Assessment of recognition of emotions by healthy persons and patients with focal brain pathology

To assess the involvement of different structures of the human brain into successive stages of the recognition of the principal emotions by facial expression, we examined 48 patients with local brain lesions and 18 healthy adult subjects. It was shown that at the first (intuitive) stage of the recognition, premotor areas of the right hemisphere and temporal areas of the left hemisphere are of considerable importance in the recognition of both positive and negative emotions. In this process, the left temporal areas are substantially involved into the recognition of anger, and the right premotor areas predominantly participate in the recognition of fear. In patients with lesions of the right and left brain hemispheres, at the second (conscious) stage of recognition, the critical attitude to the assessment of emotions drops depending on the sign of the detected emotion. We have confirmed the hypothesis about a correlation between the personality features of the recognition of facial expressions and the dominant emotional state of a given subject.     

Positron emission tomographic study of the brain during involuntary syntactic processing

A positron emission tomography (PET) method was used to study the human brain for involuntary processing of syntactically organized information. Eight healthy subjects counted a certain letter in a running line presented on a monitor screen. PET scanning was conducted during this task performance. In cases when the running line presented a syntactically coherent text (unlike the cases when the same task was performed during administration of a sequence of incoherent words, pseudowords, or pseudotext), PET scanning revealed activation in the temporal and temporoparietooccipital cortical areas of the left hemisphere and the right temporal pole. The inverse comparison demonstrated activation in the left occipital area probably connected with the purely visual strategy of the task performance. These results show that information presentation in the form of coherent text even without the instruction to read the text is associated with more profound involuntary linguistic stimuli processing than the presentation of incoherent words, pseudowords, or pseudotext. The activation of the polar anterior temporal areas is considered evidence for activation of the system of syntactic processing, which functioned, in this case, in the involuntary (automatic) mode.     

Recognition of emotions by facial and verbal samples in healthy humans and patients with local brain pathology

The efficiency of emotion recognition by verbal and facial samples was tested in 81 persons (25 healthy subjects and 56 patients with focal pathology of premotor and temporal areas of brain hemispheres). The involvement of some cortical structures in the recognition of the basic emotional states (joy, anger, grief, and fear) and the neutral state was compared. It was shown that the damage to both right and left hemispheres impaired the recognition of emotional states by not only facial but also verbal samples. Damage to the right premotor area and to the left temporal area impaired the efficiency of the emotion recognition by both kinds of samples to the highest degree.     

Spatial synchronization of potentials in the frontal zones of the brain during performance of nominative speech in children

Characteristics of spatial-temporal relations of the frontal zones potentials with those of other brain centres were studied in five- to six-year old children during naming of visually presented objects. EEG cross correlation analysis has shown that during visual perception of familiar objects the correlations of frontal areas with the interior pariental area of the left hemisphere are enhanced; the rhythms of the inferior parietal and occipital zones in the left hemisphere precede the potentials in the frontal area, while in the right hemispere synphasic relations are set up between the frontal and occipital zones. Naming the objects by the appropriate word as compared with rest and showing of the object, leads to enhancement of both intra- and interhemispheric correlations between potentials in the frontal zone and the inferior parietal and temporal zones. The frontal lobe rhythms begin to precede the inferior parietal and occipital potentials and form synphasic relations with the temporal and motor zone potentials in the left hemisphere.     

Hemispheric Asymmetry of Evoked Potentials in Performance of Visuospatial Tasks

We studied the time and amplitude parameters of visual evoked potential components during performance of a visuospatial task under conditions of involuntary and voluntary attention. The right hemisphere dominated to a great extent with respect to the latencies of the components studied. Transient stagewise dominance of each hemisphere with respect to the level of cortical activity was also observed.     

Change in parameters of interhemispheric asymmetry during simulation of a destructive action

Interhemispheric EEG asymmetry was studied in 26 male subjects aged 8-23 with different behavioral destructiveness levels. Subjects with higher destructiveness level in the state of rest had the focus of interhemispheric asymmetry in the temporal and frontal areas of the left hemisphere, whereas in subjects with lower destructiveness level the asymmetry focus was found in the same areas of the right hemisphere. Simulation of aggressive activity led to displacement of the asymmetry focus to the right hemisphere in both groups. However, in the group with higher destructiveness the changes in the focus were observed in the EEG theta band, which suggested the involvement of mainly stem oscillators of EEG activity in the destructive behavior. In the group with lower destructiveness changes were observed mainly in the alpha3 and beta1 bands, which indicated that cortical oscillators of EEG activity were involved in the control of the destructive behavior. The results suggest better perception and assessment of stimuli by subjects with lower aggressiveness and their choice of more adequate models of behavior.     

The participation of cortical brain areas in the processes of perceiving and reproducing human emotional states]

New method of mapping intracortical interactions was used to study the participation of cortical brain areas in the processes of perception and of mental reproduction of emotional states in humans. When an emotion was identified, the activity focus was observed in the left temporal cortex. If emotion was not identified, the temporal focus did not appear, but activity foci were seen in frontal regions of both hemispheres. When emotional states were mentally reproduced, activity foci were encountered mostly in the frontal cortical areas.     

Hemispheric lateralization in the processing of odor pleasantness versus odor names

It is well established that for most people linguistic processing is primarily a left hemisphere activity, whereas recent evidence has shown that basic odor perception is more lateralized to the right hemisphere. Importantly, under certain conditions, emotional responding also shows right hemisphere laterality. Hedonic (pleasantness) assessments constitute basic level emotional responses. Given that olfaction is predominantly ipsilateral in function, it was hypothesized that odor pleasantness evaluations may be accentuated by right nostril perception and that odor naming would be superior with left nostril perception. To test this prediction we presented eight familiar neutral-mildly pleasant odors for subjects to sniff through the left and right nostrils. Subjects smelled each odor twice (once through each nostril) at two different sessions, separated by 1 week. At each session subjects provided pleasantness, arousal and naming responses to each odorant. Results revealed that odors were rated as more pleasant when sniffed through the right nostril and named more correctly when sniffed through the left. No effects for arousal were obtained. These findings are consistent with previously demonstrated neural laterality in the processing of olfaction, emotion and language, and suggest that a local and functional convergence may exist between olfaction and emotional processing.     

Organization of Regional Interactions of the Brain Cortical Activity during the Common-root Word Derivation Task

This study analyzed specificities in the activity of the neurophysiological mechanisms underlying the organization of active word-derivation processes. The regularities in the reorganization of the spatial structure for the systemic interaction of bioelectrical activity between different cortical areas of the cerebral hemispheres were studied in adult subjects during the test for mental derivation of common root words (i.е., using the modern methods of the so-called “functional connectome” investigations). Сross-correlation and coherent analysis of EEG has shown that the ipsilateral statistical EEG interactions in the left hemisphere, including Broca’s and Wernicke’s areas, were significantly increased in adults during mental derivation of common root words and, simultaneously, the interhemispheric connectivity and the EEG interactions in the right hemisphere were reduced. Comparison of our results with the previous data of verbal activity associated with speech perception and production has revealed significant differences in the degree of involvement of the left and right hemisphere cortical activity in verbal processing. For example, unlike the data of current study, an equal involvement of both hemispheres cortical activity was recorded during the phoneme recognition in auditory perceived words, grammatical and semantic errors in sentences, as well as during mental formation of words from a set of phonemes and sentences from a set of words, which was particularly manifested in the increased of hemispheric interactions, predominantly, in the inferior frontal and temporal areas and the overlapped areas of the temporal, parietal, and occipital cortical zones (TPO) of both hemispheres. Thus, the data obtained in this study indicate the presence of expressed specificities in the lateralization of activity in the neurophysiological mechanisms underlying the processes of active word derivation and inflexion.     

Electrophysiologic analysis of the process of recognizing target and non-target stimuli in healthy and oligophrenic children

In an automatized experiment, with a computer on line, amplitude-temporal parameters of evoked potentials (EPs) to purposive and non-purposive stimuli (digits), were analyzed in normal and mental retarded children. At unilateral stimuli presentation to the left or right visual half-fields EPs were recorded simultaneously in projection, TPO, parietal and central areas of the left and right hemispheres. It has been shown that in normal children, differential involvement of projection and associative structures in the analysis of sensory information takes place in both hemispheres. The amplitudes of most EP components in the range of 100-400 ms to the purposive stimuli are higher than to the non-purposive ones. Considerable similarity of EPs developing in response to ipsi- and contralateral stimulations of visual fields ("direct" and "transmitted" EP) is observed. In mental retarded children significant changes are revealed in intra- and interhemisphere organization of the process of perception of purposive and non-purposive stimuli. In the right hemisphere structures there are no differential EP reactions to the two types of stimuli. Significant, in comparison with the norm, prolongation of the latencies of most EP components is noted, especially in the structures of the left hemisphere, to the purposive stimuli. In the process of perception, changes are seen of the integration of functions of both hemispheres. The totality of disturbances of systemic brain organization at perceptive activity in mental retarded children may reflect neurophysiological mechanisms of mental deficiency.     

Functional brain organization of global and local visual perception: an ERP study

Adult subjects were asked to recognize a hierarchical visual stimulus (a letter) while their attention was drawn to either the global or local level of the stimulus. Event-related potentials (ERP) and psychophysical indices (reaction time and percentage of correct responses) were measured. An analysis of psychophysical indices showed the global level precedence effect, i.e., the increase in a small letter recognition time when this letter is a part of incongruent stimulus. An analysis of ERP components showed level-related (global vs. local) differences in the timing and topography of the brain organization of perceptual processing and regulatory mechanisms of attention. Visual recognition at the local level was accompanied by (1) stronger activation of the visual associative areas (Pz and T6) at the stage of sensory features analysis (P1 ERP component), (2) involvement mainly of inferior temporal cortices of the right hemisphere (T6) at the stage of sensory categorization (P2 ERP component), and (3) involvement of prefrontal cortex of the right hemisphere at the stage of the selection of the relevant features of the target (N2 ERP component). Visual recognition at the global level was accompanied by (1) pronounced involvement of mechanisms of early sensory selection (N1 ERP component), (2) prevailing activation of parietal cortex of the right hemisphere (P4) at the stage of sensory categorization (P2 ERP component) as well as at the stage of the target stimulus identification (P3 ERP component). It is suggested that perception at the global level of the hierarchical stimulus is related primarily to the analysis of the spatial features of the stimulus in the dorsal visual system whereas the perception at the local level primarily involves an analysis of the object-related features in the ventral visual system.     

Lateralization of olfactory processes

Over the last ten years, methods of cerebral imaging have revolutionized our knowledge of cognitive processes in humans. An impressive number of papers dealing with cerebral imaging for olfaction have been published to date. Whereas the early works revealed those structures participating in the processing of odours presented passively to subjects, researchers later recorded brain activity when subjects performed specific olfactory tasks based on memory, emotion and identification. From these results, we suggest that there is a dissociation of olfactory processes, with involvement of the right hemisphere in memory processes and the left hemisphere in emotional processes. The review concludes with a summary of how these lateralized processes are consistent with the gestalt-nature of our olfactory perception.     

Neuropsychophysiological correlates of reactive depression

To justify neurophysiological correlates of depressive disorders, the spetral parameters of EEG, peak latencies of the “late” components of auditory cognitive evoked potentials, and latencies of sensorimotor reactions in middle age and elderly patients (aged 53–72 years) during therapy of prolonged psychogenic depressive reaction (F43.21 according to ICD-10) have been studied. Initial depression severity was associated to the EEG signs of decreased functional state of the anterior areas of the left hemisphere and increased activation of the right hemisphere (especially, its temporal areas). Pronounced improvement of clinical state under the affect of psychopharmacotherapy was accompanied by acceleration of the sensorimotor reactions, a decrease in peak latencies of the “late” components (P2, N2, and P3) of auditory cognitive evoked potentials and associated with the EEG signs of improvement of functional state of the posterior areas of the brain, an enforcement of inhibitory processes in the right hemisphere (especially, in its frontal, central, and temporal areas) and more pronounced activation of frontal areas of the left hemisphere. The data are in good agreement with the concept on the systemic character of impairments of brain functioning in depression, as well as on the preferential role of the left hemisphere in control of positive emotions and the right one, of negative emotions.     

Hemispheric specialization in dogs for processing different acoustic stimuli

Considerable experimental evidence shows that functional cerebral asymmetries are widespread in animals. Activity of the right cerebral hemisphere has been associated with responses to novel stimuli and the expression of intense emotions, such as aggression, escape behaviour and fear. The left hemisphere uses learned patterns and responds to familiar stimuli. Although such lateralization has been studied mainly for visual responses, there is evidence in primates that auditory perception is lateralized and that vocal communication depends on differential processing by the hemispheres. The aim of the present work was to investigate whether dogs use different hemispheres to process different acoustic stimuli by presenting them with playbacks of a thunderstorm and their species-typical vocalizations. The results revealed that dogs usually process their species-typical vocalizations using the left hemisphere and the thunderstorm sounds using the right hemisphere. Nevertheless, conspecific vocalizations are not always processed by the left hemisphere, since the right hemisphere is used for processing vocalizations when they elicit intense emotion, including fear. These findings suggest that the specialisation of the left hemisphere for intraspecific communication is more ancient that previously thought, and so is specialisation of the right hemisphere for intense emotions.     

Study of Thresholds of Motor Evoked Responses during Transcranial Magnetic Stimulation in Healthy Subjects and Patients with Brain Tumors

Since 1985, transcranial magnetic stimulation (TMS) has been widely used for the investigation of different processes in the human central nervous system. We studied the thresholds of the motor-evoked responses (MER) during TMS and their hemispheric differences in healthy subjects and patients with brain tumors of different localization: in the brainstem projection, left and right motor areas, and left frontal-temporal area. The obtained results testify to a lower threshold of MER in healthy subjects during TMS of the dominant hemisphere. In patients with brainstem tumors, there was a decrease in the thresholds of MER during TMS. In patients with tumors in the motor area, the thresholds of MER were increased on the lesion side, whereas in patients with tumors in the left temporal area, the thresholds were significantly decreased during TMS of the lesioned hemisphere.     

Hemispheric asymmetry of visual evoked potentials during human recognition of facial emotional expressions

Visual evoked potentials (VEP) in standard 16 EEG derivations were recorded in 26 young men and 20 women during recognition of facial emotional expressions and geometric figures. The stimuli were presented on a computer screen in the center of the visual field or randomly in the right or left vision hemifields. Peak VEP latency and mean amplitude in 50-ms epochs were measured; spatiotemporal VEP dynamics was analyzed in a series of topographic maps. The right hemisphere was shown to be more important in processing emotional faces. The character of the asymmetry was dynamic: at earlier stages of emotion processing the electrical activity was higher in the right inferior temporal region compared to the left symmetrical site. Later on the activity was higher in the right frontal and central areas. The dynamic mapping of "face-selective" component N180 of VEPs revealed the onset of activation over the right frontal areas that was followed by the fast activation of symmetrical left zones. Notably, this dynamics didn't correlate with the hemifield of stimuli exposition. The degree of asymmetry was lower during presentation of figures, especially in the inferior temporal and frontal regions. The prominent asymmetry of information processes in the inferior temporal and frontal areas was suggested to be specific for recognition of facial expression.     

Thermoencephaloscopy of brain responses to emotionally significant visual stimuli in depressive patients

The thermoencephaloscopic study of patients with reactive depression during exposure to emotionally significant visual stimuli detected a functional change in the state of the frontal associative area of the right hemisphere and the parietal associative area of the left hemisphere and the activation of the left temporal area, closely related to the limbic system. The data obtained may be used for the elaboration of new methods of diagnosis and therapy of reactive depressions.     

Erratum to: Functional Brain Organization of Global and Local Visual Perception: An Event-Related Potentials Study

Adult subjects were asked to recognize a hierarchical visual stimulus (a letter) while their attention was drawn to either the global or local level of the stimulus. Event-related potentials (ERP) and behavioral indices (reaction time and percentage of correct responses) were measured. An analysis of behavioral indices showed the global level precedence effect, i.e. the increase in a small letter recognition time when this letter is a part of incongruent stimulus. An analysis of ERP components showed level-related (global vs. local) differences in the timing and topography of the brain organization of perceptual processing and regulatory mechanisms of attention. Visual recognition at the local level was accompanied by (1) stronger activation of the visual associative areas (P _z and T ₆) at the stage of sensory features analysis (P1 ERP component), (2) involvement mainly of inferior temporal cortices of the right hemisphere (T ₆) at the stage of sensory categorization (P2 ERP component), and (3) involvement of prefrontal cortex of the right hemisphere at the stage of selection of the relevant features of the target (N2 ERP component). Visual recognition at the global level was accompanied by (1) pronounced involvement of mechanisms of early sensory selection (N1 ERP component), (2) prevailing activation of parietal cortex of the right hemisphere (P ₄) at the stage of sensory categorization (P2 ERP component) as well as at the stage of the target stimulus identification (P3 ERP component). We suggested that perception of the hierarchical stimulus at the global level is related primarily to the analysis of its spatial features in the dorsal visual system whereas the perception at the local level primarily involves an analysis of the object-related features in the ventral visual system.     

Hemispheric organization of verbal memory functions in seasonal winter depression: electrophysiological analysis

Spatial organization of EEG power and coherence during memorization of dichotically presented lists of words were studied in patients with winter depression (N = 17) and control subjects (N = 22). In contrast to the control subjects, the depressed patients were characterized by the higher theta power in the right parietal and posterior temporal regions and the dominance of the alpha 2 in the left midfrontal area. The patients also differed in the lower theta 2 coherence in the left hemisphere and lower alpha 1 coherence in the right hemisphere. These effects showed different intrahemispheric distribution. The interhemispheric EEG coherence in the theta 2 range between the frontal areas and alpha 1 coherence between the left frontal and right posterior areas was lower in the patients than in the control subjects. Verbal-emotional interaction in depressions are discussed.     

Amplitude-temporal parameters of the evoked potentials of the visual and motor areas in the visual perception and mental representation of an image

Amplitude-temporal analysis was carried out of the EP components of the visual and motor areas elicited by neutral (diffuse light) and structural (checker board pattern) stimuli in different situations, defined by instruction. Interserial comparisons showed that at any instruction, the latency of the first EP component of the motor areas is reduced; as a result it can appear here simultaneously with the EP of the visual areas. At the instruction involving the subject in the process of active change of perception, activation of the right hemisphere, including the motor area, is manifest by EP parameters, while the right occipital area is activated in response to the structural stimulus, and the left one--in response to the neutral stimulus. At complication of the stimulus or instruction, the period is prolonged when the latency of EP components of the motor area is shorter than the latency of the isopolar components of the visual area--from 120 to 150 ms in response to the neutral stimuli and the neutral with their counting; from 90 to 150 ms in response to the structural stimuli; from 80 to 210 ms in response to the neutral stimuli with mental representation of the structural one.