Learning and memory in a rat model of social jetlag that also incorporates mealtime

Impaired Morris water task retention following T21 light dark cycle exposure is not due to reduced hippocampal c-FOS expression

Circadian rhythms influence virtually all aspects of physiology and behavior. This is problematic when circadian rhythms no longer reliably predict time. Circadian rhythm disruption can impair memory, yet we don’t know how this fully works at the systems and molecular level. When trying to determine the root of a memory impairment, assessing neuronal activation with c-FOS is useful. This has yet to be assessed in the hippocampi of circadian rhythm disrupted rats in a hippocampal gold standard task. Rats were trained on the Morris water task (MWT), then received 6 days of a 21-h day (T21), 13 days of a normal light dark cycle, probe trial, and tissue extraction an hour later. Despite having impaired memory in the probe trial, compared to controls there were no differences in c-FOS expression in hippocampal sub regions: CA1; CA3; Dentate gyrus. These data confirm others in hamsters demonstrating that arrhythmicity which produces an impairment in spontaneous alternation does not affect c-FOS in the dentate gyrus. The current study indicates that the memory impairment induced by a lighting manipulation is likely not due to attenuated neuronal activation. Determining how the master clock in the brain communicates with the hippocampus is needed to untangle the relationship between circadian rhythms and memory.

Social Jetlag in adolescents: From a nursing perspective

PROBLEM

Social Jetlag (SJL) is a condition leading to many important physical, mental, behavioral, and cognitive problems in adolescents.

METHODS

The sample of this study, which used a descriptive and correlational design, consisted of 247 high school students. The SJL parameters were informed by the literature, while chronotype was identified using the Morningness-Eveningness Scale for Children. The factors associated with SJL were determined using a structured questionnaire.

FINDINGS

Students' SJL value was 2 h 10 min ± 01:11. As students' tendency to be an evening chronotype increased, the SJL value increased, as well (r = -0.472; p < 0.001). In terms of SJL, student's grade level (β = -0.167; p = 0.004) and chronotype (β = -0.438; p < 0.001) were a negative risk factor, while spending time in bed with TV/computer/smartphone before sleeping (β = 0.127; p = 0.031) was a positive risk factor.

CONCLUSIONS

The students had a high SJL value. The results might be useful for nurses to develop intervention strategies to improve adolescents sleep habits.

Online learning in proton radiation therapy: the future in the post-Covid-19 pandemic era?

Objective:

The Covid-19 pandemic placed unprecedented strain on medical education and led to a vast increase in online learning. Subsequently, the Christie International Proton School moved from face-to-face to online. Delegate feedback and current literature were studied to determine benefits, challenges, and potential solutions, for online proton therapy education.

Methods:

The course was converted to a 6-week online course with twice weekly 2-h sessions. Feedback was studied pre-, during-, and post-course regarding demographics, learning objectives, proton therapy knowledge, ease of engagement, technical difficulties, and course format. Statistical analyses were performed for proton therapy knowledge pre- and post-course.

Results:

An increase in delegate attendance was seen with increased international and multidisciplinary diversity. Learner objectives included treatment planning, clinical applications, physics, and centre development. Average learner reported scores of confidence in proton therapy knowledge improved significantly from 3, some knowledge, to 4, adequate knowledge after the course (p<0.0001). There were minimal reported difficulties using the online platform, good reported learner engagement, and shorter twice weekly sessions were reported conducive for learning. Recordings for asynchronous learning addressed time zone difficulties.

Conclusion:

The obligatory switch to online platforms has catalysed a paradigm shift towards online learning with delegates reporting educational benefit. We propose solutions to challenges of international online education, and a pedagogical model for online proton therapy education.

Advances in knowledge:

Online education is an effective method to teach proton therapy to international audiences. The future of proton education includes a hybrid of online and practical face-to-face learning depending on the level of cognitive skill required.

Online learning in proton radiation therapy: the future in the post-Covid-19 pandemic era?

OBJECTIVE

The Covid-19 pandemic placed unprecedented strain on medical education and led to a vast increase in online learning. Subsequently, the Christie International Proton School moved from face-to-face to online. Delegate feedback and current literature were studied to determine benefits, challenges, and potential solutions, for online proton therapy education.

METHODS

The course was converted to a 6-week online course with twice weekly 2-h sessions. Feedback was studied pre-, during-, and post-course regarding demographics, learning objectives, proton therapy knowledge, ease of engagement, technical difficulties, and course format. Statistical analyses were performed for proton therapy knowledge pre- and post-course.

RESULTS

An increase in delegate attendance was seen with increased international and multidisciplinary diversity. Learner objectives included treatment planning, clinical applications, physics, and centre development. Average learner reported scores of confidence in proton therapy knowledge improved significantly from 3, some knowledge, to 4, adequate knowledge after the course (p<0.0001). There were minimal reported difficulties using the online platform, good reported learner engagement, and shorter twice weekly sessions were reported conducive for learning. Recordings for asynchronous learning addressed time zone difficulties.

CONCLUSION

The obligatory switch to online platforms has catalysed a paradigm shift towards online learning with delegates reporting educational benefit. We propose solutions to challenges of international online education, and a pedagogical model for online proton therapy education.

ADVANCES IN KNOWLEDGE

Online education is an effective method to teach proton therapy to international audiences. The future of proton education includes a hybrid of online and practical face-to-face learning depending on the level of cognitive skill required.

Use of a social jetlag-mimicking mouse model to determine the effects of a two-day delayed light- and/or feeding-shift on central and peripheral clock rhythms plus cognitive functioning

Social jetlag (SJL) is defined as the discrepancy between social and biological rhythms and calculated by the difference between the midpoint of sleep time on working-days and free-days. Previous human and mouse studies showed SJL is positively related to evening chronotype and significantly related to smoking habit, cardiovascular risk, cognitive ability, and that SJL-mimicking conditions, simulating the real lifestyle situation of SJL in many humans, disrupt the regularity of estrous cycles of female animals. The effects of SJL-mimicking conditions on circadian rhythms and cognitive function and the reasons why the discrepancy between social and biological rhythms is involved in SJL have not yet been investigated. Therefore, in this study, we utilized a mouse model of SJL-mimicking conditions - 6-hour delayed-light/dark (LD) conditions for 2 days and normal-LD conditions for the following 5 days - applied for several weeks during which biological rhythms were monitored. Circadian rhythms of central and peripheral clocks and metabolism of the mice under the SJL-mimicking condition were always delayed for 2-3 hours compared with those under the normal-LD condition. Moreover, SJL-mimicking conditions impaired their cognitive function using a novel object recognition test. Only the delayed timing of either the light phase of the LD or of feeding for 2 days, comparable to the free-days situation of humans, delayed the circadian staging of rhythms the following 5 days. Furthermore, sleep deprivation during the early mornings for 5 days, which is comparable to early rise times experienced by humans on working-days and does affect the staging of circadian rhythms (circadian misalignment schedule), delayed the locomotor activity rhythms the next 2 days, comparable to free-days in humans, which is similar to the lifestyle rhythm of the evening chronotype. Our results demonstrated that the circadian misalignment schedule for 5 days changed the locomotor activity rhythms the following 2 days to the evening chronotype, that light- and/or feeding-shift conditions for 2 days exacerbate SJL, and that SJL-mimicking conditions delay the metabolic rhythm and cause cognitive impairment.

Assessment of Sleep, K-Complexes, and Sleep Spindles in a T21 Light-Dark Cycle

Circadian rhythm misalignment has a deleterious impact on the brain and the body. In rats, exposure to a 21-hour day length impairs hippocampal dependent memory. Sleep, and particularly K-complexes and sleep spindles in the cortex, have been hypothesized to be involved in memory consolidation. Altered K-complexes, sleep spindles, or interaction between the cortex and hippocampus could be a mechanism for the memory consolidation failure but has yet to be assessed in any circadian misalignment paradigm. In the current study, continuous local field potential recordings from five rats were used to assess the changes in aspects of behavior and sleep, including wheel running activity, quiet wakefulness, motionless sleep, slow wave sleep, REM sleep, K-complexes and sleep spindles, in rats exposed to six consecutive days of a T21 light-dark cycle (L9:D12). Except for a temporal redistribution of sleep and activity during the T21, there were no changes in period, or total amount for any aspect of sleep or activity. These data suggest that the memory impairment elicited from 6 days of T21 exposure is likely not due to changes in sleep architecture. It remains possible that hippocampal plasticity is affected by experiencing light when subjective circadian phase is calling for dark. However, if there is a reduction in hippocampal plasticity, changes in sleep appear not to be driving this effect.