Magnetic induction tomography (MIT) is a contactless method for mapping the electrical conductivity of tissue. MIT is based on the perturbation of an alternating magnetic field by a conducting object. The perturbation is detected by a voltage change in a receivercoil. At physiologically interesting frequencies (10 kHz-10 MHz) and conductivities (< 2 S m(-1)) the lower limit for the relative voltage change (signal/carrier ratio = SCR) to be resolved is 10(-7)-10(-10). A new MIT hardware has been developed consisting of a coil system with planar gradiometers and a high-resolution phase detector (PD). The gradiometer together with the PD resolves an SCR of 2.5 x 10(-5) (SNR = 20 dB at 150 kHz, acquisition speed: 100 ms). The system operates between 20 and 370 kHz with the possibility of extending the range up to 1 MHz. The feasibility of measuring conductivity spectra in the beta-dispersion range of biological tissues is experimentally demonstrated. An improvement of the resolution towards SCR = 10(-7) with an SNR of > or = 20 dB at frequencies > 100 kHz is possible. On-line spectroscopy of tissue conductivity with low spatial resolution appears feasible, thus enabling applications such as non-invasive monitoring of brain oedema.

The objective of this study was to investigate the synchronization between low-frequency breathing patterns and respiratory sinus arrhythmia (RSA) of heart rate during guided recitation of poetry, i.e., recitation of hexameter verse from ancient Greek literature performed in a therapeutic setting. Twenty healthy volunteers performed three different types of exercises with respect to a cross-sectional comparison: 1 ) recitation of hexameter verse, 2 ) controlled breathing, and 3 ) spontaneous breathing. Each exercise was divided into three successive measurements: a 15-min baseline measurement (S1), 20 min of exercise, and a 15-min effect measurement (S2). Breathing patterns and RSA were derived from respiratory traces and electrocardiograms, respectively, which were recorded simultaneously using an ambulatory device. The synchronization was then quantified by the index γ , which has been adopted from the analysis of weakly coupled chaotic oscillators. During recitation of hexameter verse, γ was high, indicating prominent cardiorespiratory synchronization. The controlled breathing exercise showed cardiorespiratory synchronization to a lesser extent and all resting periods (S1 and S2) had even fewer cardiorespiratory synchronization. During spontaneous breathing, cardiorespiratory synchronization was minimal and hardly observable. The results were largely determined by the extent of a low-frequency component in the breathing oscillations that emerged from the design of hexameter recitation. In conclusion, recitation of hexameter verse exerts a strong influence on RSA by a prominent low-frequency component in the breathing pattern, generating a strong cardiorespiratory synchronization.

We investigated the effect of postural changes on various cardiovascular parameters across gender. Twenty-eight healthy subjects (16 male, 12 female) were observed at rest (supine) and subjected to 3 interventions; head-down tilt (HDT), HDT with lower body negative pressure (HDT+ LBNP at -30 mm Hg), and head-up tilt (HUT), each for 10 minutes separated by a 10 minutes recovery period. Measurements were recorded for heart rate (HR), standard deviation of the normal-to-normal intervals, root mean square of successive differences between the normal-to-normal intervals, heart rate variability-low frequency (LFRRI), heart rate variability-high frequency (HFRRI), low frequency/high frequency ratio (LFRRI/HFRRI), systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP), total peripheral resistance index (TPRI), stroke index (SI), cardiac index (CI), index of contractility (IC), left ventricular work index, and left ventricular ejection time. Across all cardiovascular parameters, there was a significant main effect of the intervention applied but there was no significant main effect of gender across all parameters. The results suggest that there are no specific gender differences in regards to the measured variables under the conditions of this study. Furthermore, these results suggest that in healthy subjects, there appears to be evidence that LBNP partially elicits similar cardiovascular responses to HUT, which supports the use of LBNP as an intervention to counteract the effects of central hypovolemia.

Encouraging patients to use cognitive reappraisal constitutes the core of modern psychotherapeutic approaches. However, evidence for specific neural correlates of the capacity for cognitive reappraisal, which is a necessary prerequisite for the effective implementation of cognitive reappraisal in everyday life, has been sparse to date. In the present study, the capacity for cognitive reappraisal was studied in terms of the participants’ inventiveness in generating alternative appraisals of anger-evoking events, and was correlated with frontal EEG alpha asymmetry recorded while the participants were generating reappraisals as well as during a common creative idea generation task. During cognitive reappraisal efforts, individuals higher on the capacity for generating cognitive reappraisals showed more left-lateralized activity in lateral prefrontal cortex, specifically in ventrolateral prefrontal cortex extending toward the frontal pole. This effect was observed independently from the activation during novel idea generation without emotional component, indicating that specific demands are implicated in the generation of reappraisals of emotional events. Taken together, the results indicate that individuals higher on the capacity for cognitive reappraisal are more capable or more prone to recruit appropriate brain regions when the situation demands coming up with alternative appraisals of stressful events. The findings may stimulate the development of more individually targeted interventions.