Singing-related neural activity distinguishes four classes of putative striatal neurons in the songbird basal ganglia.
The striatum-the primary input nucleus of the basal ganglia-plays a major role in motor control and learning. Four main classes of striatal neuron are thought to be essential for normal striatal function: medium spiny neurons, fast-spiking interneurons, cholinergic tonically active neurons, and low-threshold spiking interneurons. However, the nature of the interaction of these neurons during behavior is poorly understood. The songbird area X is a specialized striato-pallidal basal ganglia nucleus that contains two pallidal cell types as well as the same four cell types found in the mammalian striatum. We recorded 185 single units in Area X of singing juvenile birds and, based on singing-related firing patterns and spike waveforms, find six distinct cell classes--two classes of putative pallidal neuron that exhibited a high spontaneous firing rate (> 60 Hz), and four cell classes that exhibited low spontaneous firing rates characteristic of striatal neurons. In this study, we examine in detail the four putative striatal cell classes. Type-1 neurons were the most frequently encountered and exhibited sparse temporally precise singing-related activity. Type-2 neurons were distinguished by their narrow spike waveforms and exhibited brief, high-frequency bursts during singing. Type-3 neurons were tonically active and did not burst, whereas type-4 neurons were inactive outside of singing and during singing generated long high-frequency bursts that could reach firing rates over 1 kHz. Based on comparison to the mammalian literature, we suggest that these four putative striatal cell classes correspond, respectively, to the medium spiny neurons, fast-spiking interneurons, tonically active neurons, and low-threshold spiking interneurons that are known to reside in area X.
Goldberg
Jesse H
JH
McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Fee
Michale S
MS
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001479:Basal Ganglia / Q000166:cytology / Q000502:physiology*; D046369:Finches / Q000502:physiology*; D007395:Interneurons / Q000145:classification / Q000166:cytology / Q000502:physiology; D008297:Male; D023421:Models, Animal; D009474:Neurons / Q000145:classification* / Q000166:cytology / Q000502:physiology; D014828:Vocalization, Animal / Q000502:physiology*