Intelligence and spatiotemporal patterns of event-related desynchronization (ERD)

Intelligence and information processing during a visual search task in children: an event-related potential study

To investigate the differences in event-related potential parameters related to children's intelligence, we selected 15 individuals from an experimental class of intellectually gifted children and 13 intellectually average children as control to finish three types of visual search tasks (Chinese words, English letters and Arabic numbers). We recorded the electroencephalogram and calculated the peak latencies and amplitudes. Our results suggest comparatively increased P3 amplitudes and shorter P3 latencies in brighter individuals than in less intelligent individuals, but this expected neural efficiency effect interacted with task content. The differences were explained by a more spatially and temporally coordinated neural network for more intelligent children.

Superior performance and neural efficiency: the impact of intelligence and expertise

Superior cognitive performance can be viewed from an intelligence perspective, emphasising general properties of the human information processing system (such as mental speed and working memory), and from an expertise perspective, highlighting the indispensable role of elaborated domain-specific knowledge and acquired skills. In exploring its neurophysiological basis, recent research has provided considerable evidence of the neural efficiency hypothesis of intelligence, indicating lower and more focussed brain activation in brighter individuals. The present EEG study investigates the impacts of intelligence and expertise on cognitive performance and the accompanying cortical activation patterns in the domain of tournament chess. Forty-seven tournament chess players of varying intelligence and expertise level worked on tasks drawing on mental speed, memory, and reasoning. Half of the tasks were representative for chess, while the other half was not. The cortical activation was quantified by means of event-related desynchronisation (ERD) in the upper alpha band. Independent effects of expertise and intelligence emerged at both, the performance and the neurophysiological level. Brighter participants performed better than less intelligent ones which was associated with more efficient brain functioning (lower ERD) across all tasks. Additionally, a high expertise level was beneficial for good task performance but exerted a topographically differentiated influence on the cortical activation patterns. The findings suggest that superior cognitive performance and the underlying cortical activation are not only a function of knowledge and domain-specific competences but also of the general efficiency of the information processing system.

Timing Performance as a Predictor of Psychometric Intelligence as Measured by Speed and Power Tests

In the present study, the relationship between timing performance and psychometric intelligence as measured by a speed and a power test of intelligence was examined. For this purpose performance on the Zahlen-Verbindungs-Test (ZVT), the Wiener Matrizen-Test (WMT), seven psychophysical temporal tasks, and the Hick reaction-time paradigm was obtained in 190 participants. Correlational and principal component analyses suggested a unitary timing mechanism referred to as temporal g. Performance on single temporal tasks and individual factor scores on temporal g were substantially related to both speed and power measures of psychometric intelligence. Temporal g exhibited higher sensitivity to the prediction of performance on the power test than on the speed test. Furthermore, stepwise multiple regression analysis and commonality analysis revealed that timing performance provides a more powerful predictor of psychometric intelligence than traditional reaction-time measures derived from the Hick paradigm. These findings support the notion that the temporal resolution capacity of the brain as assessed with psychophysical temporal tasks reflects an essential property of brain functioning, which is relevant to a wide range of intelligence-related aspects of neural information processing.

Sensitivity of alpha band ERD to individual differences in cognition

According to the neural efficiency hypothesis, brighter individuals might be characterized by lower and topographically more differentiated brain activation than less intelligent individuals, presumably reflecting a more specialized recruitment of task-related areas. The findings of several studies analyzing the event-related desynchronization (ERD) in the (upper) alpha frequency band have corroborated and elaborated the original neural efficiency hypothesis. In this chapter, we review classical and recent findings and argue in favor of a more differentiated picture of this phenomenon, emphasizing the role of participants' sex, task complexity, and material specificity, as well as the importance to select an adequate external criterion (intelligence measure). Also, recent ERD findings related to emotional intelligence and creativity as well as recent studies focusing on practice, learning ability, and expertise are presented, which point to the need of a broader neurophysiological ability concept. The reviewed findings point at the high suitability of the ERD method to uncover consistent and stable individual differences in people's brain activation patterns when engaged in performing cognitively demanding tasks.

Attention, psychomotor functions and age

Nutrition might play an important role to ameliorate or to buffer age-related declines in attention and psychomotor functions. The assessment of nutritional effects in aged subjects has to take into account that attention and psychomotor functions can be subdivided in different functions that are differentially affected by age. This paper gives an overview of changes in different facets of attention and psychomotor functions beyond fifty as well as assessment methods for attention and psychomotor performance. It also provides a review of models to explain the pattern of changes with increasing age, and discusses the problems of high performance variance and of age related confounding variables like health status. Two different approaches are discussed that analyse a performance profile and an experimentally oriented functional microanalysis of changes in performance with respect to the effects of nutrition on attention and psychomotor functions. Addressed are examples of missing age-related deficits or even age-related superiority. Caffeine and Ginseng are considered as examples to enhance performance in older persons. Results are in accordance with data on the positive role of physical fitness for mental performance in older persons. Performance of older persons can well be enhanced by functional food components or nutritional supplementation. The effects are comparable to the effects obtained in younger groups, while there is only weak evidence for specific compensatory effects in aged persons. Finally the role of nutrition for the processes of healthy aging is discussed.

Individual differences in brain activity during visuo-spatial processing assessed by slow cortical potentials and LORETA

Using slow-cortical potentials (SCPs), Vitouch et al. demonstrated that subjects with low ability to solve a complex visuo-spatial imagery task show higher activity in occipital, parietal and frontal cortex during task processing than subjects with high ability. This finding has been interpreted in the sense of the so-called "neural efficiency" hypothesis, which assumes that the central nervous system of individuals with higher intellectual abilities is functioning in a more efficient way than the one of individuals with lower abilities. Using a higher spatial resolution of SCP recordings, and by employing the source localization method of LORETA (low-resolution electromagnetic tomography), we investigated this hypothesis by performing an extended replication of Vitouch et al.'s study. SCPs during processing of a visuo-spatial imagery task were recorded in pre-selected subjects with either high or low abilities in solving the imagery task. Topographic and LORETA analyses of SCPs revealed that a distributed network of extrastriate occipital, superior parietal, temporal, medial frontal and prefrontal areas was active during task solving. This network is well in line with former studies of the functional neuroanatomy of visuo-spatial imagery. Contrary to our expectations, however, the results of Vitouch et al. as well as of other studies supporting the neural efficiency hypothesis could not be confirmed since no difference in brain activity between groups was observed. This inconsistency between studies might be due to differing task processing strategies. While subjects with high abilities in the Vitouch et al. study seemed to use a visuo-perceptual task solving approach, all other subjects relied upon a visuo-motor task processing strategy.

Sex differences in brain activity related to general and emotional intelligence

The study investigated gender differences in resting EEG (in three individually determined narrow alpha frequency bands) related to the level of general and emotional intelligence. Brain activity of males decreased with the level of general intelligence, whereas an opposite pattern of brain activity was observed in females. This difference was most pronounced in the upper-alpha band which is related to semantic memory processes. It was further found that highly intelligent males displayed greater decoupling of frontal brain areas, whereas highly intelligent females showed more coupling between frontal and parietal/occipital brain areas. Similar, but less significant differences were observed for the two area scores of strategic and experiential emotional intelligence. It appears that males and females have different resting EEG correlates of IQ.

Intelligence and neural efficiency: Further evidence of the influence of task content and sex on the brain–IQ relationship

In the field of physiological study of human intelligence, strong evidence of a more efficient operation (i.e., less activation) of the brain in brighter individuals (the neural efficiency hypothesis) can be found. Most studies in this field have used single, homogeneous tasks and have not examined sex differences. In analyzing the extent of Event-related Desynchronization (ERD) in the EEG during the performance of a verbal and a visuo-spatial task, we recently found that males and females display neural efficiency primarily in the domain where they usually perform better (i.e., verbal in females and spatial in males; cf. A.C. Neubauer, A. Fink, D.G. Schrausser, Intelligence and neural efficiency: the influence of task content and sex on brain-IQ relationship. Intelligence, 30 (2002) 515-536). However, this interpretation was complicated by differences in the complexity of the two tasks. By using a verbal (semantic) and a spatial (rotation) task of comparable complexity in this research, we sought to replicate and extend our earlier findings by additionally considering the individual differences in intelligence structure and the topographical distribution over the cortex. Findings were similar to the previous study: Females (n = 35) display neural efficiency (i.e., less brain activation in brighter individuals) primarily during the verbal task, males (n = 31) in the spatial task. However, the strength of this brain activation-IQ relationship varies with the intelligence factor: In males, the highest correlations were observed for spatial IQ, in females for verbal IQ. Furthermore, the sexes displayed topographical differences of neural efficiency patterns.

Long-term stability and consistency of EEG event-related (de-)synchronization across different cognitive tasks

OBJECTIVE

We examined whether task-related band power changes (event-related desynchronization/synchronization; ERD/ERS) that have been linked to individual differences in cognitive ability demonstrate satisfying temporal stability and cross-situational consistency.

METHODS

Multi-channel EEG recordings from 29 adults, assessed at three different occasions over 2 years were examined. Between-session correlations and consistency coefficients (Cronbach's alpha) across the three experiments were evaluated for both, spectral power features of the resting EEG and ERD/ERS estimates while the participants performed some cognitive task (i.e. different elementary cognitive tasks that put comparable demands on the participants).

RESULTS

ERD/ERS values, while subjects performed a cognitive task, demonstrated satisfactory stability and consistency (i.e. >0.7), whereby the degree of consistency varied as a function of frequency band and brain region. Highest consistency was found for the 8-10 Hz ERD in parieto-occipital recording sites (i.e. >0.9). In resting EEG, mean alpha (gravity) frequency was the most stable EEG feature.

CONCLUSIONS

The present data suggest that ERD/ERS phenomena in different narrow frequency bands are rather stable over time and across different situations. The relatively high reproducibility of ERD/ERS promotes the usefulness of this measure in assessing individual differences of physiological activation patterns accompanying cognitive performance.

SIGNIFICANCE

This study addresses the issue of reproducibility of EEG in general and ERD/ERS experiments in particular, which is a prerequisite for both basic research and clinical studies.

Intelligence related upper alpha desynchronization in a semantic memory task

Recent evidence shows that event-related (upper) alpha desynchronization (ERD) is related to cognitive performance. Several studies observed a positive, some a negative relationship. The latter finding, interpreted in terms of the neural efficiency hypothesis, suggests that good performance is associated with a more 'efficient', smaller extent of cortical activation. Other studies found that ERD increases with semantic processing demands and that this increase is larger for good performers. Studies supporting the neural efficiency hypothesis used tasks that do not specifically require semantic processing. Thus, we assume that the lack of semantic processing demands may at least in part be responsible for the reduced ERD. In the present study we measured ERD during a difficult verbal-semantic task. The findings demonstrate that during semantic processing, more intelligent (as compared to less intelligent) subjects exhibited a significantly larger upper alpha ERD over the left hemisphere. We conclude that more intelligent subjects exhibit a more extensive activation in a semantic processing system and suggest that divergent findings regarding the neural efficiency hypotheses are due to task specific differences in semantic processing demands.

Intelligence related differences in EEG-bandpower

Several studies on the relationship between event-related desynchronization/synchronization (ERD/ERS) and cognitive performance revealed contradictory results particularly for the alpha band. Studies from our laboratory have shown that good performers show a larger upper alpha ERD (interpreted in terms of larger cortical activation) than bad performers. In contrast, other researchers found evidence for the neural efficiency hypothesis, which states that more intelligent subjects exhibit a smaller extent of cortical activation, which is assumed to be reflected by a smaller upper alpha ERD. Here we address the question whether these divergent results may be due to differences in general task difficulty. Using a modified version of the RAVEN, individually divided into easy and difficult tasks, a group of average and a group of highly intelligent subjects (IQ- and IQ+) have been investigated. While in the theta frequency IQ+ subjects generally exhibited a significantly stronger activation, we found a significant interaction of task difficulty and IQ group in the upper alpha band, indicating both, a weaker activation for the high IQ group during the easy tasks, and a significant increase from easy to difficult tasks for IQ+ only.

Alpha rhythms in mild dements during visual delayed choice reaction time tasks: A MEG study

Can simple delayed response tasks affect latency and amplitude of magnetoencephalographic midline alpha rhythms (6-12 Hz) in early dementia? We recruited 15 mild Alzheimer's disease (AD) and 10 vascular dementia (VaD) patients (paired mini mental state exam of 17-24). The control groups comprised 18 young and 22 elderly normal subjects. In the first task, a simple "cue" stimulus (one bit) was memorized along a brief delay period (3.5-5.5s) up to a "go" stimulus triggering (right or left) button press. In the second task, the "cue" stimulus remained available along the delay period. Event-related reduction in power of the alpha rhythms indexed the cortical activation (event-related desynchronization, ERD) for the trials associated with correct behavioral responses. Behavioral performances to both tasks were lower in the AD and VaD patients than in the normal subjects. In particular, just four AD and five VaD patients executed a sufficient amount of correct responses for the alpha ERD analysis, so they were included in a unique group. In both tasks, the alpha ERD peak was later in latency in the demented and normal elderly subjects than in the normal young subjects. Furthermore, the alpha ERD peak was stronger in amplitude in the demented patients than in the normal subjects. These results suggest that simple delayed response tasks during physiological recordings are quite difficult for patients even at an early dementia stage. Such difficulty may induce the abnormal amount of the related cortical activation in dementia as revealed by the alpha ERD.

Increasing Individual Upper Alpha Power by Neurofeedback Improves Cognitive Performance in Human Subjects

The hypothesis was tested of whether neurofeedback training (NFT)--applied in order to increase upper alpha but decrease theta power--is capable of increasing cognitive performance. A mental rotation task was performed before and after upper alpha and theta NFT. Only those subjects who were able to increase their upper alpha power (responders) performed better on mental rotations after NFT. Training success (extent of NFT-induced increase in upper alpha power) was positively correlated with the improvement in cognitive performance. Furthermore, the EEG of NFT responders showed a significant increase in reference upper alpha power (i.e. in a time interval preceding mental rotation). This is in line with studies showing that increased upper alpha power in a prestimulus (reference) interval is related to good cognitive performance.

Visual discrimination performance is related to decreased alpha amplitude but increased phase locking

This study investigated the question whether good and bad performance in a visual discrimination task is related to resting alpha power in a different way as it is known from memory tasks. The results show that good perceptual but not memory performance is related to low alpha amplitudes. In addition, we found that large phase resetting in the alpha band, and enhanced early components in the ERP are related to good performance in the discrimination task. The conclusion of this study is that in contrast to memory performance which is related to large resting alpha activity low alpha amplitudes are an indicator for good perceptual performance.

Differences in induced gamma and upper alpha oscillations in the human brain related to verbal/performance and emotional intelligence

Participating in the study were 30 respondents, who could be clustered as high-average verbal/performance intelligent (HIQ/AIQ), or emotionally intelligent (HEIQ/AEIQ). The EEG was recorded while students were performing two tasks: the Raven's advanced progressive matrices (RAPM), and identifying emotions in pictures (IDEM). Significant differences in event-related desynchronization/synchronization (ERD/ERS) related to verbal/performance intelligence were only observed while respondents solved the RAPM. The HIQ and AIQ groups displayed temporal and spatial differently induced gamma band activity. Significant differences in ERD/ERS related to emotional intelligence were only observed for the IDEM task. HEIQ individuals displayed more gamma band ERS and less upper alpha band ERD than did AEIQ individuals. It can be concluded that HIQ and HEIQ individuals employed more adequate strategies for solving the problems at hand. The results further suggest that emotional intelligence and verbal/performance intelligence represent distinct components of the cognitive architecture.

Intelligence and working memory systems: evidence of neural efficiency in alpha band ERD

Starting from the well-established finding that brighter individuals display a more efficient brain function when performing cognitive tasks (i.e., neural efficiency), we investigated the relationship between intelligence and cortical activation in the context of working memory (WM) tasks. Fifty-five male (n=28) and female (n=27) participants worked on (1) a classical forward digit span task demanding only short-term memory (STM), (2) an attention-switching task drawing on the central executive (CE) of WM and (3) a WM task involving both STM storage and CE processes. During performance of these three types of tasks, cortical activation was quantified by the extent of Event-Related Desynchronization (ERD) in the alpha band of the human EEG. Correlational analyses revealed associations between the amount of ERD in the upper alpha band and intelligence in several brain regions. In all tasks, the males were more likely to display the negative intelligence-cortical activation relationship. Furthermore, stronger associations between ERD and intelligence were found for fluid rather than crystallized intelligence. Analyses also point to topographical differences in neural efficiency depending on sex, task type and the associated cognitive subsystems engaged during task performance.

Intelligence and individual differences in becoming neurally efficient

Physiological approaches to human psychometric intelligence have shown a higher neural efficiency (i.e. less cortical activation) during cognitive performance in brighter subjects. The main aim of this study was to explore the relationship between intelligence and cortical activation patterns in the framework of the learning test concept. In 27 participants we assessed the topography and extent of cortical activation by means of event-related desynchronization (ERD) during reasoning tests in a pre-test--training--post-test design and related it to psychometric intelligence (measured by the German Leistungs-Prüf-System, LPS). Significant associations between intelligence and cortical activation patterns were exclusively found at anterior (frontal) recording sites, which corroborates the central role of the frontal lobe for higher-order cognitive functions. The hypothesized negative intelligence-activation correlation was observed only after the training, i.e. in the post-test, but not in the pre-test. More important, the decrease in cortical investment from pre-test to post-test correlated negatively with intelligence, indicating that the higher the subjects' general mental ability the larger the decrease in the amount of cortical activation. These findings suggest intelligence-related individual differences in becoming neurally efficient.

Manipulation of frontal brain asymmetry by cognitive tasks

The purpose of the present study was to evaluate whether verbal fluency tasks may specifically induce relatively greater left than right hemispheric activation in the dorsolateral prefrontal cortex. The effectiveness of the manipulation was evaluated by EEG, which was recorded during performance of the verbal fluency task and during two control conditions, i.e., a baseline condition without cognitive demands, and a mental arithmetic task, respectively. The results demonstrate that the desired effect can only be achieved in individuals with good performance on the verbal fluency task. Good and poor performers do not only differ in lateral asymmetry, but also in the most affected region within the prefrontal cortex. Whereas good performers show relatively increased activation in the cortical region and hemisphere putatively most specialized for this kind of task (i.e., the left dorsolateral frontal cortex), poor performers show a marked shift of frontopolar asymmetry to the right.

Differences in induced brain activity during the performance of learning and working-memory tasks related to intelligence

Thirteen high intelligent (H-IQ) and 13 low intelligent (L-IQ) individuals solved two figural working-memory (WM) tasks and two figural learning tasks while their EEG was recorded. For the WM tasks, only in the theta band group related differences in induced event-related desynchronization/synchronization (ERD/ERS) were observed. L-IQ individuals displayed greater theta synchronization in the later phases of task completion (1000-2000 ms) as compared to H-IQ individuals. For the learning tasks group related differences in the three alpha bands were observed. In the upper alpha band L-IQ individuals showed greater ERD in the frontal brain areas, whereas H-IQ individuals displayed greater ERD in the parieto-occipital brain areas.

Anterior asymmetrical alpha activity predicts Iowa gambling performance: distinctly but reversed

Animal research indicates that the prefrontal cortex (PFC) plays a crucial role in decision making. In concordance, deficits in decision making have been observed in human patients with damage to the PFC. Contemporary accounts of decision making suggest that emotion guides the process of decision making by ways of providing for reward-punishment contingencies. A task capable of assessing the influence of reward and punishment on decision making is the Iowa gambling task. In this task decisions become motivated by inherent punishment and reward schedules. Insensitivity for punishment together with a strong reward dependency results in risk taking, which is in the gambling task the disadvantageous strategy. Interestingly, the processing of punishment and reward is argued to be lateralized over the right and left PFC, respectively. Here we investigated whether more relative left compared to right-sided frontal brain activity (left-sided dominance) quantified as reduced alpha (8-12 Hz) activity in the electroencephalogram (EEG) would lead to a more risky, disadvantageous pattern of decision making. Contrary to what was expected, relatively more right compared to left frontal brain activity was strongly associated with the disadvantageous strategy. The results are discussed in terms of recent theoretical accounts which argue that the functional interpretation of baseline frontal alpha activity depends on the mental operation involved and does not necessarily imply inactivity.

When intelligence loses its impact: neural efficiency during reasoning in a familiar area

Several studies have revealed that persons with a lower IQ show more cortical activity when solving intelligence-related tasks than more intelligent persons do. Such results are interpreted in terms of neural efficiency: the more intelligent a person is, the fewer mental resources have to be activated. In an experiment with 31 experienced taxi drivers of varying IQs (measured by Raven's advanced progressive matrices test), we investigated cortical activation by measuring the amount of event-related desynchronization in the electroencephalogram during a familiar task (thinking about routes to take in their city) and a novel task (memorizing routes of an artificial map). A comparison of participants with lower and higher IQs (median split) revealed higher cortical activation in the less intelligent group for the novel task, but not for the familiar task. These results suggest that long-term experience can compensate for lower intellectual ability, even at the level of cortical activation.

Spatiotemporal brain activity related to intelligence: a low resolution brain electromagnetic tomography study

Differences in current density between high intelligent (IQ=124), and average intelligent individuals (IQ=110), while solving two complex cognitive tasks (analytical-figural, and identification of emotions) were analyzed with low resolution brain electromagnetic tomography (LORETA). High intelligent individuals, as compared with average ones in both tasks displayed a lesser full width at half maximum (FWHM) volume-indicating the amount of spatial dispersion of the source. High and average intelligent individuals also differed in their source location. The source location of high intelligent individuals was in the inferior right hemispheric brain areas, whereas the source location of average intelligent individuals was in the superior left hemispheric brain areas. The findings were explained in the light of the neural efficiency model.

Enhancing cognitive performance with repetitive transcranial magnetic stimulation at human individual alpha frequency

We applied rapid-rate repetitive transcranial magnetic stimulation (rTMS) at individual alpha frequency (IAF) to improve cognitive performance by influencing the dynamics of alpha desynchronization. Previous research indicates that a large upper alpha power in a reference interval preceding a task is related to both large suppression of upper alpha power during the task and good performance. Here, we tested the hypothesis that rTMS at individual upper alpha frequency (IAF + 1 Hz) can enhance alpha power in the reference interval, and can thus improve task performance. Repetitive TMS was delivered to the mesial frontal (Fz) and right parietal (P6) cortex, and as sham condition with 90 degrees-tilted coil (P6 position). The behavioural effect was assessed in a mental rotation task. Further control conditions were rTMS at a lower IAF (IAF - 3 Hz) and at 20 Hz. The results indicate that rTMS at IAF + 1 Hz can enhance task performance and, concomitantly, the extent of task-related alpha desynchronization. This provides further evidence for the functional relevance of oscillatory neuronal activity in the alpha band for the implementation of cognitive performance.

Integrative neurocomputational perspectives on cognitive aging, neuromodulation, and representation

Besides neuroanatomical changes, neuromodulatory mechanisms are also compromised during aging. Neural network models are suitable tools for exploring the relatively broad and homogenous neuromodulatory influences on cortical function. Computational approaches for understanding neuromodulation of the dynamic properties of cortical function and recent neurocomputational theories relating different aspects of cognitive aging with declines in neuromodulation are reviewed. Considered within an integrative cross-level neurocomputational framework, aging-related decline in dopaminergic neuromodulation reduces the fidelity of neural information and gives rise to less distinctive neural pattern representations that may underlie various facets of aging cognitive and, possibly also, sensorimotor phenomena.

On the time resolution of event-related desynchronization: a simulation study

OBJECTIVES

To investigate the time resolution of different methods for the computation of event-related desynchronization/synchronization (ERD/ERS), including one based on Hilbert transform.

METHODS

In order to better understand the time resolution of ERD/ERS, which is a function of factors such as the exact computation method, the frequency under study, the number of trials, and the sampling frequency, we simulated sudden changes in oscillation amplitude as well as very short and closely spaced events.

RESULTS

Hilbert-based ERD yields very similar results to ERD integrated over predefined time intervals (block ERD), if the block length is half the period length of the studied frequency. ERD predicts the onset of a change in oscillation amplitude with an error margin of only 10-30 ms. On the other hand, the time the ERD response needs to climb to its full height after a sudden change in oscillation amplitude is quite long, i.e. between 200 and 500 ms. With respect to sensitivity to short oscillatory events, the ratio between sampling frequency and electroencephalographic frequency band plays a major role.

CONCLUSIONS

(1) The optimal time interval for the computation of block ERD is half a period of the frequency under investigation. (2) Due to the slow impulse response, amplitude effects in the ERD may in reality be caused by duration differences. (3) Although ERD based on the Hilbert transform does not yield any significant advantages over classical ERD in terms of time resolution, it has some important practical advantages.

Differences in autonomic physiological responses between good and poor inductive reasoners

We investigated individual- and task-related differences in autonomic physiological responses induced by time limited figural and verbal inductive reasoning tasks. In a group of 52 participants, the percentage of correctly responded task items was evaluated together with nine different autonomic physiological response measures and respiration rate (RR). Weighted multidimensional scaling analyses of the physiological responses revealed three underlying dimensions, primarily characterized by RR, parasympathetic, and sympathetic activity. RR and sympathetic activity appeared to be relatively more important response dimensions for poor reasoners, whereas parasympathetic responsivity was relatively more important for good reasoners. These results suggest that poor reasoners showed higher levels of cognitive processing intensity than good reasoners. Furthermore, for the good reasoners, the dimension of sympathetic activity was relatively more important during the figural than during the verbal reasoning task, which was explained in terms of hemispheric lateralization in autonomic function.

Restriction of task processing time affects cortical activity during processing of a cognitive task: an event-related slow cortical potential study

As is known from psychometrics, restriction of task processing time by the instruction to respond as quickly and accurately as possible leads to task-unspecific cognitive processing. Since this task processing mode is used in most functional neuroimaging studies of human cognition, this may evoke cortical activity that is functionally not essential for the particular task under investigation. Using topographic recordings of event-related slow cortical potentials, two experiments have been performed to investigate whether cortical activity during processing of a visuo-spatial imagery task is substantially influenced by the time provided to process the task. Furthermore, it was investigated whether this effect is additionally modulated by a subject's task-specific ability. The instruction to respond as quickly and accurately as possible led to increased negative slow cortical potential amplitudes over parietal and frontal regions and significantly interacted with task-specific ability. While cortical activity recorded over parietal and frontal regions was different between subjects with low and high spatial ability when processing time was unrestricted, no such differences were found between ability groups when subjects were instructed to answer both quickly and accurately. These results suggest that restricting processing time has considerable effects on the amount and the pattern of brain activity during cognitive processing and should be taken into account more explicitly in the experimental design and interpretation of neuroimaging studies of cognition.

Correlations between ERP parameters and intelligence: a reconsideration

The present study investigated differences in ERP parameters related to intelligence. For that purpose 74 individuals (Intelligence: M=107; S.D.=12; range 73-135), of average creativity passively listened to two tones and performed two auditory, and two visual oddball tasks while their EEG was recorded. The approximate entropy parameters, peak latencies and amplitudes were determined. The correlation coefficients indicated that in the attended conditions, the more intelligent individuals showed more regular ERP waveforms than less intelligent individuals. It was further found that less intelligent individuals showed increased P300 latencies and reduced amplitudes. The differences were explained with a more specific engagement of neural networks in more intelligent individuals.

Differences in event-related and induced brain oscillations in the theta and alpha frequency bands related to human intelligence

High (intelligence quotient (IQ)=126) and low intelligent individuals (IQ=88) were listening to tone pips and performed an auditory oddball task while their electroencephalogram was recorded. Significant differences relating to intelligence were observed in induced and event related band power in the theta (4-7 Hz) and upper alpha band (10-13 Hz). In the oddball task high intelligent individuals displayed less theta synchronization and more synchronization in the upper alpha band. The results were explained by the more efficient engagement of neural networks in more intelligent individuals.

Informationsverarbeitungsgeschwindigkeit und Schulerfolg:Weisen basale Maße der Intelligenz prädiktive Validität auf?

Zusammenfassung. Neben Lehrerurteilen gelten Intelligenztests als die besten Prädiktoren zur Vorhersage des Schulerfolgs. In “klassischen” Intelligenztestverfahren werden Aufgabentypen mittleren Komplexitätsgrades mit steigendem Schwierigkeitsgrad eingesetzt. Im Gegensatz dazu stehen Verfahren, die über die Informationsverarbeitungsgeschwindigkeit (IVG) grundlegende Prozesse der allgemeinen Intelligenz messen wollen: Beispielsweise werden im Zahlen-Verbindungs-Test und im Kodierungs-Test einfache, nicht im Schwierigkeitsgrad ansteigende Aufgaben wie Zahlenverbinden oder Buchstabenreihung verwendet. Erhebungen an Gymnasien (N = 445 Schüler) erlaubten Analysen des Zusammenhangs zwischen verschiedenen IVG- und Fähigkeits-Tests sowie Schulnoten. IVG und Intelligenz korrelieren im Schnitt mit r = .26, IVG und Kreativität mit r = .31. Zwischen IVG und Schulnoten besteht eine Beziehung in der Höhe von r = |.37|, Intelligenz und Schulnoten korrelieren zu r = |.43|. Diese Zusammenhänge können nicht durch eine gemeinsame Wissenskomponente (Inhaltsspezifität) oder durch motivationale Merkmale erklärt werden, eher scheint mit der IVG eine grundlegende Eigenschaft des zentralen Nervensystems erfaßt zu werden, die eine Vorhersage von Schulerfolg erlaubt. Der Beitrag der IVG gegenüber anderen Variablen für die Vorhersage des Schulerfolgs wird diskutiert.

Event-related EEG/MEG synchronization and desynchronization: basic principles

An internally or externally paced event results not only in the generation of an event-related potential (ERP) but also in a change in the ongoing EEG/MEG in form of an event-related desynchronization (ERD) or event-related synchronization (ERS). The ERP on the one side and the ERD/ERS on the other side are different responses of neuronal structures in the brain. While the former is phase-locked, the latter is not phase-locked to the event. The most important difference between both phenomena is that the ERD/ERS is highly frequency band-specific, whereby either the same or different locations on the scalp can display ERD and ERS simultaneously. Quantification of ERD/ERS in time and space is demonstrated on data from a number of movement experiments.

Differences in the ability to process a visuo-spatial task are reflected in event-related slow cortical potentials of human subjects

Recent positron emission tomography (PET) and electroencephalographic (EEG) studies suggest that higher ability in a cognitive task is associated with a more efficient neuronal processing of this task. However, the validity and generalizability of these studies is limited for several reasons. We investigated 20 male and 18 female human subjects with good vs. poor spatial ability performing a visuo-spatial task (cube test). Processing-related slow event-related potentials were recorded via 22 electrodes, evenly distributed over the scalp. Significant differences between good and poor performers were found in both sexes: poor subjects showed higher activity in the parietal region, and their topography was more extended into fronto-central regions. Since the amount and topography of brain activity may vary considerably depending on subjects' ability, we conclude that careful (experimental) control of task-specific ability of subjects is mandatory for cognitive neuroscience studies.

Cortical activity of good and poor spatial test performers during spatial and verbal processing studied with Slow Potential Topography

Whether essential processing of spatial information is lateralized asymmetrically in the human cortex is still a matter of debate. In this study, items of an Item Response Theory calibrated test for spatial ability were used to ensure stimulus homogeneity and validity. Subjects were preselected as extreme groups of good and poor spatializers. Mapping of true DC-recorded slow potential shifts (SPSs) resulted in distinctly discriminable topographies with spatial and verbal-analytic material as well as with spatial performance groups within the spatial block. Left fronto-central negativity maxima in the verbal condition clearly contrasted with occipito-parietal peak activity in the spatial condition. Poor spatializers showed higher amplitudes as well as a tendency to asymmetric activity in right parietal (parieto-temporal) areas, whereas in good spatializers the activity was localized symmetrically in occipital and occipito-parietal regions. The findings emphasize the importance of the right posterior cortex for spatial processing (negativity maxima at occipital and right parietal sites) and suggest a task-specific lower cortical efficiency or, seen from a processing perspective, a higher Investment of Cortical Effort (ICE) on the part of poor spatializers.