Massachusetts Institute of Technology

Elemind Technologies, Inc.

Nuvu LLC

Nir Grossman

Edward Stuart Boyden

David Wang

David Bono

In illustrative implementations of this invention, interferential stimulation is precisely directed to arbitrary regions in a brain. The target region is not limited to the area immediately beneath the electrodes, but may be any superficial, mid-depth or deep brain structure. Targeting is achieved by positioning the region of maximum envelope amplitude so that it is located at the targeted tissue. Leakage between current channels is greatly reduced by making at least one of the current channels anti-phasic: that is, the electrode pair of at least one of the current channels has a phase difference between the two electrodes that is substantially equal to 180 degrees. Pairs of stimulating electrodes are positioned side-by-side, rather than in a conventional crisscross pattern, and thus produce only one region of maximum envelope amplitude. Typically, current sources are used to drive the interferential currents.

Methods and apparatus for stimulation of biological tissue

A neuromodulator may output stimuli that causes a user to fall asleep faster than the user would in the absence of the stimuli. Alternatively, the stimuli may modify a sleep state or behavior associated with a sleep state, or may cause or hinder a transition from a waking state to a sleep state or from a sleep state to another sleep state. The neuromodulator may take electroencephalography measurements. Based on these measurements, the neuromodulator may detect, in real time, instantaneous amplitude and instantaneous phase of an endogenous brain signal. The neuromodulator may output stimulation that is, or that causes sensations which are, phase-locked with the endogenous brain signal. In the course of calculating instantaneous phase and amplitude, the neuromodulator may perform an endpoint-corrected Hilbert transform. The stimuli may comprise auditory, visual, electrical, magnetic, vibrotactile or haptic stimuli.

Methods and apparatus for inducing or modifying sleep

A neuromodulator accurately measures&#x2014;in real time and over a range of frequencies&#x2014;the instantaneous phase and amplitude of a natural signal. For example, the natural signal may be an electrical signal produced by neural tissue, or a motion such as a muscle tremor. The neuromodulator generates signals that are precisely timed relative to the phase of the natural signal. For example, the neuromodulator may generate an exogenous signal that is phase-locked with the natural signal. Or, for example, the neuromodulator may generate an exogenous signal that comprises short bursts which occur only during a narrow phase range of each period of an oscillating natural signal. The neuromodulator corrects distortions due to Gibbs phenomenon. In some cases, the neuromodulator does so by applying a causal filter to a discrete Fourier transform in the frequency domain, prior to taking an inverse discrete Fourier transform.

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Lorrach, Germany

Nir Grossman