children in the pre-operational phase were asked to prospectively estimate the duration of a thirty-second interval. Estimated intervals were either filled by a task demanding non-temporal information processing, or were 'empty'. Children were either expecting a prize after the termination of the to-be-estimated interval, or were not expecting such a prize. Prospective time estimates were highest when a prize was expected and the to-be-estimated interval was 'empty', and lowest when a prize was not expected and the to-be-estimated interval was filled by the task. Accuracy was highest when a prize was expected and a non-temporal task required. These findings were accounted for by an attentional model of prospective time estimation. The similarity between children and adults' prospective time estimation processes was discussed.

Attention↗
PubMed2006

Electrophysiological and information processing variability predicts memory decrements associated with normal age-related cognitive decline and Alzheimer's disease (AD).

Recent theoretical models of cognitive aging have implicated increased intra-individual variability as a critical marker of decline. The current study examined electrophysiological and information processing variability and memory performance in normal younger and older controls, and older adults with Alzheimer's disease (AD). It was hypothesized that higher levels of variability would be indicative of age-related and disease-related memory deficits. Results indicated both implicit and explicit memory deficits associated with AD. Consistent with previous research, behavioral speed and variability emerged as sensitive to age- and disease-related change. Amplitude variability of P3 event-related potentials was a unique component of electrophysiological activity and accounted for significant variance in reaction time (RT) mean and RT standard deviation, which in turn accounted for significant variance in memory function. Results are discussed in light of theoretical and applied issues in the field of cognitive aging.

Adult↗
PubMed2001

N-methyl-D-aspartate receptors and information processing: human choice reaction time under a subanaesthetic dose of ketamine.

Ketamine is an N-methyl-D-aspartate antagonist that induces cognitive dysfunctions. The purpose of the present study was to investigate the effects of a subanesthetic dose of ketamine on human information processing, using the additive factor method. During perfusion of a subanesthetic dose of ketamine (0.5 mg/kg over 60 min) or a placebo (randomized double-blind, cross-over design), eight adults (aged 22-33, mean=27) performed a two-choice visual reaction time (RT) task. Signal intensity, stimulus-response mapping, and foreperiod duration were manipulated. The effects of these three variables were found to be additive on RT, indicating that three independent stages - namely, stimulus preprocessing, response selection and motor selection- were manipulated. Ketamine altered RT performance in a specific way: it interacted with foreperiod duration but its effect was additive with those of signal intensity and stimulus-response mapping. These results show that ketamine specifically affects the stage of motor adjustment, which suggests that the glutamatergic system plays an important role in motor processes.

Acoustic Stimulation↗
PubMed1992

Information processing in the auditory brainstem.

The past year has seen significant advances in our understanding of the structural (circuitry and chemistry of synaptic connections) and functional characteristics of the auditory brainstem. Some of the findings that shed light on the mechanisms underlying complex auditory information processing are highlighted.

Animals↗
PubMed1995

Social information-processing patterns partially mediate the effect of early physical abuse on later conduct problems.

The authors tested the hypothesis that early physical abuse is associated with later externalizing behavior outcomes and that this relation is mediated by the intervening development of biased social information-processing patterns. They assessed 584 randomly selected boys and girls from European American and African American backgrounds for the lifetime experience of physical abuse through clinical interviews with mothers prior to the child's matriculation in kindergarten. Early abuse increased the risk of teacher-rated externalizing outcomes in Grades 3 and 4 by fourfold, and this effect could not be accounted for by confounded ecological or child factors. Abuse was associated with later processing patterns (encoding errors, hostile attributional biases, accessing of aggressive responses, and positive evaluations of aggression), which, in turn, predicted later externalizing outcomes.

Age of Onset↗
PubMed1982

Manipulation of event-related potential manifestations of information processing stages.

The timing of two event-related potential components was differentially affected by two experimental variables. The earlier component (NA) was affected by degradation of the stimuli and the later component (N2) by the nature of a classification task. The results support the hypothesis that NA and N2 reflect sequential stages of information processing, namely, pattern recognition and stimulus classification.

Action Potentials↗
PubMed1995

Information-processing patterns in specific reading disability.

This research investigated specific processing strengths and weaknesses among three groups of readers who ranged in age from 6 through 10 years. The first-grade unsuccessful and the older unsuccessful readers had similar information-processing patterns, whereas collectively they differed significantly from the first-grade successful readers on short-term auditory/working memory and decoding/encoding. When separately compared to the controls, the age-matched high-risk group showed additional weakness in rapid automatized naming, and the reading-level-matched older disabled group showed additional weakness in phonological coding as well as visual sequential memory. Examination of second-level classifications using cluster analysis suggested the presence of three potential subtypes among the 50 poor readers. All were characterized by difficulty in what was interpreted as symbolic processing/memory (Subtype 1), which occurred in combination with visual processing deficiencies (Subtype 2) and with deficits in both visual processing and rapid automatized naming (Subtype 3).

Attention↗
PubMed2005

Properties of synaptically evoked astrocyte calcium signal reveal synaptic information processing by astrocytes.

The synaptic control of the astrocytic intracellular Ca2+ is crucial in the reciprocal astrocyte-neuron communication. Using electrophysiological and Ca2+ imaging techniques in rat hippocampal slices, we investigated the astrocytic Ca2+ signal modulation induced by synaptic terminals that use glutamate and acetylcholine. Ca2+ elevations were evoked by glutamate released from Schaffer collaterals and by acetylcholine, but not glutamate, released by alveus stimulation, indicating that astrocytes discriminate the activity of different synapses belonging to different axon pathways. The Ca2+ signal was modulated bidirectionally by simultaneous activation of both pathways, being depressed at high stimulation frequencies and enhanced at low frequencies. The Ca2+ modulation was attributable to astrocytic intrinsic properties, occurred at discrete regions of the processes, and controlled the intracellular expansion of the Ca2+ signal. In turn, astrocyte Ca2+ signal elicited NMDA receptor-mediated currents in pyramidal neurons. Therefore, because astrocytes discriminate and integrate synaptic information, we propose that they can be considered as cellular elements involved in the information processing by the nervous system.

4-Aminopyridine↗