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At least 595 records · Page 33Linked to original sources
PubMed2000

Schizophrenia: reduced signal-to-noise ratio and impaired phase-locking during information processing.

OBJECTIVE: This study was performed in order to clarify the mechanisms which underlie the reduced signal-to-noise of event-related potentials in schizophrenic patients. Specifically, we wanted to find out, whether it is reduced activation and/or synchronization (phase-locking) in specific frequency bands of the ongoing EEG which is related to the decreased signal amplitude and signal-to-noise ratio in schizophrenics. METHODS: We investigated 41 unmedicated schizophrenics (10 of them drug-naïve) and compared them with healthy control subjects (n = 233) as well as unmedicated subjects with schizotypal personality (n = 21), who were considered to be high-risk subjects for schizophrenia, and unmedicated depressive patients (n = 71). We measured event-related activity during an acoustical choice reaction paradigm and calculated the signal-to-noise ratio, signal power and noise for a time interval of 50-200 ms after stimulus presentation. Signal-to-noise ratio was calculated from the power of the averaged trials (signal power) divided by the mean power of the single trials minus the power of the average (noise power). Also, we performed a frequency analysis of the pre- and poststimulus EEG based on a factor analytical approach. Group comparisons were performed with ANCOVA. RESULTS: As expected, a decreased signal-to-noise ratio of evoked activity was found in the schizophrenic and a non-significant trend in the schizotypal subjects and the depressive patients. We were able to show that the observed decrease is due to a reduced signal power and an increase of absolute noise power. Frequency analysis of the evoked activity revealed that normals, schizophrenics schizotypal subjects and depressive patients increased theta/delta activity between pre- and poststimulus interval to a similar extend. However, this theta/delta-augmentation does not correlate with signal power in schizophrenics. Also, normals and depressive subjects augment coherence between both temporal lobes during information processing, which is not found in schizophrenics and schizotypal subjects. In contrast, these two groups augment frontal lobe coherence, which goes along with an increase of noise. CONCLUSIONS: Reduced stimulus-induced phase-locking and bitemporal coherence of cortically evoked activity but not a failure to activate the cortex may be responsible for the observed low signal-to-noise ratio during information processing in schizophrenics. Accordingly, schizophrenics increase noise after stimulus presentation instead of building up a signal. This is discussed in the framework of the theory of stochastic resonance.

Acoustic Stimulation↗
PubMed1986

The comparative and developmental study of auditory information processing in autistic adults.

The present study examined brain functions related to information processing in autistic subjects, using auditory evoked potentials (AEP) and missing stimulus potentials (MSP). In order to study the development of autism, autistic adults served as subjects. Normal adults and children also served as control groups. Both normal and autistic adults showed normal patterns and lateralities with respect to AEP for music stimuli, but normal children did not show such matured patterns and lateralities. On the other hand, with respect to MSP, autistic adults showed matured patterns with a specific laterality. These results suggest that autistic subjects might develop some cognitive functions.

Adult↗
PubMed1985

Information processing and speech lateralization in learning-disabled children.

The relationship between information processing and speech lateralization was investigated in learning-disabled children. The Kaufman Assessment Battery for Children (K-ABC) assessed simultaneous and successive processing while a dichotic listening paradigm with free recall and directed attention conditions assessed speech lateralization. A three-factor ANOVA design conducted on the dichotic data revealed that normal children demonstrated stronger right ear advantage (REA); whereas learning-disabled showed weaker right ear advantage. Further, lambda analyses conducted on individual subjects revealed that the learning-disabled did not demonstrate the REA, were not biased attenders, and did not get more right ear than left ear items when attention was directed to one ear. Multiple-regression analysis was used to predict sequential processing from the dichotic data for both groups. Learning-disabled children demonstrated a substantial deficit in sequential processing as compared to normal children. These results indicate that learning-disabled children may not have adequate cerebral lateralization of receptive speech processes, shift their attention more readily, and are more inadequate in sequential processing that presumably subserves language functioning. Perhaps learning-disabled children have deficiencies of processor capacity of salient areas of the left (language) hemisphere.

Attention↗
PubMed1996

Visuospatial information processing in intoxicated, recently detoxified, and long-term abstinent alcoholics.

Visuospatial information processing has been shown to be particularly sensitive to acute alcohol intoxication and chronic alcohol abuse. This study extended previous studies by determining if recently detoxified alcoholics recover visuospatial processing after long-term abstinence. If visuospatial function returns to the level displayed by intoxicated alcoholics, then the deficit displayed by recently detoxified alcoholics may represent a short-term adjustment due to the removal of alcohol. However, if the visuospatial deficit remains in long-term abstinent alcoholics, then the superior processing of the intoxicated alcoholic could reflect a normalization of processing produced by alcohol ingestion. Twenty active and 40 recovering alcoholic male volunteers participated. The active alcoholics were seen intoxicated at the time of admission into a 21-day alcohol detoxification and treatment program. Of the recovering alcoholics, 20 were designated as recently detoxified alcoholics and had just completed the same treatment program. The remaining 20 long-term abstinent alcoholics had completed alcohol treatment several years previously with no relapse. Participants selected were similar in general demographic status, alcohol treatment histories, and psychomotor ability. Two main effects emerged from the results: First, the intoxicated alcoholics displayed visuospatial learning that was superior to the learning of alcoholics recently detoxified or abstinent for several years; a second principal finding was nearly identical visuospatial learning displayed by recently detoxified and long-term abstinent alcoholics.

Adult↗
PubMed2002

Implementation of conditional phase-shift gate for quantum information processing by NMR, using transition-selective pulses.

Experimental realization of quantum information processing in the field of nuclear magnetic resonance (NMR) has been well established. Implementation of conditional phase-shift gate has been a significant step, which has lead to realization of important algorithms such as Grover's search algorithm and quantum Fourier transform. This gate has so far been implemented in NMR by using coupling evolution method. We demonstrate here the implementation of the conditional phase-shift gate using transition selective pulses. As an application of the gate, we demonstrate Grover's search algorithm and quantum Fourier transform by simulations and experiments using transition selective pulses.

Journal Article↗
PubMed2004

Effects of diffuse axonal injury on speed of information processing following severe traumatic brain injury.

To test the hypothesis that slowed information processing in traumatic brain injury is related to diffuse axonal injury (DAI), the authors compared 10 patients with predominant DAI (diffuse group) and minimal DAI (mixed injury group) on the Symbol Digit Modalities Test, simple and choice reaction time, Trail Making Tests A and B, and the Stroop Neuropsychological Screening Test. The diffuse group was slower than the mixed injury and control groups on basic speed of processing tasks. This difference was not apparent on complex speeded tasks once basic speed of processing was controlled for. The diffuse group's slower speed of processing was not accounted for by differences in injury severity, age, or time postinjury. The diffuse group showed greater recovery over time.

Adolescent↗
PubMed2004

A simple method for the preparation of pseudopure states in nuclear magnetic resonance quantum information processing.

The use of nuclear magnetic resonance (NMR) to carry out quantum information processing (QIP) often requires the preparation, transformation, and detection of pseudopure states. In our previous work, it was shown that the use of pairs of pseudopure states (POPS) as a basis for QIP is very convenient because of the simplicity in experimental execution. It is now further demonstrated that the product of the NMR spectra corresponding to two sets of POPS that share a common pseudopure state has the same peak frequencies as those of the common (single) pseudopure state. Examples of applying two different quantum logic gates to a 5-qubit system are given.

Algorithms↗
PubMed1978

[Hemispheric differences in the mode of information processing (author's transl)].

To examine hemispheric differences in the mode of information processing, 24 normal right-handed subjects were required to make same or different responses to a set of letters varying in number from two to four which were all identical or contained one letter differing from the rest. When letters were presented in the normal upright position, the left hemisphere showed serial processing wherein reaction times increased as a function of number of letters. The right hemisphere, however, showed no increase of reaction times, i.e. parallel processing. When letters were presented in the inverted upside-down position, the left hemisphere showed partial serial processing, despite letters being analyzed physically. The results suggest that visuopatial analysis doesn't always force parallel processing in the left hemisphere.

Adult↗
PubMed1998

Eye movements in reading and information processing: 20 years of research.

Recent studies of eye movements in reading and other information processing tasks, such as music reading, typing, visual search, and scene perception, are reviewed. The major emphasis of the review is on reading as a specific example of cognitive processing. Basic topics discussed with respect to reading are (a) the characteristics of eye movements, (b) the perceptual span, (c) integration of information across saccades, (d) eye movement control, and (e) individual differences (including dyslexia). Similar topics are discussed with respect to the other tasks examined. The basic theme of the review is that eye movement data reflect moment-to-moment cognitive processes in the various tasks examined. Theoretical and practical considerations concerning the use of eye movement data are also discussed.

Cognition↗
PubMed2005

Information processing of geometrical features of a surface based on binocular disparity cues: an fMRI study.

Cortical areas related to the information processing of binocular disparity-defined geometrical features of a surface, such as depth, orientation and shape are examined by functional magnetic resonance imaging while subjects discriminated these three types of geometrical feature in random dot stereograms. Results indicate that disparity-defined information of depth and that of orientation are processed in the parietal area. Furthermore, the visual system for 3D vision in the parietal area may be organized in a hierarchical manner and the posterior part of the right intraparietal sulcus may be involved in cognitive process of 3D vision. On the other hand, disparity-defined shape information seems to be processed in the occipital visual areas and the crucial involvement of human LOS for this process is suggested.

Adult↗
PubMed2000

Information processing with population codes.

Information is encoded in the brain by populations or clusters of cells, rather than by single cells. This encoding strategy is known as population coding. Here we review the standard use of population codes for encoding and decoding information, and consider how population codes can be used to support neural computations such as noise removal and nonlinear mapping. More radical ideas about how population codes may directly represent information about stimulus uncertainty are also discussed.

Animals↗
PubMedDate not supplied

Finding commonalities: social information processing and domain theory in the study of aggression.

The Arsenio and Lemerise (this issue) proposal integrating social information processing (SIP) and domain theory to study children's aggression is evaluated from a domain theory perspective. Basic tenets of domain theory rendering it compatible with SIP are discussed as well as points of divergence. Focus is directed to the proposition that domains constitute latent structures of SIP. Latent structures are described as cogenerative elements of online processing rather than cumulative stores of social information. Microgenetic studies of the reciprocal role of productive systems described within SIP and latent structures attributed to domain theory are proposed as important to the study of children' aggression. Domain theory studies of social exclusion and bullying are proposed as rich contexts for future research.

Aggression↗
PubMed1996

The enzymatic basis of information processing in the living cell.

Analogies are drawn between the computational aspects of information processing and the enzymatic events of cellular metabolism. The origin thereof is linked to the logic-elements involved in the reaction-diffusion processes of the metabolic operation. It is shown how such function entails a 'molecular machine' quality when associated with organized non-equilibrium energy sources in the cell.

Cells↗
PubMed1997

A user-centred design approach for introducing computer-based process information systems.

There has been an increasing tendency to use computer-based process information systems as the main interface through which operators interact with complex industrial systems. Although the new technology has produced greater hardware reliability and maintainability, the corresponding potential benefits for operability have not always been achieved. Automation has introduced new forms of design and operating errors. One of the major reasons for this problem has been the lack of human factors advice and user participation early in the design process. This paper discusses a user-centred design approach to increase operability and user acceptance of new technologies and working practices. Application of this approach in the context of a chemical plant indicates its promise, but also highlights the difficulties involved in gaining user participation and management commitment.

Chemical Industry↗
PubMed2001

Information processing and cognitive organization in unipolar depression: specificity and comorbidity issues.

This study investigated information processing and cognitive organization in clinical depression. The specificity of various cognitive mechanisms to depression was also examined. Twenty-six depressed/anxious individuals, 24 pure depressives, 25 never-depressed anxious controls, and 25 nonpsychiatric controls completed a modified Stroop task, the Self-Referent Encoding Task, and two tasks designed to assess cognitive structure. Comorbid depressed/anxious, depressed, and anxious groups performed similarly to one another but differed significantly from nonpsychiatric controls, on the processing and organization of negative content. Specificity to depression was also obtained, as both depressed groups endorsed and recalled less positive information and organized positive self-relevant information with less interconnectedness than anxious individuals and nonpsychiatric controls. These results suggest that depressed individuals have an interconnected negative self-representational system and lack a well-organized positive template of self. These findings are discussed in terms of cognitive models of depression and the tripartite model of depression and anxiety.

Adult↗
PubMed1996

A fronto-parietal network for rapid visual information processing: a PET study of sustained attention and working memory.

The rapid visual information processing (RVIP) task, a test of sustained attention which also requires working memory for its successful execution, has been used in a number of human psychopharmacological studies. Single digits are presented in quick succession (100 or 200 digits/min) on a computer screen, and target sequences of numbers must be detected with a button press. Although previous neuroimaging studies have implicated the frontal and parietal cortices in performance of simple sustained attention tasks, the neuroanatomical substrates of RVIP performance are not yet known. This information would prove invaluable in the interpretation of drug effects on this task, possibly delineating a neuronal network for neurotransmitter action. Therefore, this study investigated the functional anatomy of the RVIP task using positron emission tomography (PET) derived measures of regional cerebral blood flow (rCBF) in eight healthy volunteers. Subjects were required to perform variants of the RVIP task which manipulated both the level of working memory load and the speed of stimulus presentation. Compared with a rest condition (eyes closed), the RVIP task increased rCBF bilaterally in the inferior frontal gyri, parietal cortex and fusiform gyrus, and also in the right frontal superior gyrus rostrally. In comparison with a simple sustained attention control condition, the aforementioned right frontal activations were no longer apparent. We suggest that these data are consistent with the existence of a right fronto-parietal network for sustained, and possibly selective, attention, and a left fronto-parietal network for the phonological loop component of working memory.

Adult↗
PubMed2006

Cortical responses to invisible faces: dissociating subsystems for facial-information processing.

Perceiving faces is critical for social interaction. Evidence suggests that different neural pathways may be responsible for processing face identity and expression information. By using functional magnetic resonance imaging (fMRI), we measured brain responses when observers viewed neutral, fearful, and scrambled faces, either visible or rendered invisible through interocular suppression. The right fusiform face area (FFA), the right superior temporal sulcus (STS), and the amygdala responded strongly to visible faces. However, when face images became invisible, activity in FFA to both neutral and fearful faces was much reduced, although still measurable; activity in the STS was robust only to invisible fearful faces but not to neutral faces. Activity in the amygdala was equally strong in both the visible and invisible conditions to fearful faces but much weaker in the invisible condition for the neutral faces. In the invisible condition, amygdala activity was highly correlated with that of the STS but not with FFA. The results in the invisible condition support the existence of dissociable neural systems specialized for processing facial identity and expression information. When images are invisible, cortical responses may reflect primarily feed-forward visual-information processing and thus allow us to reveal the distinct functions of FFA and STS.

Amygdala↗
PubMed1975

Auditory and phonetic levels of processing in speech perception: neurophysiological and information-processing analyses.

Two new experimental operations were used to distinguish between auditory and phonetic levels of processing in speech perception: the first based on reaction time data in speeded classification tasks with synthetic speech stimuli, and the second based on average evoked potentials recorded concurrently in the same tasks. Each of four experiments compared the processing of two different dimensions of the same synthetic consonant-vowel syllables. When a phonetic dimensions was compared to an auditory dimension, different patterns of results were obtained in both the reaction time and evoked potential data. No such differences were obtained for isolated acoustic components of the phonetic dimension or for two purely auditory dimensions. Together with other recent evidence, the present results constitute additional converging operations on the distinction between auditory and phonetic processes in speech perception and on the idea that phonetic processing involves mechanisms that are lateralized in one cerebral hemisphere.

Acoustic Stimulation↗