István Sulykos

Visual mismatch negativity is sensitive to symmetry as a perceptual category

We investigated the sensitivity of visual mismatch negativity (vMMN) to an abstract and non‐semantic category, vertical mirror symmetry. Event‐related potentials (ERPs) elicited by random and symmetric square patterns, delivered in passive oddball paradigm (participants played a video game), were recorded. In one of the conditions, symmetric patterns were frequent (standard) stimuli and the random patterns were infrequent (deviant) stimuli; in the other condition, the probabilities were reversed. We compared the ERPs elicited by symmetric stimuli as deviants and as standards, and, similarly, the ERPs elicited by the random deviants and random standards. As the difference between the ERPs elicited by random deviant and random standard stimuli, a posterior negativity emerged in two latency ranges (112–120 and 284–292 ms). These negativities were considered to be vMMN components. We suggest that the two vMMN components are organised in cascade error signals. However, there was no significant difference between the ERPs elicited by symmetric deviants and those elicited by symmetric standards. The emergence of vMMN in response to the deviant random stimuli is considered to be a deviation of a perceptual category (in the symmetric standard sequence presented). Accordingly, random stimuli acquired no perceptual category; for this reason, the symmetric deviant (in the random standard sequence presented) elicited no vMMN. The results show that the memory system underlying vMMN is capable of coding perceptual categories such as bilateral symmetry, even if the stimulus patterns are unrelated to the ongoing behavior.

One plus one is less than two: Visual features elicit non-additive mismatch-related brain activity

In a passive oddball task (performing in a video game), participants were presented with sequences of either standard stimuli or patterns containing deviant orientation, deviant spatial frequency or both deviant orientation and spatial frequency. Orientation deviants presented to the lower half of the visual field elicited a posterior negative component with a peak latency of 130 ms. Spatial frequency deviants elicited a similarly negative component that was later followed by another negative component. Activity elicited by the double-deviant stimulus was identical to activity elicited by the orientation deviant alone. The subtraction difference of the peak latency and scalp distribution of the deviant minus the standard difference potentials were unequal to those of the exogenous event-related potential (ERP) components and were therefore considered visual mismatch negativities (vMMNs). The non-additivity of the feature-related responses is interpreted as sensitivity of the implicit change-detection system to deviant events rather than an exclusive sensitivity to individual features. Deviant stimuli presented to the upper half of the field elicited responses with positive polarity, but this activity was less pronounced than the vMMN. Polarity reversal of the response to upper half-field stimulation suggests that the origin of the activity lies in retinotopic areas. Because of the emergence of a mismatch component with positive polarity, we propose that the term visual mismatch negativity (vMMN) be replaced with the more general term visual mismatch response (vMMR).

Is it a face of a woman or a man? Visual mismatch negativity is sensitive to gender category

The present study investigated whether gender information for human faces was represented by the predictive mechanism indexed by the visual mismatch negativity (vMMN) event-related brain potential (ERP). While participants performed a continuous size-change-detection task, random sequences of cropped faces were presented in the background, in an oddball setting: either various female faces were presented infrequently among various male faces, or vice versa. In Experiment 1 the inter-stimulus-interval (ISI) was 400 ms, while in Experiment 2 the ISI was 2250 ms. The ISI difference had only a small effect on the P1 component, however the subsequent negativity (N1/N170) was larger and more widely distributed at longer ISI, showing different aspects of stimulus processing. As deviant-minus-standard ERP difference, a parieto-occipital negativity (vMMN) emerged in the 200–500 ms latency range (~350 ms peak latency in both experiments). We argue that regularity of gender on the photographs is automatically registered, and the violation of the gender category is reflected by the vMMN. In conclusion the results can be interpreted as evidence for the automatic activity of a predictive brain mechanism, in case of an ecologically valid category.

Oblique effect in visual mismatch negativity

We investigated whether visual orientation anisotropies (known as oblique effect) exist in non-attended visual changes using event-related potentials (ERP). We recorded visual mismatch negativity (vMMN) which signals violation of sequential regularities. In the visual periphery unattended, task-irrelevant Gábor patches were displayed in an oddball sequence while subjects performed a tracking task in the central field. A moderate change (50°) in the orientation of stimuli revealed no consistent change-related components. However, we found orientation-related differences around 170 ms in occipito-temporal areas in the amplitude of the ERPs evoked by standard stimuli. In a supplementary experiment we determined the amount of orientation difference that is needed for change detection in an active, attended paradigm. Results exhibited the classical oblique effect; subjects detected 10° deviations from cardinal directions, while threshold from oblique directions was 17°. These results provide evidence that perception of change could be accomplished at significantly smaller thresholds, than what elicits vMMN. In Experiment 2 we increased the orientation change to 90°. Deviant-minus-standard difference was negative in occipito-parietal areas, between 120 and 200 ms after stimulus onset. VMMNs to changes from cardinal angles were larger and more sustained than vMMNs evoked by changes from oblique angles. Changes from cardinal orientations represent a more detectable signal for the automatic change detection system than changes from oblique angles, thus increased vMMN to these “larger” deviances might be considered a variant of the magnitude of deviance effect rarely observed in vMMN studies.

Asymmetric effect of automatic deviant detection: The effect of familiarity in visual mismatch negativity.

The visual mismatch negativity (vMMN) component is regarded as a prediction error signal elicited by events violating the sequential regularities of environmental stimulation. The aim of the study was to investigate the effect of familiarity on the vMMN. Stimuli were patterns comprised of familiar (N) or unfamiliar (И) letters. In a passive oddball paradigm, letters (N and И) were presented as either standard or deviant in separate conditions. VMMNs emerged in both conditions; peak latency of vMMN was shorter to the И deviant compared to the vMMN elicited by the N deviant. To test the orientation-specific effect of the oblique lines on the vMMN, we introduced a control experiment. In the control experiment, the patterns were constructed solely from oblique lines, identical to the oblique lines of the N and И stimuli. Contrary to the first experiment, there was no significant difference between the vMNNs elicited by the two orientations. Therefore, the differences in vMMNs to И and N deviants are not attributable to the physical difference between the И and N stimuli. Consequently, the vMMN is sensitive to the familiarity of the stimuli. This article is part of a Special Issue entitled SI: Prediction and Attention.

Visual mismatch negativity to vanishing parts of objects in younger and older adults

We investigated visual mismatch negativity (vMMN) to vanishing parts of continuously present objects by comparing the event-related potentials (ERPs) to infrequently (deviant) and frequently (standard) disappearing parts of the objects. This paradigm both excludes low-level stimulus-specific adaptation differences between the responses to deviants and standards, and increases the ecological validity of the stimuli. In comparison to frequently disappearing parts of the stimulus objects, infrequently vanishing parts elicited posterior negative event-related brain activity (vMMN). However, no vMMN emerged to the reappearance of the same parts of the objects. We compared the ERPs of an older and a younger sample of participants. In the 120–180 ms time period vMMN was similar in the two age groups, but in the 180–220 ms time period vMMN emerged only in the younger participants. We consider this difference as an index of more elaborate automatic processing of infrequent stimulus changes in younger adults.

Visual mismatch negativity (vMMN) for low- and high-level deviances: A control study

The aim of our studies was to separate the effects of violating a sequential rule (genuine visual mismatch negativity; gvMMN) from the decreased activity in response to repeated stimuli (stimulus-specific adaptation; SSA) for simple and more complex stimuli. To accomplish this goal, different control procedures were applied with the aim of finding the correct control for vMMN studies. Event-related brain electric activity (ERPs) was measured in response to nonattended visual stimuli that were presented either in an oddball manner or in various control sequences. To identify the cortical sources of the different processes, the sLORETA inverse solution was applied to the average ERP time series. In Experiment 1, the stimuli were line textures, and the deviancy was different line orientations. SSA fully explained the deviant-related ERP effects (increased posterior negativity in the 105–190 ms range). In Experiments 2 and 3, windmill patterns were used. Infrequent windmill patterns with 12 vanes elicited gvMMN (posterior negativities in the 100–200 and 200–340 ms ranges), whereas in the case of the less complex (six vanes) stimuli, SSA explained the negative deflection in both latency ranges (178–216 and 270–346 ms). In Experiment 3, infrequent stimuli with six vanes elicited deviant-related posterior negativity within the sequence of less complex (four vanes) frequent patterns. We reconcile the discrepant results by proposing that the underlying processes of vMMN are not uniform but depend strongly on the eliciting stimulus and that the complexity difference between the infrequent and frequent stimuli has considerable influence on the deviant-related response.

Automatic change detection in vision: Adaptation, memory mismatch, or both? II: Oddball and adaptation effects on event-related potentials

In this study we compared the event-related potentials (ERPs) obtained in two different paradigms: a passive visual oddball paradigm and an adaptation paradigm. The aim of the study was to investigate the relation between the effects of activity decrease following an adaptor (stimulus-specific adaptation) and the effects of an infrequent stimulus within sequences of frequent ones. In Experiment 1, participants were presented with different line textures. The frequent (standard) and rare (deviant) texture elements differed in their orientation. In Experiment 2, windmill pattern stimuli were presented in which the number of vanes differentiated the deviant and standard stimuli. In Experiment 1 the ERP differences elicited between the oddball deviant and the standard were similar to the differences between the ERPs to the nonadapted and adapted stimuli in the adaptation paradigm. In both paradigms the differences appeared as a posterior negativity with the latency of 120–140 ms. This finding demonstrates that the representation of a sequential rule (successive presentation of the standard) and the violation of this rule are not necessary for deviancy effects to emerge. In Experiment 2 (windmill pattern), in the oddball paradigm the difference potentials appeared as a long-lasting negativity. In the adaptation condition, the later part of this negativity (after 200 ms) was absent. We identified the later part of the oddball difference potential as the genuine visual mismatch negativity—that is, an ERP correlate of sequence violations. The latencies of the difference potentials (deviant minus standard) and the endogenous components (P1 and N1) diverged; therefore, the adaptation of these particular ERP components cannot explain the deviancy effect. Accordingly, the sources contributing to the standard-versus-deviant modulations differed from those related to visual adaptation; that is, they generated distinct ERP components.

Automatic change detection and spatial attention: a visual mismatch negativity study

Visual mismatch negativity (vMMN) is the electrophysiological correlate of automatic detection of unattended changes in the visual environment. However, vMMNs’ relatedness to spatial attention has not been explicitly tested. Thus, the aim of the study was to investigate the effects of spatial attention on the vMMN event‐related potential component. To this end, participants were instructed to fixate and attend to task‐related stimuli. In an oddball sequence, offset stimuli were applied, i.e., from time‐to time, the two sides of permanently presented objects disappeared. Distance between the task‐related and unrelated events resulted in the typical finding of spatial attention; the amplitude of the N1 component was larger at the shorter distance between the two kinds of events. VMMN was elicited by the deviant vanishing parts, with no reliable effect of distance between the task‐field and vMMN‐related stimuli. In terms of the difference potentials, vMMN was followed by a positive posterior component in the 270–330 ms range. This positivity was much larger when the task‐field was close to vMMN‐related stimuli. The reappearance of the vanishing parts was also investigated. The reappearance of the whole objects after a deviant offset elicited vMMN but only when the task‐field was close to the oddball sequence. We concluded that infrequently vanishing parts of objects are detected automatically. However, these deviant events initiate orientation only if the objects are close to the field of task‐relevant events. Similarly, automatic registration of the rare but expected events are registered only in the visual field close to the focus of attention.

S141 Aging and automatic detection of deviancy in vision: Event-related potential studies

Objectives We investigated the possibility of age-related differences in automatic visual change detection. It is well-established that efficiency of various kinds of attentional processes decreases in elderly, but our knowledge on the field of automatic information processing is limited. Methods Visual mismatch negativity (vMNN) component of event-related brain activity was investigated in three experiments. Using checkerboard stimuli we developed a method capable of quick assessment of vMMN. In a new paradigm with offset responses we controlled low-level adaptation processes, and in the third experiment we investigated the possibility of age-related change in visual persistence. Results Early phase of vMMN was preserved in the older group. However, in a later range of vMMN we obtained decreased amplitude in elderly. In the older group vMMN indicated a longer perceptual persistence. Discussion Automatic detection of environmental change is preserved in older age, but evaluation of the changing stimulation become less efficient. The increased persistence is a sign of compromised temporal acuity in the older sample. Conclusion Like in the field of attentive visual processing, we obtained event-related brain electric activity changes in the domain of automatic perceptual processing. Significance VMMN seems to be a proper method for assessing compromised visual processing in “healthy” aging, and the results open a possibility for investigating various pathological conditions frequently present in aged populations.