Oscillatory synchronized activities are generated among visual neurons in a manner that depends on certain key features of light stimulation. Although these activities are assumed to play an important role in perceptual integration, their functional significance has yet to be elucidated. We performed behavioral tests and multi-electrode recordings from retinas isolated from the frog. Pharmacological manipulation of the oscillatory synchronized activities in a class of retinal ganglion cells (dimming detectors) induced correlated changes in escape behavior. The retinal oscillatory synchronized activities are likely to encode escape-related information in frogs.
Many studies reported that membrane potential of a neuron fluctuates between two stable states (depolarized ‘up’ state and hyperpolarized ‘down’ state). A neuron fires at the up state but rarely fires at the down state. Thus, the two states fluctuation is likely to influence information processing in the brain, because spike activity of a neuron conveys information in the brain. In this review, I will discuss possible functional roles and underlying mechanisms of the two states fluctuation.
The replay of behaviorally induced multi-neuronal activity patterns during subsequent sleep or quiet waking is conjectured to play an important role in the consolidation process of certain types of memory. During the early stages of memory consolidation, the hippocampus appears to be critical; however, over time the involvement of the hippocampus decreases as the memories become gradually consolidated in the neocortex. In this article, we review how temporal spike patterns are replayed during sleep and the possible interactions of the hippocampus and neocortex through these patterns.
Understanding perceptual consciousness is one of the most important problems of the contemporary neuroscience. Because sensory information is inevitably ambiguous, it is to be clarified how the brain selects and constructs a certain interpretation of the sensory information. Such typical phenomena are figure perception such as the Necker cube perception and binocular rivalry, both of which provide different conscious percepts during observation of the same visual stimulus and spontaneous alternations between the possible percepts. The present article explains the recent research progress on the brain regions associated with binocular rivalry and common dynamical properties to these kinds of ambiguous perception.
Dynein is an AAA+ type motor complex that utilizes ATP hydrolysis to move toward the minus end of microtubules. Mechanistic studies on dynein have been hampered by its enormous size (a molecular mass of > 1 MDa) and molecular complexity. However, recent advances in structural and functional studies, including electron microscopic observations and mutational analyses along with establishment of recombinant expression systems, are now beginning to shed light on the molecular mechanism of dynein. Here, I summarize these recent studies, focusing on the coupling between ATP hydrolysis cycle and conformational changes that is critical for the dynein-based motility.
Applications of molecular simulation in the field of polymer physical chemistry are presented in terms of crystallization, interaction to small molecules, and hydration. Full atomistic models are suitable for investigating these phenomena since atomistic interaction plays important roles. From a different point of view, these studies in the field of polymer science lead to fundamental understandings of various biophysical problems, such as physical chemistry of amyloid fibrils, which may cause neurodegenerative diseases.