Ken Mogi

From the evolutionary viewpoint, animals need to monitor the surrounding environment and capture salient features, such as motion, for survival. The visual system is highly developed for monitoring a wide area of visual field and capturing such salient features. In humans and primates, there is a wide binocular field, suggesting a necessity of integrating the images from the two eyes. Binocular rivalry [R. Blake, A neural theory of binocular rivalry, Psychol. Rev. 96 (1989) 145–167; R. Blake, N.K. Logothetis, Visual competition, Nat. Rev. Neurosci. 3 (2002) 13–21], where incompatible inputs from the two eyes compete to emerge in the subject’s visual percept, has been shown to exhibit highly adaptive behavior [I. Kovacs, T.V. Parathomas, M. Yang, A. Feher, When the brain changes its mind: interocular grouping during binocular rivalry. Proc. Natl. Acad. Sci. U.S.A. 93 (1996) 15508–15511; N.K. Logothetis, Single units and conscious vision, Philos. Trans. R. Soc. Lond. B. Biol. Sci. 353 (1998) 1801–1818]. Here we investigated the spatio-temporal dynamics of the ocular dominance pattern in binocular rivalry under conditions where conflicting salient features were presented in a temporally varying manner. We found a striking example of the detailed structure of the dominance wave propagation, by using a spatio-temporal sampling method. The data show in detail the ability of the visual system to dynamically adapt to the changing stimuli in the context of the massively parallel visual field. We show by model prediction that the globally coherent dominance change in the presence of multiple stimuli can be explained by a mechanism based on local saliency comparison. © 2005 Elsevier Ireland Ltd. All rights reserved

_In what computational aspect is the brain different from the_ _computer? In what objective measures can the brain said to be_ _“creative”? These are the fundamental questions that concerns the_ _neural basis of human mental activity. Here we discuss several_ _important aspects of the essential computational ingredients of human_ _mind in order to understand the “creative” process going on in the_ _brain. One of the key concepts is the nature of the source of_ _"externality" that adds new ingredients to the system and its output. We_ _argue that in addition to information input and stochasticity, we need to_ _consider a third possibility, namely "dynamics-embedded externality"._ _We discuss how the neural origin of the subjective sensory qualities_ _ is related to this aspect of creativity. The invariance of qualia _ _under a certain class of transformation, and the mapping of discrete,_

We analyzed the variability of response in records obtained from MT (V5) of awake, behaving monkeys and kindly provided to us by Newsome and Bair (see Newsome et al 1990 for Methods). Some sets of random dot kinematograms had been generated with a constant randomization seed (novar stimuli), while others had been generated with varying randomization seeds (var stimuli). The neural responses to novar stimuli exhibited a remarkable degree of consistent temporal modulation, while the responses to var stimuli were homogeneous over the presentation time. We suspected that correspondence noise might be a major source of variability and to test this we compared the variability of response to novar and var stimuli, making the assumption that the variability observed in responses to novar stimuli reflected the internal noise only, whereas variability in the case of var stimuli reflected internal noise and external noise. From this assumption, we could estimate the relative importance of external noise and internal noise in this system. The main conclusions are:- (1) Efficiency values (up to about 35%) calculated from neural responses in MT are of the same order as those of human observers, (Barlow and Tripathy 1997) (2) External correspondence noise is a significant factor in limiting the detectability of coherent motion in these random dot stimuli.