Appendix 1.

Active clusters and their approximate locations during mental effort rating

Region	Peak X	Peak Y	Peak Z	n (vox)	t	P
Inferior frontal gyrus, opercular part	−43	16	24	48	9.48	0.000001
Anterior insula	35	13	6	483	8.89	0.000002
	−37	13	6	47	8.11	0.000006
Precentral sulcus	50	4	12	832	9.18	0.000002
Precentral gyrus	−55	1	24	80	8.46	0.000004
	−52	−2	33	56	6.70	0.000034
Precentral gyrus/superior frontal sulcus	41	−14	48	1835	10.28	0.000001
	−28	−14	54	2551	9.78	0.000001
Postcentral sulcus	32	−41	39	2141	11.27	0.000000
	−34	−38	42	3488	9.27	0.000002
Cingulate gyrus	−4	−14	48	3890	11.99	0.000000
Ventral lateral posterior thalamic nucleus	14	−23	9	692	8.57	0.000003
	−19	−26	6	1160	9.29	0.000002
Parietooccipital trans. zone/Angular gyrus	14	−68	36	315	9.16	0.000002
Intraparietal sulcus	−25	−56	45	196	8.13	0.000006
Lateral occipitotemporal sulcus	38	−62	−9	906	10.36	0.000001
	−37	−59	−12	80	7.89	0.000007
Medial occipital gyrus	26	−83	−6	4289	14.86	0.000000
	−4	−77	−12	815	10.03	0.000001
Lateral occipital gyrus	−28	−71	−15	496	8.00	0.000007

P values represent the peak P-value of a cluster.