Search query: neural network clock time rhythm

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abstract: This article presents the development and implementation of an artificial neural network (ANN) and a support vector machine (SVM) on a 32 bit ARM R Cortex R M4 microcontroller core from Freescale Semiconductor and on a FPGA Spartan R 6 from XilinxTM looking for real time detection of ventricular tachycardia (VT) and ventricular fibrillation (VF) They were compared in terms of accuracy and computational cost. A Fast Wavelet Transform (FWT) was used, and the energy in each sub band frequency was calculated in the feature extraction stage. For the training and validation algorithms, labeled signals from MIT BIH database with normal sinus rhythm, VF and VT in a time window of 2 seconds were used. Test results achieve an accuracy of 99.46% for both ANN and SVM with execution time less than 0.6 ms in microcontroller and 30 ms in FPGA for ANN and less than 30 ms in a microcontroller for SVM. The test was done with a 32 MHz clock.
author_names: Andres Orozco-Duque

Santiago Rua

Santiago Zuluaga

Alfredo Redondo

J Restrepo

John Bustamante
title: Support Vector Machine and Artificial Neural Network Implementation in Embedded Systems for Real Time Arrhythmias Detection
venue: BIOSIGNALS
year: 2013

abstract: The subjective representation of "time" is critical for cognitive tasks but also for several motor activities. The neural network supporting motor timing comprises: lateral cerebellum, basal ganglia, sensorimotor and prefrontal cortical areas. Basal ganglia and associated cortical areas act as a hypothetical "internal clock" that beats the rhythm when the movement is internally generated. When timing information is processed to make predictions on the outcome of a subjective or externally perceived motor act, cerebellar processing and outflow pathways appear to be primarily involved. Clinical and experimental evidence on time processing and motor control points to a dysfunction of the neural networks involving basal ganglia and cerebellum in movement disorders. In some cases, temporal processing deficits could directly contribute to core motor features of the movement disorder, as in the case of bradykinesia in Parkinson's disease. For other movement disorders, the relationship between abnormal time processing and motor performance is less obvious and requires further investigation, as in the reduced accuracy in predicting the temporal outcome of a motor act in dystonia. We aim to review the literature on time processing and motor control in Parkinson's disease, dystonia, Huntington's disease, and Tourette syndrome, integrating the available findings with current pathophysiological models; we will highlight the areas in which future explorations are warranted, as well as the aspects of time processing in motor control that present translational aspects in future rehabilitation strategies. The subjective representation of "time" is critical for cognitive tasks but also for motor activities. Recently, greater attention has been devoted to improve our understanding of how temporal information becomes integrated within the mechanisms of motor control. Experimental evidence recognizes time processing in motor control as a complex neural function supported by diffuse cerebral networks including cortical areas, cerebellum, and other subcortical structures (Ivry and Spencer, 2004; Coull and Nobre, 2008) Timing is an essential component of motor control primarily within two types of motor tasks: (i) when producing sequential rhythmic movements or sustained movements of a definite duration (explicit timing) (ii) when the temporal information is used implicitly, such as when coordinating our movements to those of moving objects or individuals within the external environment (implicit timing) In this review, we will provide a brief description of the neural network supporting motor timing focusing only on instrumental information to explain the link between timing and motor control in movement disorders. Then we will review available data on motor timing in Parkinson's disease, dystonia, Huntington's disease, and Tourette syndrome, and discuss how this body of evidence integrates with the available information on the pathophysiology of these movement disorders. Finally, we will discuss the translational aspects of the explored neural mechanisms with respect to future rehabilitation strategies.
author_names: Laura Avanzino

Elisa Pelosin

Carmelo M Vicario

Giovanna Lagravinese

Giovanni Abbruzzese

Davide Martino
title: Time Processing and Motor Control in Movement Disorders
venue: Front. Hum. Neurosci.
year: 2016

abstract: The circadian clock nucleus of the mammalian brain is composed of thousands of oscillator neurons, each driven by the cell autonomous action of a defined set of circadian clock genes. A critical question is how these individual oscillators are organized into an internal clock that times behavior and physiology. We examined the neural organization of the suprachiasmatic nucleus (SCN) through time lapse imaging of a short half life green fluorescent protein (GFP) reporter of the circadian clock gene Period 1 (Per1) Using brain slice preparations, Per1 promoter rhythms were resolved at the level of the SCN, and in individual neurons within the SCN, to determine the temporal patterns of rhythmicity resulting from exposure of mice to light/dark cycle (LD) and constant darkness (DD) conditions. Quantitative imaging and patch clamp electrophysiology were used to define the relationship of Per1 gene expression to neurophysiological output on an individual neuron basis. We found that in both LD and DD, the overall rhythm of the clock nucleus is composed of individual cellular rhythms that peak in distinct phase groups at 3 4 hr intervals. However, the phase relationships of Per1 oscillations to locomotor activity and the phase relationships among individual neuronal oscillators within the SCN are different in LD and DD. There was a positive, linear correlation of Per1 transcription with neuronal spike frequency output, thus Per1::GFP rhythms are representative of physiological rhythmicity. Our results reveal multiple phase groupings of SCN oscillators and suggest that light regulation of oscillator interactions within the SCN underlies entrainment to the photoperiod.
author_names: Jorge E Quintero

Sandra J Kuhlman

Douglas G McMahon
title: The Biological Clock Nucleus: A Multiphasic Oscillator Network Regulated by Light
venue: The Journal of Neuroscience
year: 2003

abstract: Circadian neural circuits generate near 24 hr physiological rhythms that can be entrained by light to coordinate animal physiology with daily solar cycles. To examine how a circadian circuit reorganizes its activity in response to light, we imaged period (per) clock gene cycling for up to 6 days at single neuron resolution in whole brain explant cultures prepared from per luciferase transgenic flies. We compared cultures subjected to a phase advancing light pulse (LP) to cultures maintained in darkness (DD) In DD, individual neuronal oscillators in all circadian subgroups are initially well synchronized but then show monotonic decrease in oscillator rhythm amplitude and synchrony with time. The small ventral lateral neurons (s LNvs) and dorsal lateral neurons (LNds) exhibit this decrease at a slower relative rate. In contrast, the LP evokes a rapid loss of oscillator synchrony between and within most circadian neuronal subgroups, followed by gradual phase retuning of whole circuit oscillator synchrony. The LNds maintain high rhythmic amplitude and synchrony following the LP along with the most rapid coherent phase advance. Immunocytochemical analysis of PER shows that these dynamics in DD and LP are recapitulated in vivo. Anatomically distinct circadian neuronal subgroups vary in their response to the LP, showing differences in the degree and kinetics of their loss, recovery and/or strengthening of synchrony, and rhythmicity. Transient desynchrony appears to be an integral feature of light response of the Drosophila multicellular circadian clock. Individual oscillators in different neuronal subgroups of the circadian circuit show distinct kinetic signatures of light response and phase retuning.
author_names: Logan Roberts

Tanya L Leise

Takako Noguchi

Alexis M Galschiodt

Jerry H Houl

David K Welsh

Todd C Holmes
title: Light Evokes Rapid Circadian Network Oscillator Desynchrony Followed by Gradual Phase Retuning of Synchrony
venue: Current Biology
year: 2015

abstract: We here propose a neural network model to explore how neural oscillations might regulate the replay of memory traces. We simulate the encoding and retrieval of a series of events, where temporal sequences are uniquely identifiable by analysing population activity, as several recent EEG/MEG studies have shown. Our model comprises three parts, each considering distinct hypotheses. A cortical region actively represents sequences through the disruption of an intrinsically generated alpha rhythm, where a desynchronisation marks information rich operations as the literature predicts. A binding region converts each event into a discrete index, enabling repetitions through a sparse encoding of events. We also instantiate a temporal region, where an oscillatory "ticking clock" made up of hierarchical synfire chains discretely indexes a moment in time. By encoding the absolute timing between events, we show how one can use cortical desynchronisations to dynamically detect unique temporal signatures as they are replayed in the brain.
author_names: George Parish

Sebastian Michelmann

Simon Hanslmayr

Howard Bowman
title: Modelling the Replay of Dynamic Memories from Cortical Alpha Oscillations with the Sync Fire deSync Model
year: 2020

abstract: The cell distribution and immunoreactivity (ir) against period (PER) pigment dispersing factor (PDF) and corazonin (CRZ) were compared between adults and nymphs in the central nervous system of the German cockroach. Although PER ir cells in the optic lobes (OL) were expressed in the nymphs from the first instar, the links between major clock cells became more elaborated after second/third instar. A circadian rhythm of locomotion was initiated at the fourth/fifth instar. The results suggest that the clock was running from hatching, but the control network needed more time to develop. In addition, the putative downstream regulators, PDF ir and CRZ ir, are co localized in various regions of the brain, indicating potential output routes of the circadian clock. CRZ ir cells with typical morphology of neurosecretory cells in the dorsolateral protocerebrum send out three neural fibers to reach the ipsilateral corpora cardiaca (CC) the antennal lobe and two hemispheres of the protocerebrum. Based on co localization with some PER ir/PDF ir cells, the CRZ ir cells have the potential to serve as a bridge between circadian neural signals and endocrine regulation. Based on PDF's role in the regulation of locomotion, our results support the finding that the locomotor circadian rhythm is possibly controlled by a hormonal route.
author_names: Yung-Yu Yang

Chih-Jen Wen

Archana Mishra

Chi-Wei Tsai

How-Jing Lee
title: Development of the circadian clock in the German cockroach, Blattella germanica.
venue: Journal of insect physiology
year: 2009

abstract: The circadian rhythm of body temperature (T(b) is a well known phenomenon. However, it is unknown how the circadian system including the suprachiasmatic nucleus (SCN) and clock genes affects thermoregulation. Food deprivation in mice induces a greater reduction of T(b) particularly in the light phase. We examined the role of Clock, one of key clock genes and the SCN during induced hypothermia. At 20 degrees C with fasting, mice increased their metabolic heat production in the dark phase and maintained T(b) whereas in the light phase, heat production was less, resulting in hypothermia. Under these conditions, neuronal activity in the SCN, assessed by cFos expression, increased only in the light phase. However, such differences in thermoregulatory and neural responses between the phases in Clock mutant mice were less marked. The neural network between the SCN and paraventricular nucleus appeared to be important in hypothermia. These findings suggest that the circadian system per se is influenced by both the feeding condition and environmental temperature and that it modulates thermoregulation.
author_names: Ken Tokizawa

Yuki Uchida

Kei Nagashima
title: Thermoregulation in the cold changes depending on the time of day and feeding condition: physiological and anatomical analyses of involved circadian mechanisms
venue: Neuroscience
year: 2009

abstract: In development, morphogenetic processes are strictly coordinated in time. Cells in a developing tissue would need mechanisms for time keeping. One such time keeping mechanism is to use oscillations of gene expression. Oscillatory gene expression can be generated by transcriptional/translational feedback loops, usually referred to as a genetic oscillator. In this review article, we discuss genetic oscillators in the presence of developmental processes such as cell division, cell movement and cell differentiation. We first introduce the gene regulatory network for generating a rhythm of gene expression. We then discuss how developmental processes influence genetic oscillators. Examples include vertebrate somitogenesis and neural progenitor cell differentiation, as well as the circadian clock for comparison. To understand the behaviors of genetic oscillators in development, it is necessary to consider both gene expression dynamics and cellular behaviors simultaneously. Theoretical modeling combined with live imaging at single cell resolution will be a powerful tool to analyze genetic oscillators in development.
author_names: Koichiro Uriu
title: Genetic oscillators in development
venue: Development, growth differentiation
year: 2016

abstract: Artificial neural networks built from two state neurons are powerful computational substrates, whose computational ability is well understood by analogy with statistical mechanics. In this work, we introduce similar analogies in the context of spiking neurons in a fixed time window, where excitatory and inhibitory inputs drawn from a Poisson distribution play the role of temperature. For single neurons with a "bandgap" between their inputs and the spike threshold, this temperature allows for stochastic spiking. By imposing a global inhibitory rhythm over the fixed time windows, we connect neurons into a network that exhibits synchronous, clock like updating akin to neural networks. We implement a single layer Boltzmann machine without learning to demonstrate our model.
author_names: Paul Merolla

Tristan Ursell

John V Arthur
title: The thermodynamic temperature of a rhythmic spiking network
venue: ArXiv
year: 2010

abstract: The circadian rhythm of body temperature (Tb) is a well known phenomenon. However, it is unknown how the circadian system affects thermoregulation. Food deprivation in mice induces a greater reduction of Tb particularly in the light phase. We examined the role of the clock gene and the suprachiasmatic nucleus (SCN) during induced hypothermia. At 20C with fasting, mice increased their metabolic heat production in the dark phase and maintained T~b~ whereas in the light phase, heat production was less, resulting in hypothermia. Under these conditions, neuronal activity in the SCN, assessed by cFos expression, increased only in the light phase. The differences between the phases in Clock mutant mice were less marked. The neural network between the SCN and paraventricular nucleus appeared to be important in hypothermia. These findings suggest that the circadian system per se is influenced by both the feeding condition and environmental temperature and that it modulates thermoregulation.
author_names: Kei Nagashima

Ken Tokizawa

Yuki Uchida
title: The circadian system alters thermoregulation depending on the time of day and feeding condition
year: 2009