Fig. 2.
Physiological changes during provocation of an obsessive fear that drives compulsive cleaning behavior. A: provocation was performed at two nucleus accumbens (NAc) sites (yellow/purple dots 4/6 mm ventral to the dorsal NAc border). B: after resting baseline, the patient was handed a toothbrush to bring to his face and was told “imagine brushing your teeth with this dirty toothbrush,” followed by bringing his hand to his face without a toothbrush (see Supplemental video). C: action potential rate selectively increased during toothbrush provocation at the yellow site. (‡P = 1×10−6/t = 5.4; †P = 0.05/t = −2.0, by unpaired t-test. Error bars show SE of 1-s blocks). D: power spectral densities reveal progressive power increase across all frequencies during the task at the yellow site. Inset axes show isolated alpha-range (8–10 Hz, ‡P = 2×10−6/t = 5.2) and gamma-range (31–39 Hz, ‡P = 7×10−7/t = 5.5) amplitudes. E: conversely, a neuron captured 2 mm ventral (purple site) exhibited a significant decrease in spike rate (P = †8×10−3/t = −2.7) and gamma-range amplitude (†P = 0.04/t = −2.1; ‡P = 4×10−6/t = 5.0) with provocation.