# rTMS and Neuromodulation

> rTMS and neuromodulation notes for NEET-PG Psychiatry covering DLPFC stimulation, tDCS, vagus nerve stimulation, deep brain stimulation and indications.

- Canonical URL: https://prepelephant.com/topics/neet-pg/psychiatry/rtms-and-neuromodulation
- Exam / course: NEET-PG · Subject: Psychiatry
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "rTMS and Neuromodulation", PrepElephant, https://prepelephant.com/topics/neet-pg/psychiatry/rtms-and-neuromodulation

## Direct answer

Neuromodulation in psychiatry refers to non-pharmacological techniques that modulate brain circuit activity — repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), vagus nerve stimulation (VNS), deep brain stimulation (DBS) and magnetic seizure therapy — used mainly in treatment-resistant depression, with approved psychiatric use in obsessive-compulsive disorder for some devices. rTMS applies a magnetic coil over the scalp to induce cortical currents: high-frequency stimulation of the left dorsolateral prefrontal cortex (DLPFC) is excitatory and antidepressant, while low-frequency right-sided stimulation is inhibitory. Unlike electroconvulsive therapy, rTMS needs no anaesthesia and does not deliberately provoke a seizure, though efficacy is slower and more modest.

## What you must remember

- **rTMS principle:** a pulsed magnetic field passes painlessly through the scalp to induce cortical currents; high-frequency stimulation (above about 5 Hz) is excitatory, low frequency (about 1 Hz) inhibitory.
- **Depression protocol:** daily outpatient high-frequency left DLPFC sessions over four to six weeks — slower and smaller in effect than ECT, suited to resistant but not urgently ill patients.
- **Safety of rTMS:** no anaesthesia; main risks are scalp discomfort and headache, seizure rare with screening; contraindicated with ferromagnetic implants and pacemakers.
- **Other rTMS uses:** low-frequency right-sided or bilateral protocols, and growing evidence in auditory hallucinations, negative symptoms and obsessive-compulsive disorder.
- **tDCS:** weak scalp current shifting cortical excitability — anodal excitatory, cathodal inhibitory; portable with evolving evidence.
- **Vagus nerve stimulation:** implanted left cervical device; adjunct for epilepsy and chronic treatment-resistant depression in several jurisdictions.
- **DBS and MST:** deep brain stimulation remains investigational for depression and OCD; magnetic seizure therapy is an experimental refinement.
- **Comparison with ECT:** ECT stays the most effective acute treatment for severe, psychotic or catatonic depression and refusal of food — neuromodulation suits resistant depression without those emergencies.

## Common confusion

rTMS versus ECT is the comparison to master: ECT requires anaesthesia, deliberately induces a seizure, has strong efficacy in severe and psychotic depression and causes transient memory disturbance; rTMS is awake, outpatient, focal and seizure-free by design, milder and largely free of cognitive effects. Within neuromodulation, keep the frequency rule straight and the device-target pairs distinct — TMS over DLPFC, tDCS as weak current, VNS as an implanted vagal pacemaker, DBS as depth electrodes.

## Exam-focused takeaway

NEET-PG frames neuromodulation as device-matching (magnetic coil over left DLPFC for resistant depression equals rTMS; implanted vagal stimulator equals VNS) or as an ECT-comparison stem where ECT wins for psychosis, catatonia and suicidality. One-liners test the frequency rule, ferromagnetic-implant contraindications, and tDCS as weak-current neuromodulation.

## Frequently asked questions

### What is repetitive transcranial magnetic stimulation?

An outpatient technique in which a pulsed magnetic coil over the scalp induces cortical currents — high-frequency left prefrontal stimulation is the standard antidepressant use.

### How does rTMS differ from electroconvulsive therapy?

rTMS is awake, needs no anaesthesia and does not intentionally induce seizures; ECT induces a seizure under anaesthesia and is more effective in severe, psychotic or catatonic depression.

### Which patients are contraindicated for rTMS?

Those with ferromagnetic implants (aneurysm clips, cochlear implants), pacemakers or raised seizure risk.

### What is transcranial direct current stimulation?

Weak scalp-applied current that shifts cortical excitability — anodal excites, cathodal inhibits.

### What is vagus nerve stimulation?

An implanted device stimulating the left vagus nerve, an adjunct for epilepsy and, in several jurisdictions, treatment-resistant depression.

### Is deep brain stimulation an approved depression treatment?

It remains largely investigational for depression and OCD, unlike its established role in Parkinson disease.