Transcranial Stimulation of Alpha Oscillations Up-Regulates the Default Mode Network

The default mode network (DMN) is the most-prominent intrinsic connectivity network, serving as a key architecture of the brain\u27s functional organization. Conversely, dysregulated DMN is characteristic of major neuropsychiatric disorders. However, the field still lacks mechanistic insights into the regulation of the DMN and effective interventions for DMN dysregulation. The current study approached this problem by manipulating neural synchrony, particularly alpha (8 to 12 Hz) oscillations, a dominant intrinsic oscillatory activity that has been increasingly associated with the DMN in both function and physiology. Using high-definition alpha-frequency transcranial alternating current stimulation (α-tACS) to stimulate the cortical source of alpha oscillations, in combination with simultaneous electroencephalography and functional MRI (EEG-fMRI), we demonstrated that α-tACS (versus Sham control) not only augmented EEG alpha oscillations but also strengthened fMRI and (source-level) alpha connectivity within the core of the DMN. Importantly, increase in alpha oscillations mediated the DMN connectivity enhancement. These findings thus identify a mechanistic link between alpha oscillations and DMN functioning. That transcranial alpha modulation can up-regulate the DMN further highlights an effective noninvasive intervention to normalize DMN functioning in various disorders

Distributed under Creative Commons CC-BY 4.0 The relationship between cannabis use and measures of anxiety and depression in a sample of college campus cannabis users and non-users post state legalization in Colorado

ABSTRACT As part of an ongoing research program into the relationship between cannabis use and emotion processing, participants were assessed on their level of cannabis exposure using the Recreational Cannabis Use Examination, a measure developed specifically to assess cannabis use in Colorado post state legalization. Three groups were created based on self-reported use: a control group who have never used, a casual user group and a chronic user group. Each participant also completed two measures of mood assessment, the Center for Epidemiologic Studies Depression Scale and the State-Trait Anxiety Inventory. Relationships between cannabis use groups and scores on these measures were then analyzed using both correlations and multivariate analysis of variance. Results indicate a relationship between casual cannabis use and scoring highly for depressive symptomatology on the Center for Epidemiologic Studies Depression Scale. There were no significant relationships between cannabis use and scores on the State-Trait Anxiety Inventory. Subjects Psychiatry and Psychology, Public Healt

The relationship between cannabis use and measures of anxiety and depression in a sample of college campus cannabis users and non-users post state legalization in Colorado

As part of an ongoing research program into the relationship between cannabis use and emotion processing, participants were assessed on their level of cannabis exposure using the Recreational Cannabis Use Examination, a measure developed specifically to assess cannabis use in Colorado post state legalization. Three groups were created based on self-reported use: a control group who have never used, a casual user group and a chronic user group. Each participant also completed two measures of mood assessment, the Center for Epidemiologic Studies Depression Scale and the State-Trait Anxiety Inventory. Relationships between cannabis use groups and scores on these measures were then analyzed using both correlations and multivariate analysis of variance. Results indicate a relationship between casual cannabis use and scoring highly for depressive symptomatology on the Center for Epidemiologic Studies Depression Scale. There were no significant relationships between cannabis use and scores on the State-Trait Anxiety Inventory

An Event-Related Potential Study on the Effects of Cannabis on Emotion Processing.

The effect of cannabis on emotional processing was investigated using event-related potential paradigms (ERPs). ERPs associated with emotional processing of cannabis users, and non-using controls, were recorded and compared during an implicit and explicit emotional expression recognition and empathy task. Comparisons in P3 component mean amplitudes were made between cannabis users and controls. Results showed a significant decrease in the P3 amplitude in cannabis users compared to controls. Specifically, cannabis users showed reduced P3 amplitudes for implicit compared to explicit processing over centro-parietal sites which reversed, and was enhanced, at fronto-central sites. Cannabis users also showed a decreased P3 to happy faces, with an increase to angry faces, compared to controls. These effects appear to increase with those participants that self-reported the highest levels of cannabis consumption. Those cannabis users with the greatest consumption rates showed the largest P3 deficits for explicit processing and negative emotions. These data suggest that there is a complex relationship between cannabis consumption and emotion processing that appears to be modulated by attention

Neuroplastic changes in anterior cingulate cortex gray matter volume and functional connectivity following attention bias modification in high trait anxious individuals

Attention bias modification (ABM) was developed to alleviate anxious symptoms by way of a reduction in anxiety-linked attentional bias to threat. Central to the rational of ABM is a learning-related reconfiguration of attentional biases. Yet, the neuroplastic changes in brain structure that underlie this learning are unresolved. The amygdala, anterior cingulate cortex, and lateral prefrontal cortex are part of a system linked to attentional bias to threat and its modification with ABM. We assessed the extent to which ABM modulates gray matter volume and resting-state functional connectivity. Sixty-one individuals selected for attentional bias to threat and heightened trait anxiety completed a 6-week multi-session ABM protocol with 7200 total training trials. Participants were assigned to either an ABM (n = 30) or a control (n = 31) condition. We found that participants' levels of attentional bias and anxiety did not differ following ABM and control training interventions. However, the ABM group displayed greater levels of anterior cingulate cortex gray matter volume as well as greater superior frontal gyrus resting-state functional connectivity with the anterior cingulate cortex and insula. Changes in anterior cingulate cortex gray matter volume were linked to reduced anxious symptoms in the ABM, but not control, group. These findings suggest that ABM distinctively impacts structural and functional neural mechanisms associated with emotion reactivity and cognitive control processes

Mean Reaction Times and Response Scores for Emotion Processing Tasks.

<p>Effect Sizes for Group Differences are also shown.</p

Statistical Analysis of P3 Mean Amplitudes across Electrode Sites.

<p>Statistical Analysis of P3 Mean Amplitudes across Electrode Sites.</p

Grand average ERPs for controls and users collapsed over task and emotion for analyzed electrodes.

<p>Significant group differences at α = .05 with Bonferroni correction for planned multiple comparisons are signaled in black.</p