Wires and Nerves

Wires and Nerves

Our central nervous system (CNS), made of our brain and spinal cord, exists in an environment essentially separated from the rest of our bodies, and for good reason. The CNS coordinates the disparate organs in our bodies and is responsible for our thoughts and decision-making. As such, it is vital to protect it from pathogens, harmful molecules, and other damage. Our natural defenses include physical barriers like the skull as well as the tissues comprising the endothelial blood-brain barrier (BBB) and epithelial blood-cerebrospinal fuid barrier (BCSFB).

While usually helpful, these barriers can hinder medical treatment. Whether for stroke recovery, preventing neurodegenerative disease, or treating mental illness, medical intervention can be more efective than any natural healing process. However, it has historically been difcult to afect the brain in the same way we do other parts of the body. Surgery and Drug Treatment O ne issue lies in the risks associated with brain surgery. Unlike with other organs, where scarring and lesions can heal, any accidental damage to our neurons can result in loss of function. For example, while electrode implants for epilepsy can prevent seizures, the surgery is risky and seen as a last resort rather than standard treatment.

Another major problem has been targeting drugs for delivery to the brain. Drugs circulate through the blood until they reach their intended organs. Not so for the brain: the blood-brain barrier commonly blocks out necessary treatments. Current drug development must overcome this, as illustrated by the treatment for Parkinson’s Disease.

Parkinson’s is a neurodegenerative disease where the motor system fails, resulting in tremors and rigidity. For unknown reasons, cells that produce the neurotransmitter dopamine die, and the lack of dopamine causes the motor failure. In theory, administering dopamine as a drug could alleviate many of the Parkinson’s symptoms. However, dopamine cannot cross the BBB Luckily, L-DOPA, a precursor to dopamine can, and thus it became a fxture in Parkinson’s treatments.

Although L-DOPA was a success, drug targeting to cross the BBB remains a problem How Technology Can Treat Brain Conditions that requires time and money to circumvent. In light of this, non-invasive methods for altering brain activity are rapidly developing. Non-Invasive Methods A ll the methods described below are non-invasive, requiring only that a device be placed on top of the head for roughly hour-long sessions (depending on the treatment type). Targeting specifc brain regions is as simple as changing the placement of the devices on the head. Additionally, they have few serious side efects, the most common being nausea, headaches, and tingling.

While they have not been found an effective treatment in isolation, the ease of use, low cost, and promising results means that non-invasive treatments will likely become increasingly present in clinical practice. Transcranial Magnetic Stimulation (TMS) T he frst treatment option is repetitive transcranial magnetic stimulation (rTMS). A device generates a magnetic feld which interacts with the electrical current of neurons and increases brain activity. So far, rTMS has been approved to treat depression in patients where traditional drug treatments and therapy have proved inefective. By sending pulses into the dorsolateral prefrontal cortex, a site implicated in depression, it has been found to have a meaningful efect on 50-60% of patients.

The efects last for a few months, and 30% of patients are full remission, with no trace of depression. There are also promising results in regards to stroke recovery, in which the motor cortex is stimulated. Trials are ongoing for bipolar disorder and OCD, though they are currently “of-label”. Transcranial direct current stimulation (tDCS) A nother option is tDCS. Here, a cathode and anode are placed on the skull and a weak current (1-2 mA) is sent through the brain. There is fexibility with this method: anodal stimulation excites neurons, and cathodal stimulation inhibits them. The machinery is cheap and portable, making it a treatment option that could be easily distributed.

It has been found to alleviate symptoms of depression, schizophrenia, and Parkinson’s.

However, tDCS studies sufer from low sample numbers and high variability in trials. More work must be undertaken to determine its efcacy. Focused Ultrasound (FUS) F inally, FUS uses ultrasonic waves to activate brain regions. Unlike tDCS and TMS, the region it affects can be much more targeted. For example, in Parkinson’s treatment it can treat tremor by targeting the thalamus, or akinesia (lack of movement) by targeting the pallidothalamic tract. It has also been approved to treat depression, neuropathic pain, and OCD, and trials are ongoing for addiction, ALS, dementia, and other conditions. The Future of Brain Treatment I n the future, researchers will likely focus on improving targeting and fne-tuning clinical protocols. There is also the possibility of using these methods to improve everyday cognitive function. tDCS has already gained popularity as a commercial ‘brain booster’, although experts advise against tampering with your own brain function.

Non-invasive brain stimulation has had a promising start. It is hard to compare their early stages to the sheer bulk of drug- and surgery-based treatments, but the number of positive results from clinical trials and ongoing research suggest that brain stimulation can become a regular part of disease treatment.

Maya Misra is a Biochemistry undergraduate at Brasenose College.