Table 2.

Characteristics and main findings of fMRI activation studies of the TMT. For each study, information about sample size, age, TMT variant, fMRI task characteristics, behavioural effect, fMRI contrast and identified clusters is provided.

Study	Sample size	Age (M ± SD)	TMT variant	fMRI task characteristics	Behavioural effect	fMRI contrast	Identified clusters
Moll et al. (2002)	7	24 ± 9	Verbal TMT. Covert articulation of the numerical sequence (TMT-A) and number-letter alternating sequence (TMT-B) in response to the acoustically presented cue.	Block duration: 25 s Block repetition: 10 × TMT-A, 10 × TMT-B blocks Practice: administered in standard and verbal-TMT formats	Non-tractable due to covert task requirements.	v. TMT-B > v. TMT-A	L precentral gyrus (−44, −2, 38); L inferior frontal sulcus (−40, 23, 29); L middle frontal gyrus (−36, 38, 22); L dorsal premotor cortex (−31, −16, 50); L intraparietal sulcus (−35, −55, 34); L rostral supplementary motor area/cingulate sulcus (−6, 3, 49); R intraparietal sulcus (26, −55, 34)
Zakzanis et al. (2005)	12	29 ± 5	Motor TMT. Connect the trails in the scanner using the specially designed fibre-optic drawing device ("virtual stylus") and monitor performance simultaneously onscreen inside the scanner.	Block duration: 45 s Block repetition: 4 × TMT-A, 4 × TMT-B, 8 × motor baseline conditions. Practice: 5-min practice session on the virtual stylus	Significantly fewer trails connected in the TMT-B (M = 9 ± 1) compared to the TMT-A (M = 10 ± 1) (p < 0.01).	TMT-B > TMT-A	Left-lateralised cluster comprising middle frontal gyrus (−37, 9, 31); precentral gyrus (−34, 8, 37); cingulate gyrus (−13, 9, 28); superior frontal gyrus (−20, 23, 49); medial frontal gyrus (−15, 13, 46); insula (−37, −15, 10). Left-lateralised cluster comprising middle temporal gyrus (−61, −27, 7); superior temporal gyrus (−48, 41, 10). Right-lateralised cluster comprising cingulate gyrus (20, −20, 28); insula (27, −15, 22); paracentral lobule (15, −30, 43)
Jacobson et al. (2011)	16	23 ± 4	Computerised TMT (pc-TMT). Indicate the line orientation attached to each circled number/letter stimulus by a button press.	Block duration: 45 s Block repetition: 4 × TMT-A, 4 × TMT-B Practice: session administered in both written and computerised formats. Accuracy cut-off (90%) applied prior to entering the scanner.	No significant behavioural effect.	TMT-B > TMT-A	L middle temporal gyrus (−35, −68, 28); R precentral gyrus (31, −1, 31); R inferior middle frontal gyri (36, 34, −3)