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PubMed1983

The P3 complex as an index of information processing: the effects of response probability.

The amplitude and latency of the late positive (P3b) component of the cortical evoked potential were studied in a visual search task. The main independent variables were memory load, response type and relative response frequency. In the experiment we used the varied mapping procedure, a condition in which the target and distractor stimuli were thoroughly mixed across trials. The main goal of the study was to establish the locus of relative response frequency. In many models of choice reaction time the effect of this task variable is believed to occur in the response selection stage. If the latency of the P3b only indexes stimulus evaluation, independent of response selection and organization processes, relative response frequency should only affect reaction time and not the latency of P3b. The results indicated that the latency of P3b was very sensitive to the number of comparisons, response type and relative response frequency. In addition, only a subset of subjects selectively prepared for the most probable response. Only these subjects showed the effects of relative response frequency in their reaction times too. Response preparation, however, did not affect the latency of P3b. It was concluded that the latency of P3b is a very sensitive index of the search and comparison process, the binary decision process, and the probability of the type of the decision, but insensitive to motor preparation.

Adult↗
PubMed1984

Correlations of event-related potentials with schizophrenic deficits in information processing and hemispheric dysfunction.

In order to obtain further insight into hemispheric dysfunction in schizophrenics, two experiments were conducted employing event-related potential (ERP) recording during dichotic detection tasks as well as syllable discrimination tasks. Results concerning ERPs derived from the T3 and T4 regions are reported. Based on results in the two experiments, it is concluded that schizophrenics display a dysfunction of the left hemisphere, as well as a dysfunction in the ingration mechanism of both hemispheres. It is also speculated that the left-hemisphere dysfunction in schizophrenics is particularly correlated with positive psychotic symptoms.

Adult↗
PubMed1996

Cross-scale information processing in evolution, development and intelligence.

Biological systems are treated as percolation networks in which processes at all scales participate. Macroscopic inputs are transduced to microphysical events through an interleaved hierarchy of structures and processes and microphysical events are amplified to control macroscopic structures and functions. Integrity and adaptation are achieved through self-consistency dynamics operating at all levels of organization. The unmanifest structure of the vacuum plays a vital role in these dynamics.

Biological Evolution↗
PubMed1997

A mathematical model of neural information processing at the cellular level.

The basis for this neuronal model is that the properties of excitable membranes are controlled by biochemical reactions occurring in the nerve cells. The kinetics of these supposed chemical reactions is described by a set of first order differential equations. We considered the effect of regulation of the properties of sodium channels. This allows the simulation of the changes in the neuron's electrical activity parameters occurring during learning, associated with its excitability. The neuronal model exhibits different excitability after the learning procedure relative to the different input signals that corresponds to the experimental data.

Learning↗
PubMed1992

Serotonin modulates auditory information processing in the cochlear nucleus of the rat.

The effect of iontophoretic application of serotonin (5-HT) was studied in neurons of the cochlear nucleus in the rat. 5-HT inhibited the spontaneous activity in 71%, and the tone-evoked activity in 32% of the neurons. We also observed an excitatory effect, with a longer latency than that of the inhibition, in 40% of the neurons. In some neurons 5-HT had both inhibitory and excitatory effects. Neurons with different response types seem to have different sensitivities to 5-HT. As the effects of 5-HT were generally weaker than those of other putative neurotransmitters, it probably has only a small modulatory influence on auditory processing.

Acoustic Stimulation↗
PubMed1996

Nerve growth factor modulates information processing in the auditory thalamus.

The spatio-temporal organization of spike discharges was studied in rat auditory thalamus (i.e., medial geniculate body and auditory sector of thalamic reticular nucleus) following a 2-week continuous intracerebroventricular administration of nerve growth factor (NGF). Recording of extracellular single-unit activity indicated that, in medial geniculate body, NGF induced a significant increase of the mean firing rate. In thalamic reticular nucleus, where units tend to discharge in bursts, NGF increased the average burst size (number of spikes) and the intraburst frequency without affecting the firing rate. Following white noise acoustical stimulation, in medial geniculate body, more onset excitation and a lower signal-to-noise ratio were observed in NGF-treated rats than in controls. Conversely, in thalamic reticular nucleus, NGF-treated animals showed more inhibitory responses than controls. In addition, within the medial geniculate body, functional interactions between pairs of units simultaneously recorded from different electrodes were greatly increased by the nerve growth factor treatment. These data indicate that modifications of temporal pattern of discharges in selected brain regions are among the effects induced by the intracerebroventricular administration of nerve growth factor.

Animals↗
PubMedDate not supplied

Information processing in nuclear magnetic resonance imaging.

An extended image analysis and classification system is presented to discuss the principal composition of the components as well as the methods of its realization in the field of reference based NMR diagnostics and tissue characterization.

Brain↗
PubMedDate not supplied

Afferent information processing in patients with chronic alcoholism. An evoked potential study.

Visual evoked potentials (VEP), median nerve sensory conduction velocity (SNCV) as well as sensory evoked potentials (SEP), and brainstem acoustic evoked potentials (BAEP) were investigated on both sides in 40 patients with chronic alcoholism (mean age 37 years) without clinical signs of alcohol-induced central nervous system lesions. The results were compared to those obtained in 40 normal controls (mean age 32 years). In both groups, the parameters were analysed by means of both dependence and interdependence statistics. Dependence statistics (ANOVA) revealed significant differences between both groups. In 70% of the patients, at least one pathological parameter (greater than mean +/- 2.5 SD) was found; about 38% of the patients had two or more pathological values. Most pathological parameters were observed with BAEP testing (45% of patients) followed by SNCV (33%), median nerve SEP (30%), and VEP (10%). No significant clustering of pathological parameters was found in certain patients. By means of interdependence statistics, evidence is presented for a disturbance of sensory processing in the brainstem auditory pathways of the patients.

Adult↗
PubMed1995

Information processing during eye tracking as revealed by event-related potentials in schizophrenics, alcoholics, and healthy controls.

To further explore the hypothesis that schizophrenics are more distractable and/or have reduced processing resources available, event-related potentials (ERPs) and smooth pursuit eye movements (SPEM) were investigated in 20 medicated schizophrenics, 19 detoxified chronic alcoholics, and in a control group of 20 healthy subjects. Groups were matched for age and education. Eye tracking tasks and auditory oddball tasks were performed separately as well as simultaneously. In addition, an eye tracking condition with a task-irrelevant tone sequence was used to assess the effect of distraction. Schizophrenics showed a trend for poorer SPEM performance; alcoholics had no dysfunction in this task. Tracking accuracy did not change in either group when additional auditory stimuli were presented. P300 latency was delayed in both schizophrenics and alcoholics. P300 amplitude showed no overall group difference but it increased during the dual task in normals whereas it remained constant in patients. N100 amplitude was generally larger during the more complex conditions indicating heightened unspecific arousal. It is suggested that normals use increased arousal to mobilize additional resources and to allocate them to stimulus evaluation but schizophrenics and alcoholics are unable to do so. Results are more conform to a limited resources concept than to a filter deficit model of cognitive disturbances in schizophrenia and alcoholism.

Adolescent↗
PubMed1992

Information processing in mammalian gustatory systems.

The taste system has multiple functions that are carried by three cranial nerves. It is now apparent that these functions cannot be accommodated by a single coding mechanism for taste quality. A current view emphasizes the likely existence of coding channels activated by specific sets of receptors.

Animals↗
PubMed2005

Auditory temporal information processing in preschool children at family risk for dyslexia: relations with phonological abilities and developing literacy skills.

In this project, the hypothesis of an auditory temporal processing deficit in dyslexia was tested by examining auditory processing in relation to phonological skills in two contrasting groups of five-year-old preschool children, a familial high risk and a familial low risk group. Participants were individually matched for gender, age, non-verbal IQ, school environment, and parental educational level. Psychophysical thresholds were estimated for gap-detection, frequency modulation detection, and tone-in-noise detection using a three-interval forced-choice adaptive staircase paradigm embedded within a computer game. Phonological skills were measured by tasks assessing phonological awareness, rapid serial naming, and verbal short-term memory. Significant group differences were found for phonological awareness and letter knowledge. In contrast, none of the auditory tasks differentiated significantly between both groups. However, both frequency modulation and tone-in-noise detection were significantly related to phonological awareness. This relation with phonological skills was not present for gap-detection.

Child, Preschool↗
PubMed2005

Neural networks of information processing in posttraumatic stress disorder: a functional magnetic resonance imaging study.

BACKGROUND: Neuroimaging studies report reduced medial prefrontal cortical (particularly anterior cingulate) but enhanced amygdala response to fear signals in posttraumatic Stress Disorder (PTSD). We investigated whether anterior cingulate-amygdala dysregulation in PTSD would generalize to salient, but nonthreat related signals. METHODS: Individuals with PTSD (n = 14) and age and sex-matched nontraumatized controls (n = 14) completed an auditory oddball paradigm adapted to functional magnetic resonance imaging at a 1.5-T field strength. RESULTS: Controls displayed bilateral activation in ventral anterior cingulate and amygdala networks, and PTSD subjects showed bilateral dorsal anterior cingulate and amygdala activation to targets relative to nontargets. Compared to controls, PTSD subjects showed enhanced responses to targets in the dorsal and rostral anterior cingulate, and left amygdala. Whole-brain analyses confirmed the expected pattern of distributed prefrontal-parietal responses to targets in the oddball task. Greater activity in posterior parietal somatosensory regions was observed in PTSD. CONCLUSIONS: Our findings of enhanced anterior cingulate responses in PTSD contrast with reports of reduced activity for threat stimuli, suggesting that the latter may be specific to processing of threat-related content. Activation in rostral and dorsal anterior cingulate, left amygdala and posterior parietal networks in response to salient, nonthreatening stimuli may reflect generalized hypervigilance.

Amygdala↗
PubMed2004

Endogenous eye blinks in preadolescents: relationship to information processing and performance.

Endogenous blinks--those occurring without apparent provocation--are regulated in adults with respect to the presentation, cognitive loading, and response demands of stimuli. This investigation determined the extent to which similar regulatory and response-related relationships were evident in preadolescents during a visual continuous performance task (CPT). As in adults, increased blink incidence on task, longer blink deferral following stimuli with greater cognitive loading, and blink-facilitated motor responses to imperative stimuli were observed. Reaction times significantly decreased when the button press (BP) occurred near (+/- 200 ms) blink onset and increased across the task period on blink-free but not blink-associated trials. More blinks occurred before motor responses in females, and a reaction time (RT) advantage for males on blink-free trials was maintained across blink-associated conditions. From these results, an interpretation is developed arguing that endogenous blinks are a meaningful and integral component of sensory-motor processing, indexing times of facilitated attentional and motor response capability.

Adolescent↗
PubMed2006

The level of prepulse inhibition in healthy individuals may index cortical modulation of early information processing.

This study examined whether baseline PPI levels reflect individual efficiency in tasks associated with routine versus supervisory attentional systems (SAS). PPI and neuropsychological data were collected from 30 healthy male subjects. High PPI was associated with shorter movement times on the 5-choice Reaction Time and shorter Subsequent Thinking Times in the Stockings of Cambridge test. These data suggest that high-PPI status reflects greater efficiency in tasks that engage SAS.

Acoustic Stimulation↗
PubMed2004

Visual information processing in dyslexic children.

OBJECTIVE: Several studies presented evidence for magnocellular deficits in dyslexics both in behavioural as well as in electrophysiological data of local electrode sites. We investigated two well-known paradigms (motion-onset and random-dot-kinematogram) with regard to global electrophysiological parameters. METHODS: Twenty-one-channel event-related potentials (ERPs) of 16 dyslectic and 15 control children were analyzed with reference-independent methods. For each paradigm quasi stable microstates were identified by means of a data-driven segmentation procedure and compared between both groups. RESULTS: Differences in global ERP responses between dyslexic and control children could be found for rapid moving gratings but not for the dot coherence. CONCLUSIONS: Dyslexic children seem to have some highly specific visual deficits in processing moving stimuli. These deficits can be related to the magnocellular system.

Child↗
PubMed2005

From sparks to spikes: information processing in the electrosensory systems of fish.

Recent work on electrosensory systems in fish has combined traditional neuroethological approaches with quantitative methods for characterizing neural coding. These studies have shed light on general issues in sensory processing, including how peripheral sensory receptors encode external stimuli and how these representations are transformed at subsequent stages of processing.

Animals↗