Health status of free-ranging pure and cross-mixed miniature swine population from Northeast Spain.

BACKGROUND: Miniature pigs have gained popularity as companion animals in the recent years in Spain. Due to the fact that their abandonment and crossing breeds with wild boars can cause severe problems, investigation about the health status is needed. OBJECTIVES: The aim of this study was to determine their health status according to the clinical findings during physical examination and the results of antibody serology tests against selected infectious diseases. METHODS: Two-hundred and eleven miniature pigs (Sus scrofa) were included in the study. Their origin, age, sex, housing conditions and diet were recorded. RESULTS: The housing of the animals ranged from wild animals to ones living in animal sanctuaries. The diet varied from a natural one in the wild to commercial and homemade food. Thirty animals out of two-hundred and eleven were hybrids between miniature pigs and wild boars according to morphological characteristics. Antibody serology techniques of Influenza A virus, Hepatitis E virus, brucellosis, tuberculosis, African swine fever, Classical swine fever and Aujeszky's disease was performed. The prevalence for Influenza A was 5.30%, for Hepatitis E was 5.35% and the rest tested negative. It is important to control and monitor these zoonotic infections to prevent Public Health problems. CONCLUSIONS: The results obtained from this investigation demonstrated that the animals' health status in this study is optimal and the diseases prevalence is similar or minor when compared to previous studies. This study confirms the hybridization of miniature pig and wild boar in Catalonia.

Clinical symptoms are correlated with gastrojejunal anastomosis complications only during the first year after laparoscopic Roux-en-Y gastric bypass / Los síntomas clínicos se relacionan con las complicaciones de la anastomosis gastroyeyunal solamente durante el primer año después del baipás gástrico laparoscópico

Introduction: after laparoscopic Roux-en-Y gastric bypass (LRYGBP) many patients complain of epigastric pain or food intolerance, leading to the performance of upper gastrointestinal (UGI) endoscopy. Objective: this study aims to assess which symptomatology as reported by LRYGBP patients during follow-up suggested correlation with pathological findings of endoscopy, and which factors might play a role, taking the timing of symptom presentation into account. Materials and methods: a retrospective cohort study was performed identifying LRYGBP patients presenting with food intolerance and/or epigastric pain who had undergone endoscopy. Primary outcomes were endoscopy findings, their association with patient characteristics, and timing of symptom presentation. Results: of the 514 patients complaining of epigastric pain and/or food intolerance, 81 (15.6 %) underwent endoscopy. A gastrojejunostomy complication was found in 58 % of cases. All patients who complained about food intolerance and epigastric pain presented pathological findings. The only preoperative factor associated with a gastrojejunostomy complication was being a smoker (p = 0.021). Time between surgery and endoscopy was also a predictive factor for endoscopic pathological findings (p = 0.007); in cases of epigastric pain, symptom onset during the first year (median: 10 months) was related to increased risk of gastrojejunal complications (p < 0.05). Conclusions: endoscopies performed within one year of surgery were significantly more likely to reveal pathological findings than endoscopies performed after the first postoperative year, especially in patients experiencing epigastric pain. (AU)

Introducción: tras un baipás gástrico laparoscópico en “Y de Roux” muchos pacientes refieren dolor epigástrico o intolerancia alimenticia, lo que motiva la realización de una endoscopia digestiva alta. Objetivos: el objetivo de este estudio es intentar establecer una relación entre la sintomatología referida por los pacientes sometidos a baipás gástrico con los hallazgos endoscópicos patológicos y conocer qué factores pueden estar implicados, considerando el momento de presentación. Material y métodos: estudio retrospectivo de cohortes, identificando a los pacientes sometidos a baipás gástrico laparoscópico que presentan dolor epigástrico o intolerancia alimenticia durante el seguimiento y a los que se realizó una endoscopia digestiva alta. El objetivo primario es relacionar los hallazgos endoscópicos con la sintomatología y el momento de aparición. Resultados: de los 514 pacientes que presentaban dolor epigástrico o intolerancia alimenticia, 81 (15,6 %) fueron sometidos a endoscopia digestiva alta. En un 58 % de los casos se encontraron complicaciones relacionadas con la gastroyeyunostomía. En todos los pacientes que presentaban simultáneamente dolor e intolerancia aparecieron hallazgos endoscópicos patológicos. El único factor preoperatorio relacionado con las complicaciones fue el hábito tabáquico (p = 0,021). El tiempo entre la cirugía y la realización de la endoscopia también fue un factor significativamente relacionado con los hallazgos endoscópicos (p = 0,007). En los casos de dolor epigástrico durante el primer año (media: 10 meses) existía un incremento del riesgo de aparición de complicaciones de la gastroyeyunostomía (p < 0,05). Conclusiones: las endoscopias realizadas durante el primer año postoperatorio tenían más probabilidades de presentar hallazgos patológicos, sobre todo en los pacientes afectos de dolor epigástrico. (AU)

Clinical symptoms are correlated with gastrojejunal anastomosis complications only during the first year after laparoscopic Roux-en-Y gastric bypass.

INTRODUCTION: Introduction: after laparoscopic Roux-en-Y gastric bypass (LRYGBP) many patients complain of epigastric pain or food intolerance, leading to the performance of upper gastrointestinal (UGI) endoscopy. Objective: this study aims to assess which symptomatology as reported by LRYGBP patients during follow-up suggested correlation with pathological findings of endoscopy, and which factors might play a role, taking the timing of symptom presentation into account. Materials and methods: a retrospective cohort study was performed identifying LRYGBP patients presenting with food intolerance and/or epigastric pain who had undergone endoscopy. Primary outcomes were endoscopy findings, their association with patient characteristics, and timing of symptom presentation. Results: of the 514 patients complaining of epigastric pain and/or food intolerance, 81 (15.6 %) underwent endoscopy. A gastrojejunostomy complication was found in 58 % of cases. All patients who complained about food intolerance and epigastric pain presented pathological findings. The only preoperative factor associated with a gastrojejunostomy complication was being a smoker (p = 0.021). Time between surgery and endoscopy was also a predictive factor for endoscopic pathological findings (p = 0.007); in cases of epigastric pain, symptom onset during the first year (median: 10 months) was related to increased risk of gastrojejunal complications (p < 0.05). Conclusions: endoscopies performed within one year of surgery were significantly more likely to reveal pathological findings than endoscopies performed after the first postoperative year, especially in patients experiencing epigastric pain.

INTRODUCCIÓN: Introducción: tras un baipás gástrico laparoscópico en "Y de Roux" muchos pacientes refieren dolor epigástrico o intolerancia alimenticia, lo que motiva la realización de una endoscopia digestiva alta. Objetivos: el objetivo de este estudio es intentar establecer una relación entre la sintomatología referida por los pacientes sometidos a baipás gástrico con los hallazgos endoscópicos patológicos y conocer qué factores pueden estar implicados, considerando el momento de presentación. Material y métodos: estudio retrospectivo de cohortes, identificando a los pacientes sometidos a baipás gástrico laparoscópico que presentan dolor epigástrico o intolerancia alimenticia durante el seguimiento y a los que se realizó una endoscopia digestiva alta. El objetivo primario es relacionar los hallazgos endoscópicos con la sintomatología y el momento de aparición. Resultados: de los 514 pacientes que presentaban dolor epigástrico o intolerancia alimenticia, 81 (15,6 %) fueron sometidos a endoscopia digestiva alta. En un 58 % de los casos se encontraron complicaciones relacionadas con la gastroyeyunostomía. En todos los pacientes que presentaban simultáneamente dolor e intolerancia aparecieron hallazgos endoscópicos patológicos. El único factor preoperatorio relacionado con las complicaciones fue el hábito tabáquico (p = 0,021). El tiempo entre la cirugía y la realización de la endoscopia también fue un factor significativamente relacionado con los hallazgos endoscópicos (p = 0,007). En los casos de dolor epigástrico durante el primer año (media: 10 meses) existía un incremento del riesgo de aparición de complicaciones de la gastroyeyunostomía (p < 0,05). Conclusiones: las endoscopias realizadas durante el primer año postoperatorio tenían más probabilidades de presentar hallazgos patológicos, sobre todo en los pacientes afectos de dolor epigástrico.

Paradoxical Vestibular Syndrome Caused by a Presumptive Cerebellar Infarction in a Rabbit.

A 6-year-old, female spayed rabbit (Oryctolagus cuniculus) presented with right paradoxical vestibular signs. Magnetic resonance imaging was performed and findings were consistent with an ischemic infarct of the cerebellum. The patient improved gradually and was free of clinical signs at the time this article was written. To the authors' knowledge this is the first case report of a paradoxical vestibular syndrome in a rabbit secondary to a presumptive ischemic infarct. Strokes should be included in the differential diagnosis of central vestibular syndrome in rabbits.

Utilidad de la colangioscopia digital en el diagnóstico de la colangiopatía por IgG4 y en la exclusión de colangiocarcinoma / Usefulness of digital cholangioscopy for IgG4-related cholangitis diagnosis and cholangiocarcinoma exclusion

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Utilidad de la colangiopancreatografía retrógrada endoscópica en el diagnóstico y tratamiento de las lesiones yatrogénicas de vía biliar tras colecistectomía / The role of endoscopic retrograde cholangiopancreatography in the management of iatrogenic bile duct injury after cholecystectomy

Introducción: la lesión yatrogénica de la vía biliar (LYVB) es una complicación con elevada morbilidad tras la colecistectomía. En los últimos años la endoscopia ha adquirido un papel fundamental en el manejo de esta patología. Métodos: estudio retrospectivo de LYVB tras colecistectomía abierta (CA) o colecistectomía laparoscópica (CL) tratadas en nuestro centro entre 1993 y 2017. Se analizaron los datos referentes a las características clínicas, tipo de lesión según la clasificación de Strasberg-Bismuth, diagnóstico, técnica de reparación y seguimiento. Resultados: se estudian 46 pacientes. La incidencia LYVB fue de 0,48%, 0,61% para las CL y 0,24% para las CA. El diagnóstico se realizó de forma intraoperatoria en 12 casos (26%) y mediante colangiopancreatografía retrógrada endoscópica (CPRE) en 10 (21,7%). Las características más comunes a todos los pacientes con LYVB fueron la colecistitis aguda (20/46, 43,5%), ingreso previo por patología biliar (16/46, 43,2%) y realización de CPRE previa a la colecistectomía (7/46, 18,9%). Los tipos de LYVB más frecuentes fueron el D (17/46, 36,9%) y el A (15/46, 32,6%). El tratamiento más empleado fue sutura primaria (13/46, 28,3%) seguido de CPRE (11/46, 23,9%) con esfinterotomía y/o endoprótesis. Además, la CPRE se utilizó en el postoperatorio inmediato de 6 pacientes (13%) con reparación quirúrgica de la LYVB para solucionar complicaciones inmediatas. Conclusión: la CPRE es útil en el manejo de la LYVB no diagnosticada intraoperatoriamente. Permite localizar la zona lesionada de la vía biliar, realizar maniobras terapéuticas y tratar de manera satisfactoria algunas complicaciones postoperatorias

Introduction: iatrogenic bile duct injury (IBDI) is a complication with a high morbidity after cholecystectomy. In recent years, endoscopy has acquired a fundamental role in the management of this pathology. Methods: a retrospective study of IBDI after open cholecystectomy (OC) or laparoscopic cholecystectomy (LC) of patients treated in our center between 1993 and 2017 was performed. Clinical characteristics, type of injury according to the Strasberg-Bismuth classification, diagnosis, repair techniques and follow-up were analyzed. Results: 46 patients were studied and IBDI incidence was 0.48%, 0.61% for LC and 0.24% for OC. A diagnosis was made intraoperatively in 12 cases (26%) and by endoscopic retrograde cholangiopancreatography (ERCP) in 10 (21.7%) cases. The most common IBDI patient characteristics were acute cholecystitis (20/46, 43.5%), previous admission due to biliary pathology (16/46, 43.2%) and ERCP prior to cholecystectomy (7/46, 18.9%). The most frequent types of IBDI were D (17/46, 36.9%) and A (15/46, 32.6%). The most commonly used treatment was primary suture (13/46, 28.3%) followed by ERCP (11/46, 23.9%) with sphincterotomy and/or stents. In addition, ERCP was performed during the immediate postoperative period in 6 (13%) patients with a surgical IBDI repair in order to resolve immediate complications. Conclusion: ERCP is useful in the management of IBDI that is not diagnosed intraoperatively. This procedure facilitates the localization of the injured area of the bile duct, therapeutic maneuvers and successful outcomes in postoperative complications

The role of endoscopic retrograde cholangiopancreatography in the management of iatrogenic bile duct injury after cholecystectomy.

INTRODUCTION: iatrogenic bile duct injury (IBDI) is a complication with a high morbidity after cholecystectomy. In recent years, endoscopy has acquired a fundamental role in the management of this pathology. METHODS: a retrospective study of IBDI after open cholecystectomy (OC) or laparoscopic cholecystectomy (LC) of patients treated in our center between 1993 and 2017 was performed. Clinical characteristics, type of injury according to the Strasberg-Bismuth classification, diagnosis, repair techniques and follow-up were analyzed. RESULTS: 46 patients were studied and IBDI incidence was 0.48%, 0.61% for LC and 0.24% for OC. A diagnosis was made intraoperatively in 12 cases (26%) and by endoscopic retrograde cholangiopancreatography (ERCP) in 10 (21.7%) cases. The most common IBDI patient characteristics were acute cholecystitis (20/46, 43.5%), previous admission due to biliary pathology (16/46, 43.2%) and ERCP prior to cholecystectomy (7/46, 18.9%). The most frequent types of IBDI were D (17/46, 36.9%) and A (15/46, 32.6%). The most commonly used treatment was primary suture (13/46, 28.3%) followed by ERCP (11/46, 23.9%) with sphincterotomy and/or stents. In addition, ERCP was performed during the immediate postoperative period in 6 (13%) patients with a surgical IBDI repair in order to resolve immediate complications. CONCLUSION: ERCP is useful in the management of IBDI that is not diagnosed intraoperatively. This procedure facilitates the localization of the injured area of the bile duct, therapeutic maneuvers and successful outcomes in postoperative complications.

Bowel perforation after pneumatic dilatation: Management with fully covered self-expandable metallic stent / Perforación colónica tras dilatación neumática: manejo con prótesis metálica autoexpandible totalmente recubierta

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Análisis retrospectivo multicéntrico de las incidencias asociadas a las prótesis de aposición luminal tipo Axios(TM) / A retrospective, multicenter analysis of incidents associated with Axios(TM) lumen-apposing stents

Introducción: existe controversia respecto a los riesgos asociados a las prótesis de aposición luminal (PAL), con importantes variaciones entre los trabajos disponibles. Objetivos: describir el tipo y la proporción de complicaciones durante la permanencia y retirada de PAL tipo Axios(TM). Describir la relación entre tiempo de permeabilidad, diana terapéutica y presencia de complicaciones. Métodos: serie de casos retrospectiva y multicéntrica que incluyó todos los pacientes consecutivos a los que se les colocó una PAL para acceder a estructuras extraluminales durante el año 2017. Se registraron únicamente aquellos casos que alcanzaron éxito técnico. Resultados: se incluyeron 179 pacientes de siete centros (rango 4-68 casos/centro) con edad media de 64,3 años (DE: 15,8, rango 24,6-98,8 años), 122 (68,2%) de ellos varones. Las indicaciones más frecuentes fueron las necrosis encapsuladas (58, 32,4%), seguidas de pseudoquistes (31, 17,3%) y drenajes vesiculares (26, 14,5%). Durante la permanencia de la PAL se documentaron complicaciones en 19 pacientes (10,9%), siendo las más frecuentes las obstrucciones de la luz protésica o del marco gastroduodenal en ocho (4,5%) casos y las hemorragias en siete (3,9%) pacientes. Las PAL no se retiraron en 86 pacientes (48%) por los siguientes motivos: intención permanente de la PAL en 46 (53,5%), pérdida del seguimiento en 18 (20,9%), fallecimiento del paciente en 16 (18,6%) y migración en seis (7%). Durante la retirada se observaron cinco complicaciones (5,4%), tres casos de hemorragia y dos perforaciones. No observamos una asociación entre el tiempo de permanencia y las complicaciones (p = 0,67). Conclusión: la aparición de complicaciones secundarias a la inserción de PAL es poco frecuente, aunque pueden ser graves. En este estudio no se ha observado una asociación entre la aparición de complicaciones y el tiempo de permanencia de la prótesis

Introduction: there is controversy with regard to the risks associated with lumen-apposing metal stents (LAMSs), with significant variations between available reports. Objectives: to describe the types and proportions of complications that arise during the permanence time and removal of Axios(TM) LAMS. Furthermore, the relationship between patency time, therapeutic target and the presence of complications was also described. Methods: a retrospective, multicenter case series study was performed of all patients with an implanted LAMS to access extra-luminal structures during 2017. Only technically successful cases were recorded. Results: a total of 179 patients from seven sites (range, 4-68 cases/site) were included in the study, with a mean age of 64.3 years (SD: 15.8; range: 24.6-98.8 years) and 122 (68.2%) were male. Most common indications included encapsulated necrosis (58, 32.4%), pseudocysts (31, 17.3%) and gallbladder drains (26, 14.5%). Complications during LAMS stay were reported in 19 patients (10.9%); stent lumen or gastroduodenal obstruction (8, 4.5%) and bleeding (7, 3.9%) were the most common. LAMS were not removed in 86 (48%) patients due to the following reasons: a permanent stent was used (46, 53.5%), loss to follow-up (18, 20.9%), patient demise (16, 18.6%) and stent migration (6, 7%). Five (5.4%) complications were reported during stent removal, which were three bleeds and two perforations. No association was found between stent duration and complications (p = 0.67). Conclusion: complications secondary to LAMS insertion are uncommon but may be serious. This study found no association between complications and stent duration

A retrospective, multicenter analysis of incidents associated with Axios™ lumen-apposing stents.

INTRODUCTION: there is controversy with regard to the risks associated with lumen-apposing metal stents (LAMSs), with significant variations between available reports. OBJECTIVES: to describe the types and proportions of complications that arise during the permanence time and removal of Axios™ LAMS. Furthermore, the relationship between patency time, therapeutic target and the presence of complications was also described. METHODS: a retrospective, multicenter case series study was performed of all patients with an implanted LAMS to access extra-luminal structures during 2017. Only technically successful cases were recorded. RESULTS: a total of 179 patients from seven sites (range, 4-68 cases/site) were included in the study, with a mean age of 64.3 years (SD: 15.8; range: 24.6-98.8 years) and 122 (68.2%) were male. Most common indications included encapsulated necrosis (58, 32.4%), pseudocysts (31, 17.3%) and gallbladder drains (26, 14.5%). Complications during LAMS stay were reported in 19 patients (10.9%); stent lumen or gastroduodenal obstruction (8, 4.5%) and bleeding (7, 3.9%) were the most common. LAMS were not removed in 86 (48%) patients due to the following reasons: a permanent stent was used (46, 53.5%), loss to follow-up (18, 20.9%), patient demise (16, 18.6%) and stent migration (6, 7%). Five (5.4%) complications were reported during stent removal, which were three bleeds and two perforations. No association was found between stent duration and complications (p = 0.67). CONCLUSION: complications secondary to LAMS insertion are uncommon but may be serious. This study found no association between complications and stent duration.

Tratamiento endoscópico de una membrana duodenal fenestrada mediante dilatación / Fenestrated duodenal web treated by endoscopic dilatation

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Nonlinear decoding of a complex movie from the mammalian retina.

Retina is a paradigmatic system for studying sensory encoding: the transformation of light into spiking activity of ganglion cells. The inverse problem, where stimulus is reconstructed from spikes, has received less attention, especially for complex stimuli that should be reconstructed "pixel-by-pixel". We recorded around a hundred neurons from a dense patch in a rat retina and decoded movies of multiple small randomly-moving discs. We constructed nonlinear (kernelized and neural network) decoders that improved significantly over linear results. An important contribution to this was the ability of nonlinear decoders to reliably separate between neural responses driven by locally fluctuating light signals, and responses at locally constant light driven by spontaneous-like activity. This improvement crucially depended on the precise, non-Poisson temporal structure of individual spike trains, which originated in the spike-history dependence of neural responses. We propose a general principle by which downstream circuitry could discriminate between spontaneous and stimulus-driven activity based solely on higher-order statistical structure in the incoming spike trains.

High Accuracy Decoding of Dynamical Motion from a Large Retinal Population.

Motion tracking is a challenge the visual system has to solve by reading out the retinal population. It is still unclear how the information from different neurons can be combined together to estimate the position of an object. Here we recorded a large population of ganglion cells in a dense patch of salamander and guinea pig retinas while displaying a bar moving diffusively. We show that the bar's position can be reconstructed from retinal activity with a precision in the hyperacuity regime using a linear decoder acting on 100+ cells. We then took advantage of this unprecedented precision to explore the spatial structure of the retina's population code. The classical view would have suggested that the firing rates of the cells form a moving hill of activity tracking the bar's position. Instead, we found that most ganglion cells in the salamander fired sparsely and idiosyncratically, so that their neural image did not track the bar. Furthermore, ganglion cell activity spanned an area much larger than predicted by their receptive fields, with cells coding for motion far in their surround. As a result, population redundancy was high, and we could find multiple, disjoint subsets of neurons that encoded the trajectory with high precision. This organization allows for diverse collections of ganglion cells to represent high-accuracy motion information in a form easily read out by downstream neural circuits.

Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands.

The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago. If a mantle-plume is indeed responsible for the Canaries, the onshore volcanic age-progression should be complemented by progressively younger pre-island sedimentary strata towards the west, however, direct age constraints for the westernmost pre-island sediments are lacking. Here we report on new age data obtained from calcareous nannofossils in sedimentary xenoliths erupted during the 2011 El Hierro events, which date the sub-island sedimentary rocks to between late Cretaceous and Pliocene in age. This age-range includes substantially younger pre-volcanic sedimentary rocks than the Jurassic to Miocene strata known from the older eastern islands and now reinstate the mantle-plume hypothesis as the most plausible explanation for Canary volcanism. The recently discovered Cretaceous submarine volcanic rocks in the region are, in turn, part of an older, fracture-related tectonic episode.

New evidence of early Neanderthal disappearance in the Iberian Peninsula.

The timing of the end of the Middle Palaeolithic and the disappearance of Neanderthals continue to be strongly debated. Current chronometric evidence from different European sites pushes the end of the Middle Palaeolithic throughout the continent back to around 42 thousand years ago (ka). This has called into question some of the dates from the Iberian Peninsula, previously considered as one of the last refuge zones of the Neanderthals. Evidence of Neanderthal occupation in Iberia after 42 ka is now very scarce and open to debate on chronological and technological grounds. Here we report thermoluminescence (TL) and optically stimulated luminescence (OSL) dates from El Salt, a Middle Palaeolithic site in Alicante, Spain, the archaeological sequence of which shows a transition from recurrent to sporadic human occupation culminating in the abandonment of the site. The new dates place this sequence within MIS 3, between ca. 60 and 45 ka. An abrupt sedimentary change towards the top of the sequence suggests a strong aridification episode coinciding with the last Neanderthal occupation of the site. These results are in agreement with current chronometric data from other sites in the Iberian Peninsula and point towards possible breakdown and disappearance of the Neanderthal local population around the time of the Heinrich 5 event. Iberian sites with recent dates (<40 ka) attributed to the Middle Palaeolithic should be revised in the light of these data.

Human gamma oscillations during slow wave sleep.

Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS). At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30-50 Hz) and high (60-120 Hz) frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves ("IN-phase" pattern), confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave ("ANTI-phase" pattern). This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks.

Large-scale cortical dynamics of sleep slow waves.

Slow waves constitute the main signature of sleep in the electroencephalogram (EEG). They reflect alternating periods of neuronal hyperpolarization and depolarization in cortical networks. While recent findings have demonstrated their functional role in shaping and strengthening neuronal networks, a large-scale characterization of these two processes remains elusive in the human brain. In this study, by using simultaneous scalp EEG and intracranial recordings in 10 epileptic subjects, we examined the dynamics of hyperpolarization and depolarization waves over a large extent of the human cortex. We report that both hyperpolarization and depolarization processes can occur with two different characteristic time durations which are consistent across all subjects. For both hyperpolarization and depolarization waves, their average speed over the cortex was estimated to be approximately 1 m/s. Finally, we characterized their propagation pathways by studying the preferential trajectories between most involved intracranial contacts. For both waves, although single events could begin in almost all investigated sites across the entire cortex, we found that the majority of the preferential starting locations were located in frontal regions of the brain while they had a tendency to end in posterior and temporal regions.