Genetic Studies in Normal Population

Impact of the BDNF Val66Met Polymorphism on Regional Brain Gray Matter Volumes: Relevance to the Stress Response

Genetic imaging is used to investigate the mechanism by which genetic variants influence brain structure. This study examined the effect of a polymorphism in the brain-derived neurotrophic factor (BDNF) gene on regional gray matter (GM) volumes and the correlations between the dorsolateral prefrontal (DLPFC) volume and the stress level. The Val/Val homozygotes had larger volumes in the prefrontal cortex and other brain regions than Met carriers. The Met homozygotes demonstrated a higher stress response in depression domain. In addition, the middle frontal cortex volume was negatively correlated with SRI depression. The results suggest that differences in DLPFC volume related to the BDNF Val66Met SNP are associated with resilience to stressful life events, particularly in the emotion domain.

GM volume differences in relation to the BDNF SNP.

 

Differences in depression scores according to BDNF SNP genotypes.

 

Relationship between SRI depression score and the brain GM volume of the left middle frontal gyrus.

Kim et al., 2013, Psychiat Investig

 


The impact of genetic variation in comt and bdnf on resting-state functional connectivity

This study examined the role of catechol-O-methyl transferase (COMT) and brain-derived neurotrophic factor (BDNF) polymorphisms on functional connectivity (FC) between brain areas. The Val/Val homozygote group of the COMT showed greater DMN connectivity in the medial and superior frontal gyri and cerebellum compared with the Met allele carriers. For the BDNF, the FC between the PCC and precuneus was stronger in the Val/Val homozygote group than in the Met allele carriers. These findings suggest interaction between genes and FC in the rain and indicate that altered FC may be an endophenotype of cognitive vulnerability.

Brain areas of increased DNM connectivity in the Val/Val groups of A) the COMT SNP and B) the BDNF SNP than in the Met allele carriers of each SNP.

Jang et al., 2012, Method Adv in Neuroimaging

 


Influence of brain-derived neurotrophic factor and catechol O-methyl transferase polymorphisms on effects of meditation on plasma catecholamines and stress

Meditation may show differential effects on stress and plasma catecholamines based on genetic polymorphisms in brain-derived neurotrophic factor (BDNF) and catechol O-methyl transferase (COMT). We found an interaction between groups and BDNF Val66Met polymorphism on DA/NE+DA/E and NE/E+NE/DA ratios. Also, an interaction between group and COMT Val158Met polymorphism and plasma NE concentrations. Meditation group was higher in plasma NE concentrations for COMT Met carriers. Significant differences of stress levels were found between groups in BDNF Val/Met and BDNF Met/Met, whereas stress levels in the BDNF Val/Val genotype did not differ between groups.

Different effects of meditation on plasma catecholamine concentrations according to BDNF and COMT genotypes.

Jung et al., 2011, Stress

 


 

Electrophysiology Studies in Normal Population

Generators of the gamma-band activities in response to rare and novel stimuli during the auditory oddball paradigm

In this study, we report the cortical sources of the gamma-band activity emitted during the auditory oddball paradigm using the adaptive beamformer algorithm and non-parametric permutation test and then compare them with those of the P3a and P3b components. The results of the gamma-band current sources revealed that the same gamma-band activities are in process during the rare target and novelty task. On the other hand, the P3a and P3b generators showed widespread distributions including the well-known fronto-parietal network.

Grand-average ERP waveforms at Fz, Cz and Pz in each condition.

 

Scalp topographical and cortical current source maps for potential differences of grand-average ERPs.
a) maximal distribution of P3a in fronto-central area and the corresponding cortical generators in anterior cingulate and superior frontal gyrus; b) maximal distribution of P3b in centro-parietal area and the corresponding cortical generators in precuneus/cingulate gyrus and superior frontal gyrus.

Lee et al., 2007, Neurosci Letters

 


Activity of left inferior frontal gyrus related to word repetition effects: LORETA imaging with 128-channel EEG and individual MRI

We investigated the brain substrate of word repetition effects on the implicit memory task using low-resolution electromagnetic tomography (LORETA). The subjects exhibited word repetition effects with respect to the behavioral data, in which a faster reaction time was observed to the repeated word (old word) than to the first presentation of the word (new word). We found that the source elicited by the old words exhibited a reduced current density in the left inferior frontal gyrus.

Statistical parametric map of ERP generator elicited by old (a) and new words (b) at the latency of 400 ms.

 

Statistical parametric maps displaying decreased current density by word repetition effects at 400 ms post-stimulus.

Kim et al., 2006, Neuroimage