NeuroImage
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The purpose of this study was to evaluate the effects of longitudinal drift in scanner hardware, inter-scanner variability (bias) and scanner upgrade on asymmetries of diffusion properties using longitudinal data obtained on two scanners of the exact same model at one institution. A total of 224 normal subjects (63 females and 161 males) were included in this study. Each subject was scanned twice, at an interval of about 1 year (mean interval=1.0±0.11 years, range=0.6-1.3 years), using two 3.0-T scanners of the exact same model. ⋯ Even with scanners of the exact same model, inter-scanner variability (bias) significantly affected FA and MD asymmetries, which were relatively stable within the same scanner. Scanner upgrade had a small effect on FA and MD asymmetries. The results indicate that the use of multiple scanners increases variability of DTI asymmetry measurements, and can affect the results of cross-sectional and especially longitudinal DTI asymmetry studies.
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Recognition of other people's facial expressions of emotion plays an important role in social communication in infants as well as adults. Evidence from behavioral studies has demonstrated that the ability to recognize facial expressions develops by 6 to 7 months of age. Although the regions of the infant brain involved in processing facial expressions have not been investigated, neuroimaging studies in adults have revealed that several areas including the superior temporal sulcus (STS) participate in the processing of facial expressions. ⋯ In contrast, the hemodynamic responses for angry faces increased during the presentation of angry faces, then decreased rapidly after the face disappeared. Moreover, the left temporal area was significantly activated relative to the baseline when infants looked at happy faces, while the right temporal area was significantly activated for angry faces. These findings suggest hemispheric differences in temporal areas during the processing of positive and negative facial expressions in infants.
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There is a large body of evidence that the serotonergic system plays an important role in the transmission and regulation of pain. Here we used positron emission tomography (PET) with the serotonin transporter (SERT) tracer [(11)C]DASB to study the relationship between SERT binding in the brain and responses to noxious heat stimulation in a group of 21 young healthy volunteers. Responses to noxious heat stimuli were assessed in a separate psychophysical experiment and included measurements of pain threshold, pain tolerance, and responses to phasic noxious heat stimuli and to a long lasting (7-minute) tonic noxious heat stimulus. ⋯ Finally, the VOI analysis revealed a positive correlation between pain tolerance and SERT binding in the hypothalamus (r=0.53; p=0.02) although this was not seen in the parametric analysis. These data extend our earlier observation that cortical 5-HT receptors co-determine responses to tonic but not to phasic pain. The negative correlation between SERT binding in the hypothalamus and insula with tonic pain ratings suggests a possible serotonergic control of the role of these areas in the modulation or in the affective appreciation of pain.
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Recovery of function following lesions in the nervous system requires adaptive changes in surviving circuitries. Here we investigate whether changes in cerebral activation are correlated to spinal cord atrophy and recovery of functionality in individuals with incomplete spinal cord injury (SCI). 19 chronic SCI individuals and 7 age-comparable controls underwent functional magnetic resonance imaging (fMRI) while performing rhythmic dorsiflexion of the ankle. A significant negative correlation was found between the activation in the ipsilateral motor (M1) and bilateral premotor cortex (PMC) on one hand and the functional ability of the SCI participants measured by the clinical motor score on the other. ⋯ There was a tendency for a negative correlation between cerebral activation in ipsilateral S1, M1 and PMC and the amplitude of motor evoked potentials in the tibialis anterior muscle elicited by transcranial magnetic stimulation, but this did not reach statistical significance. There was no correlation between motor score or spinal cord dimensions and the volume of the cortical motor areas. The observations show that lesion of descending tracts in the lateral part of the spinal cord results in increased activation in ipsilateral motor and sensory areas, which may help to compensate for the functional deficit following SCI.
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This fMRI study was set up to explore how cognitive empathy, i.e. the cognitive inference on another person's affective state, can be characterized as a distinct brain function relating to pre-existing neurofunctional concepts about mentalizing and empathy. In a 3 Tesla MRI scanner 28 healthy participants were presented with four different instructions randomly combined with 32 false-belief cartoon stories of 3 subsequent pictures free of direct cues for affective states, like e.g. facial expressions. Participants were instructed to judge affective or visuospatial changes from their own (1st person perspective) or the protagonists' (3rd person perspective, 3rdpp) perspective. 3rdpp-judgements about affective states differed from visuospatial 3rdpp judgements by a significantly higher activation of the anterior mentalizing network (dorsomedial prefrontal cortex, anterior superior temporal sulcus, temporal poles) and the limbic system (left amygdala and hippocampus). ⋯ The simultaneous activation of the cortical mentalizing network and the amygdala indicates that cognitive empathy actually involves reference to own affective states in the observer. Notably, the cognitive reference to own affective states activated the mentalizing network as well. Moreover our results support pre-existing ideas about a functional anterior-posterior subdivision of the mentalizing network, depending on affective content and 3rd person perspective of cognition.