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The nonlinear neutral differential equation d n dt n [x(t) + h(t)x(τ (t))] + f (t, x(g(t))) = q(t), (1) is considered under the following conditions: n ∈ N; h ∈ C[t 0 , ∞); τ ∈ C[t 0 , ∞) is strictly increasing, lim t→∞ τ (t) = ∞ and τ (t) < t for t ≥ t 0 ; g ∈ C[t 0 , ∞) and lim t→∞ g(t) = ∞; f ∈ C([t 0 , ∞) × R); q ∈ C[t 0 , ∞). It is shown that if f is(More)
To study whether or not schizophrenic patients have disturbances in voluntary control of saccades, we examined visually elicited saccade and antisaccade tasks in 10 normal control subjects and 12 schizophrenic patients. The latencies of saccades in the schizophrenic patients were not significantly different from those of normal controls. However, 6 of the(More)
The study of event-related potentials (ERPs) is capable of elucidating the abnormalities in brain network dynamics relevant to the information-processing deficits in schizophrenia patients. In contrast to P50 and P300 ERPs, however, the results of P100 ERP studies in schizophrenia patients are less consistent. We have previously reported that P100(More)
This article argues how dopamine controls working memory and how the dysregulation of the dopaminergic system is related to schizophrenia. In the dorsolateral prefrontal cortex, which is the principal part of the working memory system, recurrent excitation is subtly balanced with intracortical inhibition. A potent controller of the dorsolateral prefrontal(More)
Human neuro-imaging studies have often reported co-activation of the dorsal premotor cortex (PMd) and the posterior parietal cortex (PPC) during internal operation of visuospatial information, referred to here as "visuospatial mental operation". However, the functions assigned to the PMd and PPC during these tasks are still unclear. Here, we examined the(More)
Results of the recent electrophysiological experiments by Caminiti et al. suggest that populations of neurons of the motor areas code direction of voluntary arm movement in an intrinsic coordinate system. In this letter I propose a set of joint-related coordinate systems that rotate with the posture of the arm in which populations of motor cortical neurons(More)
1. This article reviews recent progress in the computational studies towards the architecture and operations of the prefrontal cortical circuit, which are keys to understand the mechanisms of working memory processing. 2. The recurrent excitatory connections form closed-loop circuits, which contribute to the sustainment of delay-period activity. These(More)
The observation of the locomotor and exploratory behaviors of rodents in an open field is one of the most fundamental methods used in the field of behavioral pharmacology. A variety of behaviors can be recorded automatically and can readily generate a multivariate pattern of pharmacological effects. Nevertheless, the optimal ways to characterize observed(More)
This paper proposes a seamless service platform for continuous service provision in dynamic network environments. In the future, many kinds of terminals will collectively form a pervasive computing environment that is available anywhere. The elements of a network of this type can dynamically change, merge, or separate, and users can migrate within and(More)