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PubMed1983

Information processing in the system from light to horizontal cell response of the carp retina.

In this paper, two types of experiments in the carp retina are presented. One is the analysis of responses to white-noise-modulated light at different average mean intensity levels recorded from L-type horizontal cells. For weak light, the responses fluctuated symmetrically around mean values. For brighter light, however, the distribution of amplitude of the response departed from the normal distribution. The deviation from the normal distribution was characterized in terms of symmetry rather than peakedness. The deviation also implies the existence of a nonlinearity in the system. The other type is with barium ion. Ba2+ produced dramatic effects on the spectral response patterns of horizontal cells; the depolarizing response to long wavelength light of the R/G cell and the hyperpolarizing response to deep red light of the Y/RB cell were eliminated in Ba2+-containing solutions. The response of the L cell to white-noise-modulated light was also changed by application of Ba2+. In Ba2+-containing solution, the response became larger as well as slower than that in normal solution. The results of Ba2+ are discussed in relation to the interactions between cone and horizontal cells.

Animals↗
PubMed1985

Chromatic and spatial information processing by red cones and L-type horizontal cells in the turtle retina.

Flash sensitivities to red (694 nm) and green (546 nm) light were measured intracellularly from red cones and L-type horizontal cells in the turtle retina. The horizontal cells' sensitivity to short wavelength light was significantly larger than expected from the model where horizontal cells receive input mainly from red cones. The red cone responses to chromatic stimuli were strongly dependent upon the flash colour and size. Increasing the spot size reduced the sensitivity to green relative to red and augmented the differences in kinetics between the response to red light and that evoked by green light. It was concluded that L-type horizontal cells received a short wavelength input in addition to the input from red cones. This additional green input coupled with the negative feedback pathway from horizontal cells onto red cones determined the differential spatial properties of the red cone responses to red and green test flashes.

Animals↗
PubMed1993

Effects of idebenone on information processing in aged Long-Evans rats.

Idebenone (6-(10-hydroxydecyl)-2,3-dimethoxy-5-methyl-1,4-benzoquinone) is a benzoquinone that has been shown to improve cognitive function in animals subjected to cerebral ischemia and in rats with lesions of the basal forebrain cholinergic system. Because the cognitive deficits observed in aged rats have been associated with decreased cerebral blood flow and basal forebrain cholinergic dysfunction, it was hypothesized that IDE might improve cognition in aged animals. In the present study, the effects of idebenone on cognitive function in aged Long-Evans rats were assessed using a battery of tests that evaluated attention, habituation, and spatial learning. Selective attention was assessed using an overshadowing paradigm, where IDE (30 mg/kg, IP) was injected 30 min prior to compound cue exposure. IDE enhanced the overshadowing effect in aged rats. The Morris water maze was used to assess spatial learning, where IDE (3 mg/kg, IP) was injected daily throughout the course of training. IDE did not improve the impaired performance of aged rats in the Morris task. Habituation was tested by measuring recovery from gustatory neophobia. IDE (30 mg/kg, IP) was injected 30 min prior to the first exposure to the novel taste. IDE normalized habituation rate in aged rats. It was concluded that IDE improves some forms of acquisition in aged rats, and may do so by decreasing general reactivity to novel stimuli.

Aging↗
PubMedDate not supplied

Influence of graviceptives cues at different level of visual information processing: the effect of prolonged weightlessness.

We evaluated the influence of prolonged weightlessness on the performance of visual tasks in the course of the Russian-French missions ANTARES, Post-ANTARES and ALTAIR aboard the MIR station. Eight cosmonauts were subjects in two experiments executed pre-flight, in-flight and post-flight sessions. In the first experiment, cosmonauts performed a task of symmetry detection in 2-D polygons. The results indicate that this detection is locked in a head retinal reference frame rather than in an environmentally defined one as meridional orientations of symmetry axis (vertical and horizontal) elicited faster response times than oblique ones. However, in weightlessness the saliency of a retinally vertical axis of symmetry is no longer significantly different from an horizontal axis. In the second experiment, cosmonauts performed a mental rotation task in which they judged whether two 3-D objects presented in different orientations were identical. Performance on this task is basically identical in weightlessness and normal gravity.

Aerospace Medicine↗
PubMed1986

Information processing and communication deviance in schizophrenic patients and their mothers.

Tests of attention/information processing, the continuous performance test (CPT) and the span of apprehension task (SAT), were given to 25 schizophrenic patients and their mothers. Measures of communication deviance also were obtained from the mothers. Comparison of these assessments in the mothers revealed different transactional profiles for good attenders and poor attenders on the CPT and on the SAT. The relationships between generations (patient and mother) differ from the within-individual relationships. CPT performance by the patient is not significantly correlated with scores from the mother. However, SAT performance by the patient could be related to SAT performance by the mother and specific communication deviance factor scores.

Adolescent↗
PubMed1990

Information processing deficits of schizophrenic children with formal thought disorder.

The relations among formal thought disorder, the partial report span of apprehension task, the distractibility factor on the Wechsler Intelligence Scale for Children-Revised (WISC-R), and IQ scores were examined in 31 schizophrenic children, aged 7.4 to 12.5 years. The partial report span of apprehension scores of the schizophrenic children correlated significantly with their illogical thinking scores. Their scores on loose associations were significantly associated with the WISC-R distractibility factor score. The attention/information processing deficits that might underlie the clinical manifestations of illogical thinking and loose associations in childhood onset schizophrenia are discussed.

Attention↗
PubMed1993

Anatomical aspects of information processing in primate basal ganglia.

Recent studies with double-anterograde tract-tracing methods have shed new light on the organization of the basal ganglia circuitry in primates. This paper briefly reviews some of these findings and provides a personal interpretation of their possible functional significance. Emphasis is placed on the fact that the striatum and the subthalamic nucleus have multiple representations in the two major output structures of the basal ganglia, namely the internal segment of the globus pallidus and the substantia nigra pars reticulata. It is hypothesized that this multiple representation serves as a means of amplifying and diversifying the striatal and subthalamic influences upon thalamocortical neurons that is mediated through the globus pallidus and the substantia nigra. Furthermore, evidence for the highly ordered organization of the striatopallidal and subthalamopallidal projections, which converge onto single pallidal neurons according to different but highly specific patterns, is taken as an indication that the subthalamic nucleus uniformly excites a vast collection of pallidal neurons, whereas the striatum exerts a more specific inhibitory control upon selected subsets of subthalamically driven pallidal neurons.

Animals↗
PubMed1986

Evaluation of the efficacy of piracetam in treating information processing, reading and writing disorders in dyslexic children.

Piracetam, a new class of drug (nootropil) thought to enhance specific cognitive skills, was given in a 3300 mg daily dose to half of a group of fifty-five dyslexic boys aged 8-13 years, in a 12-week, double-blind, placebo-controlled study. The other half of the subjects received placebo. All subjects met the following criteria: normal intelligence, normal educational opportunities, no severe emotional problems, no neurological handicaps, good physical health, not taking other psychotropic medication, and scoring at least one and one half years below their mental age equivalent on the Gilmore Oral Reading Test. Non-verbal (auditory and visual) and verbal perceptual, and memory skills were examined, and reading, spelling, language and writing abilities were measured using standardized instruments. Compared to the placebo control group, individuals treated with Piracetam did not show statistically significant improvements above their baseline scores on measures of perception, memory, language, reading accuracy or comprehension, or writing accuracy. However, reading speed and numbers of words written in a timed period were significantly enhanced in subjects treated with Piracetam as compared to placebo. Effective reading and writing ability, taking both rate and accuracy into consideration, were also significantly improved in the Piracetam as compared to the placebo treatment group. The medication was well-tolerated and medical examinations showed no significant adverse reactions. These results encourage further study of Piracetam to determine more precisely the mechanism of action by which specific cognitive skills are affected.

Adolescent↗
PubMed1987

Effects of spontaneous cortical slow potentials on semantic information processing.

Adult subjects were tested on a choice reaction time (RT) task for decisions of word pairs as synonyms or unrelated. For each trial the word stimuli were presented contingent upon computer-detection of a predetermined negative or positive EEG baseline shift, recorded from either parietal or frontal midline electrodes. With parietal slow potential (SP) shifts, RTs were significantly faster and less variable under negative than positive polarity conditions. No appreciable RT differences were found between negative and positive SP shifts from frontal electrodes or for control subjects. The parietal negative SP shifts are considered to reflect enhanced semantic processing. The present findings in combination with previous results (Born et al., 1982, Electroencephalogr. Clin. Neurophysiol., 54: 668-676) demonstrate a double dissociation between the functional properties of negative SP shifts from parietal and frontal cortical areas, with respective involvements in semantic processing and response selection and execution.

Adolescent↗
PubMed1987

The combining of multiple hemispheric resources in learning-disabled and skilled readers' recall of words: a test of three information-processing models.

Three theoretical models (additive, independence, maximum rule) that characterize and predict the influence of independent hemispheric resources on learning-disabled and skilled readers' simultaneous processing were tested. Predictions related to word recall performance during simultaneous encoding conditions (dichotic listening task) were made from unilateral (dichotic listening task) presentations. The maximum rule model best characterized both ability groups in that simultaneous encoding produced no better recall than unilateral presentations. While the results support the hypothesis that both ability groups use similar processes in the combining of hemispheric resources (i.e., weak/dominant processing), ability group differences do occur in the coordination of such resources.

Cerebral Cortex↗
PubMed1991

Clonidine and scopolamine: differences and similarities in how they change human information processing.

1. Humans have been tested on a choice reaction time task designed to disclose interactions between stimulus complexity and drug effect. 2. Tests were carried out using oral scopolamine (1.2 mg) and clonidine (0.2 mg). 3. Reaction times and event related potentials were measured. 4. Both drugs slowed reaction time and the N1 component of the ERP. 5. SCOP slows RTs to easy-to-discriminate stimuli more than RTs to harder stimuli. Its effect on P3 is the same for both types of stimuli. 6. CLON tends to slow P3 latencies to easy stimuli more than P3 latencies to harder stimuli, while the RT slowing is almost identical for both types of stimuli.

Adult↗
PubMed1979

Evoked potential correlates of human information processing.

The late positive component (P3) of the feedback evoked potential was investigated in two tasks: the detection of near-threshold auditory stimuli, and the estimation of 1 s time intervals. When the intensity or probability of the threshold stimuli was varied in the detection task, it became apparent that the feedback P3 was related to the 'contingent probability' of confirming or disconfirming feedback given a particular response. In the time-estimation task the relative probabiliti-s of confirming and disconfirming feedback were altered by changing the time-window wherein a response was judged correct. In these experiments it was found that the feedback P3 component was highly dependent upon the probability of the feedback, and relatively independent of its confirming or disconfirming meaning. With decreasing probability of the feedback stimuli, the P3 component became larger, later, and somewhat more frontal.

Auditory Perception↗
PubMed1981

Slow negative shifts of the human event-related potential associated with selective information processing.

Event-related potentials (ERPs) to random sequences of tones delivered to the right and left ears were recorded during a pitch discrimination task which required subjects to attend selectively to one ear at a time and respond to occasional 'target' tones in that ear. The morphology of a long-lasting negative shift, arising before the N1 peak and locating over frontal region in ERPs to the attended 'standard' tones with reference to those of the unattended standards, was investigated under different stimulus conditions. When slight pitch changes of targets were presented in the first 40 msec portion of the 240 msec stimulus duration, the largest development of the attention-related negativity was observed earlier than when presented in the last portion of the duration. The results are interpreted as supporting the view that the negativity reflects further processing carried out on each relevant input after that input is identified.

Adult↗