The Longitudinal Association of Reduced Vagal Tone With Burnout.

OBJECTIVE: Previous research indicates a link between burnout symptoms and reduced vagally mediated heart rate variability (HRV); however, the directionality of this relationship is still largely unknown. The objective of the present study was to examine the longitudinal relationship between HRV and burnout symptoms for 1 year, with a special focus on the emotional exhaustion (EE) burnout subdimension, which remains inadequately distinguished from overlapping with depressive symptoms. METHODS: Here we present HRV and behavioral data from 167 individuals (mean [SD] age = 43.43 [11.78] years; 30.5% male) who attended two biomarker samplings (T1 and T2) of the Dresden Burnout Study approximately 12 months apart. RESULTS: In hierarchical linear regression analyses, T1 HRV significantly inversely predicted T2 overall burnout symptoms (ß = -.16; p = .03) and EE (ß = -.23; p = .02), adjusting for age, sex, body mass index, adverse health behaviors, and depressive symptoms. Importantly, only high EE at T1 (ß = -.22; p = .04), and not the T1 Maslach Burnout Inventor total score, predicted reductions in HRV from T1 to T2. CONCLUSIONS: We report for the first time longitudinal evidence that HRV is associated with changes in burnout symptoms, independently of depressive symptoms. Results suggest vagal dysfunction being predictive and specific for burnout symptoms, making HRV a promising starting point for the explanation of biophysiological mechanisms underlying burnout symptoms and cardiovascular diseases. The finding of only EE at T1 being predictive for changes in HRV underscores the importance of exhaustion for modulations in autonomic regulation.

Handedness, dichotic-listening ear advantage, and gender effects on planum temporale asymmetry--a volumetric investigation using structural magnetic resonance imaging.

Previous research has often examined whether the asymmetrical structure of the planum temporale (PT) represents an anatomical correlate of lateralized language-processing functions, gathering diverging empirical evidence by comparing PT asymmetry in subjects with differing handedness, gender, or speech lateralization. Apart from other methodological problems, direct comparisons between studies are hampered by insufficient assessment and consideration of all three potential determinants of structural cerebral asymmetry. Based on volumetric assessment of structural Magnetic Resonance Imaging (MRI) scans of 104 healthy subjects, the present study replicated earlier observations of an overall leftward PT asymmetry, which was found to prevail irrespective of handedness, gender, or dichotic-listening ear advantage. However, the mean magnitude of this leftward asymmetry was not determined by either one of these factors in itself, but varied depending on their specific combination. A clear correspondence between structural and functional asymmetry was only observed among right-handed males. In this particular subgroup, more pronounced structural asymmetry was associated with an enlarged PT on the left side, while the enhanced leftward asymmetry of female sinistrals resulted from smaller adjusted volumes of their right PT. The existence of such complex interactions suggests that future research in this area can only be expected to overcome past inconsistencies by adequately considering handedness, gender, and speech lateralization.

The association of macro- and microstructure of the corpus callosum and language lateralisation.

The present study aimed to examine how differences in functional lateralisation of language are related to interindividual variations in interhemispheric connectivity. Utilising an fMRI silent word-generation paradigm, 89 left- and right-handed subjects were subdivided into four lateralisation subgroups. Applying morphological and diffusion-tensor MRI, midsagittal cross-sectional area as well as quantitative measures of molecular diffusion (anisotropy, mean diffusion) of the corpus callosum were determined to assess interhemispheric connectivity. Statistical analyses revealed group differences in molecular diffusion but not in callosal size, which may be interpreted to reflect a stronger and/or faster interhemispheric connection in strongly left-lateralised subjects as compared to moderately left-lateralised, bilateral, or moderately right-lateralised subjects.

Effects of handedness and gender on macro- and microstructure of the corpus callosum and its subregions: a combined high-resolution and diffusion-tensor MRI study.

The corpus callosum (CC) represents the major commissural tract connecting the two cerebral hemispheres and is supposed to play crucial integrative role in functional hemispheric specialization. The present study examined whether interindividual variations in macro- and microstructure of the human CC are associated with handedness and gender. Therefore, a combined diffusion-tensor (DTI) and high-resolution morphological MRI study was performed on 34 right- and 33 left-handed subjects of both sexes. The mid-sagittal surface areas and quantitative measures of molecular diffusion (relative anisotropy, mean diffusion) of the total CC and its subregions (genu, truncus, posterior third) were determined. Analysis revealed a larger total callosal area in right- as compared to left-handed subjects and in males as compared to females. Throughout all callosal subregions, anisotropy was found to be increased in left-handed as well as in male subjects, while the mean diffusion was diminished only in left-handers. For the posterior third of the CC, a significant negative correlation (r=-0.34) between anisotropy and area was detected in right-handed subjects. Summarized, significant alterations in the molecular diffusion and in the size of the CC with respect to gender and handedness were revealed in the present study. These findings can be interpreted as handedness- and gender-related differences in macro- and microstructure of the callosal pathways. It was demonstrated that the inspection of the callosal microstructure using DTI yields empirical evidence on interhemispheric connectivity that goes well beyond the information revealed by anatomical measurements alone. Thus, DTI has proven to be a useful additional method in cognitive neuroscience.

The influence of handedness and gender on the microstructure of the human corpus callosum: a diffusion-tensor magnetic resonance imaging study.

The aim of the present study was to examine whether handedness and gender are associated with microstructural differences in human corpus callosum (CC). For this purpose, diffusion-tensor magnetic resonance imaging (DTI) was performed on 34 right- and 33 left-handed subjects of both sexes. Four quantitative variables (Mean Diffusion, Relative Anisotropy, parallel and orthogonal diffusion) were computed within the CC. A significantly increased anisotropy was found in left- as compared to right-handed subjects, and in men as compared to women. Additionally, both overall and orthogonal diffusion were significantly lower in left- than in right-handed subjects. Possible interpretations of these findings are discussed. The novel DTI technique promises to further advance current understanding of morphological structure in the living brain.