Jeffrey S. Coombs

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1. The excitatory and inhibitory components in the receptive fields of unimodal simple cells in the striate cortex of the cat anaesthetized with nitrous oxide have been described using slits of light and single light-dark edges as stimuli.2. There is a small excitatory region (excitatory complex) centrally located in the receptive field that is made up of(More)
1. The properties of the receptive fields of simple cells in the cat striate cortex have been studied by preparing average response histograms both to moving slits of light of different width and to single light-dark edges or contours.2. The movement of a narrow (< 0.3 degrees ) slit across the receptive field gives rise to average response histograms that(More)
We have implemented a root-extraction stemmer for Arabic which is similar to the Khoja stemmer but without a root dictionary. Our stemmer was found to perform equivalently to the Khoja stemmer as well as so-called "light" stemmers in monolingual document retrieval tasks performed on the Arabic Trec-2001 collection. A root dictionary, therefore, does not(More)
1. The discharge frequency of simple neurones in the cat striate cortex responding to the two edges of a slit of light moving over their receptive fields was studied as a function of slit width. While one edge of the slit was discharging the cell, the other edge had a modifying influence on that discharge either by way of facilitation or of inhibition.2.(More)