**Core Concept**
Transcranial magnetic stimulation (TMS) is a non-invasive neurostimulation technique that uses magnetic fields to induce electrical currents in the brain, primarily for therapeutic purposes such as treating depression and anxiety disorders.

**Why the Correct Answer is Right**
TMS works by creating a magnetic field that induces electrical currents in the brain, which can either stimulate or suppress neural activity. This is achieved by a brief, high-intensity magnetic pulse that generates an electrical current in the underlying cortex, depending on the direction of the current flow. The correct answer is related to the effect of TMS on neural activity, specifically the ability to either inhibit or facilitate it.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect as TMS has not been shown to directly alter gene expression. While it can affect neural activity, the underlying mechanism does not involve direct gene modification.
**Option B:** This statement is incorrect as TMS does not work by directly blocking neurotransmitters. Instead, it modulates neural activity through electrical currents.
**Option C:** This statement is incorrect as TMS is not a form of electroconvulsive therapy (ECT). Although both techniques involve electrical stimulation, they work through distinct mechanisms and have different clinical applications.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that TMS has varying effects on different brain regions, and its efficacy can be influenced by the location and intensity of the magnetic field, as well as individual patient factors.

**Correct Answer: C. TMS can modulate both excitatory and inhibitory neural activity, depending on the direction of the induced current.**