Table 1. Types of TMS pulses.

CS: conditioning stimulus; ISI: inter stimulus interval; ms: milliseconds; sec: seconds; TMS: transcranial magnetic stimulation; TS: test stimulus

 

Types of pulse	Definition	Effect
Single pulse	Discharge of single pulses separated by a time interval of at least 4 sec to 8 sec, resulting in an individual effect constitutes single pulse-TMS.	The induced effects can be quantified in the form of 1) motor evoked activity in primary motor areas; 2) evoked visual activity and visual precepts, such as phosphenes; 3) short-acting disturbances in cognitive tasks, such as changes in performance.
Double pulse	Also known as paired pulse-TMS, it consists of two pulses, i.e., discharge of a CS followed by a TS that are separated by an ISI.	By using subthreshold CS and suprathreshold TS and using varying ISI from short (< 5 ms), intermediate (7 - 15 ms), and long (50 - 200 ms), the effect can be modulated from intracortical facilitation to inhibition. They can also be used to determine the presence or absence of connectivity and estimation of conduction time between two distinct cerebral sites
Repetitive pulse	Repetitive pulse-TMS consist of delivering any combination of more than two pulses with in-between time interval of 2 sec or less to generate different effect than that produced from the isolated pulse. It involves delivery of short bursts or trains of 3 - 4 pulses at high frequency and of long periods of stimulation at a fixed frequency with or without interruption by stimulation free intervals in between charges.	The effects can range from 1) online TMS effect: This results from direct and measurable interference with patterns of ongoing neuronal discharge at the time of stimulation; 2) offline TMS effect: This constitutes the lasting impact on the cerebral process that results from a previously administered pattern of repetitive stimulation.