Occurrence Of Stimuli Research Articles

Annoyance Based Vibro-Acoustic Comfort Evaluation of as Summation of Stimuli Annoyance in the Context of Human Exposure to Noise and Vibration in Buildings

This paper presents the issues of assessing the comfort of people staying indoors who are exposed to vibrations and material noise caused by vibrations of partitions like floors and walls (ground-borne noise). Current criteria in the evaluation of vibrational and acoustic comfort cannot be assessed in the context of the simultaneous occurrence of stimuli such as noise and vibration. Railway transport, including passenger and cargo transport, is becoming increasingly prevalent, and new railway lines are being planned for environmental reasons. Sometimes, there are changes in stimuli produced by existing railway lines. For example, high-speed trains appear on an old railway track. Such a situation appeared on the Central Railway Line in Poland, which is still used by old trains, yet its operator plans to raise their speed limits. The analysis of the problem of the simultaneous occurrence of stimuli presented in this paper was based on measurements performed in a residential building located near the Central Railway Main Line in the city Zawiercie. Noise and vibration as the analyzed stimuli in both cases meet comfort requirements, yet when exposure to two stimuli was considered, comfort may be at risk.

The internal representation of temporal orienting: A temporal pulse-accumulation and attentional-gating-based account.

Timing can be processed explicitly or implicitly. Temporal orienting is a typical implicit timing through which we can anticipate and prepare an optimized response to forthcoming events. It is, however, not yet clear whether mechanisms such as temporal-pulse accumulation and attentional gating (more attention, more accumulated temporal pulses) underly the internal representations of temporal orienting, as in explicit timing. To clarify this, a dual-task paradigm, consisting of a temporal orienting and an interference task, was adopted. Consistent with the temporal-pulse-accumulation and attentional-gating model, reaction times to the target detection of temporal orienting increased as the interference stimuli were temporally closer to the target, i.e., a location effect for temporal orienting. This effect is likely due to attention being diverted away from temporal orienting to monitor the occurrence of the interference stimuli for a longer time, resulting in greater temporal pulse loss and less accurate temporal orienting for conditions with later interference stimuli. The temporal-pulse-accumulation aspect in temporal orienting received further support by taking an explicit duration reproduction (containing a second temporal-pulse accumulation) as the interference task. On the one hand, temporal orienting became less accurate with increased temporal-pulse-accumulation overlaps between the dual tasks; on the other hand, two-way (one for temporal orienting and the other for duration reproduction), rather than one-way, location effects were observed, implying processing conflicts between the two temporal-pulse accumulations. Taken together, these results suggest that implicit and explicit timing may share common mechanisms upon internal temporal representations.

Comparison on Subannual Seasonality of Building Construction in European Countries

Purpose: The objective of this study involves the determination of cyclical characteristics that occur on the European construction market. Design/Methodology/Approach: In the research implementation process, time-frequency analysis was used to identify and analyze cyclicalities in the construction market. Findings: The results clearly demonstrate the absence of a homogeneous construction market in the investigated countries. The diversity of the European construction market is revealed by the various responses to the periods corresponding to the ups and downs of the economy. Practical Implications: The present research provides grounds for the clear indication of specific countries and cyclical characteristics on the construction market in them to define guidelines suitable for the identification of adequate scenarios for the development of construction markets in them. Originality/value: The conclusion derived from the study is associated with the classification of construction markets and identification of various responses of individual markets to the occurrence of macroeconomic or microeconomic stimuli.

Contextual Modulation of Emotional Distraction: Attentional Capture and Motivational Significance.

Emotional stimuli engage corticolimbic circuits and capture attention even when they are task-irrelevant distractors. Whether top-down or contextual factors can modulate the filtering of emotional distractors is a matter of debate. Recent studies have indicated that behavioral interference by emotional distractors habituates rapidly when the same stimuli are repeated across trials. However, little is known as to whether we can attenuate the impact of novel (never repeated) emotional distractors when they occur frequently. In two experiments, we investigated the effects of distractor frequency on the processing of task-irrelevant novel pictures, as reflected in both behavioral interference and neural activity, while participants were engaged in an orientation discrimination task. Experiment 1 showed that, compared with a rare distractor condition (20%), frequent distractors (80%) reduced the interference of emotional stimuli. Moreover, Experiment 2 provided evidence that emotional interference was reduced by distractor frequency even when rare, and unexpected, emotional distractors appeared among frequent neutral distractors. On the other hand, in both experiments, the late positive potential amplitude was enhanced for emotional, compared with neutral, pictures, and this emotional modulation was not reduced when distractors were frequently presented. Altogether, these findings suggest that the high occurrence of task-irrelevant stimuli does not proactively prevent the processing of emotional distractors. Even when attention allocation to novel emotional stimuli is reduced, evaluative processes and the engagement of motivational systems are needed to support the monitoring of the environment for significant events.

Multisensory Audiovisual Processing in Children With a Sensory Processing Disorder (I): Behavioral and Electrophysiological Indices Under Speeded Response Conditions.

BackgroundMaladaptive reactivity to sensory inputs is commonly observed in neurodevelopmental disorders (e.g., autism, ADHD). Little is known, however, about the underlying neural mechanisms. For some children, atypical sensory reactivity is the primary complaint, despite absence of another identifiable neurodevelopmental diagnosis. Studying Sensory Processing Disorder (SPD) may well provide a window into the neuropathology of these symptoms. It has been proposed that a deficit in sensory integration underlies the SPD phenotype, but objective quantification of sensory integration is lacking. Here we used neural and behavioral measures of multisensory integration (MSI), which would be affected by impaired sensory integration and for which there are well accepted objective measures, to test whether failure to integrate across the senses is associated with atypical sensory reactivity in SPD. An autism group served to determine if observed differences were unique to SPD.MethodsWe tested whether children aged 6–16 years with SPD (N = 14) integrate multisensory inputs differently from age-matched typically developing controls (TD: N = 54), or from children with an autism spectrum disorder (ASD: N = 44). Participants performed a simple reaction-time task to the occurrence of auditory, visual, and audiovisual stimuli presented in random order, while high-density recordings of electrical brain activity were made.ResultsChildren with SPD showed large reductions in the extent to which they benefited from multisensory inputs compared to TDs. The ASD group showed similarly reduced response speeding to multisensory relative to unisensory inputs. Neural evidence for MSI was seen across all three groups, with the multisensory response differing from the sum of the unisensory responses. Post hoc tests suggested the possibility of enhanced MSI in SPD in timeframes consistent with cortical sensory registration (∼60 ms), followed by reduced MSI during a timeframe consistent with object formation (∼130 ms). The ASD group also showed reduced MSI in the later timeframe.ConclusionChildren with SPD showed reduction in their ability to benefit from redundant audio-visual inputs, similar to children with ASD. Neurophysiological recordings, on the other hand, showed that major indices of MSI were largely intact, although post hoc testing pointed to periods of potential differential processing. While these exploratory electrophysiological observations point to potential sensory-perceptual differences in multisensory processing in SPD, it remains equally plausible at this stage that later attentional processing differences may yet prove responsible for the multisensory behavioral deficits uncovered here.

Smiling as negative feedback affects social decision-making and its neural underpinnings.

A crucial aspect of social decision-making is the ability to learn from the outcomes of preceding decisions. In particular, learning might be influenced by the expectedness of feedback and its valence. Expectedness has largely been operationalized as the frequency of stimulus occurrence and not in terms of its social context. Therefore, we investigated the influence of socially unexpected feedback, i.e., smiling upon adverse events, on behavioral and neural responses. We used a modified version of the ultimatum game, a commonly used paradigm for economic decision-making, by implementing different proposer identities with a distinct reaction pattern towards accepted and rejected monetary offers. We could show that an identity, who reacted with a smile towards rejected offers, evoked lower acceptance rates compared to identities, who reward acceptance with a smile. Electrophysiological correlates indicate N170 effects for emotional identities compared to a neutral control identity. Regarding FRN and P3 brain potentials, we detected a particular function of the smiling face when used as a socially unexpected, negative feedback stimulus. Hence, individuals seek an unexpected smile despite the associated monetary loss, which is accompanied by distinct neural patterns.

Ličnost i reakcija na iznenadni događaj

Cilj je ovoga istraživanja bio ispitati interindividualne razlike u elektrodermalnim reakcijama na iznenadni podražaj. Za ispitivanje toga cilja korištene su različite metode procjene elektrodermalne reakcije. Procjena reakcije kao jednostavna razlika prosječne elektrodermalne razine prije i poslije podražaja uspoređena je s pristupima koji modeliraju krivulju elektrodermalne reakcije kroz vrijeme. Ispitana je povezanost takve reakcije, modelirane na različite načine, s upitničkim mjerama osobina ličnosti. U istraživanju je sudjelovalo 97 studenata u dobi od 18 do 28 godina, većinom ženskoga spola (60 %). Svaki je ispitanik ispunio kratku mjeru neuroticizma i ekstraverzije iz Petofaktorskoga inventara ličnosti (BFI; John i sur., 1991, 2008) te je sudjelovao u jednome laboratorijskome mjerenju elektrodermalne reakcije na iznenadni događaj u trajanju od 8 minuta. Elektrodermalna aktivnost modelirala se na tri načina: 1) kao razlika u reakcijama prije i poslije podražaja; 2) uključujući i linearne efekte vremena; 3) uključujući i kvadratne efekte vremena. Ishodi takvoga modeliranja korelirani su s upitničkim mjerama neuroticizma i ekstraverzije. Rezultati su pokazali da uzimajući u obzir efekte protoka vremena sama procjena krivulje elektrodermalne aktivnosti značajno bolje pristaje stvarnim izmjerenim podacima. Isto tako, procjene elektrodermalne reakcije koje uzimaju u obzir efekte protoka vremena rezultiraju višim prosječnim razinama i većim interindividualnim varijabilitetom. Tako modelirana elektrodermalna reakcija (linearno i kvadratno) pokazuje nešto blago više i značajne pozitivne korelacije s neuroticizmom, iako su razlike između različitih načina modeliranja relativno male. Dobiveni rezultati podupiru ideju o većoj pobudljivosti vezanoj uz crtu neuroticizma. Iako su korelacije iznimno male, ne odstupaju od onih dobivenih u drugim istraživanjima, pogotovo jer je riječ o jednome mjerenju (Stemmler i Wacker, 2010). S obzirom na intenzitet reakcije, moguće je da pobudljivost vezana uz neuroticizam i nije specifično vezana za valenciju podražaja koji tu reakciju pobuđuje. Rezultati također pokazuju da se i na malome uzorku i korištenjem samo jednoga mjerenja, uz adekvatno modeliranje elektrodermalne aktivnosti, može detektirati povezanosti s osobinama ličnosti.

Females are more proactive, males are more reactive: neural basis of the gender-related speed/accuracy trade-off in visuo-motor tasks.

In the present study, we investigated neural correlates associated with gender differences in a simple response task (SRT) and in a discriminative response task (DRT) by means of event-related potential (ERP) technique. 120 adults participated in the study, and, based on their sex, were divided into two groups matched for age and education level. Behavioral performance was assessed with computing response speed, accuracy rates and response consistency. Pre- and post-stimulus ERPs were analyzed and compared between groups. Results indicated that males were faster than females in all tasks, while females were more accurate and consistent than males in the more complex tasks. This different behavioral performance was associated with distinctive ERP features. In the preparation phase, males showed smaller prefrontal negativity (pN) and visual negativity (vN), interpreted as reduced cognitive preparation to stimulus occurrence and reduced reliance on sensory proactive readiness, respectively. In the post-stimulus phase, gender differences were present over occipital (P1, N1, P2 components) and prefrontal (pN1, pP1, pP2 components) areas, suggesting allocation of attentional resources at distinct stages of information processing in the two groups. Overall, the present data provide evidence in favor of a more proactive and cautious cognitive processing in females and a more reactive and fast cognitive processing in males. In addition, we confirm that (1) gender is an important variable to be considered in ERP studies on perceptual processing and decision making, and (2) the pre-stimulus component analysis can provide useful information concerning neural correlates of upcoming performance.

Bayesian modeling of temporal expectations in the human brain

The brain predicts the timing of forthcoming events to optimize processes in response to them. Temporal predictions are driven by both our prior expectations on the likely timing of stimulus occurrence and the information conveyed by the passage of time. Specifically, such predictions can be described in terms of the hazard function, that is, the conditional probability that an event will occur, given it has not yet occurred. Events violating expectations cause surprise and often induce updating of prior expectations. While it is well-known that the brain is able to track the temporal hazard of event occurrence, the question of how prior temporal expectations are updated is still unsettled. Here we combined a Bayesian computational approach with brain imaging to map updating of temporal expectations in the human brain. Moreover, since updating is usually highly correlated with surprise, participants performed a task that allowed partially differentiating between the two processes. Results showed that updating and surprise differently modulated activity in areas belonging to two critical networks for cognitive control, the fronto-parietal (FPN) and the cingulo-opercular network (CON). Overall, these data provide a first computational characterization of the neural correlates associated with updating and surprise related to temporal expectation.

Movement of environmental threats modifies the relevance of the defensive eye-blink in a spatially-tuned manner

Subcortical reflexive motor responses are under continuous cortical control to produce the most effective behaviour. For example, the excitability of brainstem circuitry subserving the defensive hand-blink reflex (HBR), a response elicited by intense somatosensory stimuli to the wrist, depends on a number of properties of the eliciting stimulus. These include face-hand proximity, which has allowed the description of an HBR response field around the face (commonly referred to as a defensive peripersonal space, DPPS), as well as stimulus movement and probability of stimulus occurrence. However, the effect of stimulus-independent movements of objects in the environment has not been explored. Here we used virtual reality to test whether and how the HBR-derived DPPS is affected by the presence and movement of threatening objects in the environment. In two experiments conducted on 40 healthy volunteers, we observed that threatening arrows flying towards the participant result in DPPS expansion, an effect directionally-tuned towards the source of the arrows. These results indicate that the excitability of brainstem circuitry subserving the HBR is continuously adjusted, taking into account the movement of environmental objects. Such adjustments fit in a framework where the relevance of defensive actions is continually evaluated, to maximise their survival value.

Temporal relationship between perceptual and physiological events triggered by nociceptive heat stimuli

A combined assessment tool for the perceptual-motor aspects of pain processing will be valuable to clinicians. Fifteen healthy subjects were exposed to contact-heat stimulation (Pathway, Medoc, Israel) to assess perception through a simple task (motor response or conscious appraisal of the time the stimulus was felt) or with a dual task (both responses). The outcome measure was the temporal relationship between contact heat evoked potentials (CHEPS), reaction time (RT) and conscious awareness (AW). There were different temporal profiles for CHEPs, RT and AW to changes in stimulus intensity, AW being the least affected. Performing the dual task led to a significantly more pronounced effect on RT than on AW, while CHEPS were not influenced by task performance. Our results support the dissociation between physiological, behavioral and cognitive events elicited by nociceptive stimuli. The time of conscious appraisal of stimulus occurrence is a complementary information to other responses such as evoked potentials or behavioral tasks. The combined assessment of physiological and behavioral aspects of pain processing may provide clinicians with information on the different paths followed by nociceptive afferent inputs in the central nervous system.

Modulation of sustained fear by transcranial direct current stimulation (tDCS) of the right inferior frontal cortex (rIFC)

Downregulation of emotional responses to threat is strongly associated with frontal cortex functions. Additionally pathological anxiety has been proposed to be associated with the altered frontal control. Understanding the frontal regulation of both initial and sustained fear responses seems to be crucial for further research on the treatment of anxiety disorders. Therefore, this study aims to examine the effects of transcranial direct current stimulation (tDCS) over the right inferior frontal cortex (rIFC) on the subjects’ psychophysiological responses as measured by skin conductance reaction (SCR) during a sustained threat paradigm. 80 participants were randomly assigned to an anodal and sham stimulation group in a double-blinded manner. Indicated by visual cues, participants anticipated the temporally unpredictable occurrence of aversive or neutral auditory stimuli. We found a significant interaction effect of condition x tDCS for SCR during the sustained threat. Post-hoc tests revealed a significant reduction in SCR during sustained fear in verum stimulated group. The results confirm that tDCS of the rIFC attenuates sustained fear. This supports the suggested role of the rIFC in psychophysiological emotional regulation and the potential use of tDCS to enhance these effects.

No changes in parieto-occipital alpha during neural phase locking to visual quasi-periodic theta-, alpha-, and beta-band stimulation.

Recent studies have probed the role of the parieto‐occipital alpha rhythm (8–12 Hz) in human visual perception through attempts to drive its neural generators. To that end, paradigms have used high‐intensity strictly‐periodic visual stimulation that created strong predictions about future stimulus occurrences and repeatedly demonstrated perceptual consequences in line with an entrainment of parieto‐occipital alpha. Our study, in turn, examined the case of alpha entrainment by non‐predictive low‐intensity quasi‐periodic visual stimulation within theta‐ (4–7 Hz), alpha‐ (8–13 Hz), and beta (14–20 Hz) frequency bands, i.e., a class of stimuli that resemble the temporal characteristics of naturally occurring visual input more closely. We have previously reported substantial neural phase‐locking in EEG recording during all three stimulation conditions. Here, we studied to what extent this phase‐locking reflected an entrainment of intrinsic alpha rhythms in the same dataset. Specifically, we tested whether quasi‐periodic visual stimulation affected several properties of parieto‐occipital alpha generators. Speaking against an entrainment of intrinsic alpha rhythms by non‐predictive low‐intensity quasi‐periodic visual stimulation, we found none of these properties to show differences between stimulation frequency bands. In particular, alpha band generators did not show increased sensitivity to alpha band stimulation and Bayesian inference corroborated evidence against an influence of stimulation frequency. Our results set boundary conditions for when and how to expect effects of entrainment of alpha generators and suggest that the parieto‐occipital alpha rhythm may be more inert to external influences than previously thought.

The cognitive nuances of surprising events: exposure to unexpected stimuli elicits firing variations in neurons of the dorsal CA1 hippocampus

The ability to recognize novel situations is among the most fascinating and vital of the brain functions. A hypothesis posits that encoding of novelty is prompted by failures in expectancy, according to computation matching incoming information with stored events. Thus, unexpected changes in context are detected within the hippocampus and transferred to downstream structures, eliciting the arousal of the dopamine system. Nevertheless, the precise locus of detection is a matter of debate. The dorsal CA1 hippocampus (dCA1) appears as an ideal candidate for operating a mismatch computation and discriminating the occurrence of diverse stimuli within the same environment. In this study, we sought to determine dCA1 neuronal firing during the experience of novel stimuli embedded in familiar contexts. We performed population recordings while head-fixed mice navigated virtual environments. Three stimuli were employed, namely a novel pattern of visual cues, an odor, and a reward with enhanced valence. The encounter of unexpected events elicited profound variations in dCA1 that were assessed both as opposite rate directions and altered network connectivity. When experienced in sequence, novel stimuli elicited specific responses that often exhibited cross-sensitization. Short-latency, event-triggered responses were in accordance with the detection of novelty being computed within dCA1. We postulate that firing variations trigger neuronal disinhibition, and constitute a fundamental mechanism in the processing of unexpected events and in learning. Elucidating the mechanisms underlying detection and computation of novelty might help in understanding hippocampal-dependent cognitive dysfunctions associated with neuropathologies and psychiatric conditions.

Application of a brain-computer interface for person authentication using EEG responses to photo stimuli.

In this paper, a personal authentication system that can effectively identify individuals by generating unique electroencephalogram signal features in response to self-face and non-self-face photos is presented. To achieve performance stability, a sequence of self-face photographs including first-occurrence position and non-first-occurrence position are taken into account in the serial occurrence of visual stimuli. Additionally, a Fisher linear classification method and event-related potential technique for feature analysis is adapted to yield remarkably better outcomes than those obtained by most existing

Relationship between the armed arm’s motor response and muscle activation time during the lunge in fencers of varied ability

The present work studied potential differences in activation times of selected muscles associated with the motor responses of the armed arm and differences in selected muscle pairs activation during the fencing lunge. Twenty-eight fencers (epee fencers, aged 22.1 ± 5.4 years) grouped into elite and beginning skill levels, participated in this study. Surface electromyography was used to determine muscle activation time (time period measured from visual stimulus occurrence to the moment of muscle activation threshold detection). For motor response, we measured the time between visual stimulus occurrence and armed arm movement. A significant difference was found between elite and beginning fencers in the motor response of the armed arm. Detection of armed arm’s motor response was significantly later in beginners. Greater time disparities between arm’s motor response and muscle activation time of the m. rectus femoris on the front/lunge side was also found in beginners. Lastly, difference was detected between elite and beginning fencers regarding the muscle activation time of selected muscle pairs. Future studies and trainers can use these results to further explore key areas of motor control and biomechanics for improving of fencing performance.

Beyond the Bottom of the Foot: Topographic Organization of the Foot Dorsum in Walking.

Sensory feedback from the foot dorsum during walking has only been studied globally by whole nerve stimulation. Stimulating the main nerve innervating the dorsal surface produces a functional stumble corrective response that is phase-dependently modulated. We speculated that effects evoked by activation of discrete skin regions on the foot dorsum would be topographically organized, as with the foot sole. Nonnoxious electrical stimulation was delivered to five discrete locations on the dorsal surface of the foot during treadmill walking. Muscle activity from muscles acting at the ankle, knee, hip, and shoulder were recorded along with ankle, knee, and hip kinematics and kinetic information from forces under the foot. All data were sorted on the basis of stimulus occurrence in 12 step cycle phases, before being averaged together within a phase for subsequent analysis. Results reveal dynamic changes in reflex amplitudes and kinematics that are site specific and phase dependent. Most responses from discrete sites on the foot dorsum were seen in the swing phase suggesting function to conform foot trajectory to maintain stability of the moving limb. In general, responses from lateral stimulation differed from medial stimulation, and effects were largest from stimulation at the distal end of the foot at the metatarsals; that is, in anatomical locations where actual impact with an object in the environment is most likely during swing. Responses to stimulation extend to include muscles at the hip and shoulder. We reveal that afferent feedback from specific cutaneous locations on the foot dorsum influences stance and swing phase corrective responses. This emphasizes the critical importance of feedback from the entire foot surface in locomotor control and has application for rehabilitation after neurological injury and in footwear development.

Are crossmodal correspondences relative or absolute? Sequential effects on speeded classification.

Crossmodal correspondences have often been demonstrated using congruency effects between pairs of stimuli in different sensory modalities that vary along separate dimensions. To date, however, it is still unclear the extent to which these correspondences are relative versus absolute in nature: that is, whether they result from pre-defined values that rigidly link the two dimensions or rather result from flexible values related to the previous occurrence of the crossmodal stimuli. Here, we investigated this issue in a speeded classification task featuring the correspondence between auditory pitch and visual size (e.g., congruent correspondence between high pitch/small disc and low pitch/large disc). Participants classified the size of the visual stimuli (large vs. small) while hearing concurrent high- or low-pitched task-irrelevant sounds. On some trials, visual stimuli were paired instead with "intermediate" pitch, that could be interpreted differently according to the auditory stimulus on the preceding trial (i.e., as "lower" following the presentation of a high pitch tone, but as "higher" following the presentation of a low pitch tone). Performance on sequence-congruent trials (e.g., when a small disc paired with the intermediate-pitched tone was preceded by a low pitch tone) was compared to sequence-incongruent trials (e.g., when a small disc paired with the intermediate-pitch tone was by a high-pitched tone). The results revealed faster classification responses on sequence-congruent than on sequence-incongruent trials. This demonstrates that the effect of the pitch/size correspondence is relative in nature, and subjected to trial-by-trial interpretation of the stimulus pair.

The Neural Bases of Event Monitoring across Domains: a Simultaneous ERP-fMRI Study.

The ability to check and evaluate the environment over time with the aim to detect the occurrence of target stimuli is supported by sustained/tonic as well as transient/phasic control processes, which overall might be referred to as event monitoring. The neural underpinning of sustained attentional control processes involves a fronto-parietal network. However, it has not been well-defined yet whether this cortical circuit acts irrespective of the specific material to be monitored and whether this mediates sustained as well as transient monitoring processes. In the current study, the functional activity of brain during an event monitoring task was investigated and compared between two cognitive domains, whose processing is mediated by differently lateralized areas. Namely, participants were asked to monitor sequences of either faces (supported by right-hemisphere regions) or tools (left-hemisphere). In order to disentangle sustained from transient components of monitoring, a simultaneous EEG-fMRI technique was adopted within a block design. When contrasting monitoring versus control blocks, the conventional fMRI analysis revealed the sustained involvement of bilateral fronto-parietal regions, in both task domains. Event-related potentials (ERPs) showed a more positive amplitude over frontal sites in monitoring compared to control blocks, providing evidence of a transient monitoring component. The joint ERP-fMRI analysis showed that, in the case of face monitoring, this transient component relies on right-lateralized areas, including the inferior parietal lobule and the middle frontal gyrus. In the case of tools, no fronto-parietal areas correlated with the transient ERP activity, suggesting that in this domain phasic monitoring processes were masked by tonic ones. Overall, the present findings highlight the role of bilateral fronto-parietal regions in sustained monitoring, independently of the specific task requirements, and suggest that right-lateralized areas subtend transient monitoring processes, at least in some task contexts.

Being Conscious of the Absent Stimuli: 1 - Expectation

Studies on EEG correlates of consciousness have revealed relations between the degree of consciousness and many Event Related Activity (ERA), In these studies, un or conscious state is manipulated either by controlling stimulus threshold; priming, masking or omission. Here, we decide to study the EEG correlates of consciousness using a different paradigm. We used a series of clicks presented at 1Hz during 30 seconds (phase R) in order to create an expectation about the stimulus occurrence and then we discontinued the stimulation for another 30 seconds (phase E). ERA technique was used to disclose the possible EEG components associated to conscious perception of real (phase R) and absent (phase E) clicks. Five ERA wave components Wi were identified. W1 to W4 for real clicks and W2 to W5 for absent (imagined) stimuli. It is proposed where that W1 and W5 components distinguish conscious perception of real and absent stimuli.