A retinal code for motion along the gravitational and body axes.

Self-motion triggers complementary visual and vestibular reflexes supporting image-stabilization and balance. Translation through space produces one global pattern of retinal image motion (optic flow), rotation another. We examined the direction preferences of direction-sensitive ganglion cells (DSGCs) in flattened mouse retinas in vitro. Here we show that for each subtype of DSGC, direction preference varies topographically so as to align with specific translatory optic flow fields, creating a neural ensemble tuned for a specific direction of motion through space. Four cardinal translatory directions are represented, aligned with two axes of high adaptive relevance: the body and gravitational axes. One subtype maximizes its output when the mouse advances, others when it retreats, rises or falls. Two classes of DSGCs, namely, ON-DSGCs and ON-OFF-DSGCs, share the same spatial geometry but weight the four channels differently. Each subtype ensemble is also tuned for rotation. The relative activation of DSGC channels uniquely encodes every translation and rotation. Although retinal and vestibular systems both encode translatory and rotatory self-motion, their coordinate systems differ.

Reward does not facilitate visual perceptual learning until sleep occurs.

A growing body of evidence indicates that visual perceptual learning (VPL) is enhanced by reward provided during training. Another line of studies has shown that sleep following training also plays a role in facilitating VPL, an effect known as the offline performance gain of VPL. However, whether the effects of reward and sleep interact on VPL remains unclear. Here, we show that reward interacts with sleep to facilitate offline performance gains of VPL. First, we demonstrated a significantly larger offline performance gain over a 12-h interval including sleep in a reward group than that in a no-reward group. However, the offline performance gains over the 12-h interval without sleep were not significantly different with or without reward during training, indicating a crucial interaction between reward and sleep in VPL. Next, we tested whether neural activations during posttraining sleep were modulated after reward was provided during training. Reward provided during training enhanced rapid eye movement (REM) sleep time, increased oscillatory activities for reward processing in the prefrontal region during REM sleep, and inhibited neural activation in the untrained region in early visual areas in non-rapid eye movement (NREM) and REM sleep. The offline performance gains were significantly correlated with oscillatory activities of visual processing during NREM sleep and reward processing during REM sleep in the reward group but not in the no-reward group. These results suggest that reward provided during training becomes effective during sleep, with excited reward processing sending inhibitory signals to suppress noise in visual processing, resulting in larger offline performance gains over sleep.

Olfaction Is Associated With Sexual Motivation and Satisfaction in Older Men and Women.

BACKGROUND: Sensory function declines with age and may impact sexual function in older adults. Indeed, the sense of smell plays a uniquely strong role in sexual motivation. Therefore, olfactory dysfunction in older adults may be intimately linked to changes in sexual desire and satisfaction. AIM: To test whether impaired olfactory function is associated with decreased sexual activity and motivation in older adults. METHODS: Cross-sectional analysis of a nationally representative sample of community-dwelling older U.S. adults from the National Social Life, Health, and Aging Project. OUTCOMES: 2 modalities of olfactory function were measured (sensitivity to n-butanol and odor identification) via validated methods (Sniffin' Sticks). Respondents answered survey questions about frequency of sexual thoughts (motivation) and sexual activity, and satisfaction with their most recent sexual relationship. A wide range of demographic, health, and social information were also collected. RESULTS: Decreased olfactory function in older U.S. adults was associated with decreased sexual motivation (odds ratio 0.93, P = .03) and less emotional satisfaction with sex (odds ratio 0.89, P = .04), but not decreased frequency of sexual activity or physical pleasure, in analyses that were adjusted for age, gender, race, education, cognition, comorbidities, and depression. CLINICAL IMPLICATIONS: Olfactory dysfunction may affect sexuality in older adults. Potentially treatable causes of sensory loss should be addressed by clinicians to improve quality of life. STRENGTHS & LIMITATIONS: These results rely on validated olfactory testing, detailed measures of sexual attitudes and behaviors, and extensive demographic, health, and social history in a nationally representative sample of older U.S. adults. Owing to the cross-sectional nature of these analyses, we cannot determine causality. CONCLUSIONS: Olfactory dysfunction in older U.S. adults is associated with decreased sexual motivation and emotional satisfaction, potentially due to evolutionarily-conserved neurological links between olfaction and sexuality. Siegel JK, Kung SY, Wroblewski KE, et al. Olfaction Is Associated With Sexual Motivation and Satisfaction in Older Men and Women. J Sex Med 2021;18:295-302.

Unified Airway Disease: Environmental Factors.

The unified airway is in constant exposure to environmental factors that promote inflammation and disease. Environmental allergens, including house dust mites, pets, pollens, and molds, are strongly linked with development and exacerbation of upper airway disease with nonlinear dose-dependent relationships. Occupational triggers, including combat exposures and construction workers, are associated with the development of both upper and lower airway disease resulting in a "healthy worker effect" where many people leave jobs due to significant morbidity..

Sleep-Disordered Breathing Is Associated With Impaired Odor Identification in Older U.S. Adults.

BACKGROUND: Sleep-disordered breathing (SDB) is a common, underdiagnosed condition in older adults with major health consequences, including disrupted central nervous system functioning. Whether SDB may affect sensory function is unclear. We sought to address this question by comparing 2 forms of olfactory testing which measure peripheral and central olfactory processing. METHODS: We assessed SDB (survey-reported snoring frequency, nighttime apneic events, or diagnosis of sleep apnea) in the National Social Life, Health, and Aging Project, a nationally representative sample of older U.S. adults. Odor sensitivity (peripheral) and odor identification (central) were assessed with validated instruments. Logistic regression was used to test the relationship between SDB and olfaction, accounting for relevant covariates, including demographics, cognition, and comorbidity. RESULTS: Twenty-nine percent of older U.S. adults reported symptoms of SDB (apneic events or nightly snoring). Of these, only 32% had been diagnosed with sleep apnea. Older adults with SDB (those who reported symptoms or have been diagnosed with sleep apnea) were significantly more likely to have impaired odor identification (odds ratio 2.13, 95% confidence interval 1.19-3.83, p = .012) in analyses that accounted for age, gender, race/ethnicity, education, cognition, comorbidities (including depression), and body mass index. Presence of SDB was not associated with impaired odor sensitivity (odds ratio 1.03, 95% confidence interval 0.75-1.43, p = .84). CONCLUSION: SDB is highly prevalent but underdiagnosed in older U.S. adults and is associated with impaired odor identification but not odor sensitivity. These data support the concept that SDB affects pathways in the central nervous system which involve chemosensory processing.

Olfactory dysfunction persists after smoking cessation and signals increased cardiovascular risk.

BACKGROUND: Olfaction plays a critical role in health and function in older adults, and impaired sense of smell is a strong predictor of morbidity and mortality. Smoking cigarettes causes olfactory impairment, but the mechanism of damage and ability to recover after cessation are unknown. We investigated the relationship between time since quitting and olfactory dysfunction in order to elucidate the mechanism(s) by which smoking damages the olfactory system and to inform patient counseling. METHODS: Using longitudinal data from the National Social Life Health and Aging Project (n = 3528 older adults, including 1526 former smokers), we analyzed the association between odor identification performance and time since smoking cessation using multivariate ordinal logistic regression, adjusting for cognition and demographic variables. To test whether vascular disease plays a role, we also assessed the relationship between olfactory decline and incidence of heart attack and heart disease. RESULTS: Former smokers who quit ≤15 years before testing had significantly impaired olfaction compared to never smokers (p = 0.04), but those who quit >15 years prior did not. Olfactory decline over 5 years showed modest evidence toward predicting increased incidence of heart attack or heart disease (p = 0.08). CONCLUSION: Olfactory impairment in smokers persists 15 years after quitting, which is consistent with a vascular mechanism of impairment. Indeed, olfactory decline is a predictor of the development of cardiovascular disease. Taken together, these data suggest that olfactory loss may be a useful sign of underlying vascular pathology. Further investigation of olfactory loss as an early biomarker for cardiovascular disease is warranted.