Sequence Of Standard Stimuli Research Articles

Reward alters the perception of time

Recent findings indicate that monetary rewards have a powerful effect on cognitive performance. In order to maximize overall gain, the prospect of earning reward biases visual attention to specific locations or stimulus features improving perceptual sensitivity and processing. The question we addressed in this study is whether the prospect of reward also affects the subjective perception of time. Here, participants performed a prospective timing task using temporal oddballs. The results show that temporal oddballs, displayed for varying durations, presented in a sequence of standard stimuli were perceived to last longer when they signaled a relatively high reward compared to when they signaled no or low reward. When instead of the oddball the standards signaled reward, the perception of the temporal oddball remained unaffected. We argue that by signaling reward, a stimulus becomes subjectively more salient thereby modulating its attentional deployment and distorting how it is perceived in time.

Early auditory change detection implicitly facilitated by ignored concurrent visual change during a Braille reading task

Unconscious monitoring of multimodal stimulus changes enables humans to effectively sense the external environment. Such automatic change detection is thought to be reflected in auditory and visual mismatch negativity (MMN) and mismatch negativity fields (MMFs). These are event-related potentials and magnetic fields, respectively, evoked by deviant stimuli within a sequence of standard stimuli, and both are typically studied during irrelevant visual tasks that cause the stimuli to be ignored. Due to the sensitivity of MMN/MMF to potential effects of explicit attention to vision, however, it is unclear whether multisensory co-occurring changes can purely facilitate early sensory change detection reciprocally across modalities. We adopted a tactile task involving the reading of Braille patterns as a neutral ignore condition, while measuring magnetoencephalographic responses to concurrent audiovisual stimuli that were infrequently deviated either in auditory, visual, or audiovisual dimensions; 1000-Hz standard tones were switched to 1050-Hz deviant tones and/or two-by-two standard check patterns displayed on both sides of visual fields were switched to deviant reversed patterns. The check patterns were set to be faint enough so that the reversals could be easily ignored even during Braille reading. While visual MMFs were virtually undetectable even for visual and audiovisual deviants, significant auditory MMFs were observed for auditory and audiovisual deviants, originating from bilateral supratemporal auditory areas. Notably, auditory MMFs were significantly enhanced for audiovisual deviants from about 100 ms post-stimulus, as compared with the summation responses for auditory and visual deviants or for each of the unisensory deviants recorded in separate sessions. Evidenced by high tactile task performance with unawareness of visual changes, we conclude that Braille reading can successfully suppress explicit attention and that simultaneous multisensory changes can implicitly strengthen automatic change detection from an early stage in a cross-sensory manner, at least in the vision to audition direction.

Mood Modulates Auditory Laterality of Hemodynamic Mismatch Responses during Dichotic Listening

Hemodynamic mismatch responses can be elicited by deviant stimuli in a sequence of standard stimuli even during cognitive demanding tasks. Emotional context is known to modulate lateralized processing. Right-hemispheric negative emotion processing may bias attention to the right and enhance processing of right-ear stimuli. The present study examined the influence of induced mood on lateralized pre-attentive auditory processing of dichotic stimuli using functional magnetic resonance imaging (fMRI). Faces expressing emotions (sad/happy/neutral) were presented in a blocked design while a dichotic oddball sequence with consonant-vowel (CV) syllables in an event-related design was simultaneously administered. Twenty healthy participants were instructed to feel the emotion perceived on the images and to ignore the syllables. Deviant sounds reliably activated bilateral auditory cortices and confirmed attention effects by modulation of visual activity. Sad mood induction activated visual, limbic and right prefrontal areas. A lateralization effect of emotion-attention interaction was reflected in a stronger response to right-ear deviants in the right auditory cortex during sad mood. This imbalance of resources may be a neurophysiological correlate of laterality in sad mood and depression. Conceivably, the compensatory right-hemispheric enhancement of resources elicits increased ipsilateral processing.

Visual mismatch response evoked by a perceptually indistinguishable oddball

Mismatch field (MMF) is an early magnetoencephalographic response evoked by deviant stimuli within a sequence of standard stimuli. Although auditory MMF is reported to be an automatic response, the automaticity of visual MMF has not been clearly demonstrated, partly because of the difficulty in designing an ignore condition. Our modified oddball paradigm had a masking stimulus inserted between briefly presented standard and deviant stimuli (vertical gratings with different spatial frequencies). Perceptual discrimination between masked standard and deviant stimuli was difficult, but the early magnetoencephalographic response for the deviant was significantly larger than that for the standard, when the former had a higher spatial frequency than the latter. Our findings strongly support the hypothesis that visual MMF is evoked automatically.

Demonstration of MMN in human subjects after stimulation with two complex deviant sounds

Event Abstract Back to Event Demonstration of MMN in human subjects after stimulation with two complex deviant sounds Georgia Psiouri1*, Maria L. Stavrinou1, Andrew Koupparis1, Vassileios Kokkinos1 and George K. Kostopoulos1 1 University of Patras, Department of Physiology, Medical School, Greece Mismatch negativity (MMN) is a negative EEG potential evoked when a deviant stimulus interferes in a sequence of standard stimuli. It can be observed in many modalities: visual, olfactory, as well as auditory. We used auditory stimulation to evoke the MMN, in the form of a modified oddball paradigm, where at least 3 standard sound stimuli always preceded a deviant. Our deviant stimuli were of two kinds: one (D1) comprised of two simultaneous frequencies [800+700] Hz (of 100ms duration), and a second one (D2) of two consecutive frequencies [800 and 700] Hz lasting 50ms each. The standard tone (S) was a sound of 800 Hz lasting 100 ms. Seven healthy volunteers (4 females) participated (age range 22-34 years). We conducted two kinds of experiments (of 880 number trials each), one with passive listening to the stimuli (no-attention condition) and one where subjects tried to distinguish the deviant stimuli (attention condition). We demonstrated MMN waveforms as a negative peak for each condition and deviant, approx. 200ms after onset of the stimulus. Statistical analysis (1-way ANOVA) was performed for the peak latency and amplitude of the MMN for the electrode Fz, for the following four groups: (1) attention, stimulus D2-S (subtraction of averaged curves), (2) no-attention D2-S, (3) attention D1-S, (4) no-attention D1-S. No statistically significant differences were found for the MMN peak latency. The mean MMN peak amplitude was significantly higher for the D1 stimulus in the no-attention D2-S compared to the no-attention D1-S condition (p=0.03). This result can be regarded as an indication that the MMN response is relevant to the complexity and the power of the sound stimulus. Moreover, no statistically different peak MMN value was found between the attention and the no-attention conditions for each sound stimulus. This indicates that the MMN might be related to unconscious mechanisms. Conference: 41st European Brain and Behaviour Society Meeting, Rhodes Island, Greece, 13 Sep - 18 Sep, 2009. Presentation Type: Poster Presentation Topic: Poster presentations Citation: Psiouri G, Stavrinou ML, Koupparis A, Kokkinos V and Kostopoulos GK (2009). Demonstration of MMN in human subjects after stimulation with two complex deviant sounds. Conference Abstract: 41st European Brain and Behaviour Society Meeting. doi: 10.3389/conf.neuro.08.2009.09.264 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 12 Jun 2009; Published Online: 12 Jun 2009. * Correspondence: Georgia Psiouri, University of Patras, Department of Physiology, Medical School, Patras, Greece, gpsiouri@yahoo.gr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Georgia Psiouri Maria L Stavrinou Andrew Koupparis Vassileios Kokkinos George K Kostopoulos Google Georgia Psiouri Maria L Stavrinou Andrew Koupparis Vassileios Kokkinos George K Kostopoulos Google Scholar Georgia Psiouri Maria L Stavrinou Andrew Koupparis Vassileios Kokkinos George K Kostopoulos PubMed Georgia Psiouri Maria L Stavrinou Andrew Koupparis Vassileios Kokkinos George K Kostopoulos Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Electrophysiology of spatial scene analysis: the mismatch negativity (MMN) is sensitive to the ventriloquism illusion

Objectives: The ventriloquism effect is the tendency to underestimate the spatial separation between synchronous auditory and visual signals moderately separated in space. If, as it is thought, this effect is pre-attentive, it could modulate the mismatch negativity (MMN) that indexes the automatic, pre-attentive detection of deviant auditory stimuli rarely occurring in a sequence of standard stimuli. We assessed the existence of an MMN evoked by auditory and visual signals made up of standard sounds coming from the same location as the visual signal and deviant sounds coming from lateral deviations (20 or 60°). As first observed in a behavioral study, a ventriloquism effect occurred for 20° spatial separation but not for 60°. Methods: Cortical evoked potentials were recorded using the oddball paradigm on 8 adults in auditory alone and audiovisual conditions. Results: In the auditory alone condition, each spatial localization contrast elicited a significant MMN. In the audiovisual condition, a significant MMN was only evoked for the 60° contrasts. Conclusions: The MMN evoked by spatial separation contrasts (20 and 60°) in the auditory alone condition was suppressed by the corresponding audiovisual condition only when the latter yielded a ventriloquism effect, suggesting that this effect occurs at an early perceptual level.

Impaired suppression of processing in schizophrenic patients suggested by ERPs obtained in a selective attention task

In the present study, we focused on the ability of suppression of processing in schizophrenic patients, using event-related potentials (ERPs) recorded during a selective attention task. During the task, subjects were required to focus on one ear, counting deviant stimuli, those deviating in duration from a sequence of standard stimuli. We compared amplitude data of two positive components differing in latency elicited by standard stimuli, which reflect suppression of stimulus processing, between schizophrenic patients and normal controls. Significant between-group differences were obtained specifically in the right ear attended condition, suggesting impaired suppression of processing in schizophrenics mediated in the left hemisphere.

Mismatch negativity and N2b attenuation as an indicator for dysfunction of the preattentive and controlled processing for deviance detection in schizophrenia: a topographic event-related potential study

The present study compares the amplitudes and topographic patterns of mismatch negativity (MMN) and N2b in schizophrenic patients and normal controls. Twenty-one schizophrenic outpatients and 19 normal volunteers participated in the study. Event-related potentials (ERPs) were recorded in a selective attention task. During the task, subjects were required to focus on one ear, counting deviant stimuli, those deviating in duration from a sequence of standard stimuli. MMN was significantly attenuated in the schizophrenics as compared with the normals in the frontocentral regions. In addition to MMN, the N2b amplitude was also reduced, which showed a significant correlation with the MMN amplitude in the schizophrenics. The late negativity elicited by the deviant stimuli in the unattended condition showed different topographical features between the groups. Whereas the normals showed a lateralized distribution with an ear-related asymmetry, similar to that of the N2b, the schizophrenics showed a frontal dominance, coinciding with the sustained negativity reported by Näätänen et al. (1982), which reflects the automatic preparation for detecting possible subsequent stimulus changes. The amplitude of the sustained negativity was significantly correlated with the performance level in the schizophrenics. The results indicated that although both preattentive and controlled processings are impaired, schizophrenic patients, presumably due to the deficient controlled processing, owe much to automatic processing in the deviant stimulus detection process.

Eye tracking and attentional measures in the finnish adoptive study of schizophrenia

The present study compares the amplitudes and topographic patterns of mismatch negativity (MMN) and N2b in schizophrenic patients and normal controls. Twenty-one schizophrenic outpatients and 19 normal volunteers participated in the study. Event-related potentials (ERPs) were recorded in a selective attention task. During the task, subjects were required to focus on one ear, counting deviant stimuli, those deviating in duration from a sequence of standard stimuli. MMN was significantly attenuated in the schizophrenics as compared with the normals in the frontocentral regions. In addition to MMN, the N2b amplitude was also reduced, which showed a significant correlation with the MMN amplitude in the schizophrenics. The late negativity elicited by the deviant stimuli in the unattended condition showed different topographical features between the groups. Whereas the normals showed a lateralized distribution with an ear-related asymmetry, similar to that of the N2b, the schizophrenics showed a frontal dominance, coinciding with the sustained negativity reported by Näätänen et al. (1982), which reflects the automatic preparation for detecting possible subsequent stimulus changes. The amplitude of the sustained negativity was significantly correlated with the performance level in the schizophrenics. The results indicated that although both preattentive and controlled processings are impaired, schizophrenic patients, presumably due to the deficient controlled processing, owe much to automatic processing in the deviant stimulus detection process.

Nonprimary auditory thalamic representation of acoustic change

1. The mismatch response, or mismatch negativity (MMN), is a neurophysiologic response to stimulus change. In humans and other animals, the MMN may underlie the ability to discriminate acoustic differences, a fundamental aspect of auditory perception. 2. This study investigated the role of the thalamus in the generation of a tone-evoked MMN in guinea pigs. Electrodes were placed in the caudomedial (nonprimary) and ventral (primary) subdivisions of the auditory thalamus (medial geniculate nucleus). Surface epidural electrodes were placed at the midline and over the temporal lobe. The MMN was elicited by a deviant stimulus (2,450-Hz tone burst) embedded in a sequence of standard stimuli (2,300-Hz tone bursts). 3. A tone-evoked MMN was present in nonprimary thalamus but was absent in the primary thalamus. Surface-recorded MMNs were measured at the midline but not over the temporal lobe. The correspondence between nonprimary thalamic responses and midline surface potentials, and between primary thalamic responses and temporal surface potentials, is consistent with data reported for the auditory middle latency responses in guinea pigs. 4. The results demonstrate that the nonprimary auditory thalamus contributes to the generation of a tone-evoked MMN in the guinea pig. Furthermore, the data indicate that the guinea pig is a feasible model for investigating central auditory processes underlying acoustic discrimination.

Brain Generators Implicated in the Processing of Auditory Stimulus Deviance: A Topographic Event‐Related Potential Study

The neurophysiological mechanisms underlying mismatch negativity (MMN) can be inferred from an examination of some of the brain generators involved in the process of this event-related potential (ERP) component. ERPs were recorded in two studies in which the subjects were involved in a selective dichotic listening task. Subjects were required to silently count rare stimuli deviating in pitch from a sequence of standard stimuli in one ear, while ignoring all the stimuli (standards and deviants) delivered randomly to the other ear. The results showed that, in all cases, the negative wave elicited by the deviant stimuli showed the highest amplitudes over the right hemiscalp irrespective of the ear of stimulation or the direction of attention. Scalp radial current density analysis showed that this asymmetric potential distribution could be attributed to the sum of activities of two sets of neural generators: one temporal, located in the vicinity of the primary auditory cortex, predominantly activated in the hemisphere contralateral to the ear of stimulation, and the other frontal, involving mainly the right hemisphere. The results are discussed in light of Näätänen's model: we suggest the dissociation of two functional processes on the basis of activity of distinct brain areas: a sensory memory mechanism related to the temporal generators, and an automatic attention-switching process related to the frontal generators.