Murray E. Alexander

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A neural network model based on the anatomy and physiology of the matrix compartment of the striatum is described. The model consists of a network of neurons which are mutually inhibitory within a defined domain. A membrane potassium conductance (GK) under dopaminergic-cholinergic control is included in the model. Computer simulation results show that(More)
Magnetic resonance (MR) images acquired with fast measurement often display poor signal-to-noise ratio (SNR) and contrast. With the advent of high temporal resolution imaging, there is a growing need to remove these noise artifacts. The noise in magnitude MR images is signal-dependent (Rician), whereas most de-noising algorithms assume additive Gaussian(More)
Severe acute respiratory syndrome (SARS), a new, highly contagious, viral disease, emerged in China late in 2002 and quickly spread to 32 countries and regions causing in excess of 774 deaths and 8098 infections worldwide. In the absence of a rapid diagnostic test, therapy or vaccine, isolation of individuals diagnosed with SARS and quarantine of(More)
Acquisition of MR images involves their registration against some prechosen reference image. Motion artifacts and misregistration can seriously flaw their interpretation and analysis. This article provides a global registration method that is robust in the presence of noise and local distortions between pairs of images. It uses a two-stage approach,(More)
Neuronal population activity was investigated by computer simulation of a network model based on the neostriatum. Three network topologies were studied, based on different assumptions about the synaptic connectivity among medium spiny neurons. In all networks neurons were interconnected by inhibitory synapses. The connectivity was either symmetric, in which(More)
The qualitative dynamical behaviour of a neural model based on the mammalian neostriatum was analyzed. The neostriatum was modelled as a mutually inhibitory network of physiological neurones, which was driven by excitatory afferents from the cerebral cortex. The analysis defined the conditions under which the system would enter into one of two dynamic(More)
Given the danger of an unprecedented spread of the highly pathogenic avian influenza strain H5N1 in humans, and great challenges to the development of an effective influenza vaccine, antiviral drugs will probably play a pivotal role in combating a novel pandemic strain. A critical limitation to the use of these drugs is the evolution of highly transmissible(More)
The use of antiviral drugs has been recognized as the primary public health strategy for mitigating the severity of a new influenza pandemic strain. However, the success of this strategy requires the prompt onset of therapy within 48 hours of the appearance of clinical symptoms. This requirement may be captured by a compartmental model that monitors the(More)