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PubMedDate not supplied

[Computer modeling of mechanisms of the information processing in the olfactory bulb. I. Model of the structure-functional organizations of neuronal elements in the olfactory bulb and receptor epithelium].

A computer model of the olfactory bulb was constructed. The paper describes: 1) the general architecture of a model neuron network that reflects the neurophysiological experimental and theoretical data on the structural and functional organization of the peripheral part of the olfactory system, the olfactory bulb with inputs from olfactory receptor neurons; 2) the organization of each of three levels of the model: receptors, olfactory glomeruli, and basic neurons; and 3) a scenario of the computer model work. In some aspects, in particular, in the principle of information presentation, the treatment of the role of basic neurons (mitral and tufted cells), and their interrelations in modules, the model favorably differs from the available olfactory bulb models. The model is basic and provides further refinement of the architecture, an increase in the number of modules, and the modeling of the learning process.

Animals↗
PubMed2001

Regulation of gene expression by action potentials: dependence on complexity in cellular information processing.

Nervous system development and plasticity are regulated by neural impulse activity, but it is not well understood how the pattern of action potential firing could regulate the expression of genes responsible for long-term adaptive responses in the nervous system. Studies on mouse sensory neurons in cell cultures equipped with stimulating electrodes show that specific genes can be regulated by different patterns of action potentials, and that the temporal dynamics of intracellular signalling cascades are critical in decoding and integrating information contained in the pattern of neural impulse activity. Functional consequences include effects on neurite outgrowth, cell adhesion, synaptic plasticity and axon-glial interactions. Signalling pathways involving Ca2+, CaM KII, MAPK and CREB are particularly important in coupling action potential firing to the transcriptional regulation of both neurons and glia, and in the conversion of short-term to long-term memory. Action potentials activate multiple convergent and divergent pathways, and the complex network properties of intracellular signalling and transcriptional regulatory mechanisms contribute to spike frequency decoding.

Action Potentials↗
PubMed2005

Information processing in noisy burster models of sensory neurons.

Processing of external stimuli by sensory neurons often involves bursting, when epochs of fast firing alternate with intervals of quiescence. In particular, sensory neurons of electroreceptors in paddlefish (Polyodon spathula) undergo bursting when stimulated externally with broad-band noise, but otherwise fire spontaneously in a quasiperiodic tonic manner. We use a simple phenomenological model for noise-induced bursting to quantify analytically, by means of the Kullback entropy and Fisher information, the gain in information transfer and electroreceptor sensitivity for external noisy stimuli. A good agreement between theoretical predictions, numerical simulations and experimental data is shown.

Animals↗
PubMed1995

Where did you go wrong? Errors, partial errors, and the nature of human information processing.

Human performance is seldom perfect, and even when an overt response is correct it may be accompanied by partial-error activity that does not achieve the level of a complete incorrect response. Partial errors can be detected in measures of the lateralized readiness potential, of the electromyogram, and of response force. Correct responses accompanied by partial errors tend to have slower reaction times than "clean" correct responses (because of response competition), and condition differences in reaction time can, on some occasions, be explained in terms of differences in the incidence of partial errors. In two-choice reaction time tasks, partial errors are more frequent when the imperative stimulus contains information that favors both responses, than when it contains information that favors only one response. The non-random nature of partial errors supports the inference that partial information about the stimulus is used to guide responses. A similar inference is supported by the observation that, in hybrid choice Go/No-go tasks, the kinds of partial errors that follow a No-go stimulus represent activation of the response that would have been correct had the stimulus been a Go stimulus. Finally, we note that the human processing system is capable of monitoring its own behavior and of initiating remedial actions if necessary. The activity of an error-detection system, as revealed by measures of the error-related negativity, is related to the degree to which responses are slowed after errors.

Arousal↗
PubMedDate not supplied

Clinical guidelines: attitudes, information processes and culture in English primary care.

The application to clinical medicine of evidence-based clinical guidelines is an increasingly international policy prescription, yet research on how such guidelines might be implemented has tended to focus on change initiatives without seeking to understand change processes. This paper reports an empirical study of guideline implementation in UK general practice. Most GPs welcome guidelines as a means of improving care, though have reservations about their authority, relevance and effect on professional autonomy. 'Clan' organizational culture predominates and general practices do not generally have well-functioning internal arrangements for the management of clinical evidence and related information. We found no coherent relationships between these variables and practices' actual uptake of guidelines.

Attitude of Health Personnel↗
PubMedDate not supplied

[Fundamental bases of digital information processing in nuclear cardiology (III)].

This article describes the transformation of the gamma-camera images into digital form. The incidence of a gamma photon on the detector, produces two voltage pulses, which are proportional to the coordinates of the incidence points, and a digital pulse, indicative of the occurrence of the event. The coordinate pulses passes through a analog-digital converter, that is activated by the pulse. The result is the appearance of a digital number at the out-put of the converter, which is proportional to the voltage at its in-put. This number, is stored on the accumulation memory of the system, either on a list mode or on a matrix mode. Static images can be stored on a single matrix. Dynamic data can be stored on a series of matrixes, each representing a different period of acquisition. It is also possible to capture information on a series of matrixes syncronized with the electrocardiogram of the patient. In this instance, each matrix represents a distinct period of the cardiac cycle. Data stored on the memory, can be used to process and display images and quantitative histograms on a video screen. In order to do that, it is necessary to translate the digital data on the memory to voltage levels, and to transform these on light levels on the screen. This, is achieved through a digital analog converter. The reading of the digital memory must be syncronic with the electronic scanning of the video screen.

Analog-Digital Conversion↗
PubMedDate not supplied

[Increasing mental performance by multistep oxygen therapy. Computer-assisted measurements of information processing capacity, intelligence, short-term memory and further parameters of cerebral performance].

Several basic characteristics of mental capacity were measured on 59 patients by means of computer-based-methods before and after oxygen multistep therapy (O2-MT) and compared with the results obtained from 14 volunteers serving as controls. Before and without O2-MT, an appreciable, age-dependent decline of the short-term memory capacity (general fluid intelligence) was found. O2-MT, completed by brain jogging, effected a significant increase in the presence duration by 0.4-0.7 secs, in the information flow by 1.4-1.9 bit/sec, resulting in an increase in the short-term memory capacity by 19-23% (in two experimental groups). The short-term memory itself was, however, not improved as compared to the controls. Moreover, the times needed for the accomplishment of perception, interference and reaction tests became significantly shorter by 12-18%. By using the screening test for cerebral insufficiency (CI), which is based on these parameters, the suspicion of CI could be excluded in 18 of 59 patients.

Adult↗
PubMed2006

A statistical analysis of information-processing properties of lamina-specific cortical microcircuit models.

A major challenge for computational neuroscience is to understand the computational function of lamina-specific synaptic connection patterns in stereotypical cortical microcircuits. Previous work on this problem had focused on hypothesized specific computational roles of individual layers and connections between layers and had tested these hypotheses through simulations of abstract neural network models. We approach this problem by studying instead the dynamical system defined by more realistic cortical microcircuit models as a whole and by investigating the influence that its laminar structure has on the transmission and fusion of information within this dynamical system. The circuit models that we examine consist of Hodgkin-Huxley neurons with dynamic synapses, based on detailed data from Thomson and others (2002), Markram and others (1998), and Gupta and others (2000). We investigate to what extent this cortical microcircuit template supports the accumulation and fusion of information contained in generic spike inputs into layer 4 and layers 2/3 and how well it makes this information accessible to projection neurons in layers 2/3 and layer 5. We exhibit specific computational advantages of such data-based lamina-specific cortical microcircuit model by comparing its performance with various types of control models that have the same components and the same global statistics of neurons and synaptic connections but are missing the lamina-specific structure of real cortical microcircuits. We conclude that computer simulations of detailed lamina-specific cortical microcircuit models provide new insight into computational consequences of anatomical and physiological data.

Algorithms↗
PubMed1976

Effects of density of noise field and delay on information-processing of patterned inputs.

The present paper extends current research on pattern recognition to investigate the effects of density of noise field and delay (off) times. The results indicate major effects due to density of the noise field, on time and off time. Recognition initially declined as the density of the interference increased, then subsequently leveled off at higher interference levels. The effect of density of noise field on recognition was not consistent across all levels of either on time or off time. There was a wide range of processing-ability among Ss. Some subjects were capable of high levels of performance for very fast input rates. There was a high degree of consistency among Ss in the relative difficulty of the letters.

Aptitude↗
PubMed1998

Modulation of human auditory information processing by emotional visual stimuli.

Auditory event-related potentials mismatch negativity (MMN) and N100 were recorded from seven subjects while they read text and watched emotionally negative, neutral, and positive pictures varying in valence and arousal. The MMN reflects automatic detection of change in auditory stimulus stream. Functionally different N100 is triggered by onset of various auditory stimuli. The N100 was stabile during all visual conditions. The MMN was very similar during text reading, and neutral and negative slide viewing, but was significantly attenuated during viewing of positively valenced slides. We suggest that visual emotional information of high positive valence and low arousal is a signal of nonthreatening and nonappetitive environment. This kind of environment probably reduces the need for auditory change detection.

Alpha Rhythm↗
PubMed1983

[Role of medical information processing for quality assurance in obstetrics].

The paradigma of problem-orientated assuring of the professional quality of medical case is a kind of "control loop system" consisting of the following 5 steps: routine observation, identification of the problem, analysis of the problem, translation of problem solutions into daily practice and control as to whether the problem has been solved or eliminated. Medical data processing, which involves documentation, electronic data processing and statistics, can make substantial contributions especially to the steps of observation, identification of the problem, and follow-up control. Perinatal data collection, which has already been introduced in 6 Länder of the Federal Republic of Germany, has supplied ample proof of this. These operations were conducted under the heading "internal clinical assuring of quality with external aid". Those clinics who participated in this programme, were given the necessary aid in self-observation (questionnaires, clinical statistics), and they were also given comparative informative data to help them in identifying the problems (clinical profiles, etc.). It is entirely left to the responsibility of the clinics themselves--voluntary cooperation and guarantee of remaining anonymous being a matter of course -- to draw their own consequences from the collected data and to translate these into clinical everyday practice.

Electronic Data Processing↗
PubMed1975

The late positive component (P300) and information processing in sentences.

Averaged visual evoked potentials to sequentially flashed words comprising a sentence were recorded from vertex and left and right temporoparietal electrodes in 8 right-handed subjects. In condition 1 the sentence took the form: The -eel is on the shoe, in which the first grapheme was omitted from the second word, so that the subject did not know the meaning of the second word until he viewed the last word. In condition 2, the sentence took the form: The heel is on the shoe, in which the second word was given and the last word provided no further information. P300 latency to words which delivered information (last word of condition 1, second word of condition 2) were significantly longer than P300 latency to any of the other words in the sentence, as well as to the same position word in the other condition. Comparisons of P300 latencies to redundant words (the, is, on) within and between conditions showed no significant differences. P300 amplitude to the last word was significantly larger than P300 amplitude to any of the other words within the sentence, even in condition 2 where the second word delivered information. The major effect of information delivery was on P300 latency, while "syntactic closure" had its major effect on P300 amplitude. The fact that evoked potentials to all words had P300 components was attributed to the engagement of the P300 system whenever task-related language stimuli are used.

Adolescent↗
PubMedDate not supplied

Active and passive attention in schizophrenia: an ERP study of information processing in a linguistic task.

Attentional dysfunctions in schizophrenia were investigated using a sentence priming task. Schizophrenic patients and healthy control subjects were presented with sentences to which they were required to make a response based on either semantic or physical stimulus features. Schizophrenics' behavioural responses were slower than those of controls, particularly when attending to semantic relationships, but their performance was no less accurate. Both the P300 and the N400 components of the event-related potentials (ERPs) recorded to the sentence completions were attenuated in the schizophrenic sample. The results are interpreted in terms of a deficit in the active maintenance of semantic information in memory and the integration of new information with this representation.

Adult↗
PubMed1995

Continuous versus discrete information processing in pattern recognition.

A discrete feature model (DFM) and the fuzzy logical model (FLMP) were formulated to predict the distribution of rating judgments in a pattern recognition task. The distinction was between the spoken vowels /i/ and /I/, as in beet and bit. Subjects were instructed to rate the vowel on a nine-point scale from /i/ to /I/. Two features, the first formant frequency (F1) and the vowel duration, were orthogonally varied: The vowel /i/ has a lower (F1) and a longer duration compared to a somewhat higher (F1) and shorter duration for /I/. The DFM predicts that the separate features are recognized discretely, whereas the FLMP assumes that continuous information is available about each feature. Tests of these models on the observed data indicated that the continuous information assumption of the FLMP gave a significantly better description of the distribution of rating judgments.

Adult↗
PubMed1987

Neuronal organization of rat thalamus for processing information of vibrissal movements.

Vibrissa-responding neurons were searched for in the somatosensory part of the thalamic reticular nucleus (S-TR) and in the ventrobasal nucleus (VB) in urethane-anesthetized rats. More than 90% of the recorded neurons of both species had receptive fields (RFs) on single vibrissae. Movements of RF-vibrissae produced a burst of multiple discharges in S-TR neurons and single spike discharges followed by a prominent suppression of spontaneous discharges in VB neurons. Antidromic invasion from stimulation of the somatosensory cortex in VB neurons was suppressed after RF-vibrissae were stimulated. A possible functional organization comprising VB and S-TR neurons for processing impulses of vibrissal movements was suggested.

Animals↗
PubMed1994

Visual information processing by intracerebral retinal transplants in rats.

We have developed a simple system involving the implantation of retinae over the midbrain of rodents to examine whether, in a clearly defined system such as the primary optic pathway, it is possible to re-create circuits lost as a result of injury or developmental disorder. For much of the work, immature rat hosts have been used, in part to maximise optimal conditions and to provide a baseline for similar transplants in adults. In this review we summarise the sequence of studies that has led us to the conclusion that transplanted retinae are capable not only of differentiating and responding to light but also of relaying luminance information to visual centres of the host brain where appropriate behavioural responses are elaborated.

Animals↗