OpenStim: The Open Noninvasive Brain Stimulator

THIS PROJECT HAS BEEN PUT ON HOLD, DUE TO INACTIVITY.

"The next revolution will come from within."
-- Motto for the project, announced at Foo Camp 2006


The OpenStim group has two primary goals:

1. Create a community that designs the core technology for a safe, highly functional, inexpensive, efficacious noninvasive transcranial magnetic stimulator (TMS) device for stimulating the central nervous system.

2. Facilitate experimentation and exchange of ideas, on the topic of modulation of brain function in a variety of people and contexts, so that we can learn more about the neural circuits mediating our subjective experiences, and improve mental functions (aka hacking your brain).



This page describes each of the current participants, and their personal goals:
The people and their plans



Noninvasive, safe, and effective human brain stimulation is possible via transcranial magnetic stimulation (TMS). TMS has been used in experimental and clinical settings to, amongst other things, alter emotion and mood, shift attention, treat depression, relieve symptoms of schizophrenia, and quell tinnitus (ringing in the ears).

TMS devices contain a coil of wire placed near a subject's head, through which large currents are rapidly injected. The resultant changing magnetic field causes induction of eddy currents in the tissue beneath the coil, and subsequent activation of the neurons in the tissue. The neurons may be peripheral (e.g., in the arms and legs) or central (e.g., in the spinal cord or cerebral cortex). TMS of the motor cortex of a human subject, for example, can cause the subject's limbs or fingers to twitch. TMS of the dorsolateral prefrontal cortex of a human subject can cause the subject to become happier or sadder.

Our goal is to design a simple, safe, effective TMS device for modulation of emotion, sleep, attention, and other central nervous system properties. Many commercial entities sell TMS hardware and software, often for prices exceeding $50,000. We will devise a TMS device that will be constructable by a practitioner skilled in electrical engineering, for less than $400.

The project comprises at least the following 8 components. The logical way to begin is to A) figure out the field geometry desired at the specific depth under the skull, B) design a prototype coil, preferably with standardized values, C) pick the capacitor and resistor adjoining, D) work your way back to the power supply.

1. a reinforced coil (e.g., of copper wire) geometrically appropriate for stimulating the brain (e.g., a figure-8 coil, containing two circular loops, between 3 and 7 cm in diameter),

1b. a testing tank which would hold saline, to mimic the volume conductor of the brain, and thereby permit the electric field to be mapped for various coils and pulse protocols,

2. the control circuitry for charging up a high-capacity capacitor or bank of capacitors, via a power supply system connected to an AC wall source or battery source, and then controlling the discharge of the capacitor into the coil,

3. mechanical hardware for holding and positioning the coil with respect to the head,

4. safety circuitry that limits the current discharged and the repetition rate of the stimulator,

5. an optional measurement device (e.g., fluxgate magnetometer) to measure the magnetic field induced, and

6. computer software and interface hardware for connecting a computer to the control circuitry, and for displaying hardware status and/or error events.

7. integration with EEG or IR was brought up by many attendees of the session at Foo Camp. The contributors decided this should be built in, a priori.

8. OTHER THOUGHT: transcranial direct current stimulation (tDCS) has, like TMS, been shown to improve working memory and mood. Shall we design our TMS device with the capability of doing simultaneous tDCS? It could complicate things somewhat. Hoewver, the methodology is dead simple — apply a DC current across two electrodes, attached to the scalp!

The following pages describe how to induce a certain state or alter a specific behavioral parameter, in a particular kind of person. As much detail as possible should be provided.

Protocol 1: Induce happiness, 1 Hz TMS of right dorsolateral prefrontal cortex
Protocol 2?: Increase risk-taking, 1 Hz TMS of right dorsolateral prefrontal cortex


This section includes descriptions of experiences during and after application of the above protocols.

Experiment 1?: Protocol 1, comparison of before and after
Experiment 2?: Protocol 2, comparison of before and after

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