Abstract: A neurostimulation device 1 for non-destructively stimulating neural activity in a nerve 3 in proximity to a blood vessel 5. The neurostimulation device 1 comprises a catheter 7 for insertion into the blood vessel 5; a proximal electrode 11 offset from a distal electrode 9 along a length of the catheter 7; and an insulator 13 positioned between the proximal electrode 11 and the distal electrode 9 on the catheter 7. The insulator 13 has a contracted configuration in which the size of the insulator 13 allows the catheter 7 to travel inside the blood vessel 5. The insulator 13 has an expanded configuration in which the insulator 13 blocks blood flowing through the blood vessel between the proximal electrode 11 and the distal electrode 9.