Maximilian Bruchmann

High-Normal Blood Pressure Is Associated With Poor Cognitive Performance

While the relation between systolic blood pressure (SBP) and vascular events is linear down to the high-normal range, the relation between SBP and cognition is less clear. We cross-sectionally assessed the relation between SBP and cognition in a cohort extending from mid- to late-life. From a total of 2200 community-dwelling individuals we recruited 377 aged 44 to 82 years (median: 64 years, 171 male) in the SEARCH-Health study (Systematic evaluation and alteration of risk factors for cognitive health). Participants were studied with a comprehensive neuropsychological test battery that provided, based on principal component analysis, 5 composite scores for cognition (learning and memory, attention and executive function, spatial skills, working memory, and verbal skills). Global cognition was calculated from the sum of the composite scores. SBP (corrected R2=0.007), education (corrected R2=0.203), age (corrected R2=0.102), and gender (corrected R2=0.011) explained one third of variance in global cognitive performance (P<0.001) on multivariate analyses. Moreover, the relation between SBP (based on 10 mm Hg-categories from <120 mm Hg to >170 mm Hg) and global cognitive performance was linear in this range of SBP-values, ie, even in the normotensive range (β=−0.110, P<0.05). Subgroup analysis showed that the association of SBP and cognition was driven by results in midlife (<60 years) individuals (β=−0.291, P<0.005). Thus, even in the normotensive range increasing systolic blood pressure is inversely related to cognition.

Individualized EEG source reconstruction of Stroop interference with masked color words.

A masked version of the classic color Stroop task was used to study interference effects with stimuli of variable visibility. Pattern masks with different stimulus onset asynchronies (SOAs) reduced the visibility in three steps. We took EEG recordings to measure neural correlates of Stroop interference and their relation to stimulus visibility. The analysis of event-related potentials indicated that N400 differences between congruent and incongruent trials varied with the degree of visibility, leaving no differences with stimuli near identification threshold. An equivalent current dipole model (ECD) was used to map source activity onto regions known to reflect interference-related activity. As expected, the anterior cingulate cortex (ACC) signaled the biggest differences between congruent and incongruent trials. As with event-related potentials, these differences disappeared with reduced stimulus visibility. In addition to equivalent current dipole modeling, Stroop-related neural sources were confirmed by means of current density reconstruction (SWARM) based on individualized boundary element models (BEMs) and a cortical constraint.

Variations in midcingulate morphology are related to ERP indices of cognitive control.

The midcingulate cortex (MCC; often somewhat imprecisely referred to as dorsal or cognitive part of the anterior cingulate cortex or dACC) is a core region contributing to cognitive control. Neuroanatomical deviations in the midcingulate region have been observed in a variety of mental disorders. Even in healthy subjects a high degree of morphological variability is seen, for example concerning the degree of anterior midcingulate fissurization. To investigate the relationship between anterior midcingulate morphology and function, individuals with a leftward midcingulate folding asymmetry (LEFT) were compared to individuals showing a lower degree of fissurization or a rightward asymmetric folding (REST). Data from two experiments, a masked Stroop paradigm and a combined go/no-go and stop-signal task, are reported. With the masked Stroop task, LEFT subjects revealed a better processing of incongruent Stroop stimuli when compared to REST subjects. This was reflected in both augmented N400 responses as well as significantly higher accuracy scores. In addition, similar effects were found with event-related potentials from the combined go/no-go and stop-signal task. Here, the N200 but not the P300, which have been associated with conflict-related and evaluative processing stages, respectively, was found to be significantly increased with LEFT subjects. The results of this study foster an association of midcingulate fissurization with differences in behavior and neurophysiological functioning related to cognitive control.

Metacontrast masking within and between visual channels: effects of orientation and spatial frequency contrasts.

We measured the strength and optimal target-mask onset asynchrony (SOA(max)) of metacontrast masking using Gabor patches as targets and sinusoidal rings with Gaussian envelopes as masks. We varied spatial frequencies (f) between 0.5 and 8 cpd to manipulate the degree to which spatial frequency channels in the visual system are triggered. By varying spatial frequencies as well as spatial frequency contrast (Δf) between target and mask, we measured the properties of inter- as well as intra-channel inhibition. We found that an increase of the masks spatial frequency decreased its effectiveness but did not change its SOA(max). When orientation contrast was introduced between targets and masks with the same spatial frequency, SOA(max) increased with orientation contrast. An effect of orientation contrast was not observed with low spatial frequency-on-high spatial frequency masking, indicating that orientation selectivity is a unique feature of within-channel masking. Spatial frequency contrast affects SOA(max) and effectiveness in an asymmetric fashion: low-on-high masking is strong and yields a longer SOA(max), compared to low-on-low and high-on-high masking; high-on-low masking is ineffective.

Playing and Listening to Tailor-Made Notched Music: Cortical Plasticity Induced by Unimodal and Multimodal Training in Tinnitus Patients

Background. The generation and maintenance of tinnitus are assumed to be based on maladaptive functional cortical reorganization. Listening to modified music, which contains no energy in the range of the individual tinnitus frequency, can inhibit the corresponding neuronal activity in the auditory cortex. Music making has been shown to be a powerful stimulator for brain plasticity, inducing changes in multiple sensory systems. Using magnetoencephalographic (MEG) and behavioral measurements we evaluated the cortical plasticity effects of two months of (a) active listening to (unisensory) versus (b) learning to play (multisensory) tailor-made notched music in nonmusician tinnitus patients. Taking into account the fact that uni- and multisensory trainings induce different patterns of cortical plasticity we hypothesized that these two protocols will have different affects. Results. Only the active listening (unisensory) group showed significant reduction of tinnitus related activity of the middle temporal cortex and an increase in the activity of a tinnitus-coping related posterior parietal area. Conclusions. These findings indicate that active listening to tailor-made notched music induces greater neuroplastic changes in the maladaptively reorganized cortical network of tinnitus patients while additional integration of other sensory modalities during training reduces these neuroplastic effects.

Transdiagnostic brain responses to disorder-related threat across four psychiatric disorders.

BACKGROUND There is an ongoing debate whether transdiagnostic neural mechanisms are shared by different anxiety-related disorders or whether different disorders show distinct neural correlates. To investigate this issue, studies controlling for design and stimuli across multiple anxiety-related disorders are needed. METHOD The present functional magnetic resonance imaging study investigated neural correlates of visual disorder-related threat processing across unmedicated patients suffering from panic disorder (n = 20), social anxiety disorder (n = 20), dental phobia (n = 16) and post-traumatic stress disorder (n = 11) relative to healthy controls (HC; n = 67). Each patient group and the corresponding HC group saw a tailor-made picture set with 50 disorder-related and 50 neutral scenes. RESULTS Across all patients, increased activation to disorder-related v. neutral scenes was found in subregions of the bilateral amygdala. In addition, activation of the lateral amygdala to disorder-related v. neutral scenes correlated positively with subjective anxiety ratings of scenes across patients. Furthermore, whole-brain analysis revealed increased responses to disorder-related threat across the four disorders in middle, medial and superior frontal regions, (para-)limbic regions, such as the insula and thalamus, as well as in the brainstem and occipital lobe. We found no disorder-specific brain responses. CONCLUSIONS The results suggest that pathologically heightened lateral amygdala activation is linked to experienced anxiety across anxiety disorders and trauma- and stressor-related disorders. Furthermore, the transdiagnostically shared activation network points to a common neural basis of abnormal responses to disorder-related threat stimuli across the four investigated disorders.

Effects of emotional intensity under perceptual load: An event-related potentials (ERPs) study

Effects of emotional intensity and valence on visual event-related potentials (ERPs) are still poorly understood, in particular in the context of limited attentional resources. In the present EEG study, we investigated the effect of emotional intensity of different emotional facial expressions on P1, N170, early posterior negativity (EPN) and late positive potential (LPP) while varying the amount of available attentional resources. A new stimulus set comprising 90 full color pictures of neutral, happy (low, high intensity), and angry (low, high intensity) expressions was developed. These facial expressions were presented centrally, superimposed by two horizontal bars, and participants engaged in a focal bars task. Availability of attentional resources was varied in two conditions by manipulating the difficulty of the focal bars task (low vs. high perceptual load). Our findings demonstrate intensity and valence effects of task-irrelevant facial expressions on early (N170) and intermediate processing stages (EPN). In addition, task-related effects of perceptual load evolved at intermediate processing stages and were full blown in the time window of LPP. In line with limited resource accounts, valence effects on N170 and EPN were reduced under high perceptual load. Interestingly, apart from this valence by load interaction no further interactions between stimulus and task-driven factors were obtained: Effects of emotional intensity were not modulated by the perceptual load of the focal bars task, indicating that emotional intensity was processed even though attentional resources were heavily restricted.

The effects of spatial and temporal cueing on metacontrast masking.

We studied the effects of selective attention on metacontrast masking with 3 different cueing experiments. Experiments 1 and 2 compared central symbolic and peripheral spatial cues. For symbolic cues, we observed small attentional costs, that is, reduced visibility when the target appeared at an unexpected location, and attentional costs as well as benefits for peripheral cues. All these effects occurred exclusively at the late, ascending branch of the U-shaped metacontrast masking function, although the possibility exists that cueing effects at the early branch were obscured by a ceiling effect due to almost perfect visibility at short stimulus onset asynchronies (SOAs). In Experiment 3, we presented temporal cues that indicated when the target was likely to appear, not where. Here, we also observed cueing effects in the form of higher visibility when the target appeared at the expected point in time compared to when it appeared too early. However, these effects were not restricted to the late branch of the masking function, but enhanced visibility over the complete range of the masking function. Given these results we discuss a common effect for different types of spatial selective attention on metacontrast masking involving neural subsystems that are different from those involved in temporal attention.

Brain responses to disorder-related visual threat in panic disorder

Panic disorder (PD) patients show aberrant neural responses to threatening stimuli in an extended fear network, but results are only partially comparable, and studies implementing disorder‐related visual scenes are lacking as stimuli. The neural responses and functional connectivity to a newly developed set of disorder‐related, ecologically valid scenes as compared with matched neutral visual scenes, using event‐related functional magnetic resonance imaging (fMRI) in 26 PD patients and 26 healthy controls (HC) were investigated. PD patients versus HC showed hyperactivation in an extended fear network comprising brainstem, insula, thalamus, anterior, and mid‐cingulate cortex and (dorso‐)medial prefrontal cortex for disorder‐related versus neutral scenes. Amygdala differences between groups failed significance. Subjective levels of anxiety significantly correlated with brainstem activation in PD patients. Analysis of functional connectivity by means of beta series correlation revealed no emotion‐specific alterations in connectivity in PD patients versus HC. The results suggest that subjective anxiety evoked by external stimuli is directly related to altered activation in the homeostatic alarm system in PD. With novel disorder‐related stimuli, the study sheds new light on the neural underpinnings of pathological threat processing in PD. Hum Brain Mapp 37:4439–4453, 2016.

Activity alterations in the bed nucleus of the stria terminalis and amygdala during threat anticipation in generalized anxiety disorder

Abstract Sustained anticipatory anxiety is central to Generalized Anxiety Disorder (GAD). During anticipatory anxiety, phasic threat responding appears to be mediated by the amygdala, while sustained threat responding seems related to the bed nucleus of the stria terminalis (BNST). Although sustained anticipatory anxiety in GAD patients was proposed to be associated with BNST activity alterations, firm evidence is lacking. We aimed to explore temporal characteristics of BNST and amygdala activity during threat anticipation in GAD patients. Nineteen GAD patients and nineteen healthy controls (HC) underwent functional magnetic resonance imaging (fMRI) during a temporally unpredictable threat anticipation paradigm. We defined phasic and a systematic variation of sustained response models for blood oxygen level-dependent responses during threat anticipation, to disentangle temporally dissociable involvement of the BNST and the amygdala. GAD patients relative to HC responded with increased phasic amygdala activity to onset of threat anticipation and with elevated sustained BNST activity that was delayed relative to the onset of threat anticipation. Both the amygdala and the BNST displayed altered responses during threat anticipation in GAD patients, albeit with different time courses. The results for the BNST activation hint towards its role in sustained threat responding, and contribute to a deeper understanding of pathological sustained anticipatory anxiety in GAD.