The approach of an object can be monitored from its optic flow. More specifically, it has been postulated that time-to-collision at constant velocity is perceived by relating visual angle theta to its rate of change theta, time-to-collision being theta/theta. This hypothesis is reappraised, and an alternative based on the parameters theta and angular acceleration theta is proposed. The expressi...

Theta-burst transcranial magnetic stimulation could modulate cortical excitability and has the potential to treat refractory depression. However, there has been a lack of large randomized studies of the antidepressant efficacy of different forms of theta-burst stimulation, such as intermittent and continuous theta-burst stimulation. A randomized sham-controlled study was conducted to investigat...

An appreciable percent (3-14%) of the lymphocyte-like cells of the mouse spleen lack both the theta-isoantigen and sufficient surface immunoglobulin to be detected by conventional immunofluorescence or autoradiographic procedures. These theta(-),Ig(-) cells are increased in frequency after treatment of mice with antithymocyte serum or in mice that have been thymectomized, irradiated (850 R), an...

[1] This paper reports results from a detailed analysis of theta auroras that occurred during the passage of a magnetic cloud on 8 November 2000. The interplanetary magnetic field (IMF) was generally northward for more than 12 hours, while the y-component of the IMF changed signs several times. Auroral images of the Northern Hemisphere acquired from the Ultraviolet Imager (UVI) on board the Pol...

Hippocampal (HPC) theta oscillations have long been linked to various functions of the brain. Many cortical and subcortical areas that also exhibit theta oscillations have been linked to functional circuits with the hippocampus on the basis of coupled activities at theta frequencies. We examine, in freely moving rats, the characteristics of diencephalic theta local field potentials (LFPs) recor...

Temporal coding is a means of representing information by the time, as opposed to the rate, at which neurons fire. Evidence of temporal coding in the hippocampus comes from place cells, whose spike times relative to theta oscillations reflect a rat’s position while running along stereotyped trajectories. This arises from the backwards shift in cell firing relative to local theta oscillations (p...

14 The hippocampus, along with its characteristic theta oscillation, has been widely implicated in various 15 aspects of animal memory and behavior. Given the important roles that hippocampal theta oscillations have 16 in theoretical models of brain function, it might be considered surprising that these signals have not been 17 reported as often in humans as in animals. In this chapter we revie...

Over a perfect field k of characteristic p > 0, we construct a “Witt vector cohomology with compact supports” for separated k-schemes of finite type, extending (after tensorisation with Q) the classical theory for proper k-schemes. We define a canonical morphism from rigid cohomology with compact supports to Witt vector cohomology with compact supports, and we prove that it provides an identifi...

Retention of motor learning can be enhanced or degraded by subsequent performance of a different task. Neurophysiologically this may reflect interference in synaptic plasticity by ongoing neural activity in the brain. Here we demonstrate that N-methyl-D-aspartate (NMDA) dependent aftereffects of repetitive transcranial magnetic stimulation (rTMS) also are subject to interference effects, sugges...

For the system formed by a relativistic electron beam and its plasma return current, we investigate the effects of both transverse and parallel beam and plasma temperatures on the linear stability of collective electromagnetic modes. We focus on nonrelativistic temperatures and wave-vector orientations ranging from two-stream to filamentation instabilities. Water-bag distributions are used to m...