New physics searches at kaon and hyperon factories.

Rare meson decays are among the most sensitive probes of both heavy and light new physics. Among them, new physics searches using kaons benefit from their small total decay widths and the availability of very large datasets. On the other hand, useful complementary information is provided by hyperon decay measurements. We summarize the relevant phenomenological models and the status of the searches in a comprehensive list of kaon and hyperon decay channels. We identify new search strategies for under-explored signatures, and demonstrate that the improved sensitivities from current and next-generation experiments could lead to a qualitative leap in the exploration of light dark sectors.

A Dual-Wavelength Fiber Laser Sensor with Temperature and Strain Discrimination.

This work presents a dual-wavelength C-band erbium-doped fiber laser assisted by an artificial backscatter reflector. This fiber-based reflector, inscribed by femtosecond laser direct writing, was fabricated into a single mode fiber with a length of 32 mm. The dual-wavelength laser obtained, centered at 1527.7 nm and 1530.81 nm, showed an optical signal-to-noise ratio over 46 dB when pumped at 150 mW. Another feature of this laser was that the power difference between the two channels was just 0.02 dB, regardless of the pump power, resulting in a dual emission laser with high equalization. On the other hand, an output power level and a central wavelength instability as low as 0.3 dB and 0.01 nm were measured, in this order for both channels. Moreover, the threshold pump power was 40 mW. Finally, the performance of this dual-wavelength fiber laser enhanced with a random reflector for sensing applications was studied, achieving the simultaneous measurement of strain and temperature with sensitivities around 1 pm/µÎµ and 9.29 pm/°C, respectively.

Identification of the sleep-wake states in rats using the high-frequency activity of the electroencephalogram.

The electroencephalographic signal constitutes the main sign classically used for the identification of states of alertness. However, activities in the high frequency (>100 Hz) range have not been properly studied despite their high potential for sleep scoring in rodents. In the present study, we designed a method for the identification of the sleep-wake states in rats by exclusively using high-frequency activities of the electroencephalogram. By calculating the ratio between the amplitude of the electroencephalographic signal from 110 to 200 Hz and from 110 to 300 Hz, we obtained an index that had values that were low during wakefulness, intermediate during non-REM sleep and high during REM sleep. This high-frequency index (HiFI) allowed the identification of each state without the need to study other signs such as muscle activity or eye movements. To evaluate the performance of the index, we compared it with the conventional scoring of the sleep-wake cycle based upon the study of the electromyogram and delta (0.5-4 Hz), theta (6-9 Hz) and sigma (10-14 Hz) bands of the electroencephalogram. The index had an accuracy of 90.43 ± 1.91% (Cohen's kappa value of 0.82), confirming that the study of the high-frequency activities of the electroencephalogram was sufficient to reliably identify alertness states in the rat. Compared to other sleep-scoring methods, the HiFI has several advantages. It only requires one electroencephalography electrode, thus reducing the severity of the surgical preparation of the experimental animal, and its calculation is very simple, so it can be easily implemented online to classify sleep-wake states in real time.

Second Generation Antipsychotics Monotherapy as Maintenance Treatment for Bipolar Disorder: a Systematic Review of Long-Term Studies.

Atypical or so called second generation antipsychotics (SGA) are playing a role of increasing importance in treatment of bipolar disorder (BD). This study is aimed towards a systematic review of their efficacy when used as monotherapy in order to prevent relapses in the long term treatment. Publications about this subject were identified after a thorough bibliographic research in Medline, The Cochrane Library and Web of Science, employing the PICO method for the creation of a database search strategy and carrying out a critical read and analysis of the found evidence. 14 studies were found which informed about the results of randomized and controlled clinical trials (RCT) about the efficacy of these SGA in monotherapy for BD, when it comes to prevention of relapse, in adult patients diagnosed with either type I or II BD, with a minimum follow-up time of 6 months. Evidence of the use of SGAs for maintenance treatment in BD is limited. Amongst all antipsychotics assessed only aripiprazole, olanzapine, lurasidone, risperidone and quetiapine have been found to be competent for their use in monotherapy, according to RCT.

Multidisciplinary consensus on the therapeutic recommendations for iatrogenic hyperprolactinemia secondary to antipsychotics.

Hyperprolactinemia is an underappreciated/unknown adverse effects of antipsychotics. The consequences of hyperprolactinemia compromise therapeutic adherence and can be serious. We present the consensus recommendations made by a group of experts regarding the management of antipsychotic-induced hyperprolactinemia. The current consensus was developed in 3 phases: 1, review of the scientific literature; 2, subsequent round table discussion to attempt to reach a consensus among the experts; and 3, review by all of the authors of the final conclusions until reaching a complete consensus. We include recommendations on the appropriate time to act after hyperprolactinemia detection and discuss the evidence on available options: decreasing the dose of the antipsychotic drug, switching antipsychotics, adding aripiprazole, adding dopaminergic agonists, and other type of treatment. The consensus also included recommendations for some specific populations such as patients with a first psychotic episode and the pediatric-youth population, bipolar disorder, personality disorders and the elderly population.

An accurate and portable eye movement detector for studying sleep in small animals.

Although eye movements are a highly valuable variable in attempts to precisely identify different periods of the sleep-wake cycle, their indirect measurement by electrooculography is not good enough. The present article describes an accurate and portable scleral search coil that allows the detection of tonic and phasic characteristics of eye movements in free-moving animals. Six adult Wistar rats were prepared for chronic recording of electroencephalography, electromyography and eye movements using the scleral search coil technique. We developed a miniature magnetic field generator made with two coils, consisting of 35 turns and 15 mm diameter of insulated 0.2 mm cooper wire, mounted in a frame of carbon fibre. This portable scleral search coil was fixed on the head of the animal, with each magnetic coil parallel to the eye coil and at 5 mm from each eye. Eye movements detected by the portable scleral search coil were compared with those measured by a commercial scleral search coil requiring immobilizing the head of the animal. No qualitative differences were found between the two scleral search coil systems in their capabilities to detect eye movements. This innovative portable scleral search coil system is an essential tool to detect slow changes in eye position and miniature rapid eye movements during sleep. The portable scleral search coil is much more suitable for detecting eye movements than any previously available system because of its precision and simplicity, and because it does not require immobilization of the animal's head.

Effect of the addition of aripiprazole on hyperprolactinemia associated with risperidone long-acting injection.

We sought to assess the effect of the addition of a fixed dose of 5 mg daily of aripiprazole on hyperprolactinemia induced by risperidone long-acting injectable (RLAI) treatment in patients with chronic psychoses and the adverse events related to the addition of aripiprazole and its impact on the disease. This is an open uncontrolled clinical trial with 13 patients with a severe mental disorder (schizophrenia and other unspecified psychoses) treated with RLAI and with increased serum prolactin levels. Subjects received the addition of a fixed dose of 5 mg daily of aripiprazole for 3 months. The main efficacy outcome was the change in serum prolactin levels after 3 months of treatment. Twelve of the 13 patients showed a decrease in serum prolactin levels (81 ± 46 µg/L at baseline vs 42 ± 21 µg/L at month 1, P < 0.001, 52% mean reduction). In 2 patients, prolactin levels reverted normality. In 8 patients who continued treatment for 2 more months, the decrease in prolactin levels was maintained. Symptoms associated with hyperprolactinemia improved, and no worsening of the Clinical Global Impression Scale scores was observed. The adverse effects due to the addition of aripiprazole were mild and transient. The addition of aripiprazole 5 mg daily to RLAI was associated with a significant decrease in hyperprolactinemia levels and no major additional toxicity in patients with chronic psychosis.

How Confinement and Back to Normal Affected the Well-Being and Thus Sleep, Headaches and Temporomandibular Disorders.

The COVID-19 pandemic is having negative consequences not only for people's general health but also for the masticatory system. This article aimed to assess confinement and its new normal impact on well-being, sleep, headaches, and temporomandibular disorders (TMD). An anonymous survey was distributed to a Spanish university community. Participants completed a well-being index (WHO-5), a questionnaire related to sleep quality (the BEARS test), a headache diagnostic test (the tension type headache (TTH) and migraine diagnosis test), and the DC-TMD questionnaire. Questions were addressed in three scenarios: before confinement, during confinement, and the new normal. A total of 436 responses were collected (70% women, 30% men). A reduction in well-being and sleep quality was recorded. Respondents reported more TTH and migraines during and after confinement. Overall, confinement and return to normal did not increase TMD symptoms, and only minor effects were observed, such as more intense joint pain and a higher incidence of muscle pain in women during confinement. Reduced well-being is correlated with sleep quality loss, headaches, and TMD symptoms. This study provides evidence that pandemics and confinement might have had a negative impact on population health. Well-being was strongly affected, as were sleep quality, depression risk, TTH, and migraine frequency. In contrast, the temporomandibular joint and muscles showed more resilience and were only slightly affected.

Spatiotemporal variations of tropospheric ozone in Spain (2008-2019).

This study aims to support the development of Spain's Ozone Mitigation Plan by evaluating the present-day spatial variation (2015-2019) and trends (2008-2019) for seven ground-level ozone (O3) metrics relevant for human/ecosystems exposure and regulatory purposes. Results indicate that the spatial variation of O3 depends on the part of the O3 distribution being analyzed. Metrics associated with moderate O3 concentrations depict an increasing O3 gradient between the northern and Mediterranean coasts due to climatic factors, while for metrics considering the upper end of the O3 distribution, this climatic gradient tends to attenuate in favor of hotspot regions pointing to relevant local/regional O3 formation. A classification of atmospheric regions in Spain is proposed based on their O3 pollution patterns, to identify priority areas (or O3 hotspots) where local/regional precursor abatement might significantly reduce O3 during pollution episodes. The trends assessment reveals a narrowing of the O3 distribution at the national level, with metrics influenced by lower concentrations tending to increase over time, and those reflecting the higher end of the O3 distribution tending to decrease. While most stations show no statistically significant variations, contrasting O3 trends are evident among the O3 hotspots. The Madrid area exhibits the majority of upward trends across all metrics, frequently with the highest increasing rates, implying increasing O3 associated with both chronic and episodic exposure. The Valencian Community area exhibits a mixed variation pattern, with moderate to high O3 metrics increasing and peak metrics decreasing, while O3 in areas downwind of Barcelona, the Guadalquivir Valley and Puertollano shows no variations. Sevilla is the only large Spanish city with generalized O3 decreasing trends. The different O3 trends among hotspots highlight the need for mitigation measures to be designed at a local/regional scale to be effective. This approach may offer valuable insights for other countries developing O3 mitigation plans.

Urban Accessibility in World Heritage Cities. Accessibility Considerations in Pedestrian Routes in Historic City Centres.

In Spain, fifteen cities have been declared World Heritage Cities by UNESCO. This implies a responsibility to conserve all the heritage wealth of these places. However, what is the point of heritage if it cannot be known and visited? In order to be able to do this for all people, in equal and inclusive conditions, it is essential to consider Accessibility and Universal Design principles. This is a challenge that requires a personalised study in places that were precisely built with the idea of being inaccessible. In particular, the study of the urban fabric and pedestrian itineraries are the determining spaces that this article develops. The aim of this study is to determine the keys and possible guidelines for the definition of urban accessibility indicators in the routes of historic city centres. For this purpose, significant routes have been sought in historic centres from the accessibility point of view: areas of high pedestrian traffic (in many cases for tourist reasons). Thus, six of the fifteen historic quarters of the World Heritage Cities in Spain have been selected for the study, with examples of good accessibility practices and difficulties that can be identified in their itineraries. For this analysis, an initial study of the existing documentation on the subject (secondary information sources) is carried out, in addition to a direct analysis (primary information source) of the graphic documentation compiled in each of these places. Subsequently, a complementary analysis will be made of some examples of good practice in pedestrian routes in historic city centres in cities in other countries. On the basis of this preliminary analysis, a comparison will be made to establish common points and singularities among the different case studies first, and then with other cities. This diagnosis provides results that are identified as "keys to consider in the intervention on pedestrian routes in historic centres". These keys not only address issues of mobility, but also location, orientation, understanding, etc., thus addressing a holistic consideration of accessibility as a fundamental principle for all people, and in particular for the elderly sector, which is one of the groups that is clearly growing and which, without necessarily having to have a severe or recognised disability, needs an accessible environment that is easy to use. As a main conclusion, it can be said that the results of this study do not only have an internal application for these cities but can be perfectly extrapolated as a basis for the elaboration of specific indicators for any historic city centre in any city in the world, considering the necessary adaptation to the specific characteristics of each city.

Evidence of human impact in Antarctic region by studying atmospheric aerosols.

Air quality is a global concerning topic because of its great impact on the environment and health. Because of that, the study of atmospheric aerosols looking for harmful pollutants is rising, as well as the interest in the origin of the contaminants. Depending on the nature and size of the aerosols, some elements can be detected at a great distance from the emission source, even in Antarctica, where this study is conducted. Several samples of PM filters from 2018 to 2019 (Deception Island) and 2019-2020 (Livingston Island) campaigns have been analyzed by three powerful spectroscopic techniques: FESEM (Field Emission Scanning Electron Microscopy), LIBS (Laser Induced Breakdown Spectroscopy), and ICP-MS (Inductively Coupled Plasma Mass Spectrometry). These techniques have allowed us to find some heavy metals in the air of the Antarctic region (Al, Fe, Ti, Ni, Cr, and Mn). Deeper studies on ICP-MS results have confirmed those results and have also provided information on their potential sources. Thus, while Al, Fe, Ti and Mn concentrations can be explained by crustal origin, Ni and Cr presented high values only coherent with important human contribution. The results point out that the Antarctic region is no longer a clean and isolated environment from human pollution.

Mode of action of the sesquiterpene lactones eupatoriopicrin and estafietin on Trypanosoma cruzi.

BACKGROUND: The sesquiterpene lactones (STLs) eupatoriopicrin (EP) and estafietin (ES), isolated from Stevia alpina Griseb. (Asteraceae) and Stevia maimarensis (Hieron.) Cabrera (Asteraceae) respectively, have previously showed promising trypanocidal activity, both in vitro and in vivo. PURPOSE: In this work, using biochemical studies and electron microscopy, we aimed at characterizing the mode of action of both STLs on Trypanosoma cruzi. METHODS: The interaction of STLs with hemin was examined by measuring modifications in the Soret absorption band of hemin; the thiol groups interaction was determined spectrophotometrically through its reaction with 5,5'-dithiobis-2-nitrobenzoate; the effect on cruzipain activity was also assayed by spectrophotometry. The synthesis of sterols were qualitatively and quantitatively tested by TLC. Mitochondrial functionality was assessed by measuring mitochondrial membrane potential and the activity of NADH-cytochrome c reductase and succinate-cytochrome c reductase enzymes. The status of the antioxidant system was assessed by quantifying the level of free thiols by spectrophotometry, together with the intracellular oxidative state by flow cytometry. Ultrastructural changes were analyzed by transmission electron microscopy. RESULTS: EP and ES were found to impair the functionality and the redox status of the parasite. ES produced a greater decrease in the activity of succinate dehydrogenase than eupatoriopicrin, affecting the functioning of the respiratory chain and the Krebs cycle. EP increased the formation of triglycerides leading to the presence of cytoplasmic lipid droplets. By electron microscopy, alterations in the kinetoplast and the appearance of large translucent vacuoles in the cytoplasm were observed for both compounds. CONCLUSIONS: Both sesquiterpenelactones proved to act additively on T. cruzi, supporting the hypothesis that each compound would be acting on different primary targets.. The treatment combining eupatoriopicrin and estafietin could be considered a promising alternative for the treatment of Chagas' disease.

Time to develop chronic kidney disease in an Ecuadorian Type 2 Diabetes Mellitus cohort: Survival analysis in primary care.

Chronic Kidney Disease (CKD) represents a high burden to health systems. However, the survival time for CKD in a Type 2 Diabetes Mellitus (T2DM) population is unknown. AIMS: Determine the risk factors, survival time and the incidence rate of CKD in T2DM. METHODS: Retrospective clinical cohort study (follow up 10 years). 513 patients with T2DM were included. Numerical variables were compared using the mean difference. Chi squared and odds ratios were calculated for categorical variables. Survival analysis was done through life tables and Kaplan-Meier. RESULTS: The mean difference between the group that developed CKD and those who did not, was significant in: age, age at diagnosis of T2DM and years with T2DM. Risk factors for developing CKD were: the presence of hypertension, albuminuria, retinopathy, high triglycerides and high HbA1c. The incidence rate was 32.07 per 1000 person-years of follow-up and 207 (40.4%) of patients developed CKD during the study. The median for developing CKD was 20.52 years of disease with an increasing risk with time. CONCLUSIONS: Half of the patients with T2DM will develop CKD by the second decade of disease. Time, arterial hypertension, retinopathy, albuminuria and triglycerides are factors associated with CKD in patients with T2DM.

Tonic and phasic components of eye movements during REM sleep in the rat.

Phasic oculomotor activity is one of the features identifying rapid eye movement (REM) sleep. Recently, it has been shown in cats that, despite bursts of complex two-component rapid eye movements, the eyes tend to maintain a nasal and downward rotation during REM sleep. Although the function of eye movements during sleep remains elusive, it is important to know whether the characteristics of eye movements during sleep are species-specific in mammals. In this work, quantitative characteristics of eye movements, recorded by the scleral search coil technique, were studied during wakefulness and sleep in rats. During wakefulness, rats performed conjugated saccades at a very low rate and some eye movements associated to blinking and gnawing. Throughout non-REM sleep, eye movements were slow, mostly unconjugated and the eyes maintained a divergence in the horizontal plane. The beginning of REM sleep was characterized by a convergence and downward rotation of the eyes, which tended to persist until the end of REM sleep. Rapid eye movements, isolated and monocular at the beginning, became complex and organized in high-frequency bursts. These results demonstrate that, despite the difference in extraocular anatomy and visuomotor strategies between frontal- and lateral-eyed species, eye movements during REM sleep in rats are very similar to those described in cats. This suggests that the mechanisms generating eye movements during REM sleep are largely conserved in mammals.

Compositional changes of PM2.5 in NE Spain during 2009-2018: A trend analysis of the chemical composition and source apportionment.

In this work, time-series analyses of the chemical composition and source contributions of PM2.5 from an urban background station in Barcelona (BCN) and a rural background station in Montseny (MSY) in northeastern Spain from 2009 to 2018 were investigated and compared. A multisite positive matrix factorization analysis was used to compare the source contributions between the two stations, while the trends for both the chemical species and source contributions were studied using the Theil-Sen trend estimator. Between 2009 and 2018, both stations showed a statistically significant decrease in PM2.5 concentrations, which was driven by the downward trends of levels of chemical species and anthropogenic source contributions, mainly from heavy oil combustion, mixed combustion, industry, and secondary sulfate. These source contributions showed a continuous decrease over the study period, signifying the continuing success of mitigation strategies, although the trends of heavy oil combustion and secondary sulfate have flattened since 2016. Secondary nitrate also followed a significant decreasing trend in BCN, while secondary organic aerosols (SOA) very slightly decreased in MSY. The observed decreasing trends, in combination with the absence of a trend for the organic aerosols (OA) at both stations, resulted in an increase in the relative proportion of OA in PM2.5 by 12% in BCN and 9% in MSY, mostly from SOA, which increased by 7% in BCN and 4% in MSY. Thus, at the end of the study period, OA accounted for 40% and 50% of the annual mean PM2.5 at BCN and MSY, respectively. This might have relevant implications for air quality policies aiming at abating PM2.5 in the study region and for possible changes in toxicity of PM2.5 due to marked changes in composition and source apportionment.

Lessons from the COVID-19 air pollution decrease in Spain: Now what?

We offer an overview of the COVID-19 -driven air quality changes across 11 metropolises in Spain with the focus on lessons learned on how continuing abating pollution. Traffic flow decreased by up to 80% during the lockdown and remained relatively low during the full relaxation (June and July). After the lockdown a significant shift from public transport to private vehicles (+21% in Barcelona) persisted due to the pervasive fear that using public transport might increase the risk of SARS-CoV-2 infection, which need to be reverted as soon as possible. NO2 levels fell below 50% of the WHO annual air quality guidelines (WHOAQGs), but those of PM2.5 were reduced less than expected due to the lower contributions from traffic, increased contributions from agricultural and domestic biomass burning, or meteorological conditions favoring high secondary aerosol formation yields. Even during the lockdown, the annual PM2.5 WHOAQG was exceeded in cities within the NE and E regions with high NH3 emissions from farming and agriculture. Decreases in PM10 levels were greater than in PM2.5 due to reduced emissions from road dust, vehicle wear, and construction/demolition. Averaged O3 daily maximum 8-h (8hDM) experienced a generalized decrease in the rural receptor sites in the relaxation (June-July) with -20% reduced mobility. For urban areas O3 8hDM responses were heterogeneous, with increases or decreases depending on the period and location. Thus, after canceling out the effect of meteorology, 5 out of 11 cities experienced O3 decreases during the lockdown, while the remaining 6 either did not experience relevant reductions or increased. During the relaxation period and coinciding with the growing O3 season (June-July), most cities experienced decreases. However, the O3 WHOAQG was still exceeded during the lockdown and full relaxation periods in several cities. For secondary pollutants, such as O3 and PM2.5, further chemical and dispersion modeling along with source apportionment techniques to identify major precursor reduction targets are required to evaluate their abatement potential.

Eye movements and abducens motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis.

STUDY OBJECTIVES: the aim of this work was to characterize eye movements and abducens (ABD) motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis (NRPC). METHODS: six female adult cats were prepared for chronic recording of eye movements (using the scleral search-coil technique), electroencephalography, electromyography, ponto-geniculo-occipital (PGO) waves in the lateral geniculate nucleus, and ABD motoneuron activities after microinjections of the cholinergic agonist carbachol into the NRPC. RESULTS: unilateral microinjections of carbachol in the NRPC induced tonic and phasic phenomena in the oculomotor system. Tonic effects consisted of ipsiversive rotation to the injected side, convergence, and downward rotation of the eyes. Phasic effects consisted of bursts of rhythmic rapid eye movements directed contralaterally to the injected side along with PGO-like waves in the lateral geniculate and ABD nuclei. Although tonic effects were dependent on the level of drowsiness, phasic effects were always present and appeared along with normal saccades when the animal was vigilant. ABD motoneurons showed phasic activities associated with ABD PGO-like waves during bursts of rapid eye movements, and tonic and phasic activities related to eye position and velocity during alertness. CONCLUSION: the cholinergic activation of the NRPC induces oculomotor phenomena that are somewhat similar to those described during REM sleep. A precise comparison of the dynamics and timing of the eye movements further suggests that a temporal organization of both NRPCs is needed to reproduce the complexity of the oculomotor behavior during REM sleep.

Eye movements and abducens motoneuron behavior during cholinergically induced REM sleep.

STUDY OBJECTIVES: The injection of cholinergic drugs in the pons has been largely used to induce REM sleep as a useful model to study different processes during this period. In the present study, microinjections of carbachol in the nucleus reticularis pontis oralis (NRPO) were performed to test the hypothesis that eye movements and the behavior of extraocular motoneurons during induced REM sleep do not differ from those during spontaneous REM sleep. METHODS: Six female adult cats were prepared for chronic recording of eye movements (by means of the search-coil technique) and electroencephalography, electromyography, ponto-geniculo-occipital (PGO) waves at the lateral geniculate nucleus, and identified abducens motoneuron activities after microinjections of the cholinergic agonist carbachol into the NRPO. RESULTS: Unilateral microinjections (n = 13) of carbachol in the NRPO induced REM sleep-like periods in which the eyes performed a convergence and downward rotation interrupted by phasic complex rapid eye movements associated to PGO waves. During induced-REM sleep abducens motoneurons lost their tonic activity and eye position codification, but continued codifying eye velocity during the burst of eye movements. CONCLUSION: The present results show that eye movements and the underlying behavior of abducens motoneurons are very similar to those present during natural REM sleep. Thus, microinjection of carbachol seems to activate the structures responsible for the exclusive oculomotor behavior observed during REM sleep, validating this pharmacological model and enabling a more efficient exploration of phasic and tonic phenomena underlying eye movements during REM sleep.

Tonic inhibition and ponto-geniculo-occipital-related activities shape abducens motoneuron discharge during REM sleep.

Eye movements, ponto-geniculo-occipital (PGO) waves, muscular atonia and desynchronized cortical activity are the main characteristics of rapid eye movement (REM) sleep. Although eye movements designate this phase, little is known about the activity of the oculomotor system during REM sleep. In this work, we recorded binocular eye movements by the scleral search-coil technique and the activity of identified abducens (ABD) motoneurons along the sleep-wake cycle in behaving cats. The activity of ABD motoneurons during REM sleep was characterized by a tonic decrease of their mean firing rate throughout this period, and short bursts and pauses coinciding with the occurrence of PGO waves. We demonstrate that the decrease in the mean firing discharge was due to an active inhibition of ABD motoneurons, and that the occurrence of primary and secondary PGO waves induced a pattern of simultaneous but opposed phasic activation and inhibition on each ABD nucleus. With regard to eye movements, during REM sleep ABD motoneurons failed to codify eye position as during alertness, but continued to codify eye velocity. The pattern of tonic inhibition and the phasic activations and inhibitions shown by ABD motoneurons coincide with those reported in other non-oculomotor motoneurons, indicating that the oculomotor system - contrary to what has been accepted until now - is not different from other motor systems during REM sleep, and that all motor systems are receiving similar command signals during this period.

Tonic and phasic phenomena underlying eye movements during sleep in the cat.

Mammalian sleep is not a homogenous state, and different variables have traditionally been used to distinguish different periods during sleep. Of these variables, eye movement is one of the most paradigmatic, and has been used to differentiate between the so-called rapid eye movement (REM) and non-REM (NREM) sleep periods. Despite this, eye movements during sleep are poorly understood, and the behaviour of the oculomotor system remains almost unknown. In the present work, we recorded binocular eye movements during the sleep-wake cycle of adult cats by the scleral search-coil technique. During alertness, eye movements consisted of conjugated saccades and eye fixations. During NREM sleep, eye movements were slow and mostly unconjugated. The two eyes moved upwardly and in the abducting direction, producing a tonic divergence and elevation of the visual axis. During the transition period between NREM and REM sleep, rapid monocular eye movements of low amplitude in the abducting direction occurred in coincidence with ponto-geniculo-occipital waves. Along REM sleep, the eyes tended to maintain a tonic convergence and depression, broken by high-frequency bursts of complex rapid eye movements. In the horizontal plane, each eye movement in the burst comprised two consecutive movements in opposite directions, which were more evident in the eye that performed the abducting movements. In the vertical plane, rapid eye movements were always upward. Comparisons of the characteristics of eye movements during the sleep-wake cycle reveal the uniqueness of eye movements during sleep, and the noteworthy existence of tonic and phasic phenomena in the oculomotor system, not observed until now.