Subcutaneous emphysema and pneumothorax complicating diagnostic colonoscopy

A case of subcutaneous emphysema and pneumothorax secondary to a diagnostic colonoscopy is presented. While 11 cases of retroperitoneal emphysema due to colonoscopy were identified in the literature, there are only two further reports of pneumothorax. Possible etiologic and therapeutic aspects are discussed.     

Gerontopsychosomatik

Ohne Zusammenfassung     

Left inferior parietal cortex integrates time and space during collision judgments

Left inferior parietal lobe lesions can cause perturbation of the space-time plans underlying skilled actions. But does the perceptual integration of spatiotemporal information use the same neural substrate or is the role of the left inferior parietal cortex restricted to visuomotor transformations? We use fMRI and a collision judgment paradigm to examine whether the left inferior parietal cortex integrates temporal and spatial variables in situations in which no complex action and no visuomotor transformation is required. We used a perceptual task in which healthy subjects indicated by simple button presses whether two moving objects (of the same or different size) would or would not collide with each other. This task of interest was contrasted with a control task that employed the same stimuli and identical motor responses but in which the size of the two moving objects had to be compared. To assess putative differential eye-movement effects both tasks were performed with and without central fixation. Analysis of the fMRI data (employing a random-effects model and SPM99) showed that collision judgments (relative to size judgments) provoked a significant increase in neural activity in the left inferior parietal cortex (supramarginal gyrus) only. These results show that left inferior parietal cortex is involved in the integration of perceptual spatiotemporal information and thus provide a neural correlate for the use of space-time plans (whose perturbation can lead to apraxia as originally hypothesized by Liepmann). Furthermore, the data suggest that the left supramarginal gyrus combines temporal and spatial variables more widely than previously supposed.     

The right temporoparietal junction in attention and social interaction: A transcranial magnetic stimulation study

The right temporoparietal junction (rTPJ) has been associated with the ability to reorient attention to unexpected stimuli and the capacity to understand others' mental states (theory of mind [ToM]/false belief). Using activation likelihood estimation meta‐analysis we previously unraveled that the anterior rTPJ is involved in both, reorienting of attention and ToM, possibly indicating a more general role in attention shifting. Here, we used neuronavigated transcranial magnetic stimulation to directly probe the role of the rTPJ across attentional reorienting and false belief. Task performance in a visual cueing paradigm and false belief cartoon task was investigated after application of continuous theta burst stimulation (cTBS) over anterior rTPJ (versus vertex, for control). We found that attentional reorienting was significantly impaired after rTPJ cTBS compared with control. For the false belief task, error rates in trials demanding a shift in mental state significantly increased. Of note, a significant positive correlation indicated a close relation between the stimulation effect on attentional reorienting and false belief trials. Our findings extend previous neuroimaging evidence by indicating an essential overarching role of the anterior rTPJ for both cognitive functions, reorienting of attention and ToM. Hum Brain Mapp 37:796–807, 2016. © 2015 Wiley Periodicals, Inc .     

Causality between local field potentials of the subthalamic nucleus and electromyograms of forearm muscles in Parkinson’s disease

Deep brain stimulation of the subthalamic nucleus is an effective treatment for Parkinson’s disease, although its precise mechanisms remain poorly understood. To gain further insight into the mechanisms underlying deep brain stimulation, we analysed the causal relationship between forearm muscle activity and local field potentials derived from the subthalamic nucleus. In 19 patients suffering from Parkinson’s disease of the akinetic‐rigid subtype, we calculated the squared partial directed coherence between muscles of the contralateral forearm and the subthalamic nucleus or zona incerta during both a rest and a hold condition of the arm. For both recording regions, data analysis revealed that, during the rest condition, electromyographic activity was significantly more often ‘Granger‐causal’ for the local field potentials than the opposite causation. In contrast, during the hold condition, no significant difference was found in the occurrence of causalities. Contrary to the existing basal ganglia model and the current concept of Parkinson’s disease pathophysiology, we found the subthalamic nucleus to receive more ‘afferences’ than it emitted ‘efferences’, suggesting that its role is more complex than a simple driving nucleus in the basal ganglia loop. Therefore, the effect of deep brain stimulation in the subthalamic nucleus could, at least in part, result from a blockade of pathological afferent input.     

Long-term effects of methylphenidate on neural networks associated with executive attention in children with ADHD: results from a longitudinal functional MRI study

ObjectiveLittle is known about the long-term effects of stimulants on the functional organization of the developing brain. Nonacute effects of stimulants on neural activity related to three aspects of attention (alerting, reorienting, and executive control) were examined in children with attention-deficit/hyperactivity disorder (ADHD) using a longitudinal functional magnetic resonance imaging approach.MethodNine boys with ADHD were scanned while drug naïve (t1) and after 1 year of methylphenidate treatment (t2). Eleven matched controls were also investigated twice. ADHD children stopped medication 1 week before t2.ResultsAlthough all of the children showed stable alerting and reorienting performance from t1 to t2, normal controls significantly improved their executive control performance at t2, whereas children with ADHD did not. Neurally, controls showed a larger increase in neural activity from t1 to t2 in regions critical to task performance (i.e., in the temporoparietal junction during reorienting of attention and in the anterior cingulate cortex during executive control) compared to the patient group. However, only children with ADHD showed a decrease in neural activity in the insula and putamen during reorienting, indicating a reduction in compensatory brain activation over time.ConclusionsThese data suggest that 1 year of MPH treatment may be beneficial, albeit insufficient, to show enduring normalization of neural correlates of attention.     

Functional interactions during the retrieval of conceptual action knowledge: an fMRI study

Impaired retrieval of conceptual knowledge for actions has been associated with lesions of left premotor, left parietal, and left middle temporal areas [Tranel, D., Kemmerer, D., Adolphs, R., Damasio, H., & Damasio, A. R. Neural correlates of conceptual knowledge for actions. Cognitive Neuropsychology, 409-432, 2003]. Here we aimed at characterizing the differential contribution of these areas to the retrieval of conceptual knowledge about actions. During functional magnetic resonance imaging (fMRI), different categories of pictograms (whole-body actions, manipulable and nonmanipulable objects) were presented to healthy subjects. fMRI data were analyzed using SPM2. A conjunction analysis of the neural activations elicited by all pictograms revealed ( p<.05, corrected) a bilateral inferior occipito-temporal neural network with strong activations in the right and left fusiform gyri. Action pictograms contrasted to object pictograms showed differential activation of area MT+, the inferior and superior parietal cortex, and the premotor cortex bilaterally. An analysis of psychophysiological interactions identified contribution-dependent changes in the neural responses when pictograms triggered the retrieval of conceptual action knowledge: Processing of action pictograms specifically enhanced the neural interaction between the right and left fusiform gyri, the right and left middle temporal cortices (MT+), and the left superior and inferior parietal cortex. These results complement and extend previous neuropsychological and neuroimaging studies by showing that knowledge about action concepts results from an increased coupling between areas concerned with semantic processing (fusiform gyrus), movement perception (MT+), and temporospatial movement control (left parietal cortex).     

What is "odd" in Posner's location-cueing paradigm? Neural responses to unexpected location and feature changes compared

Within the parietal cortex, the temporo-parietal junction (TPJ) and the intraparietal sulcus (IPS) seem to be involved in both spatial and nonspatial functions: Both areas are activated when misleading information is provided by invalid spatial cues in Posner's location-cueing paradigm, but also when infrequent deviant stimuli are presented within a series of standard events. In the present study, we used functional magnetic resonance imaging to investigate the distinct and shared brain responses to (i) invalidly cued targets requiring attentional reorienting, and (ii) to target stimuli deviating in color and orientation leading to an oddball-like distraction effect. Both unexpected location and feature changes were accompanied by a significant slowing of manual reaction times. Bilateral TPJ and right superior parietal lobe (SPL) activation was observed in response to invalidly as compared to validly cued targets. In contrast, the bilateral inferior occipito-temporal cortex, the left inferior parietal cortex, right frontal areas, and the cerebellum showed stronger activation in response to deviant than to standard targets. Common activations were observed in the right angular gyrus along the IPS and in the right inferior frontal gyrus. We conclude that the superior parietal and temporo-parietal activations observed here as well as previously in location-cueing paradigms do not merely reflect the detection and processing of unexpected stimuli. Furthermore, our data suggest that the right IPS and the inferior frontal gyrus are involved in attentional selection and distractor processing of both spatial and nonspatial features.