1. Pain-related depression of ICSS
Pain-related depression of ICSS. (A) A photograph of a rat pressing an operant response lever to receive pulses of electrical brain stimulation via a chronically implanted microelectrode connected via a cable to a stimulator outside the frame of the picture.
Pain-related depression of ICSS. (A) A photograph of a rat pressing an operant response lever to receive pulses of electrical brain stimulation via a chronically implanted microelectrode connected via a cable to a stimulator outside the frame of the picture. (B) Illustrative baseline data from a frequency-rate ICSS procedure. The x-axis shows the frequency of brain stimulation in Hertz available during different components of a behavioral session, and the y-axis shows rate of reinforcement normalized as the percent of maximum control rate (%MCR), with MCR defined as the peak rate at any brain-stimulation frequency. Increasing brain-stimulation frequencies maintain increasing rates of reinforcement. (C) Pretreatment with a noxious stimulus (intraperitoneal injection of 1.8% lactic acid) depresses ICSS and shifts the frequency-rate curve to the right, whereas pretreatment with intraperitoneal lactic acid vehicle does not. The number sign (#) indicates frequencies at which rates after acid were significantly lower than rates after vehicle. (D) Summary data for total ICSS in (C) collapsed across all frequencies of brain stimulation. The x-axis shows treatment with lactic acid vehicle (LA Veh) or 1.8% lactic acid (LA). The y-axis shows the total number of stimulations expressed as a percentage of noninjection controls. The number sign (#) indicates depression of ICSS by 1.8% lactic acid. Adapted from Negus (2013).
S. Stevens Negus Pharmacol Rev 2019;71:
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