RESUMO
The relationship between neurons' input and spiking output is central to brain computation. Studies in vitro and in anesthetized animals suggest nonlinearities emerge in cells' input-output (activation) functions as network activity increases, yet how neurons transform inputs in vivo has been unclear. Here, we characterize cortical principal neurons' activation functions in awake mice using two-photon optogenetics and imaging. We find responses to fixed optogenetic input are nearly unchanged as neurons are excited, reflecting a linear response regime above neurons' resting point. In contrast, responses are dramatically attenuated by suppression. This attenuation is a powerful means to filter inputs arriving to suppressed cells, privileging other inputs arriving to excited neurons. These data have two major implications: first, neural activation functions in vivo accord with the activation functions used in recent machine learning systems, and second, neurons' IO functions can enhance sensory processing by attenuating some inputs while leaving others unchanged.
RESUMO
BACKGROUND: Little is known about how physicians interpret data displays that depict preliminary or exploratory clinical data in physician-targeted sales aids for oncology drugs. Using three factorial experiments, we examined whether disclosures of data limitations and clinical uncertainty adequately communicate the limitations and practical utility of this type of data. SUBJECTS, MATERIALS, AND METHODS: The studies used a 2 (disclosure of data limitations: technical, nontechnical) × 2 (disclosure of clinical uncertainty: present, absent) + 1 (control: no disclosure) between-subjects experimental design to examine the impact of disclosures as they relate to presentations of preliminary or exploratory data in promotional communications for oncology products. In each experiment, we randomized oncologists and primary care physicians with oncology experience to view one version of a two-page sales aid. Following this exposure, physicians completed a web-based survey. The design was replicated in three concurrently conducted experiments using sales aids for different fictitious oncology drugs, each featuring one of three common data displays: a forest plot (n = 495), a Kaplan-Meier curve (n = 504), or a bar chart (n = 532). RESULTS: Results provide initial evidence that in some contexts disclosures can improve understanding of the clinical utility of certain information about a drug and the limitations of results presented in a data display. Disclosures can also temper perceptions of how much evidence is presented that supports a conclusion that the drug is an appropriate treatment. In terms of the language used in the disclosure of data limitations, physicians in all three experiments strongly preferred the nontechnical disclosures. CONCLUSION: The findings from the three experiments in this study suggest that disclosures have the potential to increase relevant knowledge, but more research is needed to establish best practice recommendations for using disclosures to convey contextual information relevant for interpreting data displays in promotional communications. IMPLICATIONS FOR PRACTICE: This article reports the results from three large, online experimental studies that address a growing concern that drug companies often share favorable clinical trial results with physicians in promotional materials that lack important context for physicians to interpret the data. This series of studies investigates whether strategic use of two types of disclosures (disclosure of data limitations and a disclosure of clinical uncertainty) improves understanding and reduces misinterpretations among physicians. The results from these studies help identify communication factors that impact how physicians critically appraise preliminary or exploratory clinical trial data to inform policy and regulatory efforts.
