Emotion-Related Visual Mismatch Responses in Schizophrenia: Impairments and Correlations with Emotion Recognition

Background and Objectives

Mismatch negativity (MMN) is an event-related potential (ERP) measure of preattentional sensory processing. While deficits in the auditory MMN are robust electrophysiological findings in schizophrenia, little is known about visual mismatch response and its association with social cognitive functions such as emotion recognition in schizophrenia. Our aim was to study the potential deficit in the visual mismatch response to unexpected facial emotions in schizophrenia and its association with emotion recognition impairments, and to localize the sources of the mismatch signals.

Experimental Design

The sample comprised 24 patients with schizophrenia and 24 healthy control subjects. Controls were matched individually to patients by gender, age, and education. ERPs were recorded using a high-density 128-channel BioSemi amplifier. Mismatch responses to happy and fearful faces were determined in 2 time windows over six regions of interest (ROIs). Emotion recognition performance and its association with the mismatch response were also investigated.

Principal Observations

Mismatch signals to both emotional conditions were significantly attenuated in patients compared to controls in central and temporal ROIs. Controls recognized emotions significantly better than patients. The association between overall emotion recognition performance and mismatch response to the happy condition was significant in the 250–360 ms time window in the central ROI. The estimated sources of the mismatch responses for both emotional conditions were localized in frontal regions, where patients showed significantly lower activity.

Conclusions

Impaired generation of mismatch signals indicate insufficient automatic processing of emotions in patients with schizophrenia, which correlates strongly with decreased emotion recognition.     

The role of the genotype in the variability of human evoked potentials at different stages of ontogeny]

The determinants of individual differences in visual EPs to stimuli of different type depending on the age of subjects were studied. EPs to flash, checkerboard pattern and some other stimuli with semantic aspect were recorded in three groups of MZ, DZ twins aged 8-9, 10-12, 18-25 years. The heritability of EPs parameters is not ontogenetically stable characteristic. It changes from one age group to another in different way for separate EPs components and parameters depending on their nature, type of stimulus, area of recording. Most of all genotypical influences are manifested in EPs parameters of 10-12 years old subjects, especially the middle latency components from vertex area and latent periods of EPs in comparison with their amplitudes.     

The thalamic integration of afferent flows in man during image recognition]

The article deals with the mechanisms of interaction of afferent flows at intrathalamic and thalamocortical levels of integration in humans identifying visual, auditory and tactile images. As the methodic model of thalamic block we used patients of surgical clinic with topically diagnosed volume process of the region of the third ventricle. Psychophysiological tests and multichannel EPs recording revealed functional significance of thalamus in the processes of perception and also mechanisms of compensation of these functions in pathological process.     

Ontogenetic characteristics of the development of slow negative and positive potentials during the performance of a visual perceptive task

In age aspect, topography and parameters were studied of late EPs and slow negative components (CNV) to successively presented visual stimuli: the preliminary signal and two compared contour images. Age characteristics of development of the frontal negativity N450 and the late positive complex (LPC) were revealed. in children 7 and 10 years old, the component N450 was present in response both to the preliminary and the first stimulus in the compared pair; LPC was recorded to all three presented visual stimuli. In 17 years old subjects and in adults, selectivity of N450 formation in the EP to the first of the compared stimuli and LPC to the second (imperative) stimulus correlates with involvement of rostral brain areas--central in youths, central and frontal ones in adults--both in the process of waiting (CNV) and evaluation of coming information (LPC).     

Visual evoked potentials to structured stimuli in children with cataracts

EPs elicited by diffuse light flashes and check patterns, were studied in children and juveniles with congenital and traumatic cataract, during different periods and various durations of deprivation, as well as in a control group of children and juveniles with normal vision. Specific age characteristics were found in the EPs to check patterns in seven years-old children. In children with congenital cataracts significant changes in the shape and amplitude-temporal EP parameters were recorded. In children with traumatic cataracts, presumably developed after the end of the sensitive period, the changes in EPs were much less pronounced. The obtained data are discussed from the point of view of the duration of the sensitive period of the formation of the visual function in humans and of informative value of different EP components.     

Changes in evoked potentials during differentiation inhibition

Evoked responses (EPs) of the auditory and the sensorimotor cortical areas were studied in experiments on cats during formation of a positive food-procuring conditioned reflex to a rhythmic sequence of clicks and during formation of the differentiation inhibition in response to the clicks of the same parameters, but with different frequency. In the positive conditioned reflex the EPs amplitude in the sensorimotor cortex increases; they are enriched by late components and in their general configuration they become much similar to EPs in the auditory area. The EPs patterns both in the auditory and in the sensorimotor areas considerably change in response to the differentiation stimulus, but differently in each of the sites.     

Some electrophysiological and hemodynamic characteristics of auditory selective attention in norm and schizophrenia

Six patients in the state of remission after the first episode ofjuvenile schizophrenia and seven sex- and age-matched mentally healthy subjects were examined by fMRI and ERP methods. The auditory oddball paradigm was applied. Differences in P300 parameters didn't reach the level of significance, however, a significantly higher hemodynamic response to target stimuli was found in patients bilaterally in the supramarginal gyrus and in the right medial frontal gyrus, which points to pathology of these brain areas in supporting of auditory selective attention.     

Arcuate fasciculus abnormalities and their relationship with psychotic symptoms in schizophrenia

Disruption of fronto-temporal connections involving the arcuate fasciculus (AF) may underlie language processing anomalies and psychotic features such as auditory hallucinations in schizophrenia. No study to date has specifically investigated abnormalities of white matter integrity at particular loci along the AF as well as its regional lateralization in schizophrenia. We examined white matter changes (fractional anisotropy (FA), axial diffusivity (AD), asymmetry indices) along the whole extent of the AF and their relationship with psychotic symptoms in 32 males with schizophrenia and 44 healthy males. Large deformation diffeomorphic metric mapping and Fiber Assignment Continuous Tracking were employed to characterize FA and AD along the geometric curve of the AF. Our results showed that patients with schizophrenia had lower FA in the frontal aspects of the left AF compared with healthy controls. Greater left FA and AD lateralization in the temporal segment of AF were associated with more severe positive psychotic symptoms such as delusions and hallucinations in patients with schizophrenia. Disruption of white matter integrity of the left frontal AF and accentuation of normal left greater than right asymmetry of FA/AD in the temporal AF further support the notion of aberrant fronto-temporal connectivity in schizophrenia. AF pathology can affect corollary discharge of neural signals from frontal speech/motor initiation areas to suppress activity of auditory cortex that may influence psychotic phenomena such as auditory hallucinations and facilitate elaboration of delusional content.     

Study of parvocellular and magnocellular visual channels in normal subjects and in patients with psychopathology

We measured susceptibility to the Müller-Lyer illusion in schizophrenic patients and normal observers. The images of the Müller-Lyer figure were digitally filtered in a high-frequency and low-frequency band by wavelet filter. Patients with schizophrenia are more susceptible to Müller-Lyer illusion, than mentally healthy examinees. The images of the Müller-Lyer figure with low spatial frequency were perceived in a similar way by the schizophrenic patients on the initial stage of disease and the control subjects. Patients with schizophrenia were more sensitive to the Müller-Lyer illusion when the image contained only high or medium spatial frequency. Schizophrenic patients in advanced stage were more susceptible to the illusion while presented with all types of images of the Müller-Lyer figure than the control group. It is hypothesized that those differences arise from the mismatch work of the magnocellular and parvocellular systems. It is known that images with the high spatial frequencies are most relevant for the parvocellular visual channels. The magnocellular visual channels are most sensitive to the images with the low spatial frequencies. Thus these findings demonstrate a significant impairment in parvocellular pathway function in patients on initial stage of schizophrenia. The patients on advanced stage of schizophrenia demonstrate impairment of both the parvocellular and magnocellular systems.     

Recognition of fragmented images and mechanisms of memory

Analysis of the topography and parameters of event-related potentials (ERPs) recorded during the presentation of incomplete images with different fragmentation aided in study of the role of different cortical zones and the order of their involvement in the recognition process. The role of the frontal cortical areas at different stages of perception of fragmented images was established. The differences in the ERPs induced by recognized and unrecognized stimuli in the frontal and frontal-temporal derivations in the interval 30–83 ms were associated with the appearance of early positivity in response to recognized images and development of early negativity in response to unrecognized stimuli. The N300 component associated with recognition was stronger in these cortical zones during identification of images. A late positive complex appeared in the frontal areas earlier than in other areas. Involvement of the caudal visual areas in the recognition process was reflected by enhancement of the components P100, P250, and N400. Our results suggest that the frontal areas play the main role in the recognition of fragmented images because they are the structures that organize extraction of traces from long-term modality-specific memory using a system of afferent and efferent links and determine the strategy of information analysis necessary for the solution of a given task.     

Role of a species-specific acoustic environment in the development of hearing in nestlings

Main parameters were studied of the acoustic evoked potentials (EPs) from L field of the caudal neostriatum of altricial nestlings of 2-8 days to pure tones in the range of species-specific signals. It has been established that auditory EPs to the tones of different frequencies differ by the terms of appearance and the degree of maturity. At every of the revealed stages of the auditory ontogenesis, including the stage of completely formed auditory sensitivity, such parameters of auditory EPs, as latencies of different phases, amplitude-temporal pattern and the course of recovery curve are different for the tones of different frequencies. The earliest to appear are the responses to the tones 0.2-4.0 kHz, corresponding to the energy of alimentary signals. Responses to tones of higher frequencies corresponding to the spectrum of other species-specific signals appear later, but the speed of their formation is higher than in the responses to the tones of low frequencies. It is suggested that the higher speed of sensitivity maturation in the high-frequency region is determined by ecologically conditioned afferentation, the function of which is fulfilled by nestlings own vocalization.     

Dissociated Roles of the Inferior Frontal Gyrus and Superior Temporal Sulcus in Audiovisual Processing: Top-Down and Bottom-Up Mismatch Detection

Visual inputs can distort auditory perception, and accurate auditory processing requires the ability to detect and ignore visual input that is simultaneous and incongruent with auditory information. However, the neural basis of this auditory selection from audiovisual information is unknown, whereas integration process of audiovisual inputs is intensively researched. Here, we tested the hypothesis that the inferior frontal gyrus (IFG) and superior temporal sulcus (STS) are involved in top-down and bottom-up processing, respectively, of target auditory information from audiovisual inputs. We recorded high gamma activity (HGA), which is associated with neuronal firing in local brain regions, using electrocorticography while patients with epilepsy judged the syllable spoken by a voice while looking at a voice-congruent or -incongruent lip movement from the speaker. The STS exhibited stronger HGA if the patient was presented with information of large audiovisual incongruence than of small incongruence, especially if the auditory information was correctly identified. On the other hand, the IFG exhibited stronger HGA in trials with small audiovisual incongruence when patients correctly perceived the auditory information than when patients incorrectly perceived the auditory information due to the mismatched visual information. These results indicate that the IFG and STS have dissociated roles in selective auditory processing, and suggest that the neural basis of selective auditory processing changes dynamically in accordance with the degree of incongruity between auditory and visual information.     

Formation of visual evoked potentials and development of visually guided behavior in the Ficedula hypoleuca nestling

Age dynamics of evoked potentials (EPs) of Wulst area of the dorsal hyperstriatum (functional analogue of mammalian visual cortex) was investigated in 2-7 days old nestlings. EPs in response to light stimuli, with the duration and intensity imitating natural alimentary signals for 5-7 days-old nestlings, were recorded parallel with the behaviour. It was found that the development of the visual system in precocious nestlings became completed in postembryonal ontogenesis. The most essential changes in the parameters of visual EPs occur between 2.5 and 4 days of nest life. By the end of the 4-th day the EPs parameters resemble those of the definite EPs. During the same period the visually directed form of the alimentary behaviour appears for the first time. Both the visual EPs and the visually directed alimentary behaviour first appear in the ontogenesis in response to the second component of two-fold luminosity change--the natural signal of alimentary behaviour.     

EEG of the interstimulus intervals during habituation of auditory evoked potentials in depressive moods

Averaging of EEG of interstimulus intervals in the process of study of habituation of auditory evoked potentials (EPs) in healthy subjects and patients with endogenous depression, revealed a rhythmic wave process (RWP) especially expressed in patients. RWP appeared and became stronger in successive averaging of 10 realizations completing each of four series of 30 clicks; often (especially in depressive patients) it was manifest in averaging of all 120 realizations with an amplitude comparable with that of main EPs components and even greater. A significant correlation was found of RWP parameters with characteristics of melancholic mood in both subgroups. It is suggested that RWP appears as a result of regular changes of EEG background during multiple stimuli repetition in connection with increased "slow" habituation and in a special manifestation of perceptive defence during depression including mechanisms of active isolation from external world.     

A cross correlation analysis of the electrical activity of different regions of the cerebral cortex during visual pattern recognition in children]

Characteristics of spatial-temporal organization of brain biopotentials were examined in one to 2.5 year old children during recognition of visual images. Crosscorrelation EEG analysis of frontal, motor, inferior parietal, temporal and occipital cortical zones has shown that recognition of familiar visual objects is accompanied by an increase in spatial synchronization of biopotentials, especially in the inferior parietal zones of both hemispheres and occipital centres of the left hemisphere. There is a considerable increase in the number of highly synchronous synphasic oscillations at the 4--5 per sec frequency with an intensified periodicity of processes. Recognition of unfamiliar objects does not produce a similar effect. Temporal organization of biopotentials of the associative (frontal and inferior parietal) and projection visual areas in the course of recognition of images depends on the existence of a notion of the whole object in the child's memory.     

Specific changes in auditory cognitive evoked potentials in those who participated in the liquidation of the Chernobyl accident: II. Analysis of the late P300 component

An integrated neuropsychological study and recording of auditory cognitive evoked potentials (EPs) using the three-stimulus oddball paradigm was performed in groups of ten subjects who participated in the liquidation of the consequences of the Chernobyl accident aged 50.5 ± 4.0 years and ten healthy subjects aged 47.0 ± 6.0 years. The neuropsychological study showed impairment of higher mental functions, including aspontaneity, fatigability, a decrease in the auditory-verbal and visual memories, and higher motor function deficiency, in cleanup workers (usually referred to as liquidators). Analysis of the amplitude and time characteristics of the P300 component of the auditory cognitive EP showed a decrease in the amplitude of this component in all cortical areas of liquidators in both experimental situations and for all stimuli compared to healthy subjects of the same age. Analysis of the latent period (LP) of P300 in liquidators showed the most distinct increase in the situation of passive audition for all types of stimuli. Analysis of the patterns of reactive rearrangements in different experimental situations showed that the P300 LPs of healthy subjects were similar for all types of stimuli during passive audition and were higher for the significant stimulus in the situation of counting. Liquidators were characterized by an type of response, with the LPs of responses to most stimuli increased in both experimental situations. Analysis of regional changes in the P300 LP showed that the differences in the P300 LP between the groups were the largest in the frontal areas of the left hemisphere. In addition, liquidators exhibited “uneconomical, excessive” responses as compared to normal responses, which suggests a decrease in the attention and memory capacities and could contribute to the impairment of higher mental functions. The changes in the amplitude and time characteristics of the P300 component of auditory EPs suggest deceleration of perception, processing, and analysis of information combined with weakened inhibition. The changes found in liquidators are similar to those observed in elderly people, which supports the hypotheses on accelerated brain aging and on pathological aging caused by low-dose irradiation.     

EEG spatial organization during intense hyperventilation (cyclic breathing): II. EEG correlates of psychovisceral phenomena

EEG correlates of two main effects of long-term hyperventilation (cyclic breathing similar to rebirthing), namely, psychotic manifestations and sensations in internal organs, are considered. Standard EEGs of 44 subjects were recorded and subsequently treated by multiparametric methods. It was shown that, in the case of psychotic phenomena (hallucinations, visual and auditory images, different scenes, virtual travels, out-of-body experiences, etc.), the changes in the spatial organization of bioelectric potentials as compared with the baseline have different patterns than in the case of sensations in internal organs. The changes are observed in the frontal regions of the cortex: a decrease in spatial synchronization (linear processes) during an increase in spatial disarray (nonlinear processes) of bioelectric potentials and the intensifying of high-frequency β activity. If sensations in internal organs appear, a decrease in the above parameters was observed in the right hemisphere and in posterior cortical areas. The data are discussed from the viewpoint of qualitative specificity of changes in functional states during an altered state of consciousness with manifestations of different psychovisceral phenomena.     

Neuroprosthetic hearing with auditory brainstem implants.

The auditory brainstem implant (ABI) does provide auditory sensations, recognition of environmental sounds and aid in spoken communication in about 300 patients worldwide. It is no more an investigative device but widely accepted for the treatment of patients who have lost hearing due to bilateral tumors of the hearing nerve who transmits the acoustic information from the cochlea to the brain. Most of the implanted patients are completely deaf when the implant is switched off. In contrast to cochlear implants, only few of the implanted patients achieve open-set speech recognition without the help of visual cues. On average, the ABI improves communicative functions like speech recognition at about 30% when compared to lip-reading only. The task for the next years is to improve the outcome of ABI further by developing new less invasive operative approaches as well as new hardware and software for the ABI device.     

Neural Effects of Auditory Distraction on Visual Attention in Schizophrenia

Sensory flooding, particularly during auditory stimulation, is a common problem for patients with schizophrenia. The functional consequences of this impairment during cross-modal attention tasks, however, are unclear. The purpose of this study was to examine how auditory distraction differentially affects task-associated response during visual attention in patients and healthy controls. To that end, 21 outpatients with schizophrenia and 23 healthy comparison subjects performed a visual attention task in the presence or absence of distracting, environmentally relevant “urban” noise while undergoing functional magnetic resonance imaging at 3T. The task had two conditions (difficult and easy); task-related neural activity was defined as difficult – easy. During task performance, a significant distraction (noise or silence) by group (patient or control) interaction was observed in the left dorsolateral prefrontal cortex, right hippocampus, left temporoparietal junction, and right fusiform gyrus, with patients showing relative hypoactivation during noise compared to controls. In patients, the ability to recruit the dorsolateral prefrontal cortex during the task in noise was negatively correlated with the effect of noise on reaction time. Clinically, the ability to recruit the fusiform gyrus during the task in noise was negatively correlated with SANS affective flattening score, and hippocampal recruitment during the task in noise was positively correlated with global functioning. In conclusion, schizophrenia may be associated with abnormalities in neural response during visual attention tasks in the presence of cross-modal noise distraction. These response differences may predict global functioning in the illness, and may serve as a biomarker for therapeutic development.