Krystyna Rymarczyk

EMG activity in response to static and dynamic facial expressions

The EMG activity associated with static and dynamic facial expressions (morphs with happy or angry emotions) were compared. We hypothesized that dynamic faces would (a) enhance facial muscular reactions and (b) evoke higher intensity ratings. Our analysis showed that dynamic expressions were rated as more intense than static ones. Subjects reacted spontaneously and rapidly to happy faces with increased zygomaticus major EMG activity and decrease corrugator supercilii EMG activity - showing greater changes in response to dynamic than to static stimuli in both muscles. In contrast, angry faces evoked no alteration of EMG activity in zygomaticus muscles and only small changes in the corrugator muscle EMG, and there was no difference between the responses to static and dynamic stimuli. It may be concluded that the dynamic property facilitates processing of facial expressions of emotions.

Duration processing in children as determined by time reproduction: implications for a few seconds temporal window.

From research carried out over recent years using different experimental paradigms, it has become apparent that central information processing is temporally segmented into sequential units of a few seconds. This segmentation presumably reflects a neuronal process of temporal integration (TI) which automatically binds successive events into temporal units. Support for such TI comes, for example, from studies on temporal reproduction where standards up to approximately 2-3 s are reproduced veridically. Using this paradigm of temporal reproduction, we investigated the effect of normal cognitive development of sensory modality and of the range of presented standards on TI. Sixty children aged 6-7, 9-10 and 13-14 years reproduced visual or auditory standard durations ranged from 1 to 5.5 s or from 1 to 3 s. The results showed that durations of approximately 2 s were reproduced correctly, whereas those longer than 2.5 s were under-reproduced in the three age groups. For standards shorter than 2 s substantial age-related differences were revealed: the youngest group displayed significant over-reproduction comparing to older subjects. These observations indicate that the upper limit for TI is a stable feature across the different age groups. Furthermore an age-related modulation within the temporal window of the operating TI seems to be linked to cognitive development.

Sex differences in brain control of prosody

Affective (emotional) prosody is a neuropsychological function that encompasses non-verbal aspects of language that are necessary for recognizing and conveying emotions in communication, whereas non-affective (linguistic) prosody indicates whether the sentence is a question, an order or a statement. Considerable evidence points to a dominant role for the right hemisphere in both aspects of prosodic function. However, it has yet to be established whether separate parts of the right hemisphere are involved in processing different kinds of emotional intonation. The aim of this study was to answer this question. In addition, the issue of sex differences in the ability to understand prosody was considered. Fifty-two patients with damage to frontal, temporo-parietal or subcortical (basal) parts of the right hemisphere and 26 controls were tested for their ability to assess prosody information in normal (well-formed) sentences and in pseudo-sentences. General impairment of prosody processing was seen in all patient groups but the effect of damage was more apparent for emotional rather than linguistic prosody. Interestingly, appreciation of emotional prosody appeared to depend on the type of emotional expression and the location of the brain lesion. The patients with frontal damage were mostly impaired in comprehension of happy intonations; those with temporo-parietal damage in assessment of sad intonations, while subcortical lesions mostly affected comprehension of angry intonations. Differential effects of lesion location on the performance of men and women were also observed. Frontal lesions were more detrimental to women, whereas subcortical lesions led to stronger impairment in men. This suggests sex differences in brain organization of prosodic functions.

Olfactory Deficits in Normal Aging and Alzheimer's Disease in the Polish Elderly Population

Alzheimers disease (AD) is the most frequent cause of dementia. For this reason, a simple, reliable, and inexpensive method of early AD detection is urgently required. The location of neuropathological changes in AD patients indicates the potential diagnostic utility of olfactory tests. The purpose of this study was to compare odor identification performance among Polish subjects and to define the correlation between olfactory deficits and cognitive impairment. Olfactory identification performance was established in AD patients, and young and elderly healthy subjects using the Pocket Smell Test. AD Assessment Scale, the cognitive subscale, was used to evaluate cognitive functioning in the elderly participants. Compared with young subjects, the elderly individuals exhibited a diminished capacity to identify odors. AD patients also identified significantly fewer odors than healthy participants of the same age. In both the AD patients and the elderly control group, odor identification ability correlated with performance in cognitive tests. It may be concluded that deficits in olfactory identification occur in AD and may be valuable as an indicator of this condition.

Dissociable contributions of the left and right posterior medial orbitofrontal cortex in motivational control of goal-directed behavior

Several findings from both human neuroimaging and nonhuman primate studies suggest that the posterior medial orbitofrontal cortex (OFC) may be critical for the motivational control of goal-directed behavior. The present study was conducted to clarify the role of the left and right posterior medial OFC in that function by examining the effects of focal unilateral lesions to this region on the performance on an incentive working memory task. The study covered patients who had undergone surgery for an ACoA aneurysm and normal control subjects (C). The patients were subdivided into three groups: those with resection of the left (LGR+) or right (RGR+) posterior part of the gyrus rectus, and without such a resection (GR-). Participants performed a 2-back working memory task under three motivational conditions (penalty, reward, and no-incentive). The C group performed worse in the penalty condition and better in the reward condition as compared to the no-incentive condition. Similar results were obtained for the GR- group. Performance of the LGR+ group did not depend on incentive manipulations, whereas the RGR+ group performed better in both the penalty and reward conditions than in the no-incentive condition. The results show that the posterior medial OFC is involved in the motivational modulation of working memory performance. Our findings also suggest that the left posterior medial OFC plays a crucial role in this function, whereas the right posterior medial OFC is particularly involved in the processing of the punishing aspect of salient events and it probably mediates in guiding behavior on the basis of negative outcomes of action.

How we empathize with others: A neurobiological perspective

Summary Empathy allows us to internally simulate the affective and cognitive mental states of others. Neurobiological studies suggest that empathy is a complex phenomenon, which can be described using a model that includes 2 modes of processing: bottom-up and top-down. Bottom-up neural processing is achieved via the mirroring representation systems that play a key role in the direct sharing of the emotional states of others. Top-down processing, known as cognitive perspective-taking or theory of mind, where the feelings of others are fully imagined and understood, is based on control and inhibition mechanisms. Available evidence indicates that empathic brain responses are likely to be influenced by several different modulating factors.

Temporal integration in a subjective accentuation task as a function of child cognitive development.

We have previously shown that temporal integration in the domain of a few seconds may be studied using a subjective accentuation paradigm. Here we report developmental effects on the limits of this temporal integration in 9-10-year-olds in comparison with 13-14-year-olds. The task was to listen to a string of identical metronome beats and mentally bind the presented beats by subjectively accentuating every second, third or nth beat. The integration interval length was defined as the number of stimuli mentally connected multiplied by the temporal interval between two successive beats. For the lowest stimulus frequency integration intervals were approximately 3 s for the older and 2.2 s for the younger children. For higher frequencies integration intervals got systematically shorter, but being always longer for the older age group. It is suggested that the prefrontal region is responsible for this developmental effect. The expansion of temporal integration correlates with cognitive development in the investigated phase of ontogenesis.

Linguistic and cognitive aspects of proverb processing in aphasia

The main purpose of this study was to explore proverb competence in aphasia within an ethnographic framework. A battery of proverb tests and a questionnaire were constructed to collect the data. The battery was designed to explore the changes in the form and the meaning of proverbs resulting from aphasia, while the questionnaire served the purpose of tapping aphasics knowledge of proverb use. The experimental battery was designed to include the dichotomy of in-context and out-of-context tasks. The basic assumption that underlay the analysis of the experimental data was that, to understand the mechanism of proverb use in aphasia, one should include qualitative as well as quantitative analyses. The aphasic subjects, who exhibited a mild level of language impairment, to a great extent preserved the ability to comprehend proverbs and the ability to use them under experimental conditions. Methodological guidelines coming from this research are discussed.

Neural Correlates of Facial Mimicry: Simultaneous Measurements of EMG and BOLD Responses during Perception of Dynamic Compared to Static Facial Expressions

Facial mimicry (FM) is an automatic response to imitate the facial expressions of others. However, neural correlates of the phenomenon are as yet not well established. We investigated this issue using simultaneously recorded EMG and BOLD signals during perception of dynamic and static emotional facial expressions of happiness and anger. During display presentations, BOLD signals and zygomaticus major (ZM), corrugator supercilii (CS) and orbicularis oculi (OO) EMG responses were recorded simultaneously from 46 healthy individuals. Subjects reacted spontaneously to happy facial expressions with increased EMG activity in ZM and OO muscles and decreased CS activity, which was interpreted as FM. Facial muscle responses correlated with BOLD activity in regions associated with motor simulation of facial expressions [i.e., inferior frontal gyrus, a classical Mirror Neuron System (MNS)]. Further, we also found correlations for regions associated with emotional processing (i.e., insula, part of the extended MNS). It is concluded that FM involves both motor and emotional brain structures, especially during perception of natural emotional expressions.

Physical attractiveness and sex as modulatory factors of empathic brain responses to pain

Empathy is a process that comprises affective sharing, imagining, and understanding the emotions and mental states of others. The brain structures involved in empathy for physical pain include the anterior insula (AI), and the anterior cingulate cortex (ACC). High empathy may lead people to undertake pro-social behavior. It is important to understand how this process can be changed, and what factors these empathic responses depend on. Physical attractiveness is a major social and evolutional cue, playing a role in the formation of interpersonal evaluation. The aim of the study was to determine how attractiveness affects the level of empathy both in relation to self-rated behavior and in terms of activation of specific empathy-related brain regions. Twenty-seven subjects (14 female and 13 male) were studied using functional magnetic resonance imaging (fMRI) method while they were watching short video scenes involving physically more and less attractive men and women who exhibited pain responses. In the absence of behavioral effects in compassion ratings, we observed stronger activation in empathic brain structures (ACC; AI) for less attractive men and for attractive women than for attractive men. Evolutionary psychology studies suggest that beauty is valued more highly in females than males, which might lead observers to empathize more strongly with the attractive woman than the men. Attractive mens’ faces are typically associated with enhanced masculine facial characteristics and are considered to possess fewer desirable personality traits compared with feminized faces. This could explain why more empathy was shown to less attractive men. In conclusion, the study showed that the attractiveness and sex of a model are important modulators of empathy for pain.