Impaired information processing triggers altered states of consciousness

Schizophrenia, intoxication with tetrahydrocannabinol (Delta-THC), and cannabis psychosis induce characteristic time and space distortions suggesting a common psychotic dysfunction. Since genetic research into schizophrenia has led into disappointing dead ends, the present study is focusing on this phenotype. It is shown that information theory can account for the dynamical basis of higher sensorimotor information processing and consciousness under physiologic as well as pathologic conditions. If Kolmogorov entropy (inherent in the processing of action and time) breaks down in acute psychosis, it is predicted that Shannon entropy (inherent in the processing of higher dimensional perception) will increase, provoking positive symptoms and altered states of consciousness. In the search for candidate genes and the protection of vulnerable individuals from cannabis abuse, non-linear EEG analysis of Kolmogorov information could thus present us with a novel diagnostic tool to directly assess the breakdown of information processing in schizophrenia.

BOLD activity during mental rotation and viewpoint-dependent object recognition

We measured brain activity during mental rotation and object recognition with objects rotated around three different axes. Activity in the superior parietal lobe (SPL) increased proportionally to viewpoint disparity during mental rotation, but not during object recognition. In contrast, the fusiform gyrus was preferentially recruited in a viewpoint-dependent manner in recognition as compared to mental rotation. In addition, independent of the effect of viewpoint, object recognition was associated with ventral areas and mental rotation with dorsal areas. These results indicate that the similar behavioral effects of viewpoint obtained in these two tasks are based on different neural substrates. Such findings call into question the hypothesis that mental rotation is used to compensate for changes in viewpoint during object recognition.

Functional modules of the brain

Building on the view of massive modularity, a number of generalized assumptions lead to an entirely new concept of functional brain modules. In contrast to the nerve centers usually considered to be active in the brain, these modules, called symbions, are non-localized, non-hierarchical, and based on subcellular molecular mechanisms rather than on neurons. They act according to local rules that may be fundamentally nonlinear, potentially leading to strong interdependencies between parallel inputs, and they interact by information, not by force. The existence of inner states, feedback loops, internal models, and information encoding provide the basis for a higher complexity than is usually assumed in neuroscience. A map of the symbion world, showing functional rather than physical localization, can be used to illustrate symbion interaction patterns. Perceptual constancy, sensory illusions, visual cognition, and eye-hand coordination are used as examples of what can be explained by using the new theory.

Beyond syntax: language-related positivities reflect the revision of hierarchies

On the basis of an experiment using event-related brain potentials (EPRs), we argue that a characterisation of language-related positivities as necessarily syntax-related is too restrictive. Our data show that, in verb-final German clauses, the processing of a verb which disconfirms the expectations with regard to the hierarchical thematic structure of a sentence (who is doing what to whom) gives rise to an early (200-600 ms) parietal positivity. Thus, positive ERP components elicited during language processing appear to be related to operations (most often revisions) applying to hierarchically structured linguistic information in general, rather than to syntactic structure in particular.

A transcranial magnetic stimulation study of information processing in the motor cortex: relationship between the silent period and the reaction time delay

The present study was aimed at deciphering whether the delay in choice reaction time (RT) and the silent period (SP) caused by transcranial magnetic stimulation (TMS) of the motor cortex in the ongoing electromyogram are due to the same physiological mechanism. To this end, the effect of TMS was studied in 6 healthy volunteers performing a between-hand choice RT task. Specific predictions were derived from a logic inspired from the "postponed stages" hypothesis (Pashler & Johnson, 1989). This logic predicts a correlation between SP duration and RT when the stimulated cortex is involved in the response, and a stronger correlation when the stimulation is delivered later during the RT interval. The effect of TMS on RT was twofold: At early stimulation times, the stimulation shortened the RT and this effect was independent of the involvement of the stimulated motor cortex in the subsequent response. At later stimulation times, TMS had a disruptive effect, provided that the stimulated cortex was involved in the response. When the stimulated cortex was involved in the response, there was a correlation between SP and RT; this correlation was stronger when the stimulation occurred later. In contrast, there was no correlation between these two variables when the stimulated cortex was not involved.

Activity in older adults: cause or consequence of cognitive functioning? A longitudinal study on everyday activities and cognitive performance in older adults

The impact of three types of everyday activities (i.e., social, experiential, and developmental) on four cognitive functions (i.e., immediate recall, learning, fluid intelligence, and information-processing speed) and one global indicator of cognitive functioning (Mini-Mental State Exam score) over a period of 6 years was studied in a large 55--85 year-old population-based sample (N = 2,076). A cross-lagged regression model with latent variables was applied to each combination of 1 cognitive function and 1 type of activity, resulting in 15 (3 x 5) different models. None of the activities were found to enhance cognitive functioning 6 years later when controlling for age, gender, level of education, and health, as well as for unknown confounding variables. Conversely, one cognitive function (i.e., information-processing speed) appeared to affect developmental activity. It is suggested that no specific activity, but rather socioeconomic status to which activities are closely connected, contributes to maintenance of cognitive functions.

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.

Effects of the "beauty is good" stereotype on children's information processing

The authors tested schematic information processing as a function of attractiveness stereotyping in two studies. An adult experimenter read children (ages 3 to 7 years) eight different stories in which a child narrator encountered two characters who varied in level of attractiveness and displayed positive or negative traits that were either consistent or inconsistent with the "beauty is good" stereotype. Following the story, the experimenter showed each child a photograph of the two characters' faces and asked the child to point to the character who displayed the positive trait. In Experiment 1, children made more errors in identifying female characters with stereotype inconsistent traits but did just the opposite with male characters. Experiment 2 replicated the findings with female characters but found no difference in errors with male characters. The findings have implications for how attractiveness and gender stereotypes affect children's information processing, how attractiveness schemata may be organized, and why physical attractiveness stereotypes are maintained.

An investigation of heat stress effects on time-sharing performance

A study was conducted to investigate the effects of heat stress on time-sharing performance. Twelve participants performed three dual-task scenarios and a multiple-task scenario for 2 h in each of six climates. The climates were obtained by generating each of three wet bulb globe temperatures (WBGT; 22, 28 and 34 degrees C) with two relative humidity levels (30 and 70%). The dual tasks selected from the Criterion Task Set (CTS) were: (1) display monitoring with mathematical processing; (2) memory search with mathematical processing; and (3) unstable tracking with memory search. The multiple task scenario was generated using the SYNTASK software. The results indicated a significant heat stress effect on CTS display monitoring and unstable tracking performance and on the SYNTASK visual monitoring and auditory discrimination tasks. Additionally, at 34 degrees C WBGT, 70% relative humidity was more detrimental to performance than 30% relative humidity. Results were interpreted using the Maximal Adaptability Model and Shingledecker's information processing stage/resource framework. To describe the results in an orderly manner, the authors propose the concept of heat stress selectivity effects. In addition, the results were used to evaluate whether the most recent NIOSH recommended heat stress standard, which is based solely on physiological and medical criteria, protects time-sharing performance. It was concluded that the NIOSH criterion does offer protection up to 28 degrees C WBGT.

fMRI study of cognitive interference processing in females with fragile X syndrome

Females with fragile X syndrome, the most common form of inherited developmental and learning problems, are known to be impaired in executive function. The current study is the first to investigate the performance of females with fragile X on a cognitive interference task utilizing functional magnetic resonance imaging (fMRI). Fourteen females with fragile X and 14 age-matched healthy controls were imaged while they performed a counting Stroop interference task. Compared to controls, females with fragile X appeared to have longer reaction times during the interference condition of the task, and adopted a strategy trading speed for accuracy. Females with fragile X also had a significantly different pattern of activation than controls. Whereas controls showed significant activation in the inferior/middle frontal gyrus and inferior/superior parietal lobe, females with fragile X showed more extensive activation in the anterior region of the prefrontal cortex, and failed to show expected activation in the inferior/superior parietal lobe. Further, between-group analyses revealed that females with fragile X had reduced activation in the left orbitofrontal gyrus, thought to be involved in modulating goal-directed behavior. Females with fragile X also demonstrated a markedly different pattern of deactivation from controls. These findings suggest that deficits in cognitive interference processing during the counting Stroop task observed in females with fragile X may arise from inability to appropriately recruit and modulate lateral prefrontal and parietal resources.

Relevant EEG features for the classification of spontaneous motor-related tasks

There is a growing interest in the use of physiological signals for communication and operation of devices for the severely motor disabled as well as for healthy people. A few groups around the world have developed brain-computer interfaces (BCIs) that rely upon the recognition of motor-related tasks (i.e., imagination of movements) from on-line EEG signals. In this paper we seek to find and analyze the set of relevant EEG features that best differentiate spontaneous motor-related mental tasks from each other. This study empirically demonstrates the benefits of heuristic feature selection methods for EEG-based classification of mental tasks. In particular, it is shown that the classifier performance improves for all the considered subjects with only a small proportion of features. Thus, the use of just those relevant features increases the efficiency of the brain interfaces and, most importantly, enables a greater level of adaptation of the personal BCI to the individual user.

Reliability and validity of day-to-day blood flow velocity reactivity in a single subject: an fTCD study

To evaluate the within-subject variability of repeated task-induced blood flow velocity (BFV) change, we measured the haemodynamics of the anterior and middle cerebral arteries of the same volunteer on 20 consecutive working days during the performance of mental arithmetic with transcranial Doppler ultrasonography. BFV changes with the arithmetic condition were compared against a resting and a counting condition. Absolute BFV data showed equally increased velocities during rest and arithmetic activity as compared to counting. The findings suggest that the resting state might not be the ideal reference paradigm to evaluate task-induced haemodynamic changes. Selecting the counting condition as the more valid baseline measure, we obtained relatively stable lateralisation indices for the MCA with 1 of 10 measurements outside the 95% confidence interval. Reproducibility was poorer in the ACA, with 3 outliers. A strategy that calculates the average of multiple short activation epochs within the same session appears to improve the reliability of the lateralisation index.

The relation between task history and movement strategy

In the present study, we examine whether subjects hit identical moving targets differently when the task history is different. Twelve subjects each took part in four experimental sessions. Each session consisted of recurring targets that were the same in all sessions, randomly interleaved with context targets that differed per session. We compared the movements that subjects made towards the recurring targets. There were clear influences of the preceding target on the hitting movements within a session, and clear differences between movements towards the same targets between sessions, but the latter differences were not consistently related to the kind of sessions involved. This indicates that influences of task history are limited to the use of information from preceding trials rather than to changes in how information is used (movement strategy).

Attentional phenotypes for the analysis of higher mental function

We outline a strategy to relate normal cognitive processes to candidate genes. First, brain imaging is used to specify a cognitive process "attention" in terms of the neural networks involved. Next, evidence is presented showing that the operation of each network involves a dominant neuromodulator. Then we discuss development of a task designed to measure the efficiency of each network in normal individuals and consider evidence on the independence, reliability, and heritability of the networks. DNA from cheek swabs of subjects who performed the task are then used to examine candidate polymorphisms in genes related to the transmitters. We then examine the ability of these candidate alleles to predict the efficiency of relevant networks. This process has demonstrated that candidate genes are related to specific networks of attention to a greater degree than to overall performance as measured by reaction time and accuracy. These findings require replication and possible extension to other cognitive processes.

The acute effects of exposure to the electromagnetic field emitted by mobile phones on human attention

The aim of our study was to investigate the effects of acute mobile phone exposure on a range of tasks which tapped capacity and processing speed within the attentional system. Thirty-eight healthy volunteers were randomly assigned to either an experimental group which was exposed to a connected mobile phone or a control group in which the mobile phone was switched off. Subjects remained blind to mobile phone status throughout duration of study. The experimental group were exposed to an electromagnetic field emitted by a 900 MHz mobile phone for 30 min. Cognitive performance was assessed at three points (prior to mobile phone exposure, at 15 and 30 min post-exposure) using six cognitive neuropsychological tests (digit span and spatial span forwards and backwards, serial subtraction and verbal fluency). Significant differences between the two groups were evident after 5 min on two tests of attentional capacity (digit span forwards and spatial span backwards) and one of processing speed (serial subtraction). In all three instances, performance was facilitated following mobile phone exposure. No deficits were evident. These findings are discussed in terms of possible functional and neuroanatomical bases.

Threat-induced cortical processing and startle potentiation

This paper presents cortical responses as reflected in event-related potentials (ERP) in an instructed fear paradigm. Safe cues and threat cues that predict shock were presented at an unprecedented fast rate (mean SOA of 2.1 s). Startle and subjective measures confirmed that threat relative to safe cues elicited fear. Several ERP correlates of fear processing were predicted and confirmed: modulation of exogenous sensory components, frontal selection positivity, and increase of P3. Furthermore, a frontal negative slow wave was observed. These results are discussed in relation to attentional selection models and emotional processing.

[Evaluation of systemic activity of the brain by means of an artificial intelligence model]

The model based on the systems representation of informational brain mechanisms reproduces the principal stages of intellectual activities: afferent synthesis, decision making, acceptor of results of actions. The imitation of behavior of subjects in the special experimental environment with the model allows quantitative estimation of parameters of systemic stages in normal subjects of different ages and subjects with different brain dysfunctions, such as arteriosclerosis, schizophrenia, etc.

Attentional selection and the processing of task-irrelevant information: insights from fMRI examinations of the Stroop task

In this chapter, we discuss our research that reveals how attentional mechanisms can modulate activity of posterior brain regions responsible for processing the unattended attribute of a stimulus. To do so, we utilized fMRI to reveal patterns of regional brain activity for variants of the Stroop task that differ in the nature of the task-irrelevant stimulus attribute. In all variants, individuals had to identify the ink color in which an item was presented. To vary attentional demands, we manipulated whether or not the task-irrelevant information contained conflicting color information. The variants differed in whether the conflicting color information was contained in a word naming a color (e.g. the word 'red' in blue ink), a word naming an object highly associated with a specific color (e.g. the word 'frog' in red ink), or a line drawing of an object highly associated with a specific color (e.g. a drawing of a frog in red ink). When the unattended stimulus attribute contained color information that conflicted with an item's ink color, increased activity was observed in the posterior brain region that processes the aspect of the task-irrelevant attribute related to color. Increased activity was observed in the left precuneus and left superior parietal cortex when the conflicting information arose from a color word; in the middle temporal gyrus and insular cortex when the word named an object highly associated with a specific color, and included extensive regions of early portions of the ventral visual processing stream when a line drawing was highly associated with a specific color. These areas have been implicated in word processing, semantic processing, and visual processing, respectively. Our results suggest that attentional selection can occur by: (1) increasing the gain on all posterior regions responsible for processing information related to the task demands, regardless of whether that information is contained in the task-relevant or task-irrelevant dimension; (2) limiting the processing of task-irrelevant information in order to reduce interference; and (3) modulating the processing of representations varying from those of a low-level perceptual nature up through those of a higher-order semantic nature.

Object-based attention and object working memory: overlapping processes revealed by selective interference effects in humans

Human observers can discriminate two attributes from the same object more efficiently than attributes from two different objects even if the retinal locations of the attributes are the same in the single and dual object cases. The single object advantage challenges the spatial spotlight view of attention and suggests that attentional selection can be object based. We report that the single object advantage is reliably reduced when an object working memory task is performed concurrently, whereas concurrent verbal and spatial working memory tasks have no effect. This selective interference effect provides support for the existence of object-based attentional processes that also contribute to the short-term retention of objects in working memory. These results are consistent with the hypothesis that both attentional and memory subsystems are organized along domain-specific lines, and suggest the importance of attention in rehearsal operations. The contributions of inferior temporal and parietal mechanisms that have been implicated in attending to and remembering objects are considered.

[Psychophysiological mechanisms of the vitauct]

Psychophysiological mechanisms of vitaukt in human information processing were studied. 90 women and 60 men and in four age groups: 20-29, 30-39, 40-49 and 50-60 were examined. The information processing was studied by three computer's tests with difference complexity. The time and accuracy of each assignment were registered for each tests. The psychophysiological organization as characteristic of human functional system was studied by entropy. The results are showed increase of determinism of psychophysiological organization with simplification of informational processing. Aging weakening of psychophysiological organization determinism reflects in the increasing of informational processing protraction. The psychophysiological mechanism of vitaukt relation with increases the stochastic of informational processing system in aging involution condition.

Turning gap acceptance decision-making: the impact of driver distraction

PROBLEM

A number of studies have found that use of in-car phones by drivers can interfere with the cognitive processing necessary for making appropriate and timely vehicle control decisions. However, the specific linkage between communication-based distraction and unsafe decision-making has not been sufficiently explored.

METHOD

In a closed-course driving experiment, 39 subjects were exposed to approximately 100 gaps each in a circulating traffic stream of eight vehicles on an instrumented test track that was wet about half the time. The subjects were at the controls of an instrumented car, which was oriented in a typical left-turn configuration (traffic-crossing situation in North America) and with parking brake on and the transmission in neutral. The subjects were instructed to press on the accelerator pedal when they felt that a gap was safe to accept. Their performances were monitored and incentives were provided for balancing safe decision-making with expeditious completion of the task. For half of the gap exposures (randomly assigned), each subject was required to listen and respond to a complex verbal message.

RESULTS

When not distracted, the subjects' gap acceptance judgment was found to be significantly influenced by their age, the gap size, the speed of the trailing vehicle, the level of "indecision," and the condition of the track surface. However, when distracted, the subjects did not factor pavement surface condition into the decision process. On wet pavement, the subjects were judged to have initiated twice the level of potential collisions when distracted by the messages that they did when not distracted.

DISCUSSION

Listening/responding to verbal messages may reduce the capacity of drivers to process adequately all the important information necessary for safe decision-making. The effects of the messages in our study seemed to cause the subjects to misjudge gap size and speed information when operating under the additional disadvantage of adverse pavement condition.

SUMMARY

Attention to complex messages while making decisions about turning through gaps in an on-coming vehicle stream was associated with significantly increased unsafe decision making by subjects in our experiment when the additional complexity of wet surface condition was introduced.

IMPACT ON INDUSTRY

While the results reflected a somewhat artificial situation where the measure was signaled intention to act rather than the act itself, nevertheless, they do strongly suggest a scenario in which mental distraction could contribute to crash risk. With the rapid proliferation of telematics in the vehicle market, even with the laudable objectives represented by the Intelligent Transportation Systems initiative, there is a danger of the primary task of the driver being subordinated to a perceived need to enhance information flow to/from the external "world." Industry and governments need to work together to ensure that apparently desirable in-vehicle communication improvements do not compromise safety.

Affective percept and voluntary action: a hypothesis

I present a hypothesis concerning the neuronal, mental and behavioral effects of all kinds of affective (emotional) stimuli, i.e., of unpleasant and pleasant stimuli. I use the term stimulus in its broad sense. Affective stimuli evoke two associated percepts: "cognitive" and "affective". A food in the mouth, for example, evokes the gustatory percept and the percept of pleasure. However, affective percepts are unstable parts of cognitive-affective compounds. Five types of affective percepts are pain, fear, pleasure, "desire" and appetite in the broad sense of these words. Desire is evoked by inadequate pleasant stimuli. Affective percepts are "lower" or "higher". The latter are not directly associated with bodily needs. Esthetic and social percepts are higher, for example. Although pain and pleasure are essentially innate, they can be modified by sensory experience. Alimentary and esthetic preferences and social values are modifiable, for example. The neurons of pain and fear and of the unpleasant components of desire and appetite motivate four types of voluntary actions. These are, respectively, escape, avoidance, "optimization" and approach actions. All these actions eliminate the motivating displeasure. In addition, avoidance actions protect from the signaled pain, optimization actions increase the existing pleasure and approach actions provide the signaled pleasure. Thus, voluntary actions associated with different percepts occur according to one universal principle. Voluntary actions are "internal" and behavioral. During internal actions a goal and then an action plan are decided. These actions often provide the images of the goal stimuli and of particular movements.

Human masticatory muscle activity and jaw position under experimental stress

The purpose of the present study was to determine whether stress induced a consistent pattern of increased electromyographic (EMG) activity in different masticatory muscles, and whether stress produced changes in jaw position. Thirty-five dental students at Taipei Medical College volunteered for this study. Mental arithmetic was used to create a stress condition and relaxation instruction was used to help relax the subjects. Subjects were asked to evaluate the stress they felt under each experimental condition with a visual analogue scale (VAS). Surface electrodes were used to monitor the EMG activities of the right masseter, right posterior temporalis and suprahyoid muscles. A kinesiograph was used to observe the jaw position. Data collected before mental arithmetic or relaxation monitored the baseline level. The VAS means were significantly increased during the stress condition and significantly decreased following relaxation, compared with the baseline. There was also a significant increase in EMG activity of all three muscles during mental arithmetic compared with baseline; different patterns of increased EMG activity were noticed in the three muscles under a continuous stress condition. Under stress, the incidence of tooth contact at intercuspal position was also increased.

Dissociations between object knowledge and everyday action

We report the case of a patient, MC, with Alzheimer's disease, who showed poor ability to name visually presented objects and poor visual access to the concepts of objects relative to a group of control patients (also with dementia). She performed well when words instead of objects were used in the various tasks. The data suggest that she has impaired access to semantic knowledge from vision. Surprisingly, she performed well when asked to perform everyday tasks with the same objects that had proved problematic in tests of visual naming and semantics. MC's pattern of performance is consistent with there being a direct route from vision to action and with the proposal that chaining between actions allows the development of action schemas which may operate even when there is impaired access to semantic knowledge.

Human brain potentials reveal similar processing of non-linguistic abstract structure and linguistic syntactic structure

This research tested the hypothesis that shared or related neurophysiological processes are required for treating (a) non-linguistic abstract structure and (b) some aspects of linguistic syntactic structure. In language, one syntactic structure can be used to create an open class of sentences. We have previously proposed a relation between this generative aspect of syntactic structure and the abstract structure of non-linguistic sequences. For instance, the sequences 'ABCBAC' and 'DEFEDF' have different serial order or serial structure, but share the same abstract structure '123213'. Our recent studies of neuropsychology, simulation and ERPs argued that similar neurophysiological processes are involved in treating non-linguistic abstract structure and certain aspects of linguistic syntactic structure. The current research tests this hypothesis by examining the ERP profile evoked during the processing of non-linguistic sequences vs. sentences. Ten healthy subjects were trained to discriminate between syntactically correct and incorrect sequences and sentences presented visually on a video screen. During the subsequent ERP recording, subjects discriminated between correct and incorrect sequences and sentences presented visually on the screen. This discrimination task yielded, for anomalies in both the abstract and syntactic conditions, a late positivity around 550 ms with partially overlapping topography. These results support our hypothesis that shared or related neurophysiological processes are required for treating non-linguistic abstract structure and aspects of linguistic syntactic structure. However, they also suggest that the overlap between these two types of processing is not complete.