NeuroImage
-
The purpose of this paper is to extend the single-subject Eve atlas from Johns Hopkins University, which currently contains diffusion tensor and T1-weighted anatomical maps, by including contrast based on quantitative susceptibility mapping. The new atlas combines a "deep gray matter parcellation map" (DGMPM) derived from a single-subject quantitative susceptibility map with the previously established "white matter parcellation map" (WMPM) from the same subject's T1-weighted and diffusion tensor imaging data into an MNI coordinate map named the "Everything Parcellation Map in Eve Space," also known as the "EvePM." It allows automated segmentation of gray matter and white matter structures. Quantitative susceptibility maps from five healthy male volunteers (30 to 33 years of age) were coregistered to the Eve Atlas with AIR and Large Deformation Diffeomorphic Metric Mapping (LDDMM), and the transformation matrices were applied to the EvePM to produce automated parcellation in subject space. ⋯ Overall, this atlas provides a time-efficient tool for automated coregistration and segmentation of quantitative susceptibility data to analyze many regions of interest. These data were used to establish a baseline for normal magnetic susceptibility measurements for over 60 brain structures of 30- to 33-year-old males. Correlating the average susceptibility with age-based iron concentrations in gray matter structures measured by Hallgren and Sourander (1958) allowed interpolation of the average iron concentration of several deep gray matter regions delineated in the EvePM.
-
Previous evidence showed that spin-echo (SE) BOLD signals offer an increased linearity and promptness with respect to gradient-echo (GE) acquisition, possibly providing a more accurate estimate of the amplitude of neuronal activity. However there is no evidence that the two sequences differ in representing different activation levels due to changes in stimulus intensity. In this study at 3T we compared GE and SE BOLD responses to visual stimuli at increasing contrast levels (5%, 20%, 60%, and 100%). ⋯ This difference was observed also when excluding voxels attributed to large vessels, suggesting a non negligible role of the extravascular contribution to the modulation of SE fMRI signal with stimulus intensity. These results are shown to be in agreement with theoretical predictions that we derived from a recently proposed model of GE and SE functional signals. The present findings suggest that, despite the limited increase in functional localization accuracy at low field, SE fMRI might offer a potential advantage in distinguishing different levels of stimulus-evoked brain activity.
-
Successful social interaction requires recognising the intention of another person's communicative gestures. At a neural level, this process may involve neural activity in different systems, such as the mentalizing system (MS) and the mirror neuron system (MNS). The aim of the present study was to explore the neural correlates of communicative gestures during observation and execution of these gestures. ⋯ The activation in IPL is enhanced during the processing of social gestures most likely due to their communicative intention. The activation of IPL together with medial frontal areas may contribute to mentalizing processes. The interaction in the mOFC suggests an involvement of self-referential processes in the processing of social gesture.
-
This study investigates neural correlates of music-evoked fear and joy with fMRI. Studies on neural correlates of music-evoked fear are scant, and there are only a few studies on neural correlates of joy in general. Eighteen individuals listened to excerpts of fear-evoking, joy-evoking, as well as neutral music and rated their own emotional state in terms of valence, arousal, fear, and joy. ⋯ These findings show that the auditory cortex functions as a central hub of an affective-attentional network that is more extensive than previously believed. PPI analyses also showed functional connectivity of SF with AC during the joy condition, taken to reflect that SF is sensitive to social signals with positive valence. During fear music, SF showed functional connectivity with visual cortex and area 7 of the superior parietal lobule, taken to reflect increased visual alertness and an involuntary shift of attention during the perception of auditory signals of danger.
-
Several studies demonstrated that resting-state EEG power differs tremendously between school-aged children and adults. Low-frequency oscillations (delta and theta, <7 Hz) are dominant in children but become less prominent in the adult brain, where higher-frequency alpha oscillations (8-12 Hz) dominate the mature brain rhythm. However, this assessment of developmental effects with EEG power mapping is restricted to the scalp level and blind to the information flow between brain regions, thus limiting insights about brain development. ⋯ In addition, significant thalamocortical connectivity was unidirectional (i.e., outflow to cortical regions) in adults, but bidirectional in children. Group comparison confirmed the results of the single subject analyses for both functional and directed connectivities. Our results suggest that both functional and directed connectivities are sensitive to brain maturation as the distribution and directionality of functional connections differ between the developing and adult brains.