RESUMEN
Noninvasive brain imaging studies have shown that higher visual processing of objects occurs in neural populations that are separable along broad semantic categories, particularly living versus nonliving objects. However, because of their limited temporal resolution, these studies have not been able to determine whether broad semantic categories are also reflected in the dynamics of neural interactions within cortical networks. We investigated the time course of neural propagation among cortical areas activated during object naming in 12 patients implanted with subdural electrode grids prior to epilepsy surgery, with a special focus on the visual recognition phase of the task. Analysis of event-related causality revealed significantly stronger neural propagation among sites within ventral temporal lobe (VTL) at early latencies, around 250 ms, for living objects compared to nonliving objects. Differences in other features, including familiarity, visual complexity, and age of acquisition, did not significantly change the patterns of neural propagation. Our findings suggest that the visual processing of living objects relies on stronger causal interactions among sites within VTL, perhaps reflecting greater integration of visual feature processing. In turn, this may help explain the fragility of naming living objects in neurological diseases affecting VTL.
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Mapeo Encefálico , Reconocimiento en Psicología , Humanos , Encéfalo , Lóbulo Temporal , Semántica , Reconocimiento Visual de ModelosRESUMEN
Over 15 million epilepsy patients worldwide have drug-resistant epilepsy. Successful surgery is a standard of care treatment but can only be achieved through complete resection or disconnection of the epileptogenic zone, the brain region(s) where seizures originate. Surgical success rates vary between 20% and 80%, because no clinically validated biological markers of the epileptogenic zone exist. Localizing the epileptogenic zone is a costly and time-consuming process, which often requires days to weeks of intracranial EEG (iEEG) monitoring. Clinicians visually inspect iEEG data to identify abnormal activity on individual channels occurring immediately before seizures or spikes that occur interictally (i.e. between seizures). In the end, the clinical standard mainly relies on a small proportion of the iEEG data captured to assist in epileptogenic zone localization (minutes of seizure data versus days of recordings), missing opportunities to leverage these largely ignored interictal data to better diagnose and treat patients. IEEG offers a unique opportunity to observe epileptic cortical network dynamics but waiting for seizures increases patient risks associated with invasive monitoring. In this study, we aimed to leverage interictal iEEG data by developing a new network-based interictal iEEG marker of the epileptogenic zone. We hypothesized that when a patient is not clinically seizing, it is because the epileptogenic zone is inhibited by other regions. We developed an algorithm that identifies two groups of nodes from the interictal iEEG network: those that are continuously inhibiting a set of neighbouring nodes ('sources') and the inhibited nodes themselves ('sinks'). Specifically, patient-specific dynamical network models were estimated from minutes of iEEG and their connectivity properties revealed top sources and sinks in the network, with each node being quantified by source-sink metrics. We validated the algorithm in a retrospective analysis of 65 patients. The source-sink metrics identified epileptogenic regions with 73% accuracy and clinicians agreed with the algorithm in 93% of seizure-free patients. The algorithm was further validated by using the metrics of the annotated epileptogenic zone to predict surgical outcomes. The source-sink metrics predicted outcomes with an accuracy of 79% compared to an accuracy of 43% for clinicians' predictions (surgical success rate of this dataset). In failed outcomes, we identified brain regions with high metrics that were untreated. When compared with high frequency oscillations, the most commonly proposed interictal iEEG feature for epileptogenic zone localization, source-sink metrics outperformed in predictive power (by a factor of 1.2), suggesting they may be an interictal iEEG fingerprint of the epileptogenic zone.
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Epilepsia , Convulsiones , Humanos , Estudios Retrospectivos , Electrocorticografía/métodos , Epilepsia/diagnóstico , Epilepsia/cirugía , BiomarcadoresRESUMEN
Speaking in sentences requires selection from contextually determined lexical representations. Although posterior temporal cortex (PTC) and Broca's areas play important roles in storage and selection, respectively, of lexical representations, there has been no direct evidence for physiological interactions between these areas on time scales typical of lexical selection. Using intracranial recordings of cortical population activity indexed by high-gamma power (70-150 Hz) modulations, we studied the causal dynamics of cortical language networks while epilepsy surgery patients performed a sentence completion task in which the number of potential lexical responses was systematically varied. Prior to completion of sentences with more response possibilities, Broca's area was not only more active, but also exhibited more local network interactions with and greater top-down influences on PTC, consistent with activation of, and competition between, more lexical representations. These findings provide the most direct experimental support yet for network dynamics playing a role in lexical selection among competing alternatives during speech production.
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Área de Broca/fisiología , Electrocorticografía/métodos , Ritmo Gamma/fisiología , Lenguaje , Habla/fisiología , Lóbulo Temporal/fisiología , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estimulación Luminosa/métodos , Tiempo de Reacción/fisiologíaRESUMEN
A pathological increase in vigilance, or hypervigilance, may be related to pain intensity in some clinical pain syndromes and may result from attention bias to salient stimuli mediated by anxiety. During a continuous performance task where subjects discriminated painful target stimuli from painful nontargets, we measured detected targets (hits), nondetected targets (misses), nondetected nontargets (correct rejections), and detected nontargets (false alarms). Using signal detection theory, we calculated response bias, the tendency to endorse a stimulus as a target, and discriminability, the ability to discriminate a target from nontarget. Owing to the relatively slow rate of stimulus presentation, our primary hypothesis was that sustained performance would result in a more conservative response bias reflecting a lower response rate over time on task. We found a more conservative response bias with time on task and no change in discriminability. We predicted that greater state and trait anxiety would lead to a more liberal response bias. A multivariable model provided partial support for our prediction; high trait anxiety related to a more conservative response bias (lower response rate), whereas high state anxiety related to a more liberal bias. This inverse relationship of state and trait anxiety is consistent with reports of effects of state and trait anxiety on reaction times to threatening stimuli. In sum, we report that sustained attention to painful stimuli was associated with a decrease in the tendency of the subject to respond to any stimulus over time on task, whereas the ability to discriminate target from nontarget remains unchanged.NEW & NOTEWORTHY During a series of painful stimuli requiring subjects to respond to targets, we separated response willingness from ability to discriminate targets from nontargets. Response willingness declined during the task, with no change in subjects' ability to discriminate, consistent with previous vigilance studies. High trait anxious subjects were less willing to respond and showed slower reaction times to hits than low anxious subjects. This study reveals an important role of trait anxiety in pain vigilance.
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Ansiedad/fisiopatología , Sesgo Atencional , Percepción del Dolor , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tiempo de ReacciónRESUMEN
The subthalamic nucleus (STN) is proposed to participate in pausing, or alternately, in dynamic scaling of behavioral responses, roles that have conflicting implications for understanding STN function in the context of deep brain stimulation (DBS) therapy. To examine the nature of event-related STN activity and subthalamic-cortical dynamics, we performed primary motor and somatosensory electrocorticography while subjects (n = 10) performed a grip force task during DBS implantation surgery. Phase-locking analyses demonstrated periods of STN-cortical coherence that bracketed force transduction, in both beta and gamma ranges. Event-related causality measures demonstrated that both STN beta and gamma activity predicted motor cortical beta and gamma activity not only during force generation but also prior to movement onset. These findings are consistent with the idea that the STN participates in motor planning, in addition to the modulation of ongoing movement. We also demonstrated bidirectional information flow between the STN and somatosensory cortex in both beta and gamma range frequencies, suggesting robust STN participation in somatosensory integration. In fact, interactions in beta activity between the STN and somatosensory cortex, and not between STN and motor cortex, predicted PD symptom severity. Thus, the STN contributes to multiple aspects of sensorimotor behavior dynamically across time.
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Estimulación Encefálica Profunda/métodos , Electrocorticografía/métodos , Fuerza de la Mano/fisiología , Corteza Motora/fisiología , Corteza Somatosensorial/fisiología , Núcleo Subtalámico/fisiología , Adulto , Anciano , Electrodos Implantados , Femenino , Humanos , Masculino , Persona de Mediana Edad , Desempeño Psicomotor/fisiologíaRESUMEN
Although hypervigilance may play a role in some clinical pain syndromes, experimental vigilance toward painful stimuli has been studied infrequently. We evaluated vigilance toward pain by using a continuous performance task (CPT), in which subjects responded to moderately intense painful target stimuli, occurring in a train of mildly painful nontargets. We assessed nondetected targets (misses), reaction times (RTs), and psychological activation (tense arousal). During time on task in CPTs of other sensory modalities, there is an increase in misses and RTs (vigilance decrement). We hypothesized that our CPT would influence vigilance performance related to pain, anxiety, and limitation of attentional resources. The results showed a decrement in vigilance over time as misses increased, although RTs were unchanged. While mind-wandering did not influence vigilance performance, intrinsic attention to pain drove both hit RTs and number of misses. This resulted in pain-focused subjects performing worse on the CPT pain task with slower RTs and more misses per block. During the CPT, the change in stimulus salience was related to the change in pain intensity, while pain unpleasantness correlated with tense arousal. CPT performance during experimental vigilance to pain and psychological activation were related to trait anxiety, as measured by the Spielberger State-Trait Anxiety Inventory and neuroticism, as measured by the NEO five factor inventory. Trait anxiety and neuroticism may play important roles in an individual's predisposition to dwell on pain and interpret pain as threatening.NEW & NOTEWORTHY Subjects detected moderately painful target stimuli in a train of mildly painful nontarget stimuli, which resulted in vigilance performance metrics including missed targets, reaction times, and psychological activation. These performance metrics were related to intrinsic attention to pain and trait anxiety. Subjects with high trait anxiety and neuroticism scores, with a predisposition to attend to pain, had greater tense arousal and poorer vigilance performance, which may be important psychological aspects of vigilance to pain.
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Ansiedad/fisiopatología , Nivel de Alerta/fisiología , Pruebas Neuropsicológicas , Dolor/fisiopatología , Personalidad/fisiología , Desempeño Psicomotor/fisiología , Adulto , Atención/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neuroticismo , Tiempo de Reacción/fisiología , Adulto JovenRESUMEN
Any given area in human cortex may receive input from multiple, functionally heterogeneous areas, potentially representing different processing threads. Alpha (8-13 Hz) and beta oscillations (13-20 Hz) have been hypothesized by other investigators to gate local cortical processing, but their influence on cortical responses to input from other cortical areas is unknown. To study this, we measured the effect of local oscillatory power and phase on cortical responses elicited by single-pulse electrical stimulation (SPES) at distant cortical sites, in awake human subjects implanted with intracranial electrodes for epilepsy surgery. In 4 out of 5 subjects, the amplitudes of corticocortical evoked potentials (CCEPs) elicited by distant SPES were reproducibly modulated by the power, but not the phase, of local oscillations in alpha and beta frequencies. Specifically, CCEP amplitudes were higher when average oscillatory power just before distant SPES (-110 to -10 ms) was high. This effect was observed in only a subset (0-33%) of sites with CCEPs and, like the CCEPs themselves, varied with stimulation at different distant sites. Our results suggest that although alpha and beta oscillations may gate local processing, they may also enhance the responsiveness of cortex to input from distant cortical sites.
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Ritmo alfa/fisiología , Ritmo beta/fisiología , Corteza Cerebral/fisiología , Epilepsia Refractaria/fisiopatología , Electrocorticografía/métodos , Electrodos Implantados , Adolescente , Adulto , Epilepsia Refractaria/diagnóstico , Femenino , Humanos , MasculinoRESUMEN
Anxiety disorders impose substantial costs upon public health and productivity in the USA and worldwide. At present, these conditions are quantified by self-report questionnaires that only apply to behaviors that are accessible to consciousness, or by the timing of responses to fear- and anxiety-related words that are indirect since they do not produce fear, e.g., Dot Probe Test and emotional Stroop. We now review the conditioned responses (CRs) to fear produced by a neutral stimulus (conditioned stimulus CS+) when it cues a painful laser unconditioned stimulus (US). These CRs include autonomic (Skin Conductance Response) and ratings of the CS+ unpleasantness, ability to command attention, and the recognition of the association of CS+ with US (expectancy). These CRs are directly related to fear, and some measure behaviors that are minimally accessible to consciousness e.g., economic scales. Fear-related CRs include non-phase-locked phase changes in oscillatory EEG power defined by frequency and time post-stimulus over baseline, and changes in phase-locked visual and laser evoked responses both of which include late potentials reflecting attention or expectancy, like the P300, or contingent negative variation. Increases (ERS) and decreases (ERD) in oscillatory power post-stimulus may be generalizable given their consistency across healthy subjects. ERS and ERD are related to the ratings above as well as to anxious personalities and clinical anxiety and can resolve activity over short time intervals like those for some moods and emotions. These results could be incorporated into an objective instrumented test that measures EEG and CRs of autonomic activity and psychological ratings related to conditioned fear, some of which are subliminal. As in the case of instrumented tests of vigilance, these results could be useful for the direct, objective measurement of multiple aspects of the risk, diagnosis, and monitoring of therapies for anxiety disorders and anxious personalities.
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Condicionamiento Clásico , Electroencefalografía , Miedo , Ansiedad , Trastornos de Ansiedad , Respuesta Galvánica de la Piel , HumanosRESUMEN
For over a century neuroscientists have debated the dynamics by which human cortical language networks allow words to be spoken. Although it is widely accepted that Broca's area in the left inferior frontal gyrus plays an important role in this process, it was not possible, until recently, to detail the timing of its recruitment relative to other language areas, nor how it interacts with these areas during word production. Using direct cortical surface recordings in neurosurgical patients, we studied the evolution of activity in cortical neuronal populations, as well as the Granger causal interactions between them. We found that, during the cued production of words, a temporal cascade of neural activity proceeds from sensory representations of words in temporal cortex to their corresponding articulatory gestures in motor cortex. Broca's area mediates this cascade through reciprocal interactions with temporal and frontal motor regions. Contrary to classic notions of the role of Broca's area in speech, while motor cortex is activated during spoken responses, Broca's area is surprisingly silent. Moreover, when novel strings of articulatory gestures must be produced in response to nonword stimuli, neural activity is enhanced in Broca's area, but not in motor cortex. These unique data provide evidence that Broca's area coordinates the transformation of information across large-scale cortical networks involved in spoken word production. In this role, Broca's area formulates an appropriate articulatory code to be implemented by motor cortex.
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Área de Broca/fisiología , Red Nerviosa/fisiología , Habla/fisiología , Adolescente , Adulto , Femenino , Humanos , Masculino , Corteza Motora/fisiologíaRESUMEN
OBJECTIVE: Introduction: With the increasing problem of obesity in the world, high prevalence of asthma in obese persons and high prevalence of sleep breathing disorders related to obesity, the number of patients with coexisting asthma and obesity hypoventilation syndrome is likely to increase. The aim: To evaluate long-term effects of obesity hypoventilation syndrome treatment in the patients with concomitant asthma. PATIENTS AND METHODS: Materials and methods: Obesity hypoventilation syndrome was diagnosed in six adult patients with asthma (body mass index 43.2±5.84 kg/m2, diurnal PaCO2 53.8±8.9 mmHg, apnea/hypopnea index 82±12.8/hour, mean SaO2 during sleep 77.7±6.6%). Four patients were treated with continuous positive airway pressure (CPAP) and two patients - with non-invasive ventilation (NIV). The patients were followed-up for 36±19 months. RESULTS: Results: During the follow-up period daytime PaCO2 decreased to normal values, mean SaO2 during sleep increased to 93±3.1%, p<0.001. No asthma exacerbations were observed. In two patients significant reduction of anti-asthmatic treatment was observed, including withdrawal of chronic oral corticosteroid treatment. CONCLUSION: Conclusions: Obese asthmatic patients with chronic respiratory insufficiency should be checked for concomitant obesity hypoventilation syndrome. Positive airway pressure treatment during sleep (CPAP or NIV) in asthmatic patients with obesity hypoventilation syndrome is well tolerated, leads to reversal of chronic respiratory insufficiency and in some patients may contribute to the improvement of asthma control.
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Asma/complicaciones , Síndrome de Hipoventilación por Obesidad/complicaciones , Síndrome de Hipoventilación por Obesidad/terapia , Presión de las Vías Aéreas Positiva Contínua , Humanos , Persona de Mediana Edad , Ventilación no Invasiva , Resultado del TratamientoRESUMEN
The forebrain somatic sensory locus for input from sensors on the surface of an active prosthesis is an important component of the Brain Machine Interface. We now review the neuronal responses to controlled cutaneous stimuli and the sensations produced by Threshold Stimulation at Microampere current levels (TMIS) in such a locus, the human thalamic Ventral Caudal nucleus (Vc). The responses of these neurons to tactile stimuli mirror those for the corresponding class of tactile mechanoreceptor fiber in the peripheral nerve, and TMIS can evoke sensations like those produced by the stimuli that optimally activate each class. These neuronal responses show a somatotopic arrangement from lateral to medial in the sequence: leg, arm, face and intraoral structures. TMIS evoked sensations show a much more detailed organization into anterior posteriorly oriented rods, approximately 300 microns diameter, that represent smaller parts of the body, such as parts of individual digits. Neurons responding to painful and thermal stimuli are most dense around the posterior inferior border of Vc, and TMIS evoked pain sensations occur in one of two patterns: (i) pain evoked regardless of the frequency or number of spikes in a burst of TMIS; and (ii) the description and intensity of the sensation changes with increasing frequencies and numbers. In patients with major injuries leading to loss of somatic sensory input, TMIS often evokes sensations in the representation of parts of the body with loss of sensory input, e.g., the phantom after amputation. Some patients with these injuries have ongoing pain and pain evoked by TMIS of the representation in those parts of the body. Therefore, thalamic TMIS may produce useful patterned somatotopic feedback to the CNS from sensors on an active prosthesis that is sometimes complicated by TMIS evoked pain in the representation of those parts of the body.
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Núcleos Talámicos , Humanos , Neuronas , Dolor , Prótesis e Implantes , TactoRESUMEN
Language tasks require the coordinated activation of multiple subnetworks-groups of related cortical interactions involved in specific components of task processing. Although electrocorticography (ECoG) has sufficient temporal and spatial resolution to capture the dynamics of event-related interactions between cortical sites, it is difficult to decompose these complex spatiotemporal patterns into functionally discrete subnetworks without explicit knowledge of each subnetwork's timing. We hypothesized that subnetworks corresponding to distinct components of task-related processing could be identified as groups of interactions with co-varying strengths. In this study, five subjects implanted with ECoG grids over language areas performed word repetition and picture naming. We estimated the interaction strength between each pair of electrodes during each task using a time-varying dynamic Bayesian network (tvDBN) model constructed from the power of high gamma (70-110Hz) activity, a surrogate for population firing rates. We then reduced the dimensionality of this model using principal component analysis (PCA) to identify groups of interactions with co-varying strengths, which we term functional network components (FNCs). This data-driven technique estimates both the weight of each interaction's contribution to a particular subnetwork, and the temporal profile of each subnetwork's activation during the task. We found FNCs with temporal and anatomical features consistent with articulatory preparation in both tasks, and with auditory and visual processing in the word repetition and picture naming tasks, respectively. These FNCs were highly consistent between subjects with similar electrode placement, and were robust enough to be characterized in single trials. Furthermore, the interaction patterns uncovered by FNC analysis correlated well with recent literature suggesting important functional-anatomical distinctions between processing external and self-produced speech. Our results demonstrate that subnetwork decomposition of event-related cortical interactions is a powerful paradigm for interpreting the rich dynamics of large-scale, distributed cortical networks during human cognitive tasks.
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Mapeo Encefálico/métodos , Corteza Cerebral/fisiología , Electrocorticografía/métodos , Lenguaje , Modelos Neurológicos , Red Nerviosa/fisiología , Simulación por Computador , Femenino , Humanos , Masculino , Lectura , Habla/fisiología , Adulto JovenRESUMEN
INTRODUCTION: Taking into account important role of apoptosis in COPD pathogenesis, we wanted to asses the serum levels of markers involved in apoptosis regulation, including apoptosis inducers such as TNF-a, sFasL or p53 protein and apoptosis inhibitor bcl-2 and, in addition, to compare these markers with selected COPD parameters. MATERIAL AND METHODS: In 181 patients (60 women) with COPD (age was 62.2+ 9.37 years; FEV1% 55.2 + 19.98 %) and in 29 controls (11 women), serum levels of TNF-a, sFasL, p53 and bcl-2 were evaluated by the enzyme-linked immunosorbent assay (ELISA) method. RESULTS: In COPD patients the mean sFasL level was 0.092 ± 0.077 ng/ml and mean TNF-a level was 2.911 ± 3.239 pg/ml. There were no differences in serum sFasL and TNF-a in COPD patients and control group. TNF-a and sFasL did not correlate with COPD parameters such as FEV1%, BMI, RV% (percentage of predicted value of residual volume) or BODE. Although we tried to evaluate bcl-2 and p53 protein serum levels with two different tests, measurable levels of bcl-2 were only detected in 15 patients and p53 in only 3 patients. Bcl-2 values were from 0.418 to 11.423 ng/ml and p53 from 90.772 to 994.749 pg/ml. CONCLUSIONS: We didn't observe any differences in serum levels of pro- and antiapoptotic markers in COPD patients and the control group or correlations between the markers studied and COPD parameters.
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Apoptosis , Biomarcadores/sangre , Proteína Ligando Fas/sangre , Proteínas Proto-Oncogénicas c-bcl-2/sangre , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Factor de Necrosis Tumoral alfa/sangre , Proteína p53 Supresora de Tumor/sangre , Adulto , Anciano , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Persona de Mediana Edad , Enfermedad Pulmonar Obstructiva Crónica/sangre , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Índice de Severidad de la EnfermedadRESUMEN
The spreading of antibiotic resistant bacteria in the environment is a threat to human health but little is known about the transmission of extended-spectrum beta-lactamases (ESBL)-producing Escherichia coli from the hospital and municipal sewage to the water basin and to the air at the WWTPs (Waste Water Treatment Plants) area and their surroundings. Accordingly, it seems particularly interesting to trace the fate of these bacteria and their genes encoding antibiotic resistance in both untreated sewage from hospitals, and in sewage after different stages of purification, and finally to examine the degree of their emissions to environment. Although wastewater treatment processes reduce number of bacteria in sewage up to 99%, in the presented study it was reported that more than 2.7×10(3) CFU/mL E. coli reached the receiving water and contributed to dissemination of resistant bacteria into the environment. We received 395 E. coli strains from sewage and environmental samples and we investigated their antibiotic susceptibility and the presence of bla gene encoding TEM, CTX, OXA and SHV. From among 167 and 147 E. coli strains isolated from hospital effluents and municipal sewage in Olsztyn, Poland, up to 37.1% and 17.7%, respectively, were ESBL-positive. From among 38 and 43 strains isolated from river water and the air up to 18.4% and 27.9%, respectively, were ESBL-producers. The blaCTX-M (blaCTX-M-1, blaCTX-M-3, blaCTX-M-5, blaCTX-M-15) genes were the predominant group of the plasmid-coded ESBLs. More than 38% out of ESBL-producing isolates carried several bla genes. The multiple-antibiotic-resistant (MAR) indexes for ESBL-positive were higher than for ESBL-negative isolates and ranged from 0.45 to 0.63. The MAR indexes for E. coli from hospital effluents and air samples were greater than the indexes calculated for strains isolated from other samples. Presumably, the preliminary disinfection of hospital sewage before its inflow into the sewage system might minimize the spreading of antibiotic-resistant bacteria to the environment.
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Microbiología Ambiental , Monitoreo del Ambiente , Escherichia coli/fisiología , Hospitales , Aguas del Alcantarillado/microbiología , Microbiología del Aire , Antibacterianos/farmacología , Farmacorresistencia Bacteriana/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Humanos , PoloniaRESUMEN
Speech requires successful information transfer within cortical-basal ganglia loop circuits to produce the desired acoustic output. For this reason, up to 90% of Parkinson's disease patients experience impairments of speech articulation. Deep brain stimulation (DBS) is highly effective in controlling the symptoms of Parkinson's disease, sometimes alongside speech improvement, but subthalamic nucleus (STN) DBS can also lead to decreases in semantic and phonological fluency. This paradox demands better understanding of the interactions between the cortical speech network and the STN, which can be investigated with intracranial EEG recordings collected during DBS implantation surgery. We analyzed the propagation of high-gamma activity between STN, superior temporal gyrus (STG), and ventral sensorimotor cortices during reading aloud via event-related causality, a method that estimates strengths and directionalities of neural activity propagation. We employed a newly developed bivariate smoothing model based on a two-dimensional moving average, which is optimal for reducing random noise while retaining a sharp step response, to ensure precise embedding of statistical significance in the time-frequency space. Sustained and reciprocal neural interactions between STN and ventral sensorimotor cortex were observed. Moreover, high-gamma activity propagated from the STG to the STN prior to speech onset. The strength of this influence was affected by the lexical status of the utterance, with increased activity propagation during word versus pseudoword reading. These unique data suggest a potential role for the STN in the feedforward control of speech.
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Neural activity emerges and propagates swiftly between brain areas. Investigation of these transient large-scale flows requires sophisticated statistical models. We present a method for assessing the statistical confidence of event-related neural propagation. Furthermore, we propose a criterion for statistical model selection, based on both goodness of fit and width of confidence intervals. We show that event-related causality (ERC) with two-dimensional (2D) moving average, is an efficient estimator of task-related neural propagation and that it can be used to determine how different cognitive task demands affect the strength and directionality of neural propagation across human cortical networks. Using electrodes surgically implanted on the surface of the brain for clinical testing prior to epilepsy surgery, we recorded electrocorticographic (ECoG) signals as subjects performed three naming tasks: naming of ambiguous and unambiguous visual objects, and as a contrast, naming to auditory description. ERC revealed robust and statistically significant patterns of high gamma activity propagation, consistent with models of visually and auditorily cued word production. Interestingly, ambiguous visual stimuli elicited more robust propagation from visual to auditory cortices relative to unambiguous stimuli, whereas naming to auditory description elicited propagation in the opposite direction, consistent with recruitment of modalities other than those of the stimulus during object recognition and naming. The new method introduced here is uniquely suitable to both research and clinical applications and can be used to estimate the statistical significance of neural propagation for both cognitive neuroscientific studies and functional brain mapping prior to resective surgery for epilepsy and brain tumors.
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Electroencefalografía , Epilepsia , Encéfalo , Mapeo Encefálico/métodos , Electroencefalografía/métodos , Epilepsia/cirugía , Humanos , Redes Neurales de la ComputaciónRESUMEN
Intracranial EEG studies in humans have shown that functional brain activation in a variety of functional-anatomic domains of human cortex is associated with an increase in power at a broad range of high gamma (>60Hz) frequencies. Although these electrophysiological responses are highly specific for the location and timing of cortical processing and in animal recordings are highly correlated with increased population firing rates, there has been little direct empirical evidence for causal interactions between different recording sites at high gamma frequencies. Such causal interactions are hypothesized to occur during cognitive tasks that activate multiple brain regions. To determine whether such causal interactions occur at high gamma frequencies and to investigate their functional significance, we used event-related causality (ERC) analysis to estimate the dynamics, directionality, and magnitude of event-related causal interactions using subdural electrocorticography (ECoG) recorded during two word production tasks: picture naming and auditory word repetition. A clinical subject who had normal hearing but was skilled in American Signed Language (ASL) provided a unique opportunity to test our hypothesis with reference to a predictable pattern of causal interactions, i.e. that language cortex interacts with different areas of sensorimotor cortex during spoken vs. signed responses. Our ERC analyses confirmed this prediction. During word production with spoken responses, perisylvian language sites had prominent causal interactions with mouth/tongue areas of motor cortex, and when responses were gestured in sign language, the most prominent interactions involved hand and arm areas of motor cortex. Furthermore, we found that the sites from which the most numerous and prominent causal interactions originated, i.e. sites with a pattern of ERC "divergence", were also sites where high gamma power increases were most prominent and where electrocortical stimulation mapping interfered with word production. These findings suggest that the number, strength and directionality of event-related causal interactions may help identify network nodes that are not only activated by a task but are critical to its performance.
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Mapeo Encefálico/métodos , Corteza Cerebral/fisiología , Vías Nerviosas/fisiología , Habla/fisiología , Electroencefalografía , Femenino , Humanos , Persona de Mediana Edad , Convulsiones/fisiopatología , Procesamiento de Señales Asistido por ComputadorRESUMEN
The Second International Workshop on Advances in Electrocorticography (ECoG) was convened in San Diego, CA, USA, on November 11-12, 2010. Between this meeting and the inaugural 2009 event, a much clearer picture has been emerging of cortical ECoG physiology and its relationship to local field potentials and single-cell recordings. Innovations in material engineering are advancing the goal of a stable long-term recording interface. Continued evolution of ECoG-driven brain-computer interface technology is determining innovation in neuroprosthetics. Improvements in instrumentation and statistical methodologies continue to elucidate ECoG correlates of normal human function as well as the ictal state. This proceedings document summarizes the current status of this rapidly evolving field.
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Mapeo Encefálico , Ondas Encefálicas/fisiología , Encéfalo/fisiopatología , Electroencefalografía , Epilepsia/diagnóstico , Encéfalo/patología , Diagnóstico por Computador , Electroencefalografía/instrumentación , Electroencefalografía/métodos , Epilepsia/fisiopatología , Humanos , Estados Unidos , Interfaz Usuario-ComputadorRESUMEN
UNLABELLED: Lung cancer is the leading cause of cancer death in the majority of developed countries. Uncontrolled cell proliferation is the hallmark of malignant tumours. Cyclins play an important role in cell cycle regulation. The aim of this study was to evaluate the expression of cyclins A, B1, D1 and E in advanced non-small cell lung cancer (stages IIIB-IV) with its prognostic significance. MATERIAL AND METHOD: An immunohistochemical assessment of cyclins A, B1, D1 and E expression was performed in the paraffin-embedded tumor tissues of 19 patients (9 men and 10 women). The mean was age 59 +/- 6.64 years. 9 patients were in IIIB and 10 in IV. The 2-years survival rate was evaluated. RESULTS: We showed positive cyclin A expression in 13 tumor tissue specimens (68%), cyclin B1 in 3 (16%), cyclin D1 in 9 (47%) and cyclin E in 7 (37%). We analyzed the prognostic value of examinated cyclins in all NSCLC patients and separately in patients with squamous cell lung cancer and adenocarcinoma and in patients in stage IIIB and IV, but we have no found any correlations. We did not find also any differences in examinated cyclins expression depending on stages nor different histopathological types. CONCLUSION: We did not observe prognostic value of cyclins A, B1, D1 or E expression in advanced non-small cell lung cancer.
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Biomarcadores de Tumor/metabolismo , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Carcinoma de Pulmón de Células no Pequeñas/patología , Ciclinas/metabolismo , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Adenocarcinoma/metabolismo , Adenocarcinoma/patología , Carcinoma de Pulmón de Células no Pequeñas/mortalidad , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patología , Ciclina A/metabolismo , Ciclina B1/metabolismo , Ciclina D1/metabolismo , Ciclina E/metabolismo , Femenino , Humanos , Inmunohistoquímica , Neoplasias Pulmonares/mortalidad , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Pronóstico , Tasa de SupervivenciaRESUMEN
Medical oxygen is the key to survival for COVID-19 patients. To meet the pandemic-driven oxygen demand spike, local hospitals began searching for a suitable medical oxygen delivery system. Among the studies published on the impact of COVID-19 on a range of aspects, including the global economy and the environment, no study has been conducted on the environmental impact of medical oxygen supply to hospitals under epidemic conditions. In this paper the authors perform a comparative Life Cycle Assessment (LCA) to evaluate the environmental and economic impact of three scenarios (oxygen cylinders, liquid oxygen in tanks and on-site oxygen production) of local oxygen supply to hospitals in Poland. The LCA was performed according to ISO 14040 -14044 standards requirements, using the SimaPro 9.0 software. Results from the analysis showed that the Global Warming Potential (GWP) and Fine Particulate Matter Formation Potential (FPMFP) indicators for the liquid oxygen in tank scenario are the lowest and equal 265 kg CO2 eq and 0.309 kg PM2.5 eq. respectively. The greatest terrestrial acidification reductions (-1.38 kg SO2 eq) can be achieved when applying the on-site oxygen production scenario. Our findings revealed that the oxygen in cylinders scenario has the most harmful impact on the environment. The economic analysis was performed in order to compare the monthly and annual operational costs of analysed scenarios. The results show that hospitals sustain the lowest annual costs when using the on-site oxygen production scenario.