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PubMed1989

The effects of nicotine on attention, information processing, and short-term memory in patients with dementia of the Alzheimer type.

Nicotine in patients with dementia of the Alzheimer type (DAT) produced a significant and marked improvement in discriminative sensitivity and reaction times on a computerised test of attention and information processing. Nicotine also improved the ability of DAT patients to detect a flickering light in a critical flicker fusion test. These results suggest that nicotine may be acting on cortical mechanisms involved in visual perception and attention, and support the hypothesis that acetylcholine transmission modulates vigilance and discrimination. Nicotine may therefore be of some value in treating deficits in attention and information processing in DAT patients.

Adult↗
PubMed1988

Internal and external information processing by lateral hypothalamic glucose-sensitive and insensitive neurons during bar press feeding in the monkey.

Single neuron activities in the lateral hypothalamic area (LHA) were recorded during bar press feeding task in the monkey. First registered neurons were sorted into 2 groups, glucose-sensitive (GS) and glucose-insensitive (GIS) neurons, depending on their glucose sensitivity. The firing variations to feeding, electrophoretically applied catecholamines and opiate, and to odor and taste stimuli were investigated. GS neurons responded to dopamine, noradrenaline and morphine more often than GIS neurons. In feeding task GS neurons responded during bar press (BP) and reward (RW) periods with long-lasting inhibition of firing and at cue tone (CT) with transient inhibition, while GIS neurons responded during BP and RW periods mainly with excitation and at cue light (CL) with excitation. A majority of GS neurons responded to both odor and taste stimuli more often than GIS neurons. Data suggest that these two kinds of neurons in the LHA may be involved in different functional aspects of feeding: GS neurons, mainly in internal information processing and reward mechanism, and GIS neurons, in external information processing and motor aspects.

Action Potentials↗
PubMedDate not supplied

Effects of subanesthetic doses of ketamine on sensorimotor information processing in healthy subjects.

Ketamine, an antagonist N-Methyl-D-Aspartate receptor, induces a broad range of anomalies in healthy subjects similar to those observed in psychosis. Previous studies have shown that information sensorimotor processing was impaired in patients with schizophrenia. The aim of the study was to assess the effects of subanesthetic doses of ketamine on behavior symptoms and information processing in healthy volunteers. A double-blind, crossover, placebo-controlled study was performed with eight subjects. Brief Psychiatric Rating Scale, Scale for the Assessment of Negative Symptoms, and Scale for the Assessment of Positive Symptoms assessed behavior changes. Information processing was assessed using a choice reaction time. Three experimental factors (stimulus intensity, stimulus response compatibility, and foreperiod duration) chosen to affect a different stage of information processing were manipulated. Our study has demonstrated that administration of ketamine produced significant effects on Brief Psychiatric Rating Scale, Scale for the Assessment of Negative Symptoms, and Scale for the Assessment of Positive Symptoms scores. Results on choice reaction time demonstrated a significant longer reaction time under ketamine. Effects of stimulus intensity and compatibility stimulus response were similar under ketamine and under placebo. Moreover, there was a specific interaction between ketamine and foreperiod. This interaction indicated that foreperiod's effect was more prolonged under ketamine (29 ms) than under placebo (17 ms). These results showed that the clinical effects of ketamine were associated with schizophrenic-like impairments on choice reaction time in healthy subjects.

Adult↗
PubMed1997

Visual information-processing impairments in deficit and nondeficit schizophrenia.

OBJECTIVE: Previous studies of covert visuospatial attention in schizophrenia suggest a subtle form of right hemispatial neglect in acutely ill patients but not in chronic, stable patients. Because of previous work documenting various visual information-processing abnormalities in deficit schizophrenia, the authors investigated whether the deficit/nondeficit categorization would help clarify the presence of visual attentional asymmetries in schizophrenia. METHOD: Performance on a covert visuospatial attention task was examined in clinically stable outpatients with schizophrenia (17 in a deficit subgroup and 28 in a nondeficit subgroup) and 25 normal subjects. Peripheral cue and central cue versions of the covert visuospatial attention task, at 100-, 200-, and 800-msec intervals between cue and target, were administered a week apart. RESULTS: The nondeficit patients exhibited a significant and abnormal asymmetry, with slower reaction time to targets presented in the right visual field than in the left visual field. This right visual field disadvantage was found with both versions of the task, but only at the 100-msec cue-target interval. The deficit patients were slowest in overall reaction time but, similar to the normal subjects, showed no asymmetry. CONCLUSIONS: The results are consistent with slower visual information processing in the left compared to the right cerebral hemisphere in nondeficit schizophrenia. This finding cannot be accounted for by differences between the deficit and nondeficit subgroups in demographic characteristics, chronicity, or medication effects, nor is it secondary to generalized cognitive impairment.

Adolescent↗
PubMed1988

Unfamiliar environments impair information processing as measured by behavioral and cardiac orienting responses to auditory stimuli in preweanling and adult rats.

Placing animals in an unfamiliar environment triggers at least two major reactions: (1) a heightened state of arousal, fear, or distress and (2) a sharp increase in information processing as the animal attempts to learn about its new environment. These changes could have a profound effect on the way in which the animal reacts to the types of extraneous innocuous stimuli typically used to study learning and memory. For example, an increase in arousal or fear could either (1) make the animal more "attentive" to stimulus change resulting in a larger orienting response, or (2) produce a shift from orienting to defensive responding. Conversely, processing of the new stimuli present in the unfamiliar environment may make the animal less responsive to additional extrinsic stimulation. These possibilities were examined experimentally using both autonomic and behavioral measures of orienting and defensive responses. The results demonstrated that animals fail to exhibit either an orienting response or a defensive response to a novel auditory stimulus when they are first placed in an unfamiliar environment. With continued exposure to the test environment the orienting response appears and then shows a time-dependent increase in magnitude. This pattern of results was obtained in both preweaning and young adult rats. On the basis of additional research and analysis, it was concluded that a limitation in information processing capacity was the primary reason for the failure of the orienting response to occur when an animal is first placed in an unfamiliar test chamber.

Aging↗
PubMed2005

Short-term regulation of information processing at the corticoaccumbens synapse.

In relation to expectation and delivery of reward, pyramidal neurons of the prefrontal cortex either switch from a single spiking mode to transient phasic bursting, or gradually increase their sustained tonic activity. Here, we examined how switching between firing modes affects information processing at the corticoaccumbens synapse. We report that increasing presynaptic firing frequency in a tonic manner either depresses or facilitates synaptic transmission, depending on initial probability of release. In contrast, repeated bursts of stimulation of cortical afferents trigger a new form of short-term potentiation of synaptic transmission (RB-STP) in the nucleus accumbens (NAc). RB-STP involves the regulation of axonal excitability mediated by 4-AP-sensitive potassium channels in afferent cortical neurons. Thus, in a tonic mode, information flow is tightly controlled by regulatory mechanisms at the level of presynaptic terminals, whereas switching to a bursting mode reliably enhances efficacy of information processing for all cortical afferents to NAc neurons.

Animals↗
PubMed1988

Basic module for an adaptive control system based on neurone information processing.

The design of such devices as robotic aids for handicapped people, powered prostheses and manipulative aids such as page turners would benefit from the use of an adaptive control system. Much recent work on adaptive networks has been based on simplified models of the information processing capabilities of neurones. Neurones are now known to be capable of association learning and memory and this study incorporates these features in a neurone model. A single neuronal input system, the NMDA-type glutamate receptor, is modelled by deriving finite difference equations from its reaction dynamics so that the concentration of several molecules in the receptor can be plotted as a function of time. The model shows association learning taking place at the glutamate receptor. A whole neurone with ten glutamate receptor regions is also modelled and shows that a neurone should be capable of recognizing patterns of inputs. As the neurone model is complicated and slow to run, a much simplified form of the model is described which embodies the basic features of neurone information processing in a simple algorithm.

Algorithms↗
PubMed1987

Evaluation of information-processing speed and neuropsychological functioning in patients with myotonic dystrophy.

Patients with myotonic dystrophy (MD) were compared to a control group, matched to the patients in important demographic variables including IQ, on the Sternberg Memory Scanning procedure, to investigate the hypothesis of a selective change in speed of information processing in MD patients. The neuropsychological functioning of these MD patients was also compared to normative data to provide a descriptive picture of their abilities; these results were correlated to the factors of age of onset and duration of the disease. Finally, the MD patients were also compared to the defined control group on the neuropsychological measures. There was little evidence of selective slowness of information processing or particular deficit independent of overall IQ. Neuropsychologically, the MD patients as a group performed at the low average level. There was, however, a wide range of abilities, suggesting that MD patients are not a unitary group in terms of neuropsychological functioning. Age of onset of the disease was important, at least for certain results. Further research of the neuropsychological functioning of MD patients must account for the wide range of results, with more precise measures of actual onset of the disease and muscular weakness, in a longitudinal evaluation.

Attention↗
PubMed2001

Metabolically efficient information processing.

Energy-efficient information transmission may be relevant to biological sensory signal processing as well as to low-power electronic devices. We explore its consequences in two different regimes. In an "immediate" regime, we argue that the information rate should be maximized subject to a power constraint, and in an "exploratory" regime, the transmission rate per power cost should be maximized. In the absence of noise, discrete inputs are optimally encoded into Boltzmann distributed output symbols. In the exploratory regime, the partition function of this distribution is numerically equal to 1. The structure of the optimal code is strongly affected by noise in the transmission channel. The Arimoto-Blahut algorithm, generalized for cost constraints, can be used to derive and interpret the distribution of symbols for optimal energy-efficient coding in the presence of noise. We outline the possibilities and problems in extending our results to information coding and transmission in neurobiological systems.

Action Potentials↗
PubMed1997

[The effect of prior information on perception of ongoing behavior of others: information processing at the extraction stage].

This study investigated the effect of prior information on the extraction stage, particularly on the amount of behavior extraction, of information processing when perceiving ongoing behavior of others. In terms of prior information they received, 102 subjects were randomly assigned to three groups: familiarity, desirability, and neutral conditions. Twelve video clips, each about 30 seconds long, of a male stimulus actor in daily life were made. The theme of each clip was one of the three: familiarity, desirability, or activity. The subjects were instructed to form an impression of the male actor, and to press a button when they saw an impression-relevant action and release it when it was over. Results suggested that subjects extracted behavior that was relevant to prior information more frequently, and extraction rates were higher for relevant video clips. However, impression change was found after the observation-extraction task. Hence, it implies that prior information affects the extraction stage, but not the judgment stage, of perceiving ongoing behavior of others.

Adult↗
PubMed2000

Rectal tone and brain information processing in irritable bowel syndrome.

We studied differences in rectal tone between healthy controls, nonpsychiatric irritable bowel syndrome (IBS) patients, and IBS patients with comorbid phobic anxiety disorders to assess the impact of psychiatric comorbidity on rectal tone. The groups were additionally compared with respect to brain information processing of everyday words with emotional content to see if we could identify an association between perception of emotional material in the brain and rectal tone. We found that both nonpsychiatric IBS patients and IBS patients with phobic anxiety disorder had increased baseline rectal tone compared with healthy controls (F = 9.81, P < 0.001). The phobic anxiety patients tended to have increased tone compared with nonpsychiatric IBS patients, but the difference did not reach statistical significance. Similar differences were found in the attentional elements of brain information processing activity assessed by event-related potentials. Rectal tone significantly predicted brain reactivity to emotional words, suggesting that changes in intestinal motor function may influence brain perception.

Adult↗
PubMed1995

Information processing in patients with early and continuously-treated phenylketonuria.

UNLABELLED: A total of 33 patients with early and continuously-treated phenylketonuria (PKU) between 7 and 16 years of age and 33 matched controls participated in a study examining perceptual, central, and response-related mechanisms of information processing. The specific mechanisms studied were: perceptual filtering, memory search, response selection, response execution, and motor presetting. In addition, groups were compared on mean intelligence level and task oriented behaviour. The performance of the PKU patients practically matched that of the controls on all three tasks, suggesting that PKU patients who are continuously maintained on a well-controlled phenylalanine-restricted diet are not impaired in the elementary mechanisms of information processing. Furthermore, groups did not differ in mean IQ or task-oriented behaviour. CONCLUSION: These results underline the importance of continued, well-controlled dietary treatment. Further studies are recommended to obtain a more complete evaluation of the potential of PKU patients under these stricter dietary treatment conditions.

Adolescent↗
PubMed1986

Cognitive processing in anorexia nervosa. A disturbance in automatic information processing.

Anorexia nervosa patients were found to perform as well or better than control subjects on cognitive tasks that both require considerable cognitive effort and 'direct' the subject to the information that will be tested, but do more poorly than controls on tests that assess automatic or incidental processing of information. The implications of this particular pattern of cognitive alterations for theories concerning the etiology of anorexia nervosa are discussed.

Adult↗
PubMed1975

Brainstem substrates of sensory information processing and adaptive behavior.

Emerging clinical and experimental data suggest that the brainstem may be an important part of the functional matrix from which normal mental development and behavior evolve. Although the brainstem has not been a focal point in considering etiologies of mental retardation nor even in analyses of adaptive behavior, information processing within both the brainstem sensory nuclei and adjacent reticular formation may indeed be one of the most critical and relevant areas for such investigations. Data are summarized from several ongoing experiments which are designed to explore the capacity of the brainstem to encode sensory, especially acoustic, stimuli and to modulate the resultant sensory information so as to produce a "learned" response. Such data indicate that in the absence of forebrain or even midbrain structures, a simple conditioned response can be supported by the brainstem. The reticular neuropil is considered particularly important to this response acquisition and is conceptualized as a structure which can receive and transmit acoustic information with retention of specific stimulus coding. It is further suggested that independent associative and reflex functions of the reticular formation may be highly significant in neonatal behavior but, with the development of descending influences from higher centers during maturation, these functions may become largely masked. In order to develop a temporal frame of reference for brainstem structures potentially involved in sensory information processing and learning phenomena "time constants of response plasticity" are being established for different levels of the brainstem system.

Adaptation, Psychological↗
PubMed2006

Attention-deficit/hyperactivity disorder: neurophysiology, information processing, arousal and drug development.

In this review, we draw on literature from both animal and human neurophysiological studies to consider the neurochemical mechanisms underlying attention-deficit/ hyperactivity disorder (ADHD). Psychophysiological and neuropsychological research is used to propose possible etiological endophenotypes of ADHD. These are conceptualized as patients with distinct cortical-arousal, information-processing or maturational abnormalities, or a combination thereof, and how the endophenotypes can be used to help drug development and optimize treatment and management. To illustrate, the paper focuses on neuro- and psychophysiological evidence that suggests cholinergic mechanisms may underlie specific information-processing abnormalities that occur in ADHD. The clinical implications for a cholinergic hypothesis of ADHD are considered, along with its possible implications for treatment and pharmacological development.

Acetylcholine↗
PubMed2005

Expectation of pain replicates the effect of pain in a hand laterality recognition task: bias in information processing toward the painful side?

BACKGROUND: People in pain, or expecting pain, sometimes bias their attention towards pain-relevant cues. Perhaps they also bias their attention towards the body part in question. AIM: To determine if experimentally induced pain, and the expectation of pain, involve an information processing bias towards the hand in question. METHODS: Seventeen asymptomatic subjects performed a hand laterality recognition task during three conditions: control, during hand pain induced by intramuscular injection of hypertonic saline (pain), and during expectation of hand pain, induced by isotonic saline injection (expectation). Mean response time (RT) was determined for three 45 s epochs within each condition and RT was compared between hands, conditions and epochs using a 2 x 3 x 3 repeated measures multivariate analysis of variance. RESULTS: There was a hand x condition interaction and a hand x condition x epoch interaction (p<0.05 for both). RT to recognise the opposite hand was approximately 600 ms longer during epochs when subjects were in pain or expected pain than during control trials. During those epochs, RT to recognise the opposite hand was approximately 600 ms longer than RT to recognise the injected hand, which was consistent across conditions and across epochs. CONCLUSIONS: Both pain and the expectation of pain increased RT to recognise the opposite hand. The findings are consistent with a bias in information processing toward the painful or impending painful hand.

Adult↗
PubMed1984

Effects of methylphenidate (Ritalin) on information processing in hyperactive children.

The effect of methylphenidate on information-processing efficiency was studied in 12 hyperactive, nonretarded children. Performance on six efficiency tasks (Posner Letter Matching, Reaction Time, Memory Search, Category Verification, Item Identification, and Word-Span) and a general measure of on-task behavior were compared for children receiving methylphenidate or a placebo. The median drug dosage was .38 mg/kg, and it was ingested 1 1/2 hours prior to testing. Children blind to the drug-placebo condition were tested on 4 days. In general, methylphenidate-related improvements in attention to on-task behaviors were found. An overall analysis of processing speed suggested that methylphenidate improved efficiency. Methylphenidate significantly decreased reaction times to simple and complex stimulus arrays; differences due to the drug remained even when on-task attentive behaviors were statistically removed. Significantly fewer identification errors occurred on the Posner task in the methylphenidate condition. Results indicated that methylphenidate improved general attentional behaviors and positively influenced processes that define perceptual efficiency.

Adolescent↗
PubMedDate not supplied

Information processing in working memory and event-related brain potentials.

Information processing in working memory was investigated in a paradigm with a pseudo-random sequence of visually presented consonants. The subjects' task was to memorize seven sequentially presented letters per trial and to recall the sequence (MEMORY task). Even-related potentials (ERPs) were selectively averaged for each of the seven positions of consonant presentation within a trial. The later a consonant was presented within a trial the smaller the P300 amplitude elicited by the consonant. The number of recall errors increased, however, from first to last presentation position. In a control task identical to the MEMORY condition consonant were presented. To limit the working memory load to one element, subjects had to count the number of letters within trials showing a specific physical criteria. P300 amplitude did not depend on presentation position. P300 was shown to covary with the amount of processing resources available for a task. We assume that increasing working memory load consumes processing resources that are not available for the processing of the incoming stimuli presented later in the trial.

Adult↗