J Comp Physiol A (2007) 193:677–683 DOI 10.1007/s00359-007-0222-1 123 ORIGINAL PAPER Seasonal changes in intrinsic electrophysiological activity of song control neurons in wild song sparrows John Meitzen · David J. Perkel · Eliot A. Brenowitz Received: 30 January 2007 / Revised: 19 March 2007 / Accepted: 21 March 2007 / Published online: 14 April 2007  Springer-Verlag 2007 Abstract Song behavior and its underlying neural sub- strate can change seasonally in adult songbirds. To test whether environmental cues induce seasonal changes in electrophysiological characteristics of song control neu- rons, we measured in vitro intrinsic neuronal activity in the song control nucleus RA of adult male song sparrows (Melospiza melodia) in both the fall non-breeding and spring breeding seasons. We found that RA neurons in spring-captured birds show a more than threefold increase in spontaneous Wring rate compared to those from fall-cap- tured birds. We conclude that environmental cues are suY- cient to induce seasonal changes in electrophysiological properties of song control neurons, and that changes in these properties may underlie seasonal changes in song behavior. Keywords Spontaneous activity · Song sparrow · Electrophysiology · Songbird · Seasonal plasticity Abbreviations 13:11 13 h light:11 h dark ACSF ArtiWcial cerebrospinal Xuid AFP Anterior forebrain pathway DLM The medial portion of the dorsolateral nucleus of the anterior thalamus HVC Used as a proper name LD + T Long-day photoperiod (20 h light:4 h dark) and a systemic testosterone implant LMAN The lateral magnocellular nucleus of anterior nidopallium RA The robust nucleus of the arcopallium RIA Radioimmunoassay SD Short-day photoperiod (8 h light:16 h dark) SEM Standard error of the mean T Testosterone WC White-crowned sparrow X Area X, a subdivision of the medial striatum Introduction The arrival of the breeding season typically induces changes in reproductive-related behaviors (WingWeld and Kenagy 1991; Tramontin and Brenowitz 2000). The neural substrates that control reproductive behavior often undergo a functional reorganization, facilitating enhanced perfor- mance (Tramontin and Brenowitz 2000; Brenowitz 2004). These phenomena are observed in all vertebrate taxa, but one of the best-studied and most pronounced examples occurs in singing behavior and the song-control system in adult songbirds (Fig. 1a, Nottebohm 1981; Tramontin and Brenowitz 2000; Ball et al. 2004; Brenowitz 2004). Song is a learned vocalization used to attract mates, defend territories, and recognize mates or territorial J. Meitzen Graduate Program in Neurobiology and Behavior, University of Washington, Seattle, WA 98195, USA J. Meitzen (&) · D. J. Perkel Department of Otolaryngology, University of Washington, 1959 NE PaciWc Street, Room BB1148, Box 356515, Seattle, WA 98195, USA e-mail: jmeitzen@u.washington.edu E. A. Brenowitz Department of Psychology, University of Washington, Seattle, WA 98195, USA D. J. Perkel · E. A. Brenowitz Department of Biology, University of Washington, Seattle, WA 98195, USA