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PubMed1984

The hippocampus, context, and information processing.

Two experiments are described in which groups of rats with bilateral hippocampal lesions, cortical lesions, and operated controls are compared on tests of discrimination learning, retention, and reversal learning. Experiment 1 examined the effects of varying prior training and context on new learning. Experiment 2 used a transfer paradigm to compare extent of original learning by hippocampal and control groups in a discrimination task involving multiple discriminanada . The major findings were that rats with hippocampal damage were less efficient at processing information and were more constrained by contextual influences than control rats.

Animals↗
PubMed1996

Alpha frequency, reaction time, and the speed of processing information.

Several experiments indicate that alpha frequency is significantly correlated with the speed of information processing, as measured by reaction times. These data imply that alpha frequency is a timing mechanism for cognitive processes. However, this interpretation contradicts the well-accepted view that there is no single alpha rhythm, but instead an entire population of different alpha oscillations. We present arguments and report data in the attempt to demonstrate that this paradox can be resolved if different states of alpha oscillations are distinguished. The results of the present study show that during a state of desynchronization, task-related shifts in alpha frequency are not "real" because they are not related to reaction times. Instead, they most likely reflect power changes in different frequency bands.

Adult↗
PubMed1976

Asymmetry of information processing in hallucinators and nonhallucinators.

In previous work we had developed evidence suggesting that hallucinating schizophrenics differ from nonhallucinators in the pattern of errors made in a shadowing task. Non hallucinators appeared to be less willing to guess when they were unsure. The errors of the hallucinators seemed more semantically elaborate. The experiment had not been designed to study these factors and the current experiment was conducted using a technique reported by Pisoni et al. These workers had studied normal Ss in an immediate recall task, using semantically well integrated (SWI) or poorly integrated (SPI) sentences. Pisoni et al. had shown that right ear presentation produced more accurate recall of SWI as compared to SPI sentences, whereas left ear presentation failed to discriminate these sentences. Utilizing the methods of Pisoni et al., we replicated their findings in a normal control group. The results from our hallucinating and nonhallucinating groups were different from each other, the nonhallucinators being less accurate, discriminating semantic integration level on left rather than right ear input, and making more fragmented errors. Little support could be found for attributing this pattern of performance to nonspecific aspects of the procedures. It appears that the nonhallucinators process information differently from hallucinators. These differences may reflect alterations in language development. It is speculated that such differences might be consistent with interference with the development of brain asymmetry.

Age Factors↗
PubMed1988

Information processed by dorsal horn spinocerebellar tract neurones in the cat.

1. A group of spinocerebellar tract neurones located in the dorsal horn of the mid-lumbar segments of the spinal cord but outside of Clarke's column have been investigated by intracellular and extracellular recording from their somata. The existence of these neurones has been demonstrated previously using anatomical methods, but their properties have not been investigated in detail. In contrast to the cells of Clarke's column, these neurones were found to process information from both exteroceptors and proprioceptors. 2. All of the investigated neurones were powerfully excited following stimulation of muscle nerves at strengths sufficient to activate group II afferents while there was no evidence for actions from group I afferents onto any of them. Most were excited by group II afferents from many different nerves, including those from muscles acting on different joints. The latencies and properties of the excitatory postsynaptic potentials (EPSPs) suggest that at least a large proportion of them were monosynaptically evoked. 3. All of the neurones were powerfully excited following electrical stimulation of cutaneous afferents. The most potent effects were evoked from the saphenous and sural nerves which innervate the skin of the leg and thigh. In many cases these EPSPs had latencies indicative of a monosynaptic connection. The superficial peroneal and tibial nerves which innervate the skin of the foot evoked EPSPs which were usually smaller and of longer latency. 4. Responses to adequate stimulation of cutaneous afferents were examined in twenty extracellularly recorded neurones. All but one of them could be discharged by weak mechanical stimulation of the skin over the proximal part of the leg and thigh. None were activated from the skin of the foot. 5. Some of the neurones were influenced by stimulation of the posterior knee joint or interosseous nerves. These actions were relatively weak, however, suggesting that the powerful effects seen on stimulation of muscle nerves were unlikely to have been mediated by articular or Pacinian afferents which contaminate them. 6. Excitation from group II afferents was sometimes followed by inhibition (in 27% of the neurones). In almost all cases the inhibitory postsynaptic potentials (IPSPs) were evoked from the same nerves which evoked EPSPs. The minimal latencies of the IPSPs were approximately 1.0 ms longer than those of the EPSPs, suggesting that they were evoked disynaptically. 7. The possibility that these neurones provide information regarding limb position is discussed.

Action Potentials↗
PubMed1989

Informational processing of complex sound. I: Intensity discrimination.

This paper reports on some initial experiments using the sample discrimination paradigm to investigate normal-hearing listeners' ability to process information in complex, nonspeech sounds. An important feature of the sample discrimination experiment is that the value of the difference to be discriminated randomly varies from trial to trial. It is this variation that yields potential information. In the present study, listeners heard a pair of multitone complexes (or sequences) on each trial. The individual levels of the tones were drawn from two normal distributions differing only in mean. The listener's task was to identify the sound having the higher mean tone level. For an ideal observer in these experiments, performance in d' grows as the square root n, where n is the number of tones. Obtained d' grew more nearly as the cube root of n regardless of whether the tones were played sequentially or simultaneously or whether they were increased in number from high frequencies to low or from low frequencies to high. A preliminary model is proposed in which discrimination performance depends predominantly on the information content of the sounds and is largely independent of the physical dimensions along which the sounds vary. Information content is defined in terms of the variance of the underlying stimulus distributions and a stimulus equivocation factor that is derived from the data. Based on this model, transmitted information is estimated to be between 1.0 and 2.6 bits.

Acoustic Stimulation↗
PubMed1990

Informational processing of complex sound. II. Cross-dimensional analysis.

A series of experiments investigated listeners' ability simultaneously to process information across different acoustic dimensions. On each trial, the listener heard a pair of brief n-tone sequences (n = 1 to 12). The frequency, intensity, and duration of each tone in the sequence varied randomly from trial to trial. On average, the values of these three parameters were greater for one sequence, the target, than the other, the nontarget. The listener's task was to identify the target on each trial. For an ideal observer in this task, d' performance grows as the square root n. Obtained d' grew at a rate slightly less than the square root of n. Close to cube root of n growth was observed when the average difference occurred in only one of the three tone parameter values within a block of trials. Although performance fell short of ideal, optimum weights were consistently given to each tone and each parameter. The results are consistent with a model in which performance depends predominantly on the information content of the sounds regardless of how the information is "packaged" in the stimulus. Transmitted information is estimated to be 0.9-2.0 bits within a single acoustic dimension, 2.1-3.0 bits when distributed across dimensions.

Adult↗
PubMed1996

Information processing during general anesthesia: evidence for unconscious memory.

Memory for words presented during general anesthesia was studied in two experiments. In Experiment 1, surgical patients (n = 80) undergoing elective procedures under general anesthesia were presented shortly before and during surgery with words via headphones. At the earliest convenient time after surgery (within 5 h) and 24 h later, memory was tested by asking patients to complete auditorily presented word stems with the first word that came to mind and to leave out words they remembered having heard earlier (exclusion task). Moreover, patients were requested to perform a "yes/no" forced-choice recognition task to assess recognition memory for both the pre- and intraoperative words. Memory for the material presented during anesthesia was demonstrated immediately after surgery and 24 h later by means of both tasks. In a second similar experiment (n = 80), the results were replicated. These findings show that anesthetized patients can process information that was presented intraoperatively.

Adolescent↗
PubMed1998

Compartmentalization of information processing in an aplysia feeding circuit interneuron through membrane properties and synaptic interactions.

We describe a pair of cerebral-to-buccal interneurons, CBI-5/6, which have outputs and inputs in two ganglia. The soma in the cerebral ganglion received synaptic inputs during buccal motor programs (BMPs) and after mechanical stimulation of the lips. During BMPs the soma received antidromic spikes generated in processes in the buccal ganglion. The soma was driven into a plateau potential by each of these inputs, during which it fired orthodromically at 0-5 Hz. The soma had outputs in the cerebral ganglion consisting of electrical coupling to the adjacent CBI-5/6 and to a cerebral-to-pedal neuron (CPN1). The buccal terminals of CBI-5/6 received inputs that generated rhythmic barrages (up to 25 Hz) of antidromic spikes during BMPs. The buccal terminals had chemical and electrical outputs to motor and premotor elements of feeding circuitry. This combination of synaptic interactions and endogenous properties mean that CBI-5/6 can process information in a number of ways. During the barrage of antidromic spikes, high-frequency firing will produce strong inputs to buccal followers and on their arrival at the soma will transfer excitation electrotonically to CPN1. Subthreshold input to the soma will be transferred electrotonically to cerebral followers but will not be relayed to postsynaptic buccal neurons. Plateau potentials after the antidromic spikes or local cerebral inputs will locally excite CPN1 via electrical coupling but will have little influence on buccal events because of the low orthodromic firing rate. Thus, CBI-5/6 may transmit information locally within the cerebral ganglion or more extensively in both buccal and cerebral ganglia simultaneously.

Action Potentials↗
PubMed1975

Information processing immunogenetic analysis. IV. Information amount and predictive power of different immunogenetic models.

Principles of information theory are imposed on immunogenetic information processing, whereby the 'information amount', simplicity, 'redundancy' and 'predicatability' of different encodings, models, theories or mappings can be objectively compared. As an example, the experimental observables emanating from the Rh system at its 10 reagent-8 haplotype level is shown to obtain an information amount of 140,120 and 78 bits when interpreted (encoded according to a simple-complex, complex-simple and complex-complex theory, model or program, respectively. The 'predictive' or 'accomodating' power of the simple-complex and complex-simple theories is shown to be 134, respectively 366 bits for a given set of experimental observables emanating from a S3 universe.

Computers↗
PubMed1996

Self-organized phase transitions in neural networks as a neural mechanism of information processing.

Transitions between dynamically stable activity patterns imposed on an associative neural network are shown to be induced by self-organized infinitesimal changes in synaptic connection strength and to be a kind of phase transition. A key event for the neural process of information processing in a population coding scheme is transition between the activity patterns encoding usual entities. We propose that the infinitesimal and short-term synaptic changes based on the Hebbian learning rule are the driving force for the transition. The phase transition between the following two dynamical stable states is studied in detail, the state where the firing pattern is changed temporally so as to itinerate among several patterns and the state where the firing pattern is fixed to one of several patterns. The phase transition from the pattern itinerant state to a pattern fixed state may be induced by the Hebbian learning process under a weak input relevant to the fixed pattern. The reverse transition may be induced by the Hebbian unlearning process without input. The former transition is considered as recognition of the input stimulus, while the latter is considered as clearing of the used input data to get ready for new input. To ensure that information processing based on the phase transition can be made by the infinitesimal and short-term synaptic changes, it is absolutely necessary that the network always stays near the critical state corresponding to the phase transition point.

Animals↗
PubMed1991

[Changes in the rate and accuracy of information processing in the computer training of upper-grade pupils].

The basic activity of the student during the "computer training process" is the introduction and processing of information. In the dialogue regime of work, between student and computer, the velocity and accuracy of the information processing take important place. In this aspect, special attention is given to the changes in the indicated indices during the computer lesson, computer plays and the traditional training. Studies are carried out on 30 students from classes X and XI, educated in vocational school "V. Levski", the town of Pravets. For the purpose is used electron determinator with test programme, containing consecutively exposure to 50 visual stimulators in red, blue, green, yellow and white colours at 1,2 s/speed. The results as a whole show that the most favourable results concerning the computer plays, very likely could be explained with the diversion effect and the positive motivation adjustment to the activity performed. By means of dispersion analysis is established, that only the type of activity has an essential effect on the velocity and accuracy of the information processing.

Bulgaria↗
PubMed1985

The effect of methylphenidate on information processing.

Models of information processing currently popular in cognitive psychology divide the reaction process into a series of discrete separable stages. The distinction between one stage and another is verified by the additive factors method (AFM) as defined by Sternberg (1969). Task factors that do not interact with each other are inferred to affect different stages. The distinction between stimulus evaluation stages and response selection stages has been supported by brain event related potential (ERP) studies. The latency of the P300 component of the ERP is sensitive to changes in stimulus complexity but not to to changes in response complexity. The focus of this research is to determine the effects of stimulant drugs on stages of information processing using both reaction time (RT) and P300 latency within an AFM framework. Four doses of methylphenidate (MP) were used in a within-subjects design to examine the effects of MP on stimulus and response processing. We found that MP speeds RT, and that this effect does not interact with the effect of stimulus complexity on RT. MP dose interacts with response complexity, the dose for optimal speeding varying with the level of complexity. The latency of P300 is increased by stimulus complexity, and not by response complexity, nor is it affected by MP. These results show that the stimulant drug acts on processes involved in response selection, rather than in stimulus evaluation. Individual differences in drug response are dose dependent, but also point to an effect on response processing.

Adult↗
PubMed1987

The effects of selective inattention upon the electrodermal orienting reflex: a test of information-processing theory.

Information-processing theories of the orienting reflex (OR) predict that disruptions of attention which impede the registration of a stimulus in memory should retard habituation of the OR. Studies examining effects of selective inattention upon rate of habituation of skin conductance responses (SCRs) to concurrently presented stimuli have yielded inconsistent results. We employed a dichotic vigilance task calling for selective attention to either male-voice or female-voice words. Comparisons between previously attended versus nonattended stimuli were subsequently conducted for habituation of SCR, as well as for a direct measure of recognition memory. Although there were unequivocal differences in long-term memory between attended and non-attended material, there was no clear evidence for corresponding differences in either initial magnitude or rate of habituation of SCR. These data, which replicated results from an earlier study, failed to demonstrate an effect of memory on the OR as predicted by information-processing theories.

Attention↗
PubMed1989

Biological information processing: the use of information for the support of function.

In biological systems, the processing and use of information has evolved out of the need for survival in the face of an uncertain environment. As a consequence, the information-function relationship in these systems is shaped by their adaptability characteristics. In contrast, the information-function relationship in man-designed, goal-oriented organizational systems depends on the ability of the information processing system to support the achievement of the organization's goals. In this paper we use results from adaptability theory in the analysis of control-related aspects of the information-function relationship in man-designed organizational systems. In particular, we use a conceptual model of organizational control to characterize features of functional and control structures and their effect on the adaptability of these systems. The concept of implicit control and a design principle for adaptability-enhancing information systems are derived for this analysis.

Adaptation, Physiological↗
PubMed1995

Aging, caffeine, and information processing: an event-related potential analysis.

Structural and energetic processes in information processing were studied in young and elderly subjects. A visually focussed selective search task was used, in which subjects had to select relevant information, followed by controlled memory search processes to locate a target item. Caffeine was used to manipulate the energetic state of the subjects. During task performance event-related potentials (ERPs) and reaction time (RT) were recorded. Subjects were 15 young and 15 elderly healthy, non-smoking, moderate caffeine consumers (250-600 mg/day). Before the experimental sessions they abstained from caffeine for > or = 12 h. In the experiment subjects received 250 mg caffeine or placebo dissolved in decaffeinated coffee. RT data seem to indicate that aging effects are at least partly due to a shift in the speed-accuracy trade-off. ERP results provide evidence for decreased levels of energy resources in the elderly. The identification of relevant information and stimulus evaluation processes were delayed in the elderly, suggesting an additional effect of aging on structural processes. Caffeine improved performance and increased the amplitude of the N1, N2b, and P3b, in both young and old subjects. These results suggest that caffeine makes more energy resources available for task performance. The effects of aging on P3b latency were counteracted by caffeine. Other caffeine effects did not differ significantly between young and elderly subjects.

Adolescent↗
PubMed1998

Poor concentration and the ability to process information after glandular fever.

The symptom of poor concentration and the ability to process information were measured prospectively in 245 subjects three times in the 6 months after glandular fever or an ordinary upper respiratory tract infection. The effects of the different infections, having a fatigue state, a psychiatric disorder, sleep disturbance, and estimates of premorbid intelligence were also assessed. The most frequent complaint of poor concentration and the worst information processing occurred at the onset of the infection, but these problems decreased over time, and were not related to each other. Multiple regression modeling showed that higher socioeconomic class and vocabulary IQ were associated with information processing ability at all three interviews. In contrast, logistic regression modeling showed that the symptom of poor concentration was associated with the severity of general psychiatric morbidity (CIS score) followed by suffering from a fatigue state. These results suggest that the ability to process information after these particular infections is related to estimates of premorbid IQ, whereas poor concentration is related independently to both psychiatric morbidity and a fatigue state, but not the particular infection itself.

Adolescent↗