The generation of natural firing patterns in neostriatal neurons

Abstract

In one of the first single unit recording studies of the mammalian neostriatum, Albe-Fessard and co-workers observed that spontaneously active neostriatal neurons in unanesthetized (decerebrate) animals fired at low rates in an irregular, somewhat bursty pattern. They further observed that upon onset of chloralose anesthesia, the bursts of activity were more pronounced and began to occur rhythmically at 3–10 Hz. A later study by Sedgwick and Williams showed that this rhythmic bursting was also characteristic of light barbituate anesthesia, and deeper anesthesia could lead to slowing and complete cessation of firing. Using intracellular recordings, Sedgwick and Williams were able to demonstrate prolonged depolarizing potentials that underlay the bursts of firing in the lightly anesthetized animals, and they postulated that these arose from a rhythmic excitatory synaptic input to the neostriatum, acting in conjunction with inhibitory processes that terminated the bursts. Numerous studies published over the past 25 years have repeated these observations, usually emphasizing the low firing rates of the neurons, the large number of neurons with practically no spontaneous firing (in both anesthetized and unanesthetized preparations), and the rhythmic bursting of neurons under light anesthesia. © 1993, Academic Press Inc.