Attention-induced deactivations in very low frequency EEG oscillations: differential localisation according to ADHD symptom status

Background: the default-mode network (DMN) is characterised by coherent very low frequency (VLF) brain oscillations. The cognitive significance of this VLF profile remains unclear, partly because of the temporally constrained nature of the blood oxygen-level dependent (BOLD) signal. Previously we have identified a VLF EEG network of scalp locations that shares many features of the DMN. Here we explore the intracranial sources of VLF EEG and examine their overlap with the DMN in adults with high and low ADHD ratings.Methodology/Principal Findings: DC-EEG was recorded using an equidistant 66 channel electrode montage in 25 adult participants with high- and 25 participants with low-ratings of ADHD symptoms during a rest condition and an attention demanding Eriksen task. VLF EEG power was calculated in the VLF band (0.02 to 0.2 Hz) for the rest and task condition and compared for high and low ADHD participants. sLORETA was used to identify brain sources associated with the attention-induced deactivation of VLF EEG power, and to examine these sources in relation to ADHD symptoms. There was significant deactivation of VLF EEG power between the rest and task condition for the whole sample. Using s-LORETA the sources of this deactivation were localised to medial prefrontal regions, posterior cingulate cortex/precuneus and temporal regions. However, deactivation sources were different for high and low ADHD groups: In the low ADHD group attention-induced VLF EEG deactivation was most significant in medial prefrontal regions while for the high ADHD group this deactivation was predominantly localised to the temporal lobes.Conclusions/Significance: attention-induced VLF EEG deactivations have intracranial sources that appear to overlap with those of the DMN. Furthermore, these seem to be related to ADHD symptom status, with high ADHD adults failing to significantly deactivate medial prefrontal regions while at the same time showing significant attenuation of VLF EEG power in temporal lobe

Functional Brain Network Modularity Captures Inter- and Intra-Individual Variation in Working Memory Capacity

Cognitive abilities, such as working memory, differ among people; however, individuals also vary in their own day-to-day cognitive performance. One potential source of cognitive variability may be fluctuations in the functional organization of neural systems. The degree to which the organization of these functional networks is optimized may relate to the effective cognitive functioning of the individual. Here we specifically examine how changes in the organization of large-scale networks measured via resting state functional connectivity MRI and graph theory track changes in working memory capacity.Twenty-two participants performed a test of working memory capacity and then underwent resting-state fMRI. Seventeen subjects repeated the protocol three weeks later. We applied graph theoretic techniques to measure network organization on 34 brain regions of interest (ROI). Network modularity, which measures the level of integration and segregation across sub-networks, and small-worldness, which measures global network connection efficiency, both predicted individual differences in memory capacity; however, only modularity predicted intra-individual variation across the two sessions. Partial correlations controlling for the component of working memory that was stable across sessions revealed that modularity was almost entirely associated with the variability of working memory at each session. Analyses of specific sub-networks and individual circuits were unable to consistently account for working memory capacity variability.The results suggest that the intrinsic functional organization of an a priori defined cognitive control network measured at rest provides substantial information about actual cognitive performance. The association of network modularity to the variability in an individual's working memory capacity suggests that the organization of this network into high connectivity within modules and sparse connections between modules may reflect effective signaling across brain regions, perhaps through the modulation of signal or the suppression of the propagation of noise

Characteristics and early outcomes of cervical cancer patients at Butaro District Hospital, Rwanda: a retrospective review

Background: Cancer treatment facilities are scarce in rural areas of low-income and middle-income countries, where the highest burden of cervical cancer exists. The Butaro Cancer Center of Excellence (BCCOE), in rural Rwanda, is a Rwandan Ministry of Health facility supported by Partners In Health and Dana-Farber/Brigham and Women's Cancer Center. The cervical cancer programme includes diagnosis, staging, and treatment. However, because of resource limitations, only 15 patients per month could be referred for radiotherapy to the Uganda Cancer Institute. In this study, we describe cervical cancer treatment at BCCOE and early patient outcomes. Methods: In July, 2016, we retrospectively reviewed records for patients with cervical cancer enrolled between July 1, 2012, and June 30, 2015, at BCCOE. We extracted data on patients' characteristics, disease stage, treatment, and outcomes. Findings: We included 438 patients: median age was 52 years (IQR 42–60 years), 35 patients (8%) had laboratory-confirmed HIV, 142 (36%) smoked tobacco, median number of pregnancies was 7 (IQR 5–9), and 41 (10%) had had a hysterectomy before enrolment. 258 patients (60%) had a diagnosis confirmed by pathology, and 391 patients (91%) had a documented disease stage. Of these, 13 (3%) were Stage I, 183 (47%) were Stage II, 154 (39%) were Stage-III, and 41 (11%) were Stage IV. There was a curative, instead of palliative or undecided, intent for 85% of Stage I patients, 91% of Stage II, and, 12% of Stage III. 165 women (38%) were referred for concurrent radiation therapy, chemotherapy, and brachytherapy in Uganda, and 19 (4%) were referred for radical hysterectomy. At their last recorded visit, 77 patients (18%) had no evidence of recurrence, including: 6 (46%) Stage I patients, 66 (37%) Stage II, 5 (3%) Stage III, but no Stage IV patients (p =<0·0001). Overall, 114 patients (27%) were lost to follow-up during or after treatment. Interpretation: Our experience shows that a cervical cancer treatment programme is viable in a low-resource, rural setting. However, many challenges exist, especially the severity of disease at intake (about half of patients presented with Stage III or IV disease) and that there are no radiation facilities in Rwanda. Further, a quarter of patients were eventually lost to follow-up during the study. Future implementation interventions will focus on strategies to overcome these challenges. Funding: Partners in Health, Dana-Farber Cancer Institute, Rwandan Ministry of Health