Altered directed functional connectivity of the right amygdala in depression: high-density EEG study

Abstract

the cortico-striatal-pallidal-thalamic and limbic circuits are suggested to play a crucial role in the pathophysiology of depression. Stimulation of deep brain targets might improve symptoms in treatment-resistant depression. However, a better understanding of connectivity properties of deep brain structures potentially implicated in deep brain stimulation (DBS) treatment is needed. Using highdensity EEG, we explored the directed functional connectivity at rest in 25 healthy subjects and 26 patients with moderate to severe depression within the bipolar affective disorder, depressive episode, and recurrent depressive disorder. We computed the Partial Directed Coherence on the source EEG signals focusing on the amygdala, anterior cingulate, putamen, pallidum, caudate, and thalamus. The global efficiency for the whole brain and the local efficiency, clustering coefficient, outflow, and strength for the selected structures were calculated. In the right amygdala, all the network metrics were significantly higher (p < 0.001) in patients than in controls. The global efficiency was significantly higher (p < 0.05) in patients than in controls, showed no correlation with status of depression, but decreased with increasing medication intake (-=. =. R 0 59 and p 1 52e 05 2). the amygdala seems to play an important role in neurobiology of depression. Practical treatment studies would be necessary to assess the amygdala as a potential future DBS target for treating depression. Affective disorders belong to the most common and most serious psychiatric disorders 1. A crucial role of the cortico-striatal-pallidal-thalamic and limbic circuits in the neurobiology of depression was repeatedly reported 2-4. Magnetic resonance imaging, functional magnetic resonance imaging (fMRI), magnetoencephalographic, and electroencephalographic (EEG) studies have confirmed that depressive patients show structural impairments and functional dysbalances of brain networks that involve structures engaged in (a) emotions, i.e. amygdala, subgenual anterior cingulate, caudate, putamen and pallidum 3,5-12 ; (b) self-referential processes, i.e. medial prefrontal cortex, precuneus, and posterior cingulate cortex 13,14 ; (c) memory, i.e. hippocampus, parahippocampal cortex 15 ; (d) visual processing, i.e. fusiform gyrus, lingual gyrus, and lateral temporal cortex 16 ; and (e) attention, i.e. dorsolateral prefrontal cortex, anterior cingulate cortex (ACC), thalamus, and insula 10-12,17. Moreover, post-mortem morphometric measurements revealed smaller volumes of the hypothalamus, pallidum, putamen and thalamus in patients with affective disorders 18. Many depressive patients fail to respond to pharmacological therapy resulting in 1-3% prevalence of treatment-resistant depression (TRD) 19. One of the newest therapeutic approaches for TRD is an invasive direct electrical stimulation of relevant deep brain structures 20. Both unipolar and bipolar depression patients might benefit from deep brain stimulation (DBS) treatment 21 , although an optimal approach, incl...

Investigating the spectral features of the brain meso‐scale structure at rest

“…Therefore, the meso-scale structure might be inferred starting from others FC methods, such as phase synchronization (Zhigalov et al, 2017). As an alternative to FC, WSBM works also with directed graph, which can be estimated with hdEEG trough effective connectivity measures (Damborská et al, 2020). Finally, a new method which combines information of FC with structural connectivity from MRI (Glomb et al, 2019a) is promising to increase the quality of the hdEEG source-reconstructed signals and it has been validated using the Louvain (Blondel, Guillaume, Lambiotte, & Lefebvre, 2008) algorithm which is nevertheless limited to detect assortative community motif.…”

“…To reach this goal, we exploited high-density electroencephalography (hdEEG). Notably, hdEEG provides a unique opportunity to capture the richness of neuronal oscillations' spectral content (Siegel, Donner, & Engel, 2012), and it was recently employed to reconstruct and unravel novel features of human brain activity during resting state in health (Liu, Farahibozorg, Porcaro, Wenderoth, & Mantini, 2017;Samogin et al, 2019;Seeber et al, 2019) and disease (Cassani, Estarellas, San-Martin, Fraga, & Falk, 2018;Coito et al, 2016;Damborská et al, 2020;Waninger et al, 2020). By coupling hdEEG recordings with appropriately built head model conductors and with source reconstruction algorithms, it is possible to achieve neural sources reconstruction with relatively good (i.e., in the order of less than 1 cm) spatial resolution (He, Sohrabpour, Brown, & Liu, 2018;Seeber et al, 2019).…”

Deep Brain Stimulation of the Habenula: Systematic Review of the Literature and Clinical Trial Registries

“…the hypothalamus, brainstem nuclei, basal ganglia and limbic areas-the stria medullaris being the main afferent and the fasciculus retroflexus the main efferent fiber bundle (Figure 1B; Table 1) (17)(18)(19)(25)(26)(27)(28). Studies in humans using imaging and electrophysiological techniques have shown multiple additional cortical and cerebellar regions to be functionally connected to the habenula (Figure 1B; Table 1) (20,(22)(23)(24)28). It plays a key role in controlling the dopaminergic, serotonergic and noradrenergic systems (25,27,(29)(30)(31)(32).…”

Reduced Effective Connectivity in the Motor Cortex in Parkinson’s Disease

“…A network perspective may provide an intervention target on defective nodes: neurostimulation techniques, whether invasive or non-invasive, may restore cortico-cortical interactions [ 5 , 6 , 7 ]. Abnormalities in oscillatory activity reflect alterations in connectivity in the cortico-striato-thalamo-cortical circuit [ 8 ].…”