Similar to a camera aperture, pupil size adjusts to the surrounding luminance. Unlike a camera, pupil size is additionally modulated both by stimulus properties and by cognitive processes, including attention and arousal, though the interdependence of these factors is unclear. We hypothesized that different stimulus properties interact to jointly modulate pupil size while remaining independent from the impact of arousal. We measured pupil responses from human observers to equiluminant stimuli during a demanding rapid serial visual presentation (RSVP) task at fixation and tested how response amplitude depends on contrast, spatial frequency, and reward level. We found that under constant luminance, unattended stimuli evoke responses that are separable from changes caused by general arousal or attention. We further uncovered a double-dissociation between task-related responses and stimulus-evoked responses, suggesting that different sources of pupil size modulation are independent of one another. Our results ...

The annual Society for Neuroscience (SfN) meeting yields significant, measurable impacts that conflict with the environmental commitment of the Society and the Intergovernmental Panel on Climate Change (IPCC) recommendations to address the climate emergency ([IPCC, 2018][1]). We used 12,761 presenters’ origins, two online carbon calculators, and benchmark values to estimate 2018 meeting-related travel, event venue operations, and hotel accommodation emissions. Presenters’ conference travel resulted in between 17,298 and 8690 tons of atmospheric carbon dioxide (t CO2), with or without radiative forcing index factors. Over 92% of authors traveled by air and were responsible for >99% of total travel-related emissions. Extrapolations based on 28,691 registrants yielded between 69,592.60 metric tons of carbon dioxide equivalents (t CO2e) and 38,010.85 t CO2 from travel. Comparatively, authors’ and registrants’ hotel accommodation emissions equaled 429 and 965 t CO2e, whereas operation of the San Diego Conventio...

The levels of purines, essential molecules to sustain eukaryotic cell homeostasis, are regulated by the coordination of the de novo and salvage synthesis pathways. In the embryonic central nervous system (CNS), the de novo pathway is considered crucial to meet the requirements for the active proliferation of neural stem/progenitor cells (NSPCs). However, how these two pathways are balanced or separately used during CNS development remains poorly understood. In this study, we showed a dynamic shift in pathway utilization, with greater reliance on the de novo pathway during embryonic stages and on the salvage pathway in postnatal–adult mouse brain. The pharmacological effects of various purine synthesis inhibitors in vitro and the expression profile of purine synthesis enzymes indicated that NSPCs in the embryonic cerebrum mainly use the de novo pathway. Simultaneously, NSPCs in the cerebellum require both the de novo and the salvage pathways. In vivo administration of de novo inhibitors resulted in severe h...

Cajal–Retzius (CR) cells are transient neurons with long-lasting effects on the architecture and circuitry of the neocortex and hippocampus. Contrary to the prevailing assumption that CR cells completely disappear in rodents shortly after birth, a substantial portion of these cells persist in the hippocampus throughout adulthood. The role of these surviving CR cells in the adult hippocampus is largely unknown, partly because of the paucity of suitable tools to dissect their functions in the adult versus the embryonic brain. Here, we show that genetic crosses of the Δ Np73-Cre mouse line, widely used to target CR cells, to reporter mice induce reporter expression not only in CR cells, but also progressively in postnatal dentate gyrus granule neurons. Such a lack of specificity may confound studies of CR cell function in the adult hippocampus. To overcome this, we devise a method that not only leverages the temporary CR cell-targeting specificity of the Δ Np73-Cre mice before the first postnatal week, but al...

The Intercalated Cells of the Amygdala (ITCs) are a fundamental processing structure in the amygdala that remain relatively understudied. They are phylogenetically conserved from insectivores through primates, inhibitory, and project to several of the main processing and output stations of the amygdala and basal forebrain. Through these connections, the ITCs are best known for their role in conditioned fear, where they are required for fear extinction learning and recall. Prior work on ITC connectivity is limited, and thus holistic characterization of their afferent and efferent connectivity in a genetically defined manner is incomplete. The ITCs express the FoxP2 transcription factor, affording genetic access to these neurons for viral input-output mapping. To fully characterize the anatomical connectivity of the ITCs, we used cre-dependent viral strategies in FoxP2-cre mice to reveal the projections of the main (mITC), caudal (cITC), and lateral (lITC) clusters along with their presynaptic sources of inn...

The auditory system relies on both local and summary representations; acoustic local features exceeding system constraints are compacted into a set of summary statistics. Such compression is pivotal for sound-object recognition. Here, we assessed whether computations subtending local and statistical representations of sounds could be distinguished at the neural level. A computational auditory model was employed to extract auditory statistics from natural sound textures (i.e., fire, rain) and to generate synthetic exemplars where local and statistical properties were controlled. Twenty-four human participants were passively exposed to auditory streams while the EEG was recorded. Each stream could consist of short, medium, or long sounds to vary the amount of acoustic information. Short and long sounds were expected to engage local or summary statistics representations, respectively. Data revealed a clear dissociation. Compared to summary-based ones, auditory-evoked responses based on local information were ...

Cajal-Retzius (CR) cells are transient neurons with long-lasting effects on the architecture and circuitry of the neocortex and hippocampus. Contrary to the prevailing assumption that CR cells completely disappear in rodents shortly after birth, a substantial portion of these cells persist in the hippocampus throughout adulthood. The role of these surviving CR cells in the adult hippocampus is largely unknown, partly because of the paucity of suitable tools to dissect their functions in the adult versus the embryonic brain. Here, we show that genetic crosses of the ΔNp73-Cre mouse line, widely used to target CR cells, to reporter mice induce reporter expression not only in CR cells but also progressively in postnatal dentate gyrus granule neurons. Such a lack of specificity may confound studies of CR cell function in the adult hippocampus. To overcome this, we devise a method that not only leverages the temporary CR cell-targeting specificity of the ΔNp73-Cre mice before the first postnatal week, but also ...

The levels of purines, essential molecules to sustain eukaryotic cell homeostasis, are regulated by the coordination of the de novo and salvage synthesis pathways. In the embryonic central nervous system (CNS), the de novo pathway is considered crucial to meet the requirements for the active proliferation of neural stem/progenitor cells (NSPCs). However, how these two pathways are balanced or separately utilized during CNS development remains poorly understood. In this study, we showed a dynamic shift in pathway utilization, with greater reliance on the de novo pathway during embryonic stages and on the salvage pathway in postnatal–adult mouse brain. The pharmacological effects of various purine synthesis inhibitors in vitro and the expression profile of purine synthesis enzymes indicated that NSPCs in the embryonic cerebrum mainly utilize the de novo pathway. Simultaneously, NSPCs in the cerebellum require both the de novo and the salvage pathways. In vivo administration of de novo inhibitors resulted in ...

Spoken language contains information at a broad range of timescales, from phonetic distinctions on the order of milliseconds to semantic contexts which shift over seconds to minutes. It is not well understood how the brain's speech production systems combine features at these timescales into a coherent vocal output. We investigated the spatial and temporal representations in cerebral cortex of three phonological units with different durations: consonants, vowels, and syllables. Electrocorticography recordings were obtained from five participants while speaking single syllables. We developed a novel clustering and Kalman filter-based trend analysis procedure to sort electrodes into temporal response profiles. A linear discriminant classifier was used to determine how strongly each electrode's response encoded phonological features. We found distinct time-courses of encoding phonological units depending on their duration: consonants were represented more during speech preparation, vowels were represented eve...

The annual Neuroscience meeting yields significant, measurable impacts that conflict with the environmental commitment of the society and IPCC’s recommendations to address the climate emergency (IPCC, 2018). We used 12,761 presenters’ origins, two online carbon calculators, and benchmark values to estimate 2018 meeting-related travel, event venue operations, and hotel accommodation emissions. Presenters’ conference travel resulted in between 17,298 and 8,690 t CO2, with or without radiative forcing index factors. Over 92% of authors traveled by air and were responsible for over 99% of total travel-related emissions. Extrapolations based upon 28,691 registrants yielded between 69,592.60 t CO2e and 38,010.85 t CO2 from travel. Comparatively, authors’ and registrants’ hotel accommodation emissions equaled 429 and 965 t CO2e, whereas operation of the San Diego Convention Center equaled about 107 t CO2e. We relate SfN meeting-related emissions to potential September Arctic sea ice loss, labor productivity loss ...