Motohiro Kimura

Visual mismatch negativity: new evidence from the equiprobable paradigm.

In visual oddball studies, deviant compared to standard stimuli elicited a posterior negative ERP at around 100-250 ms. To determine the underlying processes of the negativity, we used the equiprobable sequence in which bar stimuli of five types of orientation were presented with equal probabilities (control 20% each) as well as the oddball sequence in which two stimuli with the closest orientation were presented with different probabilities (deviant 20% and standard 80%). Deviant compared to standard stimuli elicited two negativities at around 100-150 ms with no hemispheric dominance and 200-250 ms with right hemispheric dominance, while deviant compared to control stimuli elicited only a negativity at around 200-250 ms with right hemispheric dominance. These results suggest that the early negativity reflects refractory effect, while the late negativity reflects memory-comparison-based change detection effect (visual mismatch negativity).

Visual mismatch negativity and its importance in visual cognitive sciences

This review paper on visual mismatch negativity (MMN), an event-related brain potential component, provides arguments in favor of its theoretical importance in visual cognitive sciences. We propose that (a) previous visual MMN findings can be regarded as ample evidence for the existence of unintentional prediction about the next state of a visual object in the immediate future on the basis of its temporal context (‘unintentional temporal-context-based prediction in vision’); (b) such predictive processes may be qualitatively similar to those revealed by behavioral phenomena, such as representational momentum, flash–lag effect, and perceptual sequence learning; (c) such predictive processes may provide advantages for our adaptation to the visual environment at the computational, neural, and behavioral levels, and (d) in concert with such behavioral phenomena, visual MMN could be a unique and powerful tool for tapping into the predictive power of the human visual system.

Pulmonary Hypertension as a Prognostic Indicator at the Initial Evaluation in Idiopathic Pulmonary Fibrosis

Background: The impact of pulmonary hypertension (PH) on survival has been demonstrated in severe cases with idiopathic pulmonary fibrosis (IPF) who were referred for transplantation. However, whether PH is a predictor of survival remains unclear in milder cases. Objectives: To evaluate the survival impact of pulmonary artery pressure measured during the initial evaluation in patients with IPF. Methods: We retrospectively analyzed the initial evaluation data of 101 consecutive IPF patients undergoing right heart catheterization. Patients evaluated with supplemental oxygen were excluded. Predictors of 5-year survival were analyzed using the Cox proportional model. Results: The mean forced vital capacity (FVC) % predicted, diffusing capacity of the lung for carbon monoxide (DLCO) % predicted, and mean pulmonary artery pressure (MPAP) were 70.2 ± 20.1%, 47.9 ± 19.5%, and 19.2 ± 6.5 mm Hg, respectively. A univariate Cox proportional hazard model showed that the body mass index, %FVC, %DLCO, baseline PaO2, modified Medical Research Council score, 6-min walk distance, and lowest SpO2 of the 6-min walk test were significantly predictive of survival. The MPAP and pulmonary vascular resistance of right heart catheterization were also significant. With stepwise, multivariate Cox proportional analysis, MPAP (HR = 1.064; 95% CI 1.015-1.116, p = 0.010) and %FVC (HR = 0.965, 95% CI 0.949-0.982, p < 0.001) were independent determinants of survival. Analysis of the receiver operating curve revealed MPAP >20 mm Hg to be optimal for predicting the prognosis. Conclusions: Higher MPAP and lower %FVC at the initial evaluation were significant independent prognostic factors of IPF. The current results suggested the importance of the initial evaluation of PH for patients with IPF.

Unintentional Temporal Context–Based Prediction of Emotional Faces: An Electrophysiological Study

The ability to extract sequential regularities embedded in the temporal context or temporal structure of sensory events and to predict upcoming events based on the extracted sequential regularities plays a central role in human cognition. In the present study, we demonstrate that, without any intention, upcoming emotional faces can be predicted based on sequential regularities, by showing that prediction error responses as reflected by visual mismatch negativity (MMN), an event-related brain potential (ERP) component, were evoked in response to emotional faces that violated a regular alternation pattern of 2 emotional faces (fearful and happy faces) under a situation where the emotional faces themselves were unrelated to the participants task. Face-inversion and negative-bias effects in the visual MMN further indicated the involvement of holistic face representations. In addition, through successive source analyses of the visual MMN, it was revealed that the prediction error responses were composed of activations mainly in the face-responsible visual extrastriate areas and the prefrontal areas. The present results provide primary evidence for the existence of the unintentional temporal context-based prediction of biologically relevant visual stimuli as well as empirical support for the major engagement of the visual and prefrontal areas in unintentional temporal context-based prediction in vision.

Localizing sensory and cognitive systems for pre-attentive visual deviance detection: an sLORETA analysis of the data of Kimura et al. (2009).

Pre-attentive deviance detection in the visual environment has been known to be reflected by an event-related brain potential (ERP) component, deviant-related negativity. Recently, however, we demonstrated that deviant-related negativity comprises two, temporally and spatially overlapping ERP components, by using an experimental protocol consisting of oddball and equiprobable sequences [M. Kimura, J. Katayama, H. Ohira, E. Schröger, Visual mismatch negativity: new evidence from the equiprobable paradigm, Psychophysiology 46 (2009) 402-409]: (1) visual N1 that reflects a sensory, refractoriness-based deviance detection system and (2) visual mismatch negativity (MMN) that reflects a cognitive, memory-comparison-based deviance detection system. In the present paper, we further elucidated the neural generators of the visual N1 and visual MMN with standardized low-resolution brain electromagnetic tomography (sLORETA). Results showed that the visual N1 was involved in neural activations of the primary and nonprimary visual areas, while the visual MMN was involved in neural activations of the nonprimary visual areas and the prefrontal areas. These results suggest that the sensory and cognitive deviance detection systems subserved by distinct neural structures underlie our efficient pre-attentive visual deviance detection.

Visual mismatch negativity reveals automatic detection of sequential regularity violation

Sequential regularities are abstract rules based on repeating sequences of environmental events, which are useful to make predictions about future events. Here, we tested whether the visual system is capable to detect sequential regularity in unattended stimulus sequences. The visual mismatch negativity (vMMN) component of the event-related potentials is sensitive to the violation of complex regularities (e.g., object-related characteristics, temporal patterns). We used the vMMN component as an index of violation of conditional (if, then) regularities. In the first experiment, to investigate emergence of vMMN and other change-related activity to the violation of conditional rules, red and green disk patterns were delivered in pairs. The majority of pairs comprised of disk patterns with identical colors, whereas in deviant pairs the colors were different. The probabilities of the two colors were equal. The second member of the deviant pairs elicited a vMMN with longer latency and more extended spatial distribution to deviants with lower probability (10 vs. 30%). In the second (control) experiment the emergence of vMMN to violation of a simple, feature-related rule was studied using oddball sequences of stimulus pairs where deviant colors were presented with 20% probabilities. Deviant colored patterns elicited a vMMN, and this component was larger for the second member of the pair, i.e., after a shorter inter-stimulus interval. This result corresponds to the SOA/(v)MMN relationship, expected on the basis of a memory-mismatch process. Our results show that the system underlying vMMN is sensitive to abstract, conditional rules. Representation of such rules implicates expectation of a subsequent event, therefore vMMN can be considered as a correlate of violated predictions about the characteristics of environmental events.

Human visual system automatically encodes sequential regularities of discrete events

For our adaptive behavior in a dynamically changing environment, an essential task of the brain is to automatically encode sequential regularities inherent in the environment into a memory representation. Recent studies in neuroscience have suggested that sequential regularities embedded in discrete sensory events are automatically encoded into a memory representation at the level of the sensory system. This notion is largely supported by evidence from investigations using auditory mismatch negativity (auditory MMN), an event-related brain potential (ERP) correlate of an automatic memory-mismatch process in the auditory sensory system. However, it is still largely unclear whether or not this notion can be generalized to other sensory modalities. The purpose of the present study was to investigate the contribution of the visual sensory system to the automatic encoding of sequential regularities using visual mismatch negativity (visual MMN), an ERP correlate of an automatic memory-mismatch process in the visual sensory system. To this end, we conducted a sequential analysis of visual MMN in an oddball sequence consisting of infrequent deviant and frequent standard stimuli, and tested whether the underlying memory representation of visual MMN generation contains only a sensory memory trace of standard stimuli (trace-mismatch hypothesis) or whether it also contains sequential regularities extracted from the repetitive standard sequence (regularity-violation hypothesis). The results showed that visual MMN was elicited by first deviant (deviant stimuli following at least one standard stimulus), second deviant (deviant stimuli immediately following first deviant), and first standard (standard stimuli immediately following first deviant), but not by second standard (standard stimuli immediately following first standard). These results are consistent with the regularity-violation hypothesis, suggesting that the visual sensory system automatically encodes sequential regularities. In combination with a wide range of auditory MMN studies, the present study highlights the critical role of sensory systems in automatically encoding sequential regularities when modeling the world.

Involvement of memory-comparison-based change detection in visual distraction

The involvement of memory-comparison-based change detection in visual distraction was elucidated. Not only luminance increments that engaged memory-comparison-based change detection and refractoriness-based rareness detection but also luminance decrements that engaged only memory-comparison-based change detection caused behavioral distraction, which was mirrored by a posterior negativity (240-260 ms, posterior N2) and a broad positivity (420-460 ms, P3a) that reflected attentional capture. Preceding these effects, luminance increments elicited a posterior positivity (100-120 ms, change-related positivity) and a posterior negativity (120-140 ms, change-related negativity), whereas luminance decrements elicited only a posterior positivity (160-180 ms, change-related positivity). These results suggest that memory-comparison-based change detection indexed by change-related positivity is involved in visual distraction as a result of attentional capture.

Top-down attention affects sequential regularity representation in the human visual system.

Recent neuroscience studies using visual mismatch negativity (visual MMN), an event-related brain potential (ERP) index of memory-mismatch processes in the visual sensory system, have shown that although sequential regularities embedded in successive visual stimuli can be automatically represented in the visual sensory system, an existence of sequential regularity itself does not guarantee that the sequential regularity will be automatically represented. In the present study, we investigated the effects of top-down attention on sequential regularity representation in the visual sensory system. Our results showed that a sequential regularity (SSSSD) embedded in a modified oddball sequence where infrequent deviant (D) and frequent standard stimuli (S) differing in luminance were regularly presented (SSSSDSSSSDSSSSD...) was represented in the visual sensory system only when participants attended the sequential regularity in luminance, but not when participants ignored the stimuli or simply attended the dimension of luminance per se. This suggests that top-down attention affects sequential regularity representation in the visual sensory system and that top-down attention is a prerequisite for particular sequential regularities to be represented.

Neural correlates of preattentive and attentive processing of visual changes

To identify electrophysiological correlates of preattentive and attentive processing of visual changes, we compared event-related brain potentials in response to color changes at attended and unattended spatial locations using a visual S1–S2 matching task. The results showed that compared to no change, change stimuli elicited occipito-temporal positivity at around 100–160 ms (change-related positivity) and subsequent central negativity at around 220–300 ms (N270). Change-related positivity was observed in response to changes at both attended and unattended locations, while N270 was observed only when attention was directed to the location of the changes. These results suggest that change-related positivity reflects the preattentive processing of visual changes and N270 reflects the attentive processing of visual changes in the human brain.