Deep TMS for Addiction

Abraham Zangen is working on developing deep transcranial magnetic brain stimulation technology to treat reward related disorders such as addiction or depression. He's got some interesting writing on his website about deep TMS and also info about his research on addiction (main page here). Being able to target the reward regions of the brain definitely brings up a lot of interesting ethical issues.

Researchers are working on a lot of new brain stimulation techniques. Other people besides Zangen are working on new types of deep TMS coils. Magnetic brain stimulation protocols such as "theta burst stimulation" could enable longer lasting brain excitability changes for a shorter stimulation duration. Controllable pulse shape TMS devices will allow for better targeting of brain regions. Ultrasonic neuromodulation could potentially enable an even greater targeting accuracy than TMS. Or perhaps it will be used in tandem with the numerous other types of brain modulation techniques (transcranial direct current stimulation, infrared stimulation). I think future goals of brain stimulation science will continue to seek longer lasting brain changes that can be induced in a shorter period of time. Also, brain stimulation tools will have much more selectivity in their manipulation capability.

A new paper about transcranial magnetic brain stimulation is available (abstract here). It discusses the mechanisms of action of TMS. The link to the paper is below.

Transcranial magnetic stimulation, synaptic plasticity and network oscillations (pdf 1.3 MB).

The basic principle of TMS is that most neuronal axons that fall within the volume of magnetic stimulation become electrically excited, trigger action potentials and release neurotransmitter into the postsynaptic neurons. What happens afterwards remains elusive, especially in the case of repeated stimulation. Here we discuss the likelihood that certain TMS protocols produce long-term changes in cortical synapses akin to long-term potentiation and long-term depression of synaptic transmission. Beyond the synaptic effects, TMS might have consequences on other neuronal processes, such as genetic and protein regulation, and circuit-level patterns, such as network oscillations. Furthermore, TMS might have non-neuronal effects, such as changes in blood flow, which are still poorly understood.