No abstract

A barrage of information constantly assaults our senses, of which only a fraction is relevant at any given point in time. However, the neural circuitry supporting the suppression of irrelevant sensory distractors is not completely understood. The claustrum, a circuit hub with vast cortical connectivity, is an intriguing brain structure, whose restrictive anatomy, thin and elongated, has precluded functional investigation. Here, we describe the use of Egr2-CRE mice to access genetically defined claustral neurons. Utilizing conditional viruses for anterograde axonal labeling and retrograde trans-synaptic tracing, we validated this transgenic model for accessing the claustrum and extended the known repertoire of claustral input/output connectivity. Addressing the function of the claustrum, we inactivated CL neurons, chronically as well as acutely, in mice performing an automated two-alternative forced-choice behavioral task. Strikingly, inhibition of CL neurons did not significantly impact task performance under varying delay times and cue durations, but revealed a selective role for the claustrum in supporting performance in the presence of an irrelevant auditory distractor. Further investigation of behavior, in the naturalistic maternal pup-retrieval task, replicated the result of sensitization to an auditory distractor following inhibition of CL neurons. Initiating investigation into the underlying mechanism, we found that activation of CL neurons modulated cortical sensory processing, suppressing tone representation in the auditory cortex. This functional study, utilizing selective genetic access, implicates the claustrum in supporting resilience to distraction, a fundamental aspect of attention.

Introduction: Testing for active SARS-CoV-2 infection is a fundamental tool in the public health measures taken to control the COVID-19 pandemic. Because of the overwhelming use of SARS-CoV-2 reverse transcription (RT)-PCR tests worldwide, the availability of test kits has become a major bottleneck and the need to increase testing throughput is rising. We aim to overcome these challenges by pooling samples together, and performing RNA extraction and RT-PCR in pools. Methods: We tested the efficiency and sensitivity of pooling strategies for RNA extraction and RT-PCR detection of SARS-CoV-2. We tested 184 samples both individually and in pools to estimate the effects of pooling. We further implemented Dorfman pooling with a pool size of eight samples in large-scale clinical tests. Results: We demonstrated pooling strategies that increase testing throughput while maintaining high sensitivity. A comparison of 184 samples tested individually and in pools of eight samples showed that test results were not significantly affected. Implementing the eight-sample Dorfman pooling to test 26 576 samples from asymptomatic individuals, we identified 31 (0.12%) SARS-CoV-2 positive samples, achieving a 7.3-fold increase in throughput. Discussion: Pooling approaches for SARS-CoV-2 testing allow a drastic increase in throughput while maintaining clinical sensitivity. We report the successful large-scale pooled screening of asymptomatic

The claustrum is an intriguing brain structure, featuring the highest connectivity per regional volume in the brain. It is a thin and elongated structure enclosed between the striatum and the insular cortex, with widespread reciprocal connections with the sensory modalities and prefrontal cortices. Retinotopic and somatotopic organizations have been described in the claustrum, and anatomical studies in cats, monkeys, and rats have demonstrated topographic organization of cortico-claustral connections. In this study we mapped the projections from cortical modalities (visual, auditory, somatosensory, motor, and olfactory), and prefrontal regions (anterior cingulate cortex and orbitofrontal cortex) to the claustrum in mice. Utilizing expression of a virally encoded synaptic anterograde tracer, AAV-SynaptoTag, followed by 3D reconstruction of the cortical projections, we performed a comprehensive study of the organization of these projections within the mouse claustrum. Our results clearly demonstrate a dorsoventral laminar organization of projections from the sensory cortices to the claustrum, whereas frontal inputs are more extensive and overlap with the inputs from the sensory cortices. In addition, we find evidence supporting a core/shell organization of the claustrum. We propose that the overlap between the frontal inputs and the inputs from the sensory modalities may underlie executive regulation of the communication between the claustrum and the cortical modalities. J. Comp. Neurol. 525:1381-1402, 2017. © 2016 Wiley Periodicals, Inc.

Similar in appearance to preauricular tags but located in the lateral neck, cervical chondrocutaneous branchial remnants are a rather less common and less well known congenital lesion. A retrospective review of admissions at Sainte-Justine Hospital between 1980 and 1993 produced 20 cases of cervical tags, of which 17 were true cervical chrondrocutaneous branchial remnants and 3 were skin tags associated with a thyroglossal duct. Of the 17 true cervical chrondrocutaneous branchial remnants, 15 were operated on in our institution. The clinical characteristics, results of investigations, surgical data, pathologic findings, and associated anomalies were documented. Several interesting facts emerged, including a male predominance (11 of 17), a scarcity of bilateral lesions (1 of 17), the presence of an elastic cartilage core in all operated specimens (15 of 15), and a high incidence of associated anomalies (13 of 17). We suggest that the second branchial arch is the most likely origin for the lesion. We propose a clear, widely acceptable name for this anomaly in order to prevent further diagnostic confusion. Most important, although simple surgical excision is all that is required for treatment, a complete physical examination of the patient and possibly an ultrasound examination of the genitourinary tract are recommended because a cervical chrondrocutaneous branchial remnant has proven in many cases to be a visible "marker" for more serious associated anomalies.