Fig. 2

In vivo recording demonstrated differential changes in neural activity after injection of MK-801. a Sample recording of in vivo single unit recording of neural activity in the mPFC (Upper). In a fast-spiking neuron (basal spike frequency > 10 spike/sec), injection (i.p) of MK-801 (0.3 mg/kg, arrow) led to a reduction in neural spiking over time. (Lower) In a regular spiking neuron, MK-801 injection led to an increase in neural activity over time. Sample spike waveforms were shown in the inserts. b Fraction of recorded units showing no change, increase and decrease in burst spike rate in the saline (Sal) and MK-801 injection group. Burst spike rate were not altered in most neurons in the Sal group, while nearly twice as many unit showed significant decrease in burst spike rate in the MK-801 group. The group showing decrease represents the average burst firing rate following 30 to 60 min after administration of MK-801. Decrease is defined as reduced by 20% or more, increase defined as increase by 20% or over, and no change defined as values between 80 and 120%, all compared to baseline. c Normalized changes in single spike rates before, 30, 60 and 90 min after MK-801 injection. Significant increase was seen starting 30 min after MK-801 injection