Repetitive transcranial magnetic stimulation of the dorsolateral prefrontal cortex enhances working memory.

Neuroimaging and electrophysiological studies have unequivocally identified the dorsolateral prefrontal cortex (DLPFC) as a crucial structure for top-down control of working memory (WM) processes. By modulating the excitability of neurons in a targeted cortical area, transcranial magnetic stimulation (TMS) offers a unique way to modulate DLPFC function, opening the possibility of WM facilitation. Even though TMS neuromodulation effects over the left DLPFC have successfully improved WM performance in patients with depression and schizophrenia in a multitude of studies, raising the potential of TMS as a safe efficacious treatment for WM deficits, TMS interventions in healthy individuals have produced mixed and inconclusive results. Here, we stimulated the left DLPFC of healthy individuals using a high-frequency repetitive TMS protocol and evaluated behavioral performance in a battery of cognitive tasks. We found that TMS treatment enhanced WM performance in a verbal digit span and a visuospatial 2-back task.

Understanding intentionality in children with attention-deficit/hyperactivity disorder.

One of the main aspects of theory of mind is intentionality which refers to recognizing other people's intentions in their behaviors. The aim of this study was to investigate intentionality in children with attention-deficit/hyperactivity disorder (ADHD). Thirty children with ADHD were compared to thirty age- and IQ-matched normal children. All participants were assessed using the moving shapes paradigm task which contains one large red and one small blue triangle moving around a black screen. They were asked to describe what the movements mean and how the triangles interact with each other. The answers were rated based on the accuracy, type of descriptions applied, mental states, and length of phrases. With regard to intentionality score, children with ADHD performed significantly worse than normal children (P < .05). Based on appropriateness score, the accuracy of patients' answers was lower in comparison with the control group. Children with ADHD used longer phrases as compared to controls. Children with ADHD can have problems with comprehending others' intentionality. This leads to impairment in social relationship.

Long-Range Reduced Predictive Information Transfers of Autistic Youths in EEG Sensor-Space During Face Processing.

The majority of previous functional/effective connectivity studies conducted on the autistic patients converged to the underconnectivity theory of ASD: "long-range underconnectivity and sometimes short-rang overconnectivity". However, to the best of our knowledge the total (linear and nonlinear) predictive information transfers (PITs) of autistic patients have not been investigated yet. Also, EEG data have rarely been used for exploring the information processing deficits in autistic subjects. This study is aimed at comparing the total (linear and nonlinear) PITs of autistic and typically developing healthy youths during human face processing by using EEG data. The ERPs of 12 autistic youths and 19 age-matched healthy control (HC) subjects were recorded while they were watching upright and inverted human face images. The PITs among EEG channels were quantified using two measures separately: transfer entropy with self-prediction optimality (TESPO), and modified transfer entropy with self-prediction optimality (MTESPO). Afterwards, the directed differential connectivity graphs (dDCGs) were constructed to characterize the significant changes in the estimated PITs of autistic subjects compared with HC ones. By using both TESPO and MTESPO, long-range reduction of PITs of ASD group during face processing was revealed (particularly from frontal channels to right temporal channels). Also, it seemed the orientation of face images (upright or upside down) did not modulate the binary pattern of PIT-based dDCGs, significantly. Moreover, compared with TESPO, the results of MTESPO were more compatible with the underconnectivity theory of ASD in the sense that MTESPO showed no long-range increase in PIT. It is also noteworthy that to the best of our knowledge it is the first time that a version of MTE is applied for patients (here ASD) and it is also its first use for EEG data analysis.

Evaluation of Attention Bias in Morphine and Methamphetamine Abusers towards Emotional Scenes during Early Abstinence: An Eye-Tracking Study.

INTRODUCTION: We hypothesized that inappropriate attention during the period of abstinence in individuals with substance use disorder can result in an inadequate perception of emotion and unsuitable reaction to emotional scenes. The main aim of this research was to evaluate the attentional bias towards emotional images in former substance abusers and compare it to healthy adults. METHODS: Paired images of general scenes consisting of pleasant, unpleasant, and neutral images were presented to subjects for 3 s while their attentional bias and eye movements were measured by eye tracking. The participants were 72 male adults consisting of 23 healthy control, 24 morphine former abusers, and 25 methamphetamine former abusers. The former abusers were recruited from a private addiction quitting center and addiction rehabilitation campus. The healthy individuals were selected from general population. Number and duration of first fixation, duration of first gaze, and sustained attention towards emotional scenes were measured as the main variables and the data were analyzed using the repeated measures ANOVA. RESULTS: A significant difference was observed between former morphine abusers and healthy control in terms of number and duration of first fixations and first gaze duration towards pleasant images. DISCUSSION: Individuals with morphine use disorder have more problems with attending to emotional images compared to methamphetamine abusers and healthy people.

A comparative study of sustained attentional bias on emotional processing in ADHD children to pictures with eye-tracking.

OBJECTIVE: ADHD children have anomalous and negative behavior especially in emotionally related fields when compared to other. Evidence indicates that attention has an impact on emotional processing. The present study evaluates the effect of emotional processing on the sustained attention of children with ADHD type C. MATERIALS & METHODS: Sixty participants form two equal groups (each with 30 children) of normal and ADHD children) and each subject met the required selected criterion as either a normal or an ADHD child. Both groups were aged from 6-11-years-old. All pictures were chosen from the International Affective Picture System (IAPS) and presented paired emotional and neutral scenes in the following categories: pleasant-neutral; pleasant-unpleasant; unpleasant-neutral; and neutral-neutral. Sustained attention was evaluated based on the number and duration of total fixation and was compared between the groups with MANOVA analysis. RESULTS: The duration of sustained attention on pleasant in the pleasant-unpleasant pair was significant. Bias in duration of sustained attention on pleasant scenes in pleasant-neutral pairs is significantly different between the groups. CONCLUSION: Such significant differences might be indicative of ADHD children deficiencies in emotional processing. It seems that the highly deep effect of emotionally unpleasant scenes to gain the focus of ADHD children's attention is responsible for impulsiveness and abnormal processing of emotional stimuli.

Comparison between Face and Object Processing in Youths with Autism Spectrum Disorder: An event related potentials study.

OBJECTIVE: Incapability in face perception and recognition is one of the main issues in autism spectrum disorders (ASD). Event related potential (ERP) studies have revealed controversial insights on autistic brain responses to faces and objects. The current investigation examined the ERP components of young children with ASD compared to a typically developing (TD) group when looking at the upright and inverted images of faces and cars. METHODS: Fourteen children and adolescents aged between 9 and 17 diagnosed as having ASD were compared with 18 age- gender matched normally developing individuals. All participants' ERPs were recorded while they were seeing the images of human faces and objects in both upright and inverted positions. The ERP components including N170 (latency and amplitude) were compared between the two groups in two conditions of upright and inverted using the repeated measure analysis method. RESULTS: The processing speed for upright faces was faster than the inverted faces in the TD group; however, the difference was not significant. A significant difference was observed in terms of N170 latency between the two groups for different stimulus categories such as objects and faces(p<0.05). Moreover, inverted vs. upright stimuli in both groups elicited a greater response in terms of N170 amplitude in both groups, and this effect was significantly prominent in the right hemisphere (p<0.05). The N170 amplitude turned out to be greater for the inverted vs. upright stimuli irrespective of the stimuli type and group. CONCLUSION: These data suggest youths with ASD have difficulty processing information, particularly in face perception regardless of the stimuli orientation.

Attentional Bias towards Emotional Scenes in Boys with Attention Deficit Hyperactivity Disorder.

OBJECTIVE: Children with attention-deficit/hyperactivity disorder (ADHD) react explosively and inappropriately to emotional stimuli. It could be hypothesized that these children have some impairment in attending to emotional cues. Based on this hypothesis, we conducted this study to evaluate visual directions of children with ADHD towards paired emotional scenes. METHOD: Thirty boys between the ages of 6 and 11 years diagnosed with ADHD were compared with 30 age-matched normal boys. All participants were presented paired emotional and neutral scenes in the four following categories: pleasant-neutral; pleasant-unpleasant; unpleasant-neutral; and neutral - neutral. Meanwhile, their visual orientations towards these pictures were evaluated using the eye tracking system. The number and duration of first fixation and duration of first gaze were compared between the two groups using the MANOVA analysis. The performance of each group in different categories was also analyzed using the Friedman test. RESULTS: With regards to duration of first gaze, which is the time taken to fixate on a picture before moving to another picture, ADHD children spent less time on pleasant pictures compared to normal group, while they were looking at pleasant - neutral and unpleasant - pleasant pairs. The duration of first gaze on unpleasant pictures was higher while children with ADHD were looking at unpleasant - neutral pairs (P<0.01). CONCLUSION: Based on the findings of this study it could be concluded that children with ADHD attend to unpleasant conditions more than normal children which leads to their emotional reactivity.

Initial Orientation of Attention towards Emotional Faces in Children with Attention Deficit Hyperactivity Disorder.

OBJECTIVE: Early recognition of negative emotions is considered to be of vital importance. It seems that children with attention deficit hyperactivity disorder have some difficulties recognizing facial emotional expressions, especially negative ones. This study investigated the preference of children with attention deficit hyperactivity disorder for negative (angry, sad) facial expressions compared to normal children. METHOD: Participants were 35 drug naive boys with ADHD, aged between 6-11 years,and 31 matched healthy children. Visual orientation data were recorded while participants viewed face pairs (negative-neutral pairs) shown for 3000ms. The number of first fixations made to each expression was considered as an index of initial orientation. RESULTS: Group comparisons revealed no difference between attention deficit hyperactivity disorder group and their matched healthy counterparts in initial orientation of attention. A tendency towards negative emotions was found within the normal group, while no difference was observed between initial allocation of attention toward negative and neutral expressions in children with ADHD. CONCLUSION: Children with attention deficit hyperactivity disorder do not have significant preference for negative facial expressions. In contrast, normal children have a significant preference for negative facial emotions rather than neutral faces.