Can we control the brain remotely and influence behaviour?

Stimulation of the brain in order to influence behaviour is something that already exists. A therapy for Parkinson’s patient, called Deep brain stimulation, has been developed decades ago to somewhat compensate artificially the impaired subcortical circuitry resulting from neurodegeneration. This therapy nevertheless requires to insert electrodes in a very deep region of the brain (the sub thalamic nucleus) ad therefore an open-skull neurosurgical operation. It is extremely invasive. The need of less invasive or non invasive therapies might drive a line of research programmes in neuroscience.

In 2016, the Guardian published an article about the experimental remote control of mice brain using a protein called “Magneto” and another technique using heated nanoparticles. What is the aim of these research programmes in neuroscience and biotechnologies? Can we really control the brain remotely and to which extent?

Objectives

The objectives mentioned in many of these studies relate to the fine-grained understanding of the subcortical, cortical or cerebellar circuitry - no reference to potential applications in neurology or psychiatry is mentioned. These studies are carried out on animals - mice or rats, are extremely expensive and represent an important amount of investment.

Methods

The principle is basically the same across these studies. It rests on exploiting the magnetic properties of a physical or biophysical element - that can be a nanoparticle, a nanomolecule or a protein with interesting electromagnetic properties- that will act as a relay to stimulate the ions channels (i.e, the basic signaling units) on the membrane of neurons situated at a strategic location within the nervous system. Two challenges are: (i) inserting these elements at the desired location in the brain, (ii) activating them with electromagnetic waves/fields, X-ray or similar stimulation technique.
A technology that has been developed these last ten/twenty years in the field of neuroscience is called optogenetics. This technology somewhat already exists in nature, for instance in our retina. The neurons in the retina are equipped with so called ion-gated channels that opens when stimulated by certain electromagnetic wavelengths (corresponding to the visible light and colours). The protein embedded in the channels of this retinal neurons is named -opsin or rhodopsin. See below.

Optogenetics kind of extend this mechanism to neurons within the brain. It requires using genetic engineering in order to express a light sensitive protein (the so called channelrhodopsin-2 is the most commonly used) in a key region of the brain. Thus, one can directly control neuronal activity in genetic engineered mice or rats, with a very high level of spatial and temporal accuracy. The timeline is straightforward: the emission of light activates the protein, the protein activates immediately the channel, the channel opens and give rise to neuronal signaling. Depending on the site of expression of this rhodopsin, one can inhibit the behaviour or activate it, reinforce it, trigger emotions, create some memories.

What has been done so far?

Optogenetics is mainly used in experimental neuroscience, especially in living mice in order to decipher and characterise the neuronal circuitry involved in movement, navigation, learning, memory, metabolism, hunger, thirst, respiration, sleep, blood pressure, reward, motivation, fear, sensory processing.

Heated nanoparticles have been used to remotely influence activity of deep brain region with alternate magnetic fields.

The expression of a genetic engineered protein called “magneto” in a deep structure of the brain allowed a remote control of the motor behaviour of the mice. It nevertheless did not work in another region such as the cerebellum.

These techniques are anyway invasive as they require genetic engineering, injection of heat sensitive receptors or magnetic nanomaterial, surgery to implant the relay or a virus that would transport the protein. So if one targets specific brain regions, remote control is more invasive.

We are not able (to my knowledge) to inject a virus or a carrier that would selectively target specific brain regions and trigger the expression of magnetoproteins in these sites.

What are the potential applications, apart from Parkinson’s Disease?

Optogenetics has also been considered for applications in humans, for instance in translational medicine, not necessarily in neuroscience. See paper here.

These techniques potentially make possible remote control of local neuronal activity, but at that stage anticipating and controlling the effects of such stimulations does not seem possible.

BUT please note that our brain is anyway equipped with magnetoreceptors. See a paper here. All cells of all living organisms are polarised, and as such are sensitive to electromagnetic waves and fields. No need to inject anything to remotely influence our organisms.