Localization of non-stationary sources of electromagnetic radiation with the aid of phasometry

The possibility of localizing sources of electromagnetic radiation by measurement of the time of passage of the radiation or the measurement of its phase at various points of cosmic space, at which are located satellite observatories is examined. Algorithms are proposed for localization using two, three, and four astronomical observatories. The precision of the localization and several partial results of practical significance are deduced

Algorithms for locating celestial sources of X-rays and gamma flares with the aid of several spacecraft

An Algorithm is suggested for defining the coordinates of X-ray and Gamma Ray radiation sources by measuring the time lag of the transmission of radiation flares from various points of space in which spacecraft are located. Instances are cited where the 2-x, 3-x and 4x spacecraft are used

White matter microstructural differences underlying beta oscillations during speech in adults who stutter

The basal ganglia-thalamocortical (BGTC) loop may underlie speech deficits in developmental stuttering. In this study, we investigated the relationship between abnormal cortical neural oscillations and structural integrity alterations in adults who stutter (AWS) using a novel magnetoencephalography (MEG) guided tractography approach. Beta oscillations were analyzed using sensorimotor speech MEG, and white matter pathways were examined using tract-based spatial statistics (TBSS) and probabilistic tractography in 11 AWS and 11 fluent speakers. TBSS analysis revealed overlap between cortical regions of increased beta suppression localized to the mouth motor area and a reduced fractional anisotropy (FA) in the AWS group. MEG-guided tractography showed reduced FA within the BGTC loop from left putamen to subject-specific MEG peak. This is the first study to provide evidence that structural abnormalities may be associated with functional deficits in stuttering and reflect a network deficit within the BGTC loop that includes areas of the left ventral premotor cortex and putamen

A Magnetoencephalography Investigation of the Role of Stuttering Anticipation on the Preparation and Execution of Speech in Adults who Stutter

Coordination of the speech neural network in developmentally stuttering adults prior to initiation of individual speech utterances has not been explored. The objectives of this study were a) to characterize sensory-motor recruitment in preparation for and execution of speech in adults who stutter (AWS) using magneto-encephalography, and b) to investigate the effect of stuttering anticipation on such sensory-motor recruitment. Brain neural oscillatory activity was recorded during a cued overt repetition task. No differences between high and low anticipation were found. However, AWS demonstrate stronger bilateral recruitment of the mouth motor cortex compared to controls in speech preparation and execution. AWS also recruit the right mouth motor cortex before the left, while controls show a preference for the left mouth motor cortex. The study was the first to find differences in motor recruitment during speech in AWS. This is proposed to reflect facilitative mechanisms adopted in a limited motor speech network.M.Sc

Amygdala–prefrontal connectivity during appraisal of symptom-related stimuli in obsessive–compulsive disorder

Background: Cognitive models of obsessive–compulsive disorder (OCD) posit dysfunctional appraisal of disorder-relevant stimuli in patients, suggesting disturbances in the processes relying on amygdala–prefrontal connectivity. Recent neuroanatomical models add to the traditional view of dysfunction in corticostriatal circuits by proposing alterations in an affective circuit including amygdala–prefrontal connections. However, abnormalities in amygdala–prefrontal coupling during symptom provocation, and particularly during conditions that require stimulus appraisal, remain to be demonstrated directly.; Methods: Amygdala–prefrontal connectivity was examined in unmedicated OCD patients during appraisal (v. distraction) of symptom-provoking stimuli compared with an emotional control condition. Subsequent analyses tested whether hypothesized connectivity alterations could be also identified during passive viewing and the resting state in two independent samples.; Results: During symptom provocation, reductions in positive coupling between amygdala and orbitofrontal cortex were observed in OCD patients relative to healthy control participants during appraisal and passive viewing of OCD-relevant stimuli, whereas abnormally high amygdala–ventromedial prefrontal cortex coupling was found when appraisal was distracted by a secondary task. In contrast, there were no group differences in amygdala connectivity at rest.; Conclusions: Our finding of abnormal amygdala–prefrontal connectivity during appraisal of symptom-related (relative to generally aversive) stimuli is consistent with the involvement of affective circuits in the functional neuroanatomy of OCD. Aberrant connectivity can be assumed to impact stimulus appraisal and emotion regulation, but might also relate to fear extinction deficits, which have recently been described in OCD. Taken together, we propose to integrate abnormalities in amygdala–prefrontal coupling in affective models of OCD.Peer Reviewe

Sensorimotor oscillations prior to speech onset reflect altered motor networks in adults who stutter

Adults who stutter (AWS) have demonstrated atypical coordination of motor and sensory regions during speech production. Yet little is known of the speech-motor network in AWS in the brief time window preceding audible speech onset. The purpose of the current study was to characterize neural oscillations in the speech-motor network during preparation for and execution of overt speech production in AWS using magnetoencephalography (MEG). Twelve AWS and twelve age-matched controls were presented with 220 words, each word embedded in a carrier phrase. Controls were presented with the same word list as their matched AWS participant. Neural oscillatory activity was localized using minimum-variance beamforming during two time periods of interest: speech preparation (prior to speech onset) and speech execution (following speech onset). Compared to controls, AWS showed stronger beta (15-25Hz) suppression in the speech preparation stage, followed by stronger beta synchronization in the bilateral mouth motor cortex. AWS also recruited the right mouth motor cortex significantly earlier in the speech preparation stage compared to controls. Exaggerated motor preparation is discussed in the context of reduced coordination in the speech-motor network of AWS. It is further proposed that exaggerated beta synchronization may reflect a more strongly inhibited motor system that requires a stronger beta suppression to disengage prior to speech initiation. These novel findings highlight critical differences in the speech-motor network of AWS that occur prior to speech onset and emphasize the need to investigate further the speech-motor assembly in the stuttering population