Figure 9

Summary of proposed candidate genes as molecular basis of known VMN properties. A) Known VMN neurophysiological properties. Extreme temporal precision of motoneuron firing is shown by corresponding traces from an intracellular recording (bottom, red) and VN recording (top, purple) (adapted from [8]). Numbers 1–5 correspond to intrinsic neuronal and network VMN properties listed in C. B) Schematic of known VMN neuroanatomical properties. Most of the motoneuron somata appear gray with subsets of red and black somata to highlight properties that are representative of the entire VMN. Glial expression of aromatase [88] and androgen receptor beta [120] is depicted in blue and orange. One of the black somata in the left VMN also depicts each motoneuron’s dendritic arbor that branches throughout each of the midline pair of motor nuclei and a single unbranched axon that exits via the ipsilateral vocal nerve (VN) (see [8]). The subsection of dense GABAergic innervation by cells lying outside of the VMN is also representative of the entire VMN. Abbreviations: AR: androgen receptor; ER: estrogen receptor; GABA: gamma-aminobutyric acid. C) For the suite of VMN properties, we identified corresponding transcripts that were significantly upregulated in the VMN compared to the surrounding hindbrain, and provide substantiating evidence from previous midshipman studies (see reference list for numbered citations). Abbreviations: ar-a: androgen receptor alpha; esr: estrogen receptor; cyp19a1a: aromatase; nrc3c1: glucocorticoid receptor; cx: connexin (gap junction); AP: action potential; kcn: voltage-gated potassium channels; AHP; afterhyperpolarization; gabra/GABAaR: GABA_A receptor; ICC: immunocytochemistry; chrm2: muscarinic acetylcholine receptor m2. *indicates kcn subunits known to regulate the function of subunits listed in the row above.