Fig. 4.

Neuronal hyperresponsiveness in prefrontal cortex after chronic NMDA-R blockade by MK-801, assessed by paired-pulse facilitation, and normalization by BP 897. Slices were prepared from animals receiving continuous infusion of saline and a saline subchronic treatment (Sham + Sal) or a continuous infusion of MK-801 and a subchronic treatment with either saline (MK-801 + Sal) or BP 897 (1 mg kg^-1, MK-801 + BP 897) sacrificed 3 days after continuous MK-801 cessation and at least 16 h after the last injection. a Field potentials were recorded with an electrode placed in the middle layers of the prelimbic cortex (PrL) after stimulation in the adjacent region. Ac nucleus accumbens core, As nucleus accumbens shell, cc corpus callosum, Cg cingulate cortex, Cpu caudate-putamen, IL infralimbic cortex, M1 primary motor cortex, M2 secondary motor cortex, Sm primary sensorimotor cortex. b Field potentials after paired-pulse stimulation with an interpulse interval of 62.5 ms. Traces are means of eight successive recordings performed on a representative animal of each group treatment. Artifacts immediately following stimulation were removed for clarity. Color codes as in c. c Paired-pulse facilitation, measured as the ratio of amplitudes of responses to the second and first stimulations, as a function of the interpulse interval. Results are mean ± SEM. of averaged ratios recorded in five to six animals. There were significant effects of interpulse interval (F _7,98 = 16.55, P < 0.00001). *P < 0.05; ** P < 0.01