Altered amygdalar resting‐state connectivity in depression is explained by both genes and environment

Abstract

Recent findings indicate that alterations of the amygdalar resting-state fMRI connectivity play an important role in the etiology of depression. While both depression and resting-state brain activity are shaped by genes and environment, the relative contribution of genetic and environmental factors mediating the relationship between amygdalar resting-state connectivity and depression remain largely unexplored. Likewise, novel neuroimaging research indicates that different mathematical representations of resting-state fMRI activity patterns are able to embed distinct information relevant to brain health and disease. The present study analyzed the influence of genes and environment on amygdalar resting-state fMRI connectivity, in relation to depression risk. High-resolution resting-state fMRI scans were analyzed to estimate functional connectivity patterns in a sample of 48 twins (24 monozygotic pairs) informative for depressive psychopathology (6 concordant, 8 discordant and 10 healthy control pairs). A graph-theoretical framework was employed to construct brain networks using two methods: (i) the conventional approach of filtered BOLD fMRI time-series and (ii) analytic components of this fMRI activity. Results using both methods indicate that depression risk is increased by environmental factors altering amygdalar connectivity. When analyzing the analytic components of the BOLD fMRI time-series, genetic factors altering the amygdala neural activity at rest show an important contribution to depression risk. Overall, these findings show that both genes and environment modify different patterns the amygdala resting-state connectivity to increase depression risk. The genetic relationship between amygdalar connectivity and depression may be better elicited by examining analytic components of the brain resting-state BOLD fMRI signals.

Cognitive and neuroimaging changes in healthy immigrants upon relocation to a high altitude: A panel study

“…The voxel-based comparison of ReHo was conducted in REST V 2.0 (http://restfmri.net/forum/REST_V2.0) [Cordova-Palomera et al, 2015;Song et al, 2011;Yan et al, 2016]. The computation of ReHo at rest was spatially smoothed with a 4 mm 3 4 mm 3 4 mm FWHM Gaussian kernel, as previously described.…”

Environmental factors linked to depression vulnerability are associated with altered cerebellar resting-state synchronization

“…While this method has certainly led to remarkable clinical and neurobiological findings21, new reports highlight that the neural synchronization patterns observed through neuroimaging can occur at different levels, and that each of these levels may have different behavioral significance2627. The potential relevance of the different neural coupling levels observed in resting-state fMRI brain scans has been underscored during recent years, since i ) they allow increasing temporal resolution of hemodynamic (fMRI) signals28, ii ) they may explain an important extent of the relationship between brain structure and function29 and iii ) they could partly explain brain deficits in psychopathology30. A previous report on cerebral resting-state activity by our group30 described amygdalar deficits in twins with depression liability, highlighting the role of alternative neural coupling mechanisms not only to explain cerebral alterations, but also to elicit their genetic and environmental origins.…”

“…The potential relevance of the different neural coupling levels observed in resting-state fMRI brain scans has been underscored during recent years, since i ) they allow increasing temporal resolution of hemodynamic (fMRI) signals28, ii ) they may explain an important extent of the relationship between brain structure and function29 and iii ) they could partly explain brain deficits in psychopathology30. A previous report on cerebral resting-state activity by our group30 described amygdalar deficits in twins with depression liability, highlighting the role of alternative neural coupling mechanisms not only to explain cerebral alterations, but also to elicit their genetic and environmental origins. In biological terms, these observations on synchronization phenomena observed in fMRI signals would parallel the compelling evidence showing that higher-order brain function may be closely related to neural communication established from coherent oscillatory activity of brain regions at specific frequencies3132.…”

“…As co-twins of a MZ pair have almost identical DNA sequences, their phenotypic similarities and differences were investigated to gain insights on putative familial and environmental influences. Following conventions from classical quantitative genetic analysis, intrapair brain differences in genetically identical individuals (MZ twins) are considered a measure of environmental factors influencing that neural phenotype1330. Since the cerebellar fMRI signal constitutes a well-defined resting-state network33, and considering that intra-cerebellar resting-state connectivity may be especially relevant in neuropsychiatry34, an anatomically-restricted 26-node network comprising different subdivisions of the cerebellum was examined.…”

Neuron loss and dysfunctionality in hippocampus explain aircraft noise induced working memory impairment: a resting-state fMRI study on military pilots

“…For standardization purposes, each individual ReHo map was divided by that subject's global mean brain KCC value to minimize inter-individual variability for statistical analysis within the whole-brain mask. Results are shown at p < 0.05 using AlphaSim correction (with a combination of a threshold of p < 0.01 and a mini-mum cluster size of 65 voxels) (18,19).…”