Lemke Leyman

The Karolinska Directed Emotional Faces: A validation study

Although affective facial pictures are widely used in emotion research, standardised affective stimuli sets are rather scarce, and the existing sets have several limitations. We therefore conducted a validation study of 490 pictures of human facial expressions from the Karolinska Directed Emotional Faces database (KDEF). Pictures were evaluated on emotional content and were rated on an intensity and arousal scale. Results indicate that the database contains a valid set of affective facial pictures. Hit rates, intensity, and arousal of the 20 best KDEF pictures for each basic emotion are provided in an appendix.

Mood-congruent attention and memory bias in dysphoria: Exploring the coherence among information-processing biases

Recent studies indicate that depression is characterized by mood-congruent attention bias at later stages of information-processing. Moreover, depression has been associated with enhanced recall of negative information. The present study tested the coherence between attention and memory bias in dysphoria. Stable dysphoric (n = 41) and non-dysphoric (n = 41) undergraduates first performed a spatial cueing task that included negative, positive, and neutral words. Words were presented for 250 ms under conditions that allowed or prevented elaborate processing. Memory for the words presented in the cueing task was tested using incidental free recall. Dysphoric individuals exhibited an attention bias for negative words in the condition that allowed elaborate processing, with the attention bias for negative words predicting free recall of negative words. Results demonstrate the coherence of attention and memory bias in dysphoric individuals and provide suggestions on the influence of attention bias on further processing of negative material.

The influence of rTMS over the left dorsolateral prefrontal cortex on Stroop task performance.

Several studies have demonstrated that repetitive transcranial magnetic stimulation (rTMS) can improve cognitive processing. Neuroimaging studies have shown the engagement of the left dorsolateral prefrontal cortex (DLPFC) in executive functioning, and more specifically during selective attention. In the present study, the influence of high-frequency rTMS over the left DLPFC on Stroop task performance in healthy female volunteers was investigated. As expected, reaction time on both the incongruent and congruent trials decreased significantly after stimulation, and there was no difference with regard to the Stroop interference effect. Mood remained unchanged after rTMS. Such a pattern is consistent with the role of the left DLPFC in implementing top–down attentional control.

Neurocognitive effects of HF-rTMS over the dorsolateral prefrontal cortex on the attentional processing of emotional information in healthy women an event-related fMRI study

Current evidence concerning the neurocircuitry underlying the interplay between attention and emotion is mainly correlational. We used high-frequency repetitive Transcranial Magnetic Stimulation (HF-rTMS) to experimentally manipulate activity within the right or left dorsolateral prefrontal cortex (DLPFC) of healthy women and examined changes in attentional processing of emotional information using an emotional modification of the exogenous cueing task during event-related fMRI. Right prefrontal HF-rTMS resulted in impaired disengagement from angry faces, associated with decreased activation within the right DLPFC, dorsal anterior cingulate cortex (dACC) and left superior parietal gyrus, combined with increased activity within the right amygdala. Left prefrontal HF-rTMS resulted in diminished attentional engagement by angry faces and was associated with increased activity within the right DLPFC, dACC, right superior parietal gyrus and left orbitofrontal cortex. The present observations are in line with reports of a functionally interactive network of cortical-limbic pathways that play a central role in emotion regulation.

Influence of high-frequency repetitive transcranial magnetic stimulation over the dorsolateral prefrontal cortex on the inhibition of emotional information in healthy volunteers

BACKGROUND Evidence suggests that repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) might be a promising new treatment procedure for depression. However, underlying working mechanisms of this technique are yet unclear. Multiple sessions of rTMS may--apart from the reported antidepressant effects--cause primary improvements in attentional control over emotional information, modulated by changes in cortical brain excitability within stimulated prefrontal regions. METHOD In two experiments, we examined the temporary effects of high-frequency (HF) rTMS (10 Hz) applied over the left and right DLPFC on the attentional processing of emotional information and self-reported mood within samples of healthy volunteers. RESULTS The present study showed that one session of HF-rTMS over the right DLPFC produces instant impairments in the ability to inhibit negative information, in line with a characteristic cognitive vulnerability found in depressive pathology, whereas HF-rTMS of the left DLPFC did not lead to significant changes in attentional control. These effects could not be attributed to mood changes. CONCLUSIONS The findings of the present study may suggest a specific involvement of the right DLPFC in the attentional processing of emotional information.

Attention for emotional facial expressions in dysphoria: An eye-movement registration study

Former research demonstrated that depression is associated with dysfunctional attentional processing of emotional information. Most studies examined this bias by registration of response latencies. The present study employed an ecologically valid measurement of attentive processing, using eye-movement registration. Dysphoric and non-dysphoric participants viewed slides presenting sad, angry, happy and neutral facial expressions. For each type of expression, three components of visual attention were analysed: the relative fixation frequency, fixation time and glance duration. Attentional biases were also investigated for inverted facial expressions to ensure that they were not related to eye-catching facial features. Results indicated that non-dysphoric individuals were characterised by longer fixating and dwelling on happy faces. Dysphoric individuals demonstrated a longer dwelling on sad and neutral faces. These results were not found for inverted facial expressions. The present findings are in line with the assumption that depression is associated with a prolonged attentional elaboration on negative information.

The influence of rTMS over the right dorsolateral prefrontal cortex on intentional set switching

High frequency (HF) repetitive transcranial magnetic stimulation (rTMS) has an excitatory effect on neurons of a specific brain area. The dorsolateral prefrontal cortex (DLPFC) has been associated with executive functions, such as task set switching. One important experimental paradigm for investigating such higher order cognitive control is the task-switching (TS) paradigm. A TS paradigm requires switching between two conditional response tasks with mutually incompatible response–selection rules. In the present study, the influence of HF rTMS over the right DLPFC in healthy female volunteers on a modified TS paradigm was investigated. As expected, reaction time on cued switching trials decreased significant after rTMS, as compared to non-cued switch trials. No changes emerged after the placebo sham condition. Mood remained unchanged after rTMS. These findings demonstrate the role of the right DLPFC in cued intentional set switch initiation.

Left and right High Frequency repetitive Transcranial Magnetic Stimulation of the dorsolateral prefrontal cortex does not affect mood in female volunteers

OBJECTIVE High Frequency repetitive Transcranial Magnetic Stimulation (HF-rTMS) has yielded divergent results concerning its effect on mood in normal volunteers. In a former study, we were unable to demonstrate negative mood effects after one session of HF-rTMS on the left dorsolateral prefrontal cortex (DLPFC) in a large group of healthy female volunteers: researchers had focused mainly on negative mood changes, overlooking a possible positive mood induction, while no studies had yet examined mood effects of HF-rTMS delivered on the right prefrontal cortex. In this study, we have tried to replicate our previous HF-rTMS findings on the left DLPFC in a new (large) group of healthy female subjects, and we focused especially on positive mood changes. We also extended our former research by stimulating the right DLPFC in a different but comparable (large) group of healthy female volunteers with the same HF-rTMS parameters. METHODS In this sham-controlled, single blind, crossover HF-rTMS study, stimulus parameters were an exact copy of our previous healthy volunteer study. To exclude individual anatomical differences, the left and right DLPFC were targeted under magnetic resonance (MRI) guidance. To examine subjective mood changes we used Visual Analogue Scales (VAS), the Profile of Mood States (POMS), and the Positive Affect and Negative Affect Schedule (PANAS), the latter to assure assessment of positive emotions. To detect any delayed mood changes, assessments were also re-administered 30min post-HF-rTMS. RESULTS We were unable to demonstrate immediate or delayed mood changes after one single active HF-rTMS session on the left or right DLPFC. CONCLUSIONS Although we took into account several methodological problems which might have confounded previous rTMS mood induction studies, the hypothesis that one single session of HF-rTMS on the left or on the right DLPFC can influence mood in healthy female volunteers was not supported. SIGNIFICANCE One HF-rTMS session has no effect on subjective mood in healthy female volunteers.

A single session of rTMS over the left dorsolateral prefrontal cortex influences attentional control in depressed patients

Depressed patients are impaired in the ability to shift their focus of attention. This attentional control process is related to dysfunctions in the dorsolateral prefrontal cortex (DLPFC). It has been proposed that a dorsal circuit plays an important role in the interaction between emotional and attentional information processing. However, because the different emphasis of fundamental cognitive neuroscience research and clinical research of repetitive transcranial magnetic stimulation (rTMS) over the DLPFC, little research has been done on the effects of rTMS on cognitive functioning after a single stimulation session to explore the neural systems underlying depression. This study was conducted as a double-blind, placebo-controlled, crossover, within subjects design. Sixteen depressed patients performed a modified task switching paradigm, before and after receiving high frequency (HF) versus placebo rTMS over the left DLPFC. One session of HF- rTMS over the left DLPFC had a specific beneficial effect on task-switching performance, whereas mood remained stable. Antidepressant effects of rTMS could be related to the same neurochemical changes that underlie cognitive functioning. Therefore, task switching performance may provide a unique window into the extent of antidepressant effects which can be considered as second-order long-term effects possibly related to primary alternations in cognitive functioning.

Reduced left subgenual anterior cingulate cortical activity during withdrawal-related emotions in melancholic depressed female patients

BACKGROUND Research regarding the neurocircuitry in mood disorders suggests an important role for affective information processing of the subgenual part of the anterior cingulate cortex (Cg25: Brodmann area 25). OBJECTIVE In this study, we focused on Cg25 neuronal responses in depressed females using a paradigm in which emotions are elicited without explicit cognitive control, relying on the salient nature of the mood inducing stimuli eliciting approach-related emotions (like happiness) or withdrawal-related emotions (like disgust). METHODS Twelve treatment-resistant melancholic depressed women and 12 healthy female control subjects were asked to passively view blocks of emotionally valenced baby faces while undergoing functional magnetic resonance imaging (fMRI). RESULTS Compared to the healthy females, the depressed patients displayed significantly higher bilateral Cg25 neuronal activities in both emotional conditions. In melancholically depressed women, we found significantly less left-sided than right-sided Cg25 neuronal activity during the withdrawal-related emotions, while right-sided Cg25 activity was comparable for both emotional responses. CONCLUSIONS Our results indicate that in depressed women the left Cg25 modulates intense visceral emotional responses to aversive visual stimuli. This could help explain why the left Cg25 provides a valid target region for antidepressant treatment strategies in unipolar melancholic depression.