Iwona Szatkowska

Cognitive inhibition in patients with medial orbitofrontal damage

Inhibition underlies cognitive processes such as overcoming habitual responses, suppressing of goal-irrelevant information, and switching of attention between stimuli or task rules. These processes are thought to depend on the frontal lobes. However, the precise role of the ventral frontal regions (orbitofrontal cortex) in these processes remains elusive. In the present study, our goal was to clarify the role of the orbitofrontal cortex in cognitive inhibition by examining the effects of focal lesions to the medial orbitofrontal cortex (posterior part of the gyrus rectus) on performance in tasks that required inhibitory control. Patients who had undergone surgery for an anterior communicating artery aneurysm and normal control subjects (C) participated in the study. The patients were subdivided into three groups: those with resection of the left (LGR+) or right (RGR+) gyrus rectus, and without such a resection (GR-). The Stroop Color-Word test, Trail Making B test, and the Category test were used as instruments for assessing response inhibition, switching between concrete stimuli, and switching between abstract task rules, respectively. In addition, the Digit Symbol test was used to examine sustained attention and processing speed. In the Stroop Color-Word test, the RGR+ group performed worse than all other groups. In the Trail Making B test, the RGR+ and LGR+ groups performed worse than both the GR- and C groups. In the Category test and Digit Symbol test, the groups did not differ significantly from each other. Our study indicates a specific contribution of the medial orbitofrontal cortex to response inhibition and stimulus-based switching of attention.

Sex, Lies and fMRI—Gender Differences in Neural Basis of Deception

Deception has always been a part of human communication as it helps to promote self-presentation. Although both men and women are equally prone to try to manage their appearance, their strategies, motivation and eagerness may be different. Here, we asked if lying could be influenced by gender on both the behavioral and neural levels. To test whether the hypothesized gender differences in brain activity related to deceptive responses were caused by differential socialization in men and women, we administered the Gender Identity Inventory probing the participants’ subjective social sex role. In an fMRI session, participants were instructed either to lie or to tell the truth while answering a questionnaire focusing on general and personal information. Only for personal information, we found differences in neural responses during instructed deception in men and women. The women vs. men direct contrast revealed no significant differences in areas of activation, but men showed higher BOLD signal compared to women in the left middle frontal gyrus (MFG). Moreover, this effect remained unchanged when self-reported psychological gender was controlled for. Thus, our study showed that gender differences in the neural processes engaged during falsifying personal information might be independent from socialization.

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.

Do Dynamic Compared to Static Facial Expressions of Happiness and Anger Reveal Enhanced Facial Mimicry

Facial mimicry is the spontaneous response to others’ facial expressions by mirroring or matching the interaction partner. Recent evidence suggested that mimicry may not be only an automatic reaction but could be dependent on many factors, including social context, type of task in which the participant is engaged, or stimulus properties (dynamic vs static presentation). In the present study, we investigated the impact of dynamic facial expression and sex differences on facial mimicry and judgment of emotional intensity. Electromyography recordings were recorded from the corrugator supercilii, zygomaticus major, and orbicularis oculi muscles during passive observation of static and dynamic images of happiness and anger. The ratings of the emotional intensity of facial expressions were also analysed. As predicted, dynamic expressions were rated as more intense than static ones. Compared to static images, dynamic displays of happiness also evoked stronger activity in the zygomaticus major and orbicularis oculi, suggesting that subjects experienced positive emotion. No muscles showed mimicry activity in response to angry faces. Moreover, we found that women exhibited greater zygomaticus major muscle activity in response to dynamic happiness stimuli than static stimuli. Our data support the hypothesis that people mimic positive emotions and confirm the importance of dynamic stimuli in some emotional processing.

The role of the human ventromedial prefrontal cortex in memory for contextual information

There is a growing body of evidence that the ventromedial prefrontal cortex (VMPFC) is implicated in the new learning of visual items. Little is known, however, as to the involvement of that portion of the prefrontal cortex in the learning of temporal and spatial relationship of those items. The aim of the present study, therefore, was to investigate the role of the VMPFC in memory for temporal and spatial order. Patients who had undergone surgery of the anterior communicating artery aneurysm, and normal control subjects (C), participated in the study. The patients were subdivided into three groups: with resection of the left (LGR+) or right (RGR+) gyrus rectus, and without such a resection (GR-). Subjects were presented with two memory tests: a temporal order (TO) test and a spatial order (SO) test. In the TO test, the LGR+ and RGR+ groups performed worse than the C group, while the GR- group did not differ significantly from the C group. In the SO test, the LGR+ and RGR+ groups did not differ significantly from the C and GR- groups. However, the trend appears to be the same for both tests, although only the TO test provides statistically significant group differences. Our results thus suggest that the VMPFC is involved in memory for contextual information. Together with previous findings, the data suggest that the learning of the relationship between items as well as the learning of those items are mediated by overlapping areas of the VMPFC.

Evidence for the involvement of the ventro-medial prefrontal cortex in a short-term storage of visual images.

The purpose of this study was to clarify the role of the ventro-medial prefrontal cortex in short-term visual memory. Patients with focal lesions to the right gyrus rectus were impaired on a size judgement task, which required short-term retention of laterally presented visual patterns. The impairment was most evident when the stimuli were addressed to the damaged hemisphere (left visual field presentations) and when separated by very short (50–500 ms) intervals. The findings suggest that the ventro-medial part of the orbitofrontal cortex, like the ventro-lateral part, is involved in short-term storage of icon-like representations of visual objects, and also that there exists a right-hemispheric specialization for that function. Our study presents the first direct evidence of such specific memory effects in humans using a lesion method and points to the importance of the right gyrus rectus area in maintaining the representation of stimuli after they are removed from view.

Emotional Empathy and Facial Mimicry for Static and Dynamic Facial Expressions of Fear and Disgust

Facial mimicry is the tendency to imitate the emotional facial expressions of others. Increasing evidence suggests that the perception of dynamic displays leads to enhanced facial mimicry, especially for happiness and anger. However, little is known about the impact of dynamic stimuli on facial mimicry for fear and disgust. To investigate this issue, facial EMG responses were recorded in the corrugator supercilii, levator labii, and lateral frontalis muscles, while participants viewed static (photos) and dynamic (videos) facial emotional expressions. Moreover, we tested whether emotional empathy modulated facial mimicry for emotional facial expressions. In accordance with our predictions, the highly empathic group responded with larger activity in the corrugator supercilii and levator labii muscles. Moreover, dynamic compared to static facial expressions of fear revealed enhanced mimicry in the high-empathic group in the frontalis and corrugator supercilii muscles. In the low-empathic group the facial reactions were not differentiated between fear and disgust for both dynamic and static facial expressions. We conclude that highly empathic subjects are more sensitive in their facial reactions to the facial expressions of fear and disgust compared to low empathetic counterparts. Our data confirms that personal characteristics, i.e., empathy traits as well as modality of the presented stimuli, modulate the strength of facial mimicry. In addition, measures of EMG activity of the levator labii and frontalis muscles may be a useful index of empathic responses of fear and disgust.

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.

Explicit Instructions Increase Cognitive Costs of Deception in Predictable Social Context

Convincing participants to deceive remains one of the biggest and most important challenges of laboratory-based deception research. The simplest and most prevalent method involves explicitly instructing participants to lie or tell the truth before presenting each task item. The usual finding of such experiments is increased cognitive load associated with deceptive responses, explained by necessity to inhibit default and automatic honest responses. However, explicit instructions are usually coupled with the absence of social context in the experimental task. Context plays a key role in social cognition by activating prior knowledge, which facilitates behaviors consistent with the latter. We hypothesized that in the presence of social context, both honest and deceptive responses can be produced on the basis of prior knowledge, without reliance on truth and without additional cognitive load during deceptive responses. In order to test the hypothesis, we have developed Speed-Dating Task (SDT), which is based on a real-life social event. In SDT, participants respond both honestly and deceptively to questions in order to appear similar to each of the dates. The dates are predictable and represent well-known categories (i.e., atheist or conservative). In one condition participants rely on explicit instructions preceding each question (external cue). In the second condition no explicit instructions are present, so the participants need to adapt based on prior knowledge about the category the dates belong to (internal cue). With internal cues, reaction times (RTs) are similar for both honest and deceptive responses. However, in the presence of external cues (EC), RTs are longer for deceptive than honest responses, suggesting that deceptive responses are associated with increased cognitive load. Compared to internal cues, deception costs were higher when EC were present. However, the effect was limited to the first part of the experiment, only partially confirming our initial hypothesis. The results suggest that the presence of social context in deception tasks might have a significant influence on cognitive processes associated with deception.