Tonotopic organization of the auditory forebrain in a songbird,the European starling

Summary The auditory area in the caudomedial forebrain of birds is explored by microelectrode recordings in a songbird. Multi-unit recordings reveal a clear tonotopic representation of stimulus frequency (Figs. 1, 2a, 3) with a mainly dorsoventral gradient (low frequencies dorsal). Frequency tuning is lost only in peripheral parts of the nucleus where wideband responses prevail. The functional structure is related to neuroanatomical landmarks of the forebrain by means of a 3-dimensional reconstruction from cell- and fibre-stained brain sections (Figs. 3, 4). For instance, a core region of high spontaneous and evoked activity (Figs. 5, 6b) is related to the input region (field L2) of the area. Additional single unit recordings support the multi-unit data (Fig. 6). The tonotopic organization found in the starling is compared with the organization of the caudomedial forebrain reported for other bird families.Abbreviations cer cerebellum - fpl fasciculus prosencephali lateralis - lh lamina hyperstriatica - lmd lamina medullaris dorsalis - ven ventricle - 2DG 2-DeoxyglucoseThis work was supported by the Deutsche Forschungsgemeinschaft, SFB 114