Perfectly remodeled brains in science fiction movies are a major concern. Today, this dream is gradually approaching reality with genetic engineering, artificial intelligence and brain stimulation methods. Although it is not possible to build the brain from scratch, neuromodulation techniques are becoming more and more successful in curing diseases and increasing the brain’s performance in various subjects. However, methods involving brain intervention should be carefully evaluated in terms of their benefits as well as their potential risks to the individual and society.
Neurological and psychiatric disorders such as depression, chronic pain, and post-traumatic stress disorder can be resistant to standard treatments and psychotherapy. Therefore, new treatment methods are being researched. Neuromodulation can be effective in treating these problems. Neuromodulation or neurostimulation refers to the direct stimulation and regulation of the nervous system by electrical, chemical or mechanical signals. Neuromodulation therapy is currently used to treat brain-related problems such as movement disorders, chronic pain, and depression.
There are two main types of neuromodulation: invasive (interventional) and noninvasive (non-invasive). Invasive modalities are applied in the most severe cases and require surgery. Deep brain stimulation (DBS), vagal nerve stimulation and epidural prefrontal cortical stimulation are examples of this. Noninvasive treatments are electroconvulsive therapy, transcranial magnetic stimulation (TMS), theta burst stimulation, magnetic seizure therapy and transcranial direct current stimulation (tDCS). tDCS, repetitive transcranial magnetic stimulation, focused ultrasound and DBS are used in psychiatric diseases and traumatic brain injury. Each technique can be personalized according to the individual needs of the patient and the severity of the disease.
Origin of DBS
Deep brain stimulation has a relatively short history. The work of Alim Benabid in the 1980s played a role in its development. In these studies, electrical stimulation of the basal ganglia has been shown to reduce the symptoms of Parkinson’s disease. More recently, it has been observed that continuous DBS application to the subgenual cingulate may provide clinical benefit in treatment-resistant depression. While the results of DBS in tremor and dystonia in Parkinson’s disease are impressive, its effectiveness in treating depression has been mixed. It can also provide noticeable improvements in brain damage and other diseases that cause serious neurological disorders.
Repetitive Transcranial Magnetic Stimulation
Repetitive TMS (rTMS) can create a strong magnetic field near the skull, affecting neuron activity locally and distantly. These magnetic fields pass through the bone in series of pulses, changing the excitability of nerve cells. An important mechanism of stroke and brain damage after recovery , neuroplasticity may be enhanced by rTMS.
Today, rTMS is actively used in the treatment of various neurological and psychiatric disorders, and its benefits and risks are intensively researched. New research shows that daily stimulation of the dorsolateral prefrontal cortex reduces symptoms in patients with treatment-resistant acute depression. Its effects on post-traumatic stress disorder, anxiety, dementia, and traumatic brain injury are also subject to scientific studies. Clinical guidelines have been developed that address issues such as the technique’s application, dosage, and patient selection.
Transcranial Direct Current Stimulation
Transcranial direct current stimulation (tDCS) is a noninvasive technique in which direct currents reach the cortex, the outer layer of the brain. Rather than trigger action potentials like rTMS, tDCS modulates spontaneous cortical activity. In other words, while rTMS directly induces the firing of specific neurons it stimulates, tDCS changes the spontaneous action potential patterns in certain cells.
Early studies focused on the response of the motor cortex, the action center of the brain, to stimulation. More recent studies are investigating its effects on the left dorsolateral prefrontal cortex. This region was stimulated by both rTMS and tDCS techniques. While some studies have shown it to reduce various cognitive complaints (for example, memory problems in the early stages of Alzheimer’s disease), other studies have found no effect. Neuromodulation studies may show bias due to factors such as participants’ expectations and past answers. This may be one of the reasons for the conflicting results. tDCS shows promise in the treatment of fibromyalgia , depression, addiction and traumatic brain injury.
Low Intensity Focused Ultrasound Pulsation
Another noninvasive method is low-intensity focused ultrasound vibration. Ultrasound has been used in medicine for 50 years for various purposes, and its use in neuromodulation is new. First scientific study of herbal lifeIt investigated its use to “wake up” patients in the hospital and was published in 2016. In this technique, low-energy sound waves pass through the skin and skull and reach the brain. Deep structures can be clearly targeted, neural activity can be regulated, and disease symptoms can be reduced. Parameters such as appropriate dose, duration and frequency for treatment are still being investigated. The advantage of focused ultrasound pulsation therapy over other noninvasive methods is that it can reach deep structures. It is also a method that allows controlled scientific research as patients do not feel that the device is on or off.
The first applications of each technique start out crude and become perfect as knowledge and experience increase. In neuromodulation techniques, it can be said that issues such as which brain region will be selected in which patient and which method should be used at which dose are still in the initial stages. If its expected potential is realized, it will be an important tool in the treatment of many neurological and psychiatric problems.