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Background: Increasing familiarity and practice might free up mental resources during laparoscopic surgical skills training. The aim of the study was to track changes in mental resource allocation during acquisition of laparoscopic surgical skills., Methods: Medical students with no previous experience in laparoscopic surgery took part in a 5-week laparoscopic training curriculum. At the beginning and end of the training period, one of the training tasks was combined with a secondary auditory detection task that required pressing a foot switch for defined target tones, creating a dual-task situation. During execution of the two concurrent tasks, continuous electroencephalographic measurements were made, with special attention to the P300 component, an index of mental resources. Accuracy and reaction times of the secondary task were determined., Results: All 14 participants successfully completed the training curriculum. Target times for successful completion of individual tasks decreased significantly during training sessions (P  <0.001 for all tasks). Comparing results before and after training showed a significant decrease in event-related brain potential amplitude at the parietal electrode cluster (P300 component, W = 67, P = 0.026), but there were no differences in accuracy (percentage correct responses: W = 48, P = 0.518) or reaction times (W = 42, P = 0.850) in the auditory detection task., Conclusion: The P300 decrease in the secondary task over training demonstrated a shift of mental resources to the primary task: the surgical exercise. This indicates that, with more practice, mental resources are freed up for additional tasks., (© The Author(s) 2020. Published by Oxford University Press on behalf of BJS Society Ltd.)

The auditory system continuously monitors the environment for irregularities in an automatic, preattentive fashion. This is presumably accomplished by two mechanisms: a sensory mechanism detects a deviant sound on the basis of differential refractoriness of neural populations sensitive to the standard and deviant sounds, whereas the cognitive mechanism reveals deviance by comparing incoming auditory information with a template derived from previous input. Using fast event-related high-resolution functional magnetic resonance imaging at 7 Tesla we show that both mechanisms can be mapped to different parts of the auditory cortex both at the group level and the single-subject level. The sensory mechanism is supported by primary auditory areas in Heschl's gyrus whereas the cognitive mechanism is implemented in more anterior secondary auditory areas. Both mechanisms are equally engaged by simple sine-wave tones and speech-related phonemes indicating that streams of speech and non-speech stimuli are processed in a similar fashion., (Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.)

Purpose: Processing auditory scenes requires the automatic detection of unexpected acoustic irregularities which allows to reorient the attentional focus for further in-depth analysis. Even if cochlea implants (CI) may partly restore hearing capabilities in patients suffering from profound peripheral deafness, CI users complain about difficulties in identifying novel and unexpected acoustic events. To assess whether this impairment is attributable to preattentive auditory deficits, impaired automatic orienting to novel events and/or to deficits in attentional processing we recorded event-related potentials (ERPs) in an auditory novelty oddball paradigm., Methods: ERPs were obtained in 7 postlingually deafened CI patients and their age-matched controls in passive and active listening conditions. Subjects had to press a button for infrequent novel sounds but not for frequent standard sounds in the active condition., Results: In the active condition patients and controls did not differ with regard to hit-rates and reaction times. ERPs to novel stimuli in the active condition were characterized by enhanced N2b and P3b components that did not differ between groups. By contrast, the P3a component to novel sounds in the passive condition, an index of automatic orienting of attention, was greatly attenuated in the CI users., Conclusions: CI-users are impaired in the preattentive registration of novel auditory events while attentive processing of a designated auditory stream appears intact.

Objectives: Event-related brain potentials (ERPs) were recorded to investigate allocation of attention in adult developmental dyslexics., Subjects and Methods: Twelve adult developmental dyslexics and 12 matched normal controls performed three visual choice reaction tasks. In the passive oddball condition, subjects watched two different simple visual stimuli presented with 87.5 and 12.5% probability. In the active oddball condition, participants responded to the low-probability target stimulus. In the active 50/50-condition, both stimuli were presented with 50% probability and a response was required to the target stimulus only., Results: No group differences emerged for performance, P300 latency or laterality and for N200 amplitude, latency or laterality. An enhancement of P300 amplitude with a frontal distribution was found for NoGo (standard)-stimuli in both active conditions for the dyslexic sample., Conclusion: Results are discussed in the context of deviances in allocation of attentional resources in dyslexic readers.

Obsessive-compulsive disorder (OCD) has been related to altered mechanisms of action monitoring and target detection, and it has been hypothesized that hyperactive striatal-cortical circuits constitute the underlying pathophysiology. This study used event-related brain potentials (ERPs) to explore this hypothesis. A choice reaction time experiment was carried out in a group of OCD patients and a normal comparison group. The P3b component of the ERP to targets was taken as an indicator of the target-evaluation process and the response-locked error-related negativity (ERN) served as an indicator of action monitoring. We hypothesized that the OCD group would show a shortened P3b latency and an amplitude-enhanced ERN. Consistent with our expectations, the P3b latency was shorter and the ERN amplitude was higher in the OCD group. Unexpectedly, we also observed a prolonged ERN latency in the OCD group and a more posterior topography of this component. The data provide partial support for the hypothesis of a hyperactive neural network in OCD. In addition the disorder must involve pathophysiological processes that are presumably related to other aspects of its complex and heterogeneous clinical hallmarks.

Tourette syndrome has been associated with impairments of attentional functions such as distractability, even in subjects without co-morbid attention deficit hyperactivity disorder. Based on the results of earlier research we hypothesized that Tourette syndrome patients might employ altered control mechanisms of attentional processes and have concurrent difficulties in allocating their attentional resources among competing tasks. Event-related brain potentials (ERPs) were recorded in a group of Tourette syndrome patients and in a matched control group during a dual task experiment. This experiment required the simultaneous detection of visual and auditory target stimuli which were manipulated to yield two different difficulty levels each of which were varied orthogonally. The behavioural parameters confirmed the intended performance differences between difficult-to-detect targets and easy-to-detect targets. This was paralleled by lower amplitudes and longer latencies of the corresponding P3b-ERP subcomponents. Although Tourette syndrome patients were unimpaired in overall performance they showed an increased interference of visual task demands with auditory target perception. In parallel they also exhibited a reduced amplitude of the P3b component to auditory targets. The findings show that Tourette syndrome patients are not generally impaired in their dual task performance. The allocation of attentional resources to competing tasks however, is altered. We speculate that this may be related to deficient inhibitory functions.

The purpose of this study was to assess possible central side-effects of sildenafil (Viagra) on attention and memory functions. Sildenafil and placebo were administered in young male subjects in a double-blind balanced cross-over design. Behavioral patterns and event-related brain potentials (ERP) were recorded in a spatial auditory attention and a visual word recognition task. While behavioral patterns did not reveal any overt effects of sildenafil, auditory ERPs were indicative of an enhanced ability to focus attention (amplitude enhancement of Nd-effect) and to select relevant target stimuli in the sildenafil condition (P3 component). In the memory task, CNS-effects of sildenafil were evident in a reduction of a negativity in the 150-250 ms range. No overt effects on behavior were observed. Nevertheless, the data reveal CNS-effects of sildenafil necessitating further studies.

Event-related brain potentials were recorded from healthy human subjects while they attended to one of two auditory stimulus channels (defined by location, left and right of a fixation point, and pitch) in order to detect rare target events. The distracting properties of periodic noise (vs. continuous noise, experiment 1) and backward speech (vs. forward speech, experiment 2) presented from a third speaker located behind the subjects were investigated. A typical attention effect with a larger negativity for attended tones was observed in both experiments. Backward speech led to a significantly reduced target detection rate for the first four stimuli after onset of the distractor accompanied by a reduced event-related brain potential (ERP)-attention effect and a reduced fronto-central N2b component for the target stimuli. This indicates that irrelevant information leads to an attention decrement of about 1 s duration.

This study investigated cross-modal interactions in spatial attention by means of recording event-related brain potentials (ERPs). Noise bursts and light flashes were presented in random order to both left and right field locations separated by 60 degrees in free-field. One group of subjects was instructed to attend selectively to the noise bursts (attend-auditory group), and a second group attended only to the flashes (attend-visual group). On different runs attention was directed to either the right or left field stimuli of the designated modality. In the attend-auditory group, noise bursts at the attended location elicited a broad, biphasic negativity (Nd) beginning at 70 ms. The cross-modal spatial attention effect on the auditory ERPs in the attend-visual group was very similar in morphology, but the Nd was reduced in amplitude relative to the intra-modal effect. In the attend-visual group, flashes at the attended location elicited enhanced early (100-200 ms) and late (200-350 ms) ERP components relative to unattended-location flashes. The cross-modal effect in the attend-auditory group included small but significant enhancements of early components of the visual ERPs. It was concluded that spatial attention has a multi-modal organization such that the processing of stimuli at attended locations is facilitated at an early, sensory level, even for stimuli of an unattended modality.

Blood flow velocities of the posterior cerebral arteries were obtained while healthy subjects were engaged in a visual spatial attention task. Experimental runs consisted of series of stimuli comprised of four elements (two left and two right of a central fixation point) presented briefly in blue against a purple screen. After a period of passive viewing a left or right pointing arrow indicated the visual half-field to be attended by the subjects in order to detect identical symbols on the attended side. Relative to the passive viewing condition a marked increase of flow was seen in both posterior cerebral arteries during the attention period. No differential increase of flow as a function of attended field was detected. These results are discussed in comparison with recent positron-emission tomography (PET) and electrophysiological data obtained with the same task.

Event-related potentials (ERPs) were recorded from healthy subjects in response to unilaterally flashed high and low luminance bar stimuli presented randomly to left and right field locations. Their task was to covertly and selectively attend to either the left or right stimulus locations (separate blocks) in order to detect infrequent shorter target bars of either luminance. Independent of attention, higher stimulus luminance resulted in higher ERP amplitudes for the posterior N95 (80-110 ms), occipital P1 (110-140 ms), and parietal N1 (130-180 ms). Brighter stimuli also resulted in shorter peak latency for the occipital N1 component (135-220 ms); this effect was not observed for the N1 components over parietal, central or frontal regions. Significant attention-related amplitude modulations were obtained for the occipital P1, occipital, parietal and central N1, the occipital and parietal P2, and the parietal N2 components; these components were larger to stimuli at the attended location. In contrast to the relatively short latencies of both spatial attention and luminance effects, the first interaction between luminance and spatial attention effects was observed for the P3 component to the target stimuli (350-750 ms). This suggests that interactions of spatial attention and stimulus luminance previously reported for reaction time measures may not reflect the earliest stages of sensory/perceptual processing. Differences in the way in which luminance and attention affected the occipital P1, occipital N1 and parietal N1 components suggest dissociations among these ERPs in the mechanisms of visual and attentional processing they reflect.(ABSTRACT TRUNCATED AT 250 WORDS)

Visual-spatial attention is an essential brain function that enables us to select and preferentially process high priority information in the visual fields. Several brain areas have been shown to participate in the control of spatial attention in humans, but little is known about the underlying selection mechanisms. Non-invasive scalp recordings of event-related potentials (e.r.ps) in humans have shown that attended visual stimuli are preferentially selected as early as 80-90 ms after stimulus onset, but current e.r.p. methods do not permit a precise localization of the participating cortical areas. In this study we combined neuroimaging (positron emission tomography) with e.r.p. recording in order to describe both the cortical anatomy and time course of attentional selection processes. Together these methods showed that visual inputs from attended locations receive enhanced processing in the extrastriate cortex (fusiform gyrus) at 80-130 ms after stimulus onset. These findings reinforce early selection models of attention.

Event-related brain potentials were recorded from a group of developmental dyslexics using a simple visual discrimination task and compared to the results of a control group. A large P3 component was elicited which did not differ in overall amplitude between groups. While the distribution was virtually symmetrical in the dyslexic group, there was a left hemispheric preponderance in the control group. The latencies of the P3 were longer in the dyslexic group than in the control group. The results are compared to findings of neuroanatomical and neuroimaging studies which revealed less hemispheric asymmetries in dyslexics compared to control subjects.

Some theories of visuospatial attention propose that attention can be divided between separated zones of space that exclude the intervening region, whereas other theories state that the focus of attention must encompass a unitary, continuous zone. These contrasting views were evaluated in an experiment in which subjects were required to monitor two of four stimulus locations for targets; the two relevant locations were adjacent in one condition and were separated by an intervening irrelevant location in a second condition. To assess the distribution of attention across the relevant and irrelevant locations, event-related brain potentials (ERPs) were recorded to task-irrelevant "probe" stimuli that were occasionally presented at the individual stimulus locations. When the relevant locations were adjacent, probes presented at irrelevant locations elicited smaller sensory-evoked electrophysiological responses than probes presented at relevant locations, consistent with an attentional suppression of inputs from the unattended locations. When the relevant locations were separated by an irrelevant location, however, the sensory responses evoked by probes presented at this intervening irrelevant location were not suppressed, and target detection performance became slower and less accurate. These results suggest that attention forms a unitary zone that may expand to encompass multiple relevant locations but must also include the area between them; as a result, irrelevant information arising from intervening locations is not suppressed and perceptual processing is compromised.

In the discussion of whether the processing of hierarchically structured stimuli proceeds from the more global to the more local level or vice versa, it is frequently assumed that the relative speed of global/local target identification (response time (RT) advantage) and the direction of interference from local/global distractors reflect the order of processing. Studies both in brain-injured patients and in normals, however, have demonstrated that RT advantage and interference are dissociable, leading to the conclusion that they do not provide a valid index of the order of global/local processing. The aim of the present event-related brain potential (ERP) study was to assess electrophysiological correlates of global/local processing and to determine how the relative speed of responding to global and local targets is related to these ERP measurements. In a divided-attention paradigm, subjects were asked to respond to hierarchically structured letter stimuli that contained a target letter either at the global or at the local level. The behavioral results confirmed a dissociation between RT advantage and interference. ERP analysis revealed an early posterior negative component (denoted as N250) as a sign of early global/local target perception. It was found that RT advantage is not a valid measure of the onset nor of the time course of this component. Furthermore, the N250 components to global and local targets exhibited a different time course and a different topographical distribution, suggesting that they are determined by separate processing structures. Together, the behavioral and electrophysiological results support the view that global and local target perception may be mediated by separate brain systems acting, at least initially, in parallel.

Event-related potentials (ERPs) were recorded from closed head injury (CHI) patients at least 2 years postinjury and from controls in order to assess their parallel and serial processing abilities during visual search. In Experiment 1, stimuli consisted of arrays of eight triangles; half of the arrays contained a target item. In the "feature-present" condition, the target item was a triangle with an additional horizontal line that could be detected automatically and in parallel, while in the "feature-absent" condition all items except for the target triangle had an additional horizontal line, thus requiring a serial search. In Experiment 2, stimuli consisted of eight solid bars (50%), seven solid bars and a vertical open bar (25%), and seven solid bars and a horizontal open bar (25%): the array containing the horizontal bar served as a target. By recording ERPs to the arrays containing vertical open bars, which were similar to the target items, parallel processing of "pop-out" stimuli could be studied in the absence of any overt response. ERP data were compared with the results of neuropsychological and neuroimaging (MRI, CAT) examination. Patient exhibited a decreased behavioral performance both in the parallel and in the serial processing mode. Furthermore, abnormalities of early and intermediate ERP components (P1, N1, P2, N2) were found, whereas the late component (P3) was less affected by CHI. The results were interpreted as an index of CHI-induced dysfunctions in perceptual processes such as simple feature registration and early target discrimination. It was suggested that these dysfunctions contribute to impairments of parallel as well as serial processes in visual search.

The mechanisms that mediate the effects of thyroid hormones on higher cognitive processes are not well understood. In the present experiments, event-related potentials (ERPs) and behavioral measurements were recorded in a visual search paradigm where a target item had to be detected in a number of distractor items. 10 healthy subjects were given a daily dose 300 micrograms thyroxine (T4) p.o. and recordings were made before and after 3 weeks of treatment. All subjects developed hyperthyroidism with a completely suppressed TSH (1.6 +/- 0.5 mU/l vs. non detectable), a significant increase in T3 (1.5 +/- 0.2 vs. 1.9 +/- 0.2 ng/ml). T4 (6.6 +/- 1.6 micrograms/dl vs 11.9 +/- 2.7 micrograms/dl) and sex-hormone binding globulin (2.9 +/- 1.1 vs. 3.8 +/- 1.3 micrograms/ml; all p less than 0.0005). Compared to the control group (n = 15), thyroid hormones improved controlled serial visual processing, as indexed by changes of the late positive ERP component and target detection hit rate (in both cases p less than 0.01), whereas parallel detection of salient features remained unchanged. The data suggest a differential impact of thyroid hormones on visual information processing.

The effects of two dosages (200 mg, 600 mg, placebo) of a cholinergic nootropic (WEB 1881 FU) were investigated in a visual spatial attention task. Event-related brain potentials (ERPs) were used as a physiological measure of attention as they have previously been shown to be sensitive to allocation of attention to points in space. The typical enhancement of several peaks of the visual ERP due to attention was found in the present experiment. No systematic effect of the medication was revealed, suggesting that the effects of WEB 1881 FU do not extend to early perceptual processes.

In a double-blind placebo-controlled randomized study the influence of a cholinergic nootropic (WEB 1881 FU) on event-related brain potentials (ERPs) related to memory performance was investigated. Two different encoding modes were imposed on the subjects, who had to memorize word lists. No significant drug effects were obtained on memory performance and the ERP-concomitant of encoding, the Dm, while ERP effects related to memory were clearly present. However, the two dosages of the drug significantly influenced the overall amplitude of the late cognitive ERP components, suggesting its effect on cognitive processes.