Publications by authors named "Marcelo Reyes"

Building-Integrated Greenery systems, i.e., green roofs, walls, and facades, are Nature-based Solutions that make possible the renaturing of cities when there is no room for traditional greenery solutions.

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Evidence suggests that neuropsychiatric symptoms and deficits in attentional control and executive function can impair time discrimination, demonstrating the intricate link between cognitive processes, subjective well-being, and perception of time. However, the relationship between sleep quality and time discrimination remains elusive. This study aimed to understand differences in the temporal bisection task (TBT) performance.

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Unlabelled: Yoga is one of the most common Complementary and Alternative Medicines (CAM) for mind-body approaches to psychological and stress-related conditions in aging. Such wide usage demands the review and systematization of the scientific literature, searching for accumulated evidence of its effectiveness. We reviewed the literature to assess whether Yoga would offer significant improvements to neuropsychiatric aspects of the elderly: anxiety, depression, stress, memory and executive functions.

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Inferring the structural connectivity from electrophysiological measurements is a fundamental challenge in systems neuroscience. Directed functional connectivity measures, such as the generalized partial directed coherence (GPDC), provide estimates of the causal influence between areas. However, the relation between causality estimates and structural connectivity is still not clear.

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Article Synopsis
  • * It highlights the high cost of current equipment for studying operant conditioning and introduces a new low-cost, open-source platform that records both behavior and brain activity simultaneously.
  • * The platform is adaptable for different experimental tasks and is validated with experiments on freely moving rats, showcasing its effectiveness in capturing operant behavior alongside neuronal activity.
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Significant evidence shows that the acquisition of delay conditioning can occur in out-of-awareness states, such as under anesthesia. However, it is unclear to what extent and what type of conditioning animals may achieve during nonawake states. Trace conditioning is an appealing protocol to study under anesthesia, given the long empty gap separating the conditioned and unconditioned stimuli, which must be bridged for acquisition to happen.

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In multiple fixed interval schedules of reinforcement, different time intervals are signaled by different environmental stimuli which acquire control over behavior. Previous work has shown that temporal performance is controlled not only by external stimuli but also by temporal aspects of the task, depending on the order in which the different intervals are trained - intermixed across trials or in blocks of several trials. The aim of this study was to further describe the training conditions under which the stimuli acquire control over temporal performance.

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Fixed interval, peak interval, and temporal bisection procedures have been used to assess cognitive functions and address questions such as how animals perceive, represent, and reproduce time intervals. They have also been extensively used to test the effects of drugs on behavior, and to describe the neural correlates of interval timing. However, those procedures usually require several weeks of training for behavior to stabilize.

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Specific mechanisms underlying how the brain keeps track of time are largely unknown. Several existing computational models of timing reproduce behavioral results obtained with experimental psychophysical tasks, but only a few tackle the underlying biological mechanisms, such as the synchronized neural activity that occurs throughout brain areas. In this paper, we introduce a model for the peak-interval task based on neuronal network properties.

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The flow of information between different regions of the cortex is fundamental for brain function. Researchers use causality detection techniques, such as Granger causality, to infer connectivity among brain areas from time series. Generalized partial directed coherence (GPDC) is a frequency domain linear method based on vector autoregressive model, which has been applied in electroencephalography, local field potential, and blood oxygenation level-dependent signals.

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Motor sequence learning, planning and execution of goal-directed behaviors, and decision making rely on accurate time estimation and production of durations in the seconds-to-minutes range. The pathways involved in planning and execution of goal-directed behaviors include cortico-striato-thalamo-cortical circuitry modulated by dopaminergic inputs. A critical feature of interval timing is its scalar property, by which the precision of timing is proportional to the timed duration.

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Background: Recent research suggests that the CA3 subregion of the hippocampus has properties of both autoassociative network, due to its ability to complete partial cues, tolerate noise, and store associations between memories, and heteroassociative one, due to its ability to store and retrieve sequences of patterns. Although there are several computational models of the CA3 as an autoassociative network, more detailed evaluations of its heteroassociative properties are missing.

Methods: We developed a model of the CA3 subregion containing 10,000 integrate-and-fire neurons with both recurrent excitatory and inhibitory connections, and which exhibits coupled oscillations in the gamma and theta ranges.

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The ability to process time on the scale of milliseconds and seconds is essential for behaviour. A growing number of studies have started to focus on brain dynamics as a mechanism for temporal encoding. Although there is growing evidence in favour of this view from computational and in vitro studies, there is still a lack of results from experiments in humans.

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Monitoring and updating temporal predictions are critical abilities for adaptive behavior. Here, we investigated whether neural oscillations are related to violation and updating of temporal predictions. Human participants performed an experiment in which they had to generate a target at an expected time point, by pressing a button while taking into account a variable delay between the act and the stimulus occurrence.

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The detection of causality is essential for our understanding of whether distinct events relate. A central requirement for the sensation of causality is temporal contiguity: As the interval between events increases, causality ratings decrease; for intervals longer than approximately 100 msec, the events start to appear independent. It has been suggested that this effect might be due to perception relying on discrete processing.

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The crustacean pyloric Central Pattern Generator (CPG) is a nervous circuit that endogenously provides periodic motor patterns. Even after about 40 years of intensive studies, the rhythm genesis is still not rigorously understood in this CPG, mainly because it is made of neurons with irregular intrinsic activity. Using mathematical models we addressed the question of using a network of irregularly behaving elements to generate periodic oscillations, and we show some advantages of using non-periodic neurons with intrinsic behavior in the transition from bursting to tonic spiking (as found in biological pyloric CPGs) as building components.

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The processes involved in the acquisition of simultaneous temporal processing are currently less understood. For example, it is unclear whether scalar property emerges early during simultaneous temporal acquisition. Using an information-processing model which accounts for the amount of information that each temporal process provides in regard to reward time, we predicted that scalar property would emerge early during the acquisition process, but that subjects should take about 27% longer (more trials) to acquire the long duration than the short duration.

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Even though video game players frequently report losing track of time while playing, few studies have addressed whether there are long-lasting effects of such activity on time perception. We compared the performance of chronic and occasional video game players in sub- and multi-second time perception tasks. Temporal Discrimination and Temporal Bisection tasks, in the range of 100 to 1,000 milliseconds, and Time estimation and Time production tasks, in the range of 5 to 60 seconds, were used to assess sub- and multi-second time perceptions, respectively.

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Live attenuated simian immunodeficiency virus (SIV) vaccines (LAVs) remain the most efficacious of all vaccines in nonhuman primate models of HIV and AIDS, yet the basis of their robust protection remains poorly understood. Here we show that the degree of LAV-mediated protection against intravenous wild-type SIVmac239 challenge strongly correlates with the magnitude and function of SIV-specific, effector-differentiated T cells in the lymph node but not with the responses of such T cells in the blood or with other cellular, humoral and innate immune parameters. We found that maintenance of protective T cell responses is associated with persistent LAV replication in the lymph node, which occurs almost exclusively in follicular helper T cells.

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The lobster gastric mill central pattern generator (CPG) is located in the stomatogastric ganglion and consists of 11 neurons whose circuitry is well known. Because all of the neurons are identifiable and accessible, it can serve as a prime experimental model for analyzing how microcircuits generate multiphase oscillatory spatiotemporal patterns. The neurons that comprise the gastric mill CPG consist of one interneuron, five burster neurons and six tonically firing neurons.

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Although pancreatic ductal adenocarcinoma is a common and almost uniformly fatal cancer, little is known about the molecular events that lead to tumor progression. The high-mobility group A1 (HMGA1) protein is an architectural transcription factor that has been implicated in the pathogenesis and progression of diverse human cancers, including pancreatic ductal adenocarcinoma. In this study, we investigated HMGA1 expression in pancreatic ductal adenocarcinoma cell lines and surgically resected tumors to determine whether it could be a marker for more advanced disease.

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Pancreatic ductal adenocarcinoma is a highly aggressive, lethal human malignancy that continues to elude successful treatment. Although most patients present with metastatic disease, the molecular pathways that underlie tumor progression and metastases are poorly understood. The high mobility group A2 (HMGA2) protein is an architectural transcription factor that has recently been implicated in the development and progression of malignant tumors.

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The sequential firing of neurons in central pattern generators (CPGs) is generally thought to be a result of an interaction between intrinsic cellular and synaptic properties of the component neurons. Due to experimental limitations, it is usually difficult to address the role of each of these properties separately. We have done so by using the crustacean stomatogastric CPG and the dynamic clamp technique to measure how the network responds to the selective modification of an individual important synapse.

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A study of a general central pattern generator (CPG) is carried out by means of a measure of the gain of information between the number of available topology configurations and the output rhythmic activity. The neurons of the CPG are chaotic Hindmarsh-Rose models that cooperate dynamically to generate either chaotic or regular spatiotemporal patterns. These model neurons are implemented by computer simulations and electronic circuits.

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Article Synopsis
  • Irregular intrinsic behavior of neurons is common in the nervous system, even in circuits designed for consistent muscle control, such as the pyloric central pattern generator (CPG) in crustaceans.
  • These irregularities are thought to provide flexibility to neural networks, complicating the creation of deterministic Hodgkin-Huxley-type (HH-type) models, which struggle to replicate the nonlinear properties seen in these neurons.
  • A new stochastic HH-type model was developed, which successfully mimics the irregular firing patterns and dynamics of STG neurons by incorporating the probabilistic nature of ion channels without unrealistic assumptions, revealing that complex membrane dynamics can naturally arise from simple interactions.
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