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Focal neocortical seizures, induced by injection of 4-aminopyridine, were imaged in the rat neocortex using the intrinsic optical signal, with incident light at various wavelengths. We observed focal, reproducible and prolonged reflectance drops following seizure onset, regardless of wavelength, in the ictal onset zone. A persistent drop in light(More)
We investigated the dynamic spatiotemporal relationships of cerebral blood volume (CBV), deoxygenated hemoglobin (Hbr), and light scatter (LS) associated with interictal epileptiform events with multiwavelength optical recording of intrinsic signals and simultaneous field potential recording. Interictal spikes (IISs) were induced with iontophoresis of(More)
We study the nonlinear response of the crayfish caudal photoreceptor to periodic mechanical stimuli in terms of stochastic synchronization. The amplitude and frequency of the mechanical stimuli and the light level are used as control parameters. The system shows multiple locking regions as the stimulus frequency is varied. We find that the synchronization(More)
We begin by distinguishing computationalism from a number of other theses that are sometimes conflated with it. We also distinguish between several important kinds of computation: computation in a generic sense, digital computation, and analog computation. Then, we defend a weak version of computationalism-neural processes are computations in the generic(More)
Stochastic resonance is the process by which noise added to a weak external stimulus can enhance encoding efficiency in the sensory periphery and thence in the central nervous system. Stochastic synchronization is the process by which noisy phase synchronization of two periodic (or aperiodic) signals can occur. Together with a brief review of both concepts,(More)
We applied high-temporal-resolution optical imaging utilizing both the fast intrinsic optical signal (fIOS) and voltage-sensitive dyes (VSDs) to observe the spatiotemporal characteristics of rat somatosensory cortex during electrical stimulation. We find that changes in both the fIOS and VSD signals occur rapidly (<30 ms) after the stimulus is applied,(More)
We explore the variability that animals display in their movement choices as they forage in a finite-sized food patch with a uniform food distribution, and present a framework for how these choices may be adjusted to optimize foraging efficiency. Inspired by experimental studies of the zooplankton Daphnia, we model foraging animals as "agents" moving in two(More)
Our understanding of perfusion-based human brain mapping techniques relies on a detailed knowledge of the relationship between neuronal activity and cerebrovascular hemodynamics. We performed optical imaging of intrinsic signals at wavelengths sensitive to total hemoglobin (Hbt; which correlate with cerebral blood volume (CBV)) and deoxygenated hemoglobin(More)
We describe preliminary experiments on controlling in vivo atrial fibrillation using a closed-loop feedback protocol that measures the dynamics of the right atrium at a single spatial location and applies control perturbations at a single spatial location. This study allows investigation of control of cardiac dynamics in a preparation that is(More)