Neurohacking IV: Neuro chips - without salt and vinaegar. A neurosurgeons perspective on neurohacking

Neurochips are implantable devices designed to facilitate communication between the human brain and computers.

These brain-machine interfaces function by mimicking synapses, although their processing speed remains slower than natural brain activity. Synapses are the junction between two neurons where nerve signals are transmitted from one cell to another using electrical or chemical signals.

By using special artificial synapses called memristors, these systems allow the brain to communicate instantly with external devices, helping develop smarter brain-like technology.

You would want your new brain chip to restore or enhance - and not cause too much trouble. Therefore, a key aspect of neurochip development is a minimally invasive approach to implantation.

Neurochips - how to get them in there?
From a neurosurgical perspective, the implantation of neurochips requires precision and expertise.

Traditional procedures like deep brain stimulation require meticulous, time-consuming stereotactic surgery to place electrodes in specific brain regions. The deep brain stimulation electrodes have to be advanced through the brain tissue to targets deep in the brain like the basal ganglia.

That can be risky business - the risk of bleeding and damage to the brain tissue for a starter. Even surface electrodes that are placed on the brain's most superficial layer - the cortex - kind of need to get in there though a hole in the skull. And our superficial vessels on the brain surface are also important, and they can be brittle.

From the brain and into the vessels
Traditional procedures involve deep brain stimulation, but researchers are now investigating endovascular methods that, besides removing the risk of damage to the brain tissue, also reduce risks such as scarring around the implant and infection.

This technique, known as endovascular neuromodulation, involves placing electrode arrays in blood vessels near the brain cells. Because these vessels are close to critical brain areas, this approach offers a promising pathway for implanting neural interfaces.

These devices can record activity in the brain cortex and perform stimulation of discrete neuronal populations in the brain cortex, with comparable accuracy to neurosurgically implanted depth electrodes.

In a recent first-in-human trial, 4 patients with severe paralysis of both arms had such a chip inserted into the vessels near the brain. Recording devices were delivered via catheter and connected to subcutaneous electronic units. The devices communicated wirelessly to an external device for personal computer control.

At least 5 attempted movement types were decoded offline, and all 4 patients successfully controlled a computer with the brain-computer interface. That indicates it is possible to record neural signals from a blood vessel.

Are there really not any safer routes?
Researchers are exploring alternative approaches to make these implants safer and more effective over time. An example is the development of minimally invasive ways to implant neurochips using robotic-assisted techniques similar to deep brain stimulation.

These methods aim to reduce risks like scarring, infection, and long-term instability of implanted electrodes. However, maintaining a reliable connection between brain tissue and electronic interfaces remains a challenge.

And the end-vascular electrodes come with a risk too. A clot around the electrode could obliterate the vessel and cause a stroke. It may not be direct, but indirect and equally damaging brain destruction.

Neurosurgeons play a critical role not only in implanting these devices but also in shaping their design to ensure minimal disruption to surrounding neural structures.

As these technologies evolve, neurosurgical expertise will be essential in refining surgical techniques and addressing potential complications associated with long-term implantation.

About the scientific paper:

First author: Alejandra T. Rabadán, Argentina
Published in: Surgical Neurology International, April 2021
Link to paper: https://surgicalneurologyint.com/surgicalint-articles/neurochips-considerations-from-a-neurosurgeons-standpoint/ 

First author: Peter Mitchell, Australia
Published in: JAMA Neurology, March 2023
Link to paper: https://jamanetwork.com/journals/jamaneurology/fullarticle/2799839