Am 21.06.2016 trägt PhD Daniela Vallentin (NYU, New York) im Rahmen des IBU/DFN-Kolloquiums zum Thema
"Inhibition protects acquired song segments during vocal learning in zebra finches"
Zebra finches learn their songs by listening to and imitating a tutor. During development, sensory input is necessary in order to effectively imitate the tutor’s song. Here, we measured the impact of the tutor song on HVC neurons during and after learning. We recorded intracellularly from premotor cells and found that the tutor song has the potential to drive precise spiking responses in the awake juvenile zebra finch, but not in the adult bird. Local application of the GABAA antagonist gabazine led to a reemergence of tutor song-driven spiking responses in premotor neurons suggesting that inhibition suppresses this activity. We used voltage clamp to measure inhibitory currents evoked by the tutor song throughout the critical period for song learning while simultaneously quantifying each bird’s learning trajectory. Synaptic inhibition onto premotor neurons in HVC became significantly more precisely timed to the tutor song depending on the learning stage of the bird. We further trained zebra finches with a synthetic tutor song consisting of four identical syllables (AAAA). After the birds gained proficiency in the performance of syllable A, we extended the tutor song by adding syllable B (ABAB). We recorded interneuron activity and inhibitory currents onto premotor neurons in zebra finches that copied A well and copied B poorly, and found that inhibition was selectively stronger during syllable A versus syllable B. Taken together, these data suggest that inhibition within HVC progressively blocks an instructive signal in an accurate manner during motor learning, potentially to ‘write protect’ that motor skill.