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Input Neurons (input + neuron)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Learning invariants to illumination changes typical of indoor environments: Application to image color correction

INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 3 2007
B. Bascle
Abstract This paper presents a new approach for automatic image color correction, based on statistical learning. The method both parameterizes color independently of illumination and corrects color for changes of illumination. This is useful in many image processing applications, such as image segmentation or background subtraction. The motivation for using a learning approach is to deal with changes of lighting typical of indoor environments such as home and office. The method is based on learning color invariants using a modified multi-layer perceptron (MLP). The MLP is odd-layered. The middle layer includes two neurons which estimate two color invariants and one input neuron which takes in the luminance desired in output of the MLP. The advantage of the modified MLP over a classical MLP is better performance and the estimation of invariants to illumination. The trained modified MLP can be applied using look-up tables, yielding very fast processing. Results illustrate the approach and compare it with other color correction approaches from the literature. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 132,142, 2007 [source]

Analysis of the function of GABAB receptors on inhibitory afferent neurons of Purkinje cells in the cerebellar cortex of the rat

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2002
Marta Than
Abstract Purkinje cells, the output neurons of the cerebellar cortex, receive inhibitory input from basket, stellate and neighbouring Purkinje cells. The aim of the present study was to clarify the role of GABAB receptors on neurons giving inhibitory input to Purkinje cells. In sagittal slices prepared from the cerebellar vermis of the rat, the GABAB receptor agonist baclofen lowered the frequency and amplitude of spontaneous inhibitory postsynaptic currents (IPSCs) recorded in Purkinje cells. These effects were prevented by the GABAB receptor antagonist CGP 55845. Two mechanisms were involved in the depression of the inhibitory input to Purkinje cells. The first mechanism was suppression of the firing of basket, stellate and Purkinje cells. The second mechanism was presynaptic inhibition of GABA release from terminals of the afferent axons. This was indicated by the finding that baclofen decreased the amplitude of IPSCs occurring in Purkinje cells synchronously with action potentials recorded in basket cells. A further support for the presynaptic inhibition is the observation that baclofen decreased the amplitude of autoreceptor currents which are due to activation of GABAA autoreceptors at axon terminals of basket cells by synaptically released GABA. The presynaptic inhibition was partly due to direct inhibition of the vesicular release mechanism, because baclofen lowered the frequency of miniature IPSCs recorded in Purkinje cells in the presence of cadmium and in the presence of tetrodotoxin plus ionomycin. The results show that activation of GABAB receptors decreased GABAA receptor-mediated synaptic input to cerebellar Purkinje cells both by lowering the firing rate of the inhibitory input neurons and by inhibiting GABA release from their axon terminals with a presynaptic mechanism. [source]

The dusp1 immediate early gene is regulated by natural stimuli predominantly in sensory input neurons

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 14 2010
Haruhito Horita
Abstract Many immediate early genes (IEGs) have activity-dependent induction in a subset of brain subdivisions or neuron types. However, none have been reported yet with regulation specific to thalamic-recipient sensory neurons of the telencephalon or in the thalamic sensory input neurons themselves. Here, we report the first such gene, dual specificity phosphatase 1 (dusp1). Dusp1 is an inactivator of mitogen-activated protein kinase (MAPK), and MAPK activates expression of egr1, one of the most commonly studied IEGs, as determined in cultured cells. We found that in the brain of naturally behaving songbirds and other avian species, hearing song, seeing visual stimuli, or performing motor behavior caused high dusp1 upregulation, respectively, in auditory, visual, and somatosensory input cell populations of the thalamus and thalamic-recipient sensory neurons of the telencephalic pallium, whereas high egr1 upregulation occurred only in subsequently connected secondary and tertiary sensory neuronal populations of these same pathways. Motor behavior did not induce high levels of dusp1 expression in the motor-associated areas adjacent to song nuclei, where egr1 is upregulated in response to movement. Our analysis of dusp1 expression in mouse brain suggests similar regulation in the sensory input neurons of the thalamus and thalamic-recipient layer IV and VI neurons of the cortex. These findings suggest that dusp1 has specialized regulation to sensory input neurons of the thalamus and telencephalon; they further suggest that this regulation may serve to attenuate stimulus-induced expression of egr1 and other IEGs, leading to unique molecular properties of forebrain sensory input neurons. J. Comp. Neurol. 518:2873,2901, 2010. © 2010 Wiley-Liss, Inc. [source]