Natural switches in behaviour rapidly modulate hippocampal coding.

Throughout their daily lives, animals and humans often switch between different behaviours. However, neuroscience research typically studies the brain while the animal is performing one behavioural task at a time, and little is known about how brain circuits represent switches between different behaviours. Here we tested this question using an ethological setting: two bats flew together in a long 135 m tunnel, and switched between navigation when flying alone (solo) and collision avoidance as they flew past each other (cross-over). Bats increased their echolocation click rate before each cross-over, indicating attention to the other bat1-9. Hippocampal CA1 neurons represented the bat's own position when flying alone (place coding10-14). Notably, during cross-overs, neurons switched rapidly to jointly represent the interbat distance by self-position. This neuronal switch was very fast-as fast as 100 ms-which could be revealed owing to the very rapid natural behavioural switch. The neuronal switch correlated with the attention signal, as indexed by echolocation. Interestingly, the different place fields of the same neuron often exhibited very different tuning to interbat distance, creating a complex non-separable coding of position by distance. Theoretical analysis showed that this complex representation yields more efficient coding. Overall, our results suggest that during dynamic natural behaviour, hippocampal neurons can rapidly switch their core computation to represent the relevant behavioural variables, supporting behavioural flexibility.

Lived Experiences of Patients Receiving Hemodialysis during the COVID-19 Pandemic: A Qualitative Study from the Quebec Renal Network.

Background: Hemodialysis patients have faced unique challenges during the COVID-19 pandemic. They face high risk of death if infected and have unavoidable exposure to others when they come to hospital three times weekly for their life-saving treatments. The objective of this study was to gain a better understanding of the scope and magnitude of the effects of the pandemic on the lived experience of patients receiving in-center hemodialysis. Methods: We conducted semi-structured interviews with 22 patients who were undergoing dialysis treatments in five hemodialysis centers in Montreal from November 2020 to May 2021. Interviews were transcribed and then analyzed using thematic content analysis. Results: Most participants reported no negative effects of the COVID-19 pandemic on their hemodialysis care. Several patients had negative feelings related to forced changes in their dialysis schedules, and this was especially pronounced for indigenous patients in a shared living situation. Some patients were concerned about contracting COVID-19, especially during public transportation, whereas others expressed confidence that the physical distancing and screening measures implemented at the hospital would protect them and their loved ones. Some participants reported that masks negatively affected their interactions with health care workers, and for many others, the pandemic was associated with feelings of loneliness. Finally, some respondents reported some positive effects of the pandemic, including use of telemedicine and creating a sense of solidarity. Conclusions: Patients undergoing hemodialysis reported no negative effects on their medical care but faced significant disruptions in their routines and social interactions due to the COVID-19 pandemic. Nevertheless, they showed great resilience in their ability to adapt to the new reality of their hemodialysis treatments. We also show that studies focused on understanding the lived experiences of indigenous patients and patients from different ethnic backgrounds are needed in order reduce inequities in care during public health emergencies.

Effect of phototherapy on cardiorespiratory activity during sleep in neonates with physiologic jaundice.

BACKGROUND: Phototherapy is considered the standard of care for neonatal jaundice. However, its short-term cardiorespiratory effects have not been studied thoroughly. OBJECTIVES: To assess the cardiorespiratory effect of phototherapy during sleep in term infants with physiologicjaundice. METHODS: We performed two polysomnography studies during 3 hours sleep in 10 healthy term infants with physiologic jaundice; each infant served as his/her own control. The first study was performed just prior to phototherapy and the second study during phototherapy 24 hours later. Heart and respiratory rates, type and duration of apneas, and arterial oxygen saturation were analyzed during active and quiet sleep. RESULTS: Term infants (gestational age 38.6 +/- 1.4 weeks, birth weight 3.2 +/- 0.5 kg) underwent the two polysomnography studies within a short time interval and had a comparable bilrubin level (3.6 +/- 0.8 and 4.5 +/- 0.8 days; 14.5 +/- 1.4 and 13.8 +/- 2.1 mg/dl, P = NS, respectively). There was no difference in sleeping time or the fraction of active and quiet sleep before or during phototherapy. During active sleep under phototherapy there was a significant decrease in respiratory rate and increase in heart rate (54.3 +/- 10.3 vs. 49.1 +/- 10.8 breaths/minute, and 125.9 +/- 11.7 vs. 129.7 +/- 15.3 beats/minute, respectively, P < 0.05), as well as a decrease in respiratory effort in response to apnea. These effects were not found during quiet sleep. Phototherapy had no significant effect on oxygen saturation, apnea rate or periodic breathing in either sleep state. No clinical significant apnea or bradycardia occurred. CONCLUSIONS: Phototherapy affected the cardiorespiratory activity during active sleep but not during quiet sleep in term infants with physiologic jaundice. These effects do not seem to have clinical significance in "real-life" conditions.