SARS-CoV-2 is associated with changes in brain structure in UK Biobank.

There is strong evidence of brain-related abnormalities in COVID-191-13. However, it remains unknown whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here we investigated brain changes in 785 participants of UK Biobank (aged 51-81 years) who were imaged twice using magnetic resonance imaging, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans-with 141 days on average separating their diagnosis and the second scan-as well as 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including (1) a greater reduction in grey matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus; (2) greater changes in markers of tissue damage in regions that are functionally connected to the primary olfactory cortex; and (3) a greater reduction in global brain size in the SARS-CoV-2 cases. The participants who were infected with SARS-CoV-2 also showed on average a greater cognitive decline between the two time points. Importantly, these imaging and cognitive longitudinal effects were still observed after excluding the 15 patients who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease through olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious effect can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow-up.

Decision-making as discovery: Vetting clinical research in a leading precision oncology service.

Based on fieldwork carried out at the Early Drug Development Service of a world-leading cancer institution, our study sheds lights on decision-making processes at the stage where decisions are made about which clinical trial to pursue and thus which experimental drugs will feed the growing pipeline of molecularly guided therapies and therapeutic strategies available to treating physicians. The paper shows how such collective decision-making practices by a translational research unit employ formal tools and ad hoc valuation strategies that interweave technical-scientific matters of concern with patient-oriented clinical ones, as part of the institutional assetization of biomedical knowledge production. In the process, decision-making practices in part define the conditions of possibility for the provision of care in what is increasingly becoming a 'clinic of variants.' They do so by reconfiguring on an evolving basis the socio-material ecosystem through which precision oncology is enacted as a rapidly evolving assemblage of patients, physicians, research and support staff, protocols, molecular markers, drugs and administrative components.

Functional Microarchitecture of the Mouse Dorsal Inferior Colliculus Revealed through In Vivo Two-Photon Calcium Imaging.

The inferior colliculus (IC) is an obligatory relay for ascending auditory inputs from the brainstem and receives descending input from the auditory cortex. The IC comprises a central nucleus (CNIC), surrounded by several shell regions, but the internal organization of this midbrain nucleus remains incompletely understood. We used two-photon calcium imaging to study the functional microarchitecture of both neurons in the mouse dorsal IC and corticocollicular axons that terminate there. In contrast to previous electrophysiological studies, our approach revealed a clear functional distinction between the CNIC and the dorsal cortex of the IC (DCIC), suggesting that the mouse midbrain is more similar to that of other mammals than previously thought. We found that the DCIC comprises a thin sheet of neurons, sometimes extending barely 100 µm below the pial surface. The sound frequency representation in the DCIC approximated the mouse's full hearing range, whereas dorsal CNIC neurons almost exclusively preferred low frequencies. The response properties of neurons in these two regions were otherwise surprisingly similar, and the frequency tuning of DCIC neurons was only slightly broader than that of CNIC neurons. In several animals, frequency gradients were observed in the DCIC, and a comparable tonotopic arrangement was observed across the boutons of the corticocollicular axons, which form a dense mesh beneath the dorsal surface of the IC. Nevertheless, acoustically responsive corticocollicular boutons were sparse, produced unreliable responses, and were more broadly tuned than DCIC neurons, suggesting that they have a largely modulatory rather than driving influence on auditory midbrain neurons. SIGNIFICANCE STATEMENT: Due to its genetic tractability, the mouse is fast becoming the most popular animal model for sensory neuroscience. Nevertheless, many aspects of its neural architecture are still poorly understood. Here, we image the dorsal auditory midbrain and its inputs from the cortex, revealing a hitherto hidden level of organization and paving the way for the direct observation of corticocollicular interactions. We show that a precise functional organization exists in the mouse auditory midbrain, which has been missed by previous, more macroscopic approaches. The fine-scale distribution of sound-frequency tuning suggests that the mouse midbrain is more similar to that of other mammals than previously thought and contrasts with the more heterogeneous organization reported in imaging studies of auditory cortex.

Behavioural sensitivity to binaural spatial cues in ferrets: evidence for plasticity in the duplex theory of sound localization.

For over a century, the duplex theory has guided our understanding of human sound localization in the horizontal plane. According to this theory, the auditory system uses interaural time differences (ITDs) and interaural level differences (ILDs) to localize low-frequency and high-frequency sounds, respectively. Whilst this theory successfully accounts for the localization of tones by humans, some species show very different behaviour. Ferrets are widely used for studying both clinical and fundamental aspects of spatial hearing, but it is not known whether the duplex theory applies to this species or, if so, to what extent the frequency range over which each binaural cue is used depends on acoustical or neurophysiological factors. To address these issues, we trained ferrets to lateralize tones presented over earphones and found that the frequency dependence of ITD and ILD sensitivity broadly paralleled that observed in humans. Compared with humans, however, the transition between ITD and ILD sensitivity was shifted toward higher frequencies. We found that the frequency dependence of ITD sensitivity in ferrets can partially be accounted for by acoustical factors, although neurophysiological mechanisms are also likely to be involved. Moreover, we show that binaural cue sensitivity can be shaped by experience, as training ferrets on a 1-kHz ILD task resulted in significant improvements in thresholds that were specific to the trained cue and frequency. Our results provide new insights into the factors limiting the use of different sound localization cues and highlight the importance of sensory experience in shaping the underlying neural mechanisms.

Genomic evolution and polymorphism: segmental duplications and haplotypes at 108 regions on 21 chromosomes.

We describe here extensive, previously unknown, genomic polymorphism in 120 regions, covering 19 autosomes and both sex chromosomes. Each contains duplication within multigene clusters. Of these, 108 are extremely polymorphic with multiple haplotypes. We used the genomic matching technique (GMT), previously used to characterise the major histocompatibility complex (MHC) and regulators of complement activation (RCA). This genome-wide extension of this technique enables the examination of many underlying cis, trans and epistatic interactions responsible for phenotypic differences especially in relation to individuality, evolution and disease susceptibility. The extent of the diversity could not have been predicted and suggests a new model of primate evolution based on conservation of polymorphism rather than de novo mutation.

Neural processing in the primary auditory cortex following cholinergic lesions of the basal forebrain in ferrets.

Cortical acetylcholine (ACh) release has been linked to various cognitive functions, including perceptual learning. We have previously shown that cortical cholinergic innervation is necessary for accurate sound localization in ferrets, as well as for their ability to adapt with training to altered spatial cues. To explore whether these behavioral deficits are associated with changes in the response properties of cortical neurons, we recorded neural activity in the primary auditory cortex (A1) of anesthetized ferrets in which cholinergic inputs had been reduced by making bilateral injections of the immunotoxin ME20.4-SAP in the nucleus basalis (NB) prior to training the animals. The pattern of spontaneous activity of A1 units recorded in the ferrets with cholinergic lesions (NB ACh-) was similar to that in controls, although the proportion of burst-type units was significantly lower. Depletion of ACh also resulted in more synchronous activity in A1. No changes in thresholds, frequency tuning or in the distribution of characteristic frequencies were found in these animals. When tested with normal acoustic inputs, the spatial sensitivity of A1 neurons in the NB ACh- ferrets and the distribution of their preferred interaural level differences also closely resembled those found in control animals, indicating that these properties had not been altered by sound localization training with one ear occluded. Simulating the animals' previous experience with a virtual earplug in one ear reduced the contralateral preference of A1 units in both groups, but caused azimuth sensitivity to change in slightly different ways, which may reflect the modest adaptation observed in the NB ACh- group. These results show that while ACh is required for behavioral adaptation to altered spatial cues, it is not required for maintenance of the spectral and spatial response properties of A1 neurons.

Organizing precision medicine: A case study of Memorial Sloan Kettering Cancer Center's engagement in/with genomics.

Recent decades have seen a dramatic rise of in the number of initiatives designed to promote precision oncology, a domain that has played a pioneering role in the implementation of post-genomic approaches and technologies such as innovative clinical trial designs and molecular profiling. In this paper, based on fieldwork carried out at the Memorial Sloan-Kettering Cancer Center from 2019 onwards, we analyze how a world-leading cancer center has adapted, responded, and contributed to the challenge of "doing" precision oncology by developing new programs and services, and building an infrastructure that has created the conditions for genomic practices. We do so by attending to the "organizing" side of precision oncology and to the nexus between these activities and epistemic issues. We situate the work that goes into making results actionable and accessing targeted drugs within the larger process of creating a precision medicine ecosystem that includes purpose-built institutional settings, thus simultaneously experimenting with bioclinical matters and, reflexively, with organizing practices. The constitution and articulation of innovative sociotechnical arrangements at MSK provides a unique case study of the production of a large and complex clinical research ecosystem designed to implement rapidly evolving therapeutic strategies embedded in a renewed and dynamic understanding of cancer biology.

Multi-polar scripts: Techno-regulatory environments and the rise of precision oncology diagnostic tests.

The paper examines the development and marketing of five multi-gene tests, a.k.a. as tumor signatures, designed to aid clinicians and cancer patients in therapeutic decision-making, and, in particular, to avoid overtreatment. We build on a 2011 paper that investigated the emergence of this new domain by opening the 'black box' of two pioneering tests and analyzing the hybrid, scientific-regulatory 'scripts' that were built into them. In subsequent years, second-generation tests, produced by a diverse blend of academic and commercial initiatives, have become available, and they all built into their scripts the lessons learned from their predecessors. The present paper confirms the heuristic value of the initial script-analysis but expands it to consider the multi-polar nature of the space within which multigene tests mutually position themselves. We examine how the tests were first problematized - i.e. how they described and prescribed the kind of world in which they would operate - and how their initial problematization was re-specified following the emergence of a comparative arena and their resulting informational enrichment. In parallel, we explore valuation processes, i.e. the evolving definition of the set of referents against which the assays are mutually compared, and the debates about the appropriate criteria for doing so. We note that the cancer diagnostic industry is involved in the reconfiguration of the multi-polar environment defined by socio-technical, techno-scientific, and regulatory matters of concern that seamlessly blend commercial and scientific considerations.

Healthcare policy by other means: Cancer clinical research as "oncopolicy".

Social studies of biomedicine often focus on how exogenous policies shape the medical domain. While policy agendas no doubt affect complex biomedical projects, in the present paper we analyze a different dynamic, namely how oncologists enact policy as part of several flagship precision oncology endeavors. Empirically, the article focuses on the U.S. TAPUR trial, the Dutch DRUP trial, and the Canadian CAPTUR trial, which have recently been joined by similar Scandinavian studies. Taken together, these trials represent innovative forms of clinical research that, beyond their varying experimental nature, have been designed to transform the evidential processes to provide access to biomarker-driven treatments. Along with gathering evidence on effectiveness of off-label targeted therapies, their explicit goals include the recentering of a major professional organization around research, and the reframing of healthcare as a learning system seamlessly connecting epistemic, organizational, and economic issues. Accordingly, we analyze the design and implementation of these trials as a form of (onco)policy by other means.

Cochlear implant outcomes in patients with Meniere's disease: a large case series.

OBJECTIVE: To perform a matched cohort study to assess whether patients with Meniere's Disease (MD) require more intensive auditory rehabilitation following cochlear implantation (CI) and identify factors that may affect outcomes in patients with MD. METHODS: A retrospective case review was performed. MD and control patients were matched for age, biological sex, implant manufacturer and electrode design. Outcomes measured were speech scores, number of visits to audiology department following switch-on, and post-operative active MD. RESULTS: Forty consecutive implanted MD patients were identified between May 1993 and May 2019. Patients with active MD following CI required significantly more visits to the audiology department compared to controls (P < 0.01) and patients who had inactive MD post-operatively (P < 0.01). However, in MD patients, active MD was less likely following CI (P = 0.03). In patients who continued to experience active MD post-operatively, further medical and surgical ablative intervention was required to control ongoing Meniere's attacks. CONCLUSION: We present the largest case series of performance outcomes in CI patients with MD. Although speech outcomes in MD patients are comparable to controls, patients with active MD pre-operatively are more likely to experience variation in CI performance requiring a prolonged period of auditory rehabilitation compared to inactive preoperative MD.

SARS-CoV-2 is associated with changes in brain structure in UK Biobank.

There is strong evidence for brain-related abnormalities in COVID-19 1-13 . It remains unknown however whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here, we investigated brain changes in 785 UK Biobank participants (aged 51-81) imaged twice, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans, with 141 days on average separating their diagnosis and second scan, and 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including: (i) greater reduction in grey matter thickness and tissue-contrast in the orbitofrontal cortex and parahippocampal gyrus, (ii) greater changes in markers of tissue damage in regions functionally-connected to the primary olfactory cortex, and (iii) greater reduction in global brain size. The infected participants also showed on average larger cognitive decline between the two timepoints. Importantly, these imaging and cognitive longitudinal effects were still seen after excluding the 15 cases who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease via olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious impact can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow up.

Cancer clinical trials in the era of genomic signatures: biomedical innovation, clinical utility, and regulatory-scientific hybrids.

The paper examines two large-scale, North American and European clinical trials designed to validate two commercially available genomic tumor signatures that predict a patient's risk of breast cancer recurrence and response to chemotherapy. The paper builds on empirical evidence from the two trials to explore the emergence of diverse regulatory-scientific hybrids; that is, the paper discusses configurations of genomic practice and bioclinical work that depend on linkages between technical, commercial, patient, clinical, and legal interests and institutions. The development of the genomic signatures for each trial--Oncotype DX and MammaPrint--has followed quite different routes. Oncotype began as a commercial platform: the company that produced it did not discover a signature but rather constructed it by asking users at every step what clinical question they wanted the signature to answer and what data would be credible in that regard. The test has been designed to minimally disrupt existing clinical workflows. MammaPrint, on the other hand, began as a breast cancer signature: the researchers who discovered it, at the Netherlands Cancer Institute (NKI), established a company to commercialize it as a test after the fact. MammaPrint requires a change in pathologists' routines. Thus, while these two trials signify a new departure for clinical cancer trials on a number of levels--they both incorporate new models of interaction between biotech companies and public research, and they both aim to establish the clinical relevance of genomic markers--they also embody different socio-technical scripts: one attempts to accommodate established routines, while the other openly challenges prevailing evidential hierarchies and existing biomedical configurations.

Who's minding the data? Data Monitoring Committees in clinical cancer trials.

Modern biomedicine is based on a number of novel institutions and practices that, in order to function, require some degree of formal and informal regulation. This paper contributes to the ongoing investigation of these processes, and the forms of objectivity they generate, by examining the emergence, development and deployment of Data Monitoring Committees in the field of clinical trials. The idea of a DMC had originally been raised in the clinical trial methodology literature in the 1970s so as to solve the problem of the management of interim trial data. Many leading clinical trial statisticians proposed that interim data and analyses be restricted to members of a DMC. Since the late 1980s, DMCs have evolved considerably in a constant search for ethical neutrality and objectivity through the use of sophisticated statistical techniques and novel organisational strategies. They have also been beset by a fundamental tension as to who or what should count as objective in such an undertaking. The paper examines the evolution of this institution in terms of the techniques brought to bear on the issues that they are expected to solve, the organisational forms through which DMCs have evolved and the ideals of objectivity that these forms embody.

Novel sequence elements define ancestral haplotypes of the region encompassing complement factor H.

The genomic region encompassing complement factor H (CFH) is thought to be important in determining susceptibility to inflammatory diseases such as age-related macular degeneration, but only limited polymorphism has been described. After applying the genomic matching technique to three-generation families and an ethnically diverse reference panel we have demonstrated that the polymorphism resembles that found in the major histocompatibility complex. The different ancestral haplotypes carry either T or C at T1277C but also other more polymorphic alleles over a region of 2 Mb. Thus the association between age-related macular degeneration and T1277 or Y402 actually reflects multiple linked polymorphisms including an indel that cannot be dissected from any direct effect of Y402 and may be more important. We show for the first time that simple algorithms can identify genomic sequence elements that appear to be more useful haplospecific markers than single nucleotide polymorphism or microsatellites.

Correction to: Informing materials: drugs as tools for exploring cancer mechanisms and pathways.

The original version of this article unfortunately contained a mistake. Three entries are incorrect in the reference list. The corrected references are given below.

Informing materials: drugs as tools for exploring cancer mechanisms and pathways.

This paper builds on previous work that investigated anticancer drugs as 'informed materials', i.e., substances that undergo an informational enrichment that situates them in a dense relational web of qualifications and measurements generated by clinical experiments and clinical trials. The paper analyzes the recent transformation of anticancer drugs from 'informed' to 'informing material'. Briefly put: in the post-genomic era, anti-cancer drugs have become instruments for the production of new biological, pathological, and therapeutic insights into the underlying etiology and evolution of cancer. Genomic platforms characterize individual patients' tumors based on their mutational landscapes. As part of this new approach, drugs targeting specific mutations transcend informational enrichment to become tools for informing (and destabilizing) their targets, while also problematizing the very notion of a 'target'. In other words, they have become tools for the exploration of cancer pathways and mechanisms. While several studies in the philosophy and history of biomedicine have called attention to the heuristic relevance and experimental use of drugs, few have investigated concrete instances of this role of drugs in clinical research.

Thalamic input to auditory cortex is locally heterogeneous but globally tonotopic.

Topographic representation of the receptor surface is a fundamental feature of sensory cortical organization. This is imparted by the thalamus, which relays information from the periphery to the cortex. To better understand the rules governing thalamocortical connectivity and the origin of cortical maps, we used in vivo two-photon calcium imaging to characterize the properties of thalamic axons innervating different layers of mouse auditory cortex. Although tonotopically organized at a global level, we found that the frequency selectivity of individual thalamocortical axons is surprisingly heterogeneous, even in layers 3b/4 of the primary cortical areas, where the thalamic input is dominated by the lemniscal projection. We also show that thalamocortical input to layer 1 includes collaterals from axons innervating layers 3b/4 and is largely in register with the main input targeting those layers. Such locally varied thalamocortical projections may be useful in enabling rapid contextual modulation of cortical frequency representations.

Mapping the emergence and development of translational cancer research.

Cancer research is one of the principal targets of translational research, yet the nature of the relationships between different forms of cancer research remains controversial. The paper examines publications in the cancer field during the 1980-2000 period. A network analysis software program was used to map evolving patterns of inter-citations between cancer publications, their different research levels and the transformation of their relational content. Both inter-citation and content maps provide striking evidence of the consolidation in the 1990s of a translational interface that was practically non existent a few decades before. In 1980, research was polarized according to the allegiance to either a clinical or a laboratory style. This same duality obtains in the year 2000, albeit with the additional presence of a third, biomedical player whose activities are similarly structured by a common orientation, rather than by an exclusive commitment to a specific sub-domain.

Regulatory objectivity and the generation and management of evidence in medicine.

The evolution of Western medicine since World War II has resulted in the emergence of new practices based on the direct interaction of biology and medicine. The post-war realignment of biology and medicine has been accompanied by the emergence of a new type of objectivity, regulatory objectivity, that is based on the systematic recourse to the collective production of evidence. Unlike forms of objectivity that emerged in earlier eras, regulatory objectivity consistently results in the production of conventions, sometimes tacit and unintentional but most often arrived at through concerted programs of action. These actions incorporate unprecedented levels of reflexivity, in the sense that biomedical practitioners in their debates and discussions take into account the conventional dimension of their endeavors. The conventions produced by regulatory objectivity create the conditions for a clinical objectivity that relies on the existence of entities and protocols produced and maintained far outside the intimate encounter between doctor and patient. By establishing endogenous forms of regulation, regulatory objectivity operates on a different plane and in a different mode from those suggested by analysts who treat all regulation as a form of rationalization imposed upon medicine from without.