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Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP), 2011 Seventh International Conference on

Date 6-9 Dec. 2011

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Displaying Results 1 - 25 of 124
  • Electromyogram (EMG) based fingers movement recognition using Neighborhood Preserving Analysis with QR-decomposition

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (382 KB) |  | HTML iconHTML  

    Surface Electromyogram (EMG) signals recorded from an amputee's residual muscles have been investigated as a source of control for prosthetic devices for many years. Despite the extensive research focus on the EMG control of arm and gross hand movements, more dexterous individual and combined prosthetic fingers control has not received the same amount of attention. To facilitate such a control scheme, the first and the most significant step is the extraction of a set of highly discriminative feature set that can well separate between the different fingers movements and to do so in a computationally efficient manner. In this paper, an accurate and efficient feature projection method based on Fuzzy Neighborhood Preserving Analysis (FNPA) with QR-decomposition, is proposed and denoted as FNPA. Unlike existing attempts in fuzzy linear discriminant analysis, the objective of the proposed FNPA is to minimize the distance between samples that belong to the same class and maximize the distance between the centers of different classes, while taking into account the contribution of the samples to the different classes. The method also aims to efficiently overcome the singularity problems of classical LDA and Fuzzy LDA. The proposed FNPA is validated on EMG datasets collected from nine subjects performing 10 classes of individual and combined fingers movements. Practical results indicate the significance of FNPA in comparison to many other feature projection methods with an average accuracy of 91%, using only two EMG electrodes. View full abstract»

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  • Brain computer interface: Classification of EEG for left and right wrist movements using AR modeling and Bhattacharya distance

    Publication Year: 2011 , Page(s): 7 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (289 KB) |  | HTML iconHTML  

    This paper presents classification of wrist movements (Left and Right) using Autoregressive modeling (AR). Here the features were extracted from Electro Encephalographic signals and AR modeled using Burg method. The simulation results show that by using AR modeling classification of Left and Right wrist movements can be classified with accuracy up to 98.75% and 96.8% respectively for executed and imaginary movements. View full abstract»

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  • SAR distribution in microwave breast screening: Results with TWTLTLA wideband antenna

    Publication Year: 2011 , Page(s): 11 - 16
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1263 KB) |  | HTML iconHTML  

    This paper focuses on safety assessment of microwave breast screening systems. Using numerical analysis, a heterogeneous, life-like breast phantom is illuminated by an antenna, currently used in experimental microwave imaging systems, from several locations and at several frequencies. These frequencies correspond to the content of experimental pulses used in microwave detection systems. The computed specific absorption rate (SAR) values, averaged over 10g of tissue, imply that the microwave screening techniques comply with previously established safety limits for the SAR. View full abstract»

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  • Wideband antenna for microwave imaging of brain

    Publication Year: 2011 , Page(s): 17 - 20
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (646 KB) |  | HTML iconHTML  

    This paper reports the design of a wideband compact microstrip-fed tapered-slot antenna for brain imaging. The antenna is assumed to operate in a coupling liquid that is designed to improve the signal penetration of the imaged object, and thus to increase the dynamic range of the imaging system. The antenna is covered with a dielectric material in order to protect it from the harmful effects of the coupling liquid. The designed antenna operates across the band from 1 GHz to 4 GHz. Its performance is tested in the presence of a multilayer head phantom. The time domain response of the antenna indicates its capability to support distortionless pulse transmission with a high fidelity factor. View full abstract»

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  • Study on optimal bandwidth for microwave breast imaging

    Publication Year: 2011 , Page(s): 21 - 24
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB) |  | HTML iconHTML  

    This paper investigates the role bandwidth plays in ultra-wideband (UWB) microwave imaging for breast cancer detection. Most UWB microwave imaging systems operate between 3.1-10.6GHz as the FCC has authorised unlicensed use in this spectrum. Whether this is the optimal bandwidth for microwave breast imaging remains an open question. Using signals of different bandwidth and spectrum, this paper provides a computational study using an anatomical realistic breast phantom on the detection and location ability of an imaging algorithm. View full abstract»

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  • Development of adaptive noise reduction technology for in-vehicle heartbeat sensor

    Publication Year: 2011 , Page(s): 25 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (429 KB) |  | HTML iconHTML  

    We proposed a noise reduction method for in-vehicle heartbeat sensor systems. The system measures the driver's heartbeat using a steering wheel electrode and a seat electrode that has dual construction. This configuration allows measurement while driving with one hand and provides two signals for noise cancellation. However, the amplitude ratio of the common mode noise varies when driving at high speeds. We multiplied a coefficient that was derived from the Root Mean Square (RMS) ratio between the two signals. This method enabled us to obtain 80% or more of the heartbeat signal while driving at high speed with one hand. View full abstract»

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  • Metamaterial-based strain sensors

    Publication Year: 2011 , Page(s): 30 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (389 KB) |  | HTML iconHTML  

    In this paper, two metamaterial-based strain sensors at terahertz frequencies are introduced and simulated using CST Microwave Studio. They exhibit a large shift in the resonance frequency upon stretching or compression. They are very well suitable to monitoring and detecting mechanical deformation of a target structure remotely. View full abstract»

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  • Scattering robust features for classification of materials usingl terahertz

    Publication Year: 2011 , Page(s): 33 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (359 KB) |  | HTML iconHTML  

    Terahertz spectroscopy has emerged as an important tool for identification and classification of materials, which exhibit absorption features at specific and distinct frequency bins in the THz spectrum. The scattering of terahertz radiation from granular substances can significantly distort the spectral fingerprint of the material under study. In this paper we propose a signal processing based technique to mitigate the effects of scattering from the measured terahertz spectrum to produce features that can be used for scattering invariant classification of material using THz-TDS. View full abstract»

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  • A λ/30 resolution laser speckle pattern biosensor for dynamic studies on live samples

    Publication Year: 2011 , Page(s): 37 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (385 KB) |  | HTML iconHTML  

    Nowadays there is a big interest in the research of cell behaviour in different sciences, like biology, physics, and medicine. For this reason, many interdisciplinary research projects have been developed in many countries. The main goal of the realization of the proposed biosensor is to obtain a super high resolution optical detection of nano-scaled movements of live cells. We used a very straightforward principle, the interference of laser light with the membrane of the cells under investigation. The laser light is focused on the target cell, while observing the picture through an optical microscope. The laser light creates an interference image (speckle pattern) that is projected on a screen and monitored by a CCD camera. This interference pattern is perturbed by any movement or displacement of the cells, and this interaction is recorded in real time by the CCD. While the contrast in standard optical microscopy is very low, the advantage of this approach is that the coherence of laser light produce constructive or destructive patterns that can be detected with very high signal-to-noise ratio. The displacement resolution we can achieve is better than λ/30, that is in the order of 20nm. View full abstract»

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  • Influence of age on cardio-respiratory interaction assessed by joint symbolic dynamics

    Publication Year: 2011 , Page(s): 41 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    Cardio-respiratory dynamics exhibit complex behaviour and underlying mechanisms responsible for their interaction have not been fully understood. The aim of this paper was to validate the approach for detection of cardio-respiratory interaction based on joint symbolic dynamics using two simulated non-linearly coupled systems, and to investigate the influence of age on the interaction between cardiac and respiratory cycles in healthy subjects. For symbolic analysis, the time series were transformed into ternary symbol vectors based on the changes between two successive time points of each series. Subsequently, words of length `3' were formed and the correspondence between words of the two series was determined. The process was repeated using surrogate data to determine the effectiveness of the joint symbolic dynamics approach. Subsequently, the electrocardiograms (ECG) and respiratory signals of 20 young (age: 21-34 yrs) and 20 elderly (age: 68-85 yrs) healthy subjects were collected from Physionet, from which the R-R intervals and respiratory phases were extracted, respectively. Using the joint symbolic dynamics approach and an additional adaptive delay in the cardiac oscillator based on the maximization of the cross-correlation between the phases of respiration and the delayed R-R intervals, we found a significantly higher percentage of similarity in the symbolic dynamics of R-R intervals and respiratory phases in young subjects compared to elderly subjects (22.8±6.7 vs. 16.5±6.6 %, p<;0.01). In conclusion, joint symbolic dynamics provides an efficient technique for the analysis of cardio-respiratory interaction. View full abstract»

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  • Regression models for estimating gait parameters using inertial sensors

    Publication Year: 2011 , Page(s): 46 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (671 KB) |  | HTML iconHTML  

    Advanced mathematical models are now widely used in medical applications for diagnosis, prognosis, and prevention of diseases. This work looks at the application of advanced regression models for estimating key foot parameters in falls prevention research. Falls is a serious issue for the rapidly increasing elderly demographic. We propose to investigate the notion of falls prediction through the use of portable, light weight, easy to use and inexpensive sensors along with advanced computational intelligence estimation models. This study compares two mathematical models namely the Generalized Regression Neural Networks (GRNN), and the Support Vector Machine (SVM) to estimate the key gait parameters. The study deployed Inertial Measurement Units (IMU) consisting of accelerometers and gyroscopes sensors to measure the foot kinematics and an optoelectronic motion capture system to validate the results. Our results demonstrated that both mathematical models estimate the key end point foot trajectory parameters (1) mx1 - first maximum after toe-off (root mean square error (rmse) range of 2.0 mm to 12.5 mm) (2) normalized time to mx1 (rmse range of 0.4% to 3.7%) and (3) Minimum Toe Clearance (rmse range of 2.0 mm to 10.2 mm) and (4) normalized time to MTC (rmse range of 0.7% to 5.4%) using IMU features. The SVM regressor showed better estimation rmse 56 times out of the 70 comparison estimations. In all cases the best model respectively from the GRNN and SVM family of models was compared. View full abstract»

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  • Investigation of multiorientation and multiresolution features for microcalcifications classification in mammograms

    Publication Year: 2011 , Page(s): 52 - 57
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (915 KB) |  | HTML iconHTML  

    Breast cancer is one of the most common cancers among women. One of the early signs of the disease is the appearance of microcalcifications clusters, which often show up as bright spots in mammograms. It is important to be able to distinguish between the shapes of these clusters to increase the reliability and accuracy of the diagnosis. In this paper, a new method to extract features to classify the microcalcification clusters using steerable pyramid decomposition is presented. The method is motivated by the fact that microcalcification clusters can be of arbitrary sizes and orientations. Thus, it is important to extract the features in all possible orientations to capture most of the distinguishing information for classification. The proposed method shows a clear improvement in the classification performance when compared to the wavelet transform; the most commonly used multiscale analysis technique at present. View full abstract»

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  • Design and validation of an ambulatory inertial system for 3-D measurements of low back movements

    Publication Year: 2011 , Page(s): 58 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1243 KB) |  | HTML iconHTML  

    In studies of human movement, inertial sensors (accelerometers and gyroscopes) are gaining attention as a promising alternative to laboratory-constrained video capture systems. Kinematics of various body parts and joints can be quantified by attaching inertial sensors at points of interest and integrating the observed acceleration and angular velocity signals. It is broadly accepted that this measurement procedure is significantly influenced by cumulative errors arising from sensor noise, non-linearities, asymmetries, sensitivity variations and bias drifts. In addition, it is also known that linear acceleration superimposed to the gravity acceleration introduces errors when calculating tilt angles. Recently, newer techniques using sensor fusion methods have shown error reduction in orientation measurements, but require additional hardware and consume more energy. In this paper, we assess the accuracy of a low-power wireless inertial system (ViMove) that measures Low Back (lumbar spine) orientation in three dimensions. The system consists of two inertial units (sensor), with each sensor containing one tri-axis accelerometer and one single-axis gyroscope. We investigate the accuracy of 1D, 2D and 3D simultaneous movements by means of root mean square error (RMSE) computed in comparison with NDI Optotrak, an optical tracking system. The RMSE achieved for one dimensional movements in the Flexion, Lateral Flexion and Twist planes were 1.0°, 0.5° and 2.4° respectively, and 2.1°, 2.4° and 4.6° for three dimensional movements. View full abstract»

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  • Polymer and carbon nanotube based sensors for pressure and strain measurements

    Publication Year: 2011 , Page(s): 64 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1689 KB) |  | HTML iconHTML  

    In this paper we investigate the fabrication process of a novel polymer-based pressure/strain microsensor for use in pressure and strain measurements in medical environments. Our proposed flexible polymer-based pressure/strain microsensor is built using SU-8, and polyimide film (Kapton film). Single-walled carbon nanotube (SWCNTs) resistors are used as the sensing material. Here we report on our progress to date, and highlight the fabrication techniques that led us to investigate various sensor implementations, and their corresponding properties, and in particular sensitivity and reproducibility. The carbon nanotubes (CNTs) material is chosen because of its metallic and semiconducting properties and its nanoscale dimension. Published work has also shown it to provide high sensitivity and high reliability compared to Wheatsone-bridged piezoresistor sensors. This makes the CNTs ideal to be used in micro-sensor design, particularly in a medical implant scenario. We will also report on both the simulation and experimental results of this novel sensor during the prototyping stage. View full abstract»

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  • In situ 3D imaging of alveoli with a 30 gauge side-facing optical needle probe

    Publication Year: 2011 , Page(s): 68 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    In situ imaging of alveoli and small airways with optical coherence tomography (OCT) needle probes has significant potential in the study and clinical assessment of lung disease. We present the smallest reported OCT needle probe capable of acquiring 3D volumetric data. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fibre, terminated with a reflection-coated, fibre tip beam deflector. The optics are encased within a 30-gauge (outer diameter 310 μm) needle, and interfaced to a spectral-domain OCT scanner. Multiple 3D-OCT data sets were acquired on preterm lamb lungs (excised) filled with amniotic fluid and saline. Results demonstrated the ability of such a probe to image individual alveoli and bronchioles, and enabled the rendering of 3D volumetric visualisations of the data. We observed notably less tissue distortion than in earlier work with larger 23 gauge needle probes. View full abstract»

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  • Modeling inhibitory interactions shaping neural responses of target neurons to multiple features

    Publication Year: 2011 , Page(s): 73 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (622 KB) |  | HTML iconHTML  

    Flying insects chase prey and mates, skillfully exhibiting their ability to detect, track and pursue a moving target within a complex visual environment. This is a challenging task, even for the most sophisticated vision systems. Using electrophysiological techniques we record from visual neurons in the insect brain likely to underlie this pursuit behavior. These neurons respond to the presentation of small moving objects, even in the presence of background clutter. One such neuron, the centrifugal small target motion detector (CSTMD1), exhibits additional higher-order properties that may underlie a simple form of visual attention. This neuron's response is inhibited by the simultaneous presence of a second `distracter' target moving within a diffuse region of the excitatory receptive field. Intriguingly, a second distracter target moving in the visual field of the opposite eye completely suppresses the response of CSTMD1. In this study, we present distracter targets of varying sizes and determine whether the strength of these inhibitory interactions is itself a size selective phenomenon. We model CSTMD1's response to two-target stimuli presented within the excitatory hemifield as the summation of two size selective inputs, but inhibitory input from the other side as the difference. A further model elaboration includes half-wave rectification preceding the inhibition from the other eye, which results in a simple mathematical formulation encapsulating the response of CSTMD1 to both single and two target stimuli. View full abstract»

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  • Synaptic dynamics influence the phase of a neural response

    Publication Year: 2011 , Page(s): 79 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (826 KB) |  | HTML iconHTML  

    The postsynaptic response of a neuron to time-varying inputs is determined by the interaction of presynaptic spike times with the short-term dynamics of each synapse. Such synaptic dynamics makes the postsynaptic neuron more sensitive to input rate fluctuations than to average firing rates. Here we show that the postsynaptic neural spiking response to a rhythmically frequency-modulated population input can exhibit a predictive phase lead due to depressing synapses. The magnitude of the lead increases with increasing correlations between the input spike trains. Facilitation and vesicle recycling rates also influence the phase. View full abstract»

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  • Multicompartment simulations of NMDA receptor-based facilitation in insect visual neurons

    Publication Year: 2011 , Page(s): 85 - 90
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (725 KB) |  | HTML iconHTML  

    The development of tools for multicompartment simulations of a class of insect visual neuron is described. These include a system for converting morphological neural data in the Southampton Archive format into statements for the electrical simulation environment SPICE. The subject neurons, wide-field Small Target Motion-Detector cells, display strong selectivity for small moving visual objects, and also show evidence of response facilitation as stimuli move along spatially continuous tracks. We speculate that this facilitation is related to reliability of detection. We describe preliminary efforts to model the effect biophysically using the nonlinear characteristics of a class of excitatory synaptic receptors, the NMDA receptors. View full abstract»

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  • A silicon model of the inner hair cell

    Publication Year: 2011 , Page(s): 91 - 96
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1829 KB) |  | HTML iconHTML  

    In this paper we present an electrical model of the inner hair cell based on an improved mathematical model. The model is implemented in silicon in the current domain using translinear circuits. It improves on previous models by taking into consideration the potassium and calcium ion flow into and out of the inner hair cell, yielding a more accurate real-time model of the auditory pathway. View full abstract»

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  • An analogue VLSI implementation of polychromous spiking neural networks

    Publication Year: 2011 , Page(s): 97 - 102
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (747 KB) |  | HTML iconHTML  

    We present an analogue VLSI implementation of a polychronous network of spiking neurons. The network is capable of storing and retrieving spatial-temporal spike patterns. It consists of 14 leaky-integrate-and-fire neurons and corresponding axonal connections with programmable delays. View full abstract»

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  • Phosphene brightness modelling for voltage driven waveforms

    Publication Year: 2011 , Page(s): 103 - 107
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    Implants provide a means to electronically stimulate biological systems. Such stimulation may be designed to be driven by current or voltage. Although the methods are theoretically equivalent, the selection of which to employ has implications as to hardware design, stimulation strategies, and other practical impacts. We model the impact of voltage-driven stimulation, utilising models for producing current-driven approximations to voltage-driven waveforms and a current-driven model of perceived brightness of phosphenes. We give predictions as to phosphene brightness, and consider some practical impacts of choosing current or voltage driven stimulation. View full abstract»

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  • Silicon implementation of the generalized integrate-and-fire neuron model

    Publication Year: 2011 , Page(s): 108 - 112
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1931 KB) |  | HTML iconHTML  

    In this paper we present the design, implementation and preliminary results from a silicon neuron (SiN) based on the generalized integrate-and-fire neuron model. The SiN is integrated onto a chip with a number of similar SiNs. In this paper we show the results from a single neuron, however, in the future it is our aim to show that real-time, low-power and highly configurable spiking neural networks are feasible on silicon chips. View full abstract»

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  • The focus of attention under phosphenated vision through retinal implants

    Publication Year: 2011 , Page(s): 113 - 118
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB) |  | HTML iconHTML  

    In this paper, we use a state of the art saliency model to compare salient locations for unprocessed colour images with those of phosphenated images. The motivation for doing so is to estimate the impact of phosphenisation of input streams as it may occur when someone is equipped with a retinal implant. We aim to determine if there is any need to preprocess images for an implant user to help them find presumably important components of an image. This will not be answered conclusively, as whether saliency is preserved or not strongly depends on the brain's ability to spatially integrate phosphenes to smooth images at different scales. View full abstract»

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  • Computational models for spatiotemporal filtering strategies in insect motion vision at low light levels

    Publication Year: 2011 , Page(s): 119 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3800 KB) |  | HTML iconHTML  

    We explore a promising new approach to understanding the neural filter mechanisms intermediate in motion processing at low luminance. We carefully account for the known filter properties of early stages of visual processing in a nocturnal moth, and then measured spatiotemporal tuning of higher order neurons. We then use a computational model to identify likely strategies used to reject noisy signals at higher-order stages of motion detection. In so doing, we provide the first description of the spatial and temporal `pooling' filters in motion vision of nocturnal insects. View full abstract»

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  • Modelling the temporal response properties of an insect small target motion detector

    Publication Year: 2011 , Page(s): 125 - 130
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3055 KB) |  | HTML iconHTML  

    Insects are an excellent model system for investigating computational mechanisms evolved for the challenging task of visualising and tracking small moving targets. We examined a well categorised small target motion detector (STMD) neuron, the dragonfly centrifugal STMD 1 (CSTMD1). This neuron has an unusually slow response onset, with a time course in the order of hundreds of milliseconds. A parsimonious explanation for this slow onset would be temporal low-pass filtering. However other authors have dismissed this and instead proposed a facilitation mechanism derived from second order motion detectors. We tested the spatial locality of response to continuous motion on non-contiguous paths and found spatial discontinuities in otherwise continuous motion reset the neuronal response. We modelled an array of elementary motion detectors (EMDs) in the insect visual pathway. We found that whilst individual components of the response can be explained simply by modifying the properties of the EMDs, the neurons response considered as a whole requires further elaborations within the system such as the proposed second order motion pathway. View full abstract»

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