Activity in a Premotor Cortical Nucleus of Zebra Finches Is Locally Organized and Exhibits Auditory Selectivity in Neurons but Not in Glia

Abstract

Motor functions are often guided by sensory experience, most convincingly illustrated by complex learned behaviors. Key to sensory guidance in motor areas may be the structural and functional organization of sensory inputs and their evoked responses. We study sensory responses in large populations of neurons and neuron-assistive cells in the songbird motor area HVC, an auditory-vocal brain area involved in sensory learning and in adult song production. HVC spike responses to auditory stimulation display remarkable preference for the bird's own song (BOS) compared to other stimuli. Using two-photon calcium imaging in anesthetized zebra finches we measure the spatio-temporal structure of baseline activity and of auditory evoked responses in identified populations of HVC cells. We find strong correlations between calcium signal fluctuations in nearby cells of a given type, both in identified neurons and in astroglia. In identified HVC neurons only, auditory stimulation decorrelates ongoing calcium signals, less for BOS than for other sound stimuli. Overall, calcium transients show strong preference for BOS in identified HVC neurons but not in astroglia, showing diversity in local functional organization among identified neuron and astroglia populations.

Population-Level Representation of a Temporal Sequence Underlying Song Production in the Zebra Finch

“…Recent experiments have used 2-photon imaging of HVC activity in the anesthetized zebra finch to measure sensory responses within that structure (Graber et al, 2013; Peh et al, 2015). In order to adapt this approach to address motor dynamics, we developed a head-fixed singing bird preparation.…”

“…These nonuniformities may arise from a number of sources. For instance, because our recordings were spatially restricted within HVC, a sampling bias may exist if burst events from nearby cells exhibit similar timing (Graber et al, 2013; Markowitz et al, 2015; Peh et al, 2015). We next tested whether any nonuniformities could be explained by the coincident activity of neurons with motor movements.…”

Plumes of neuronal activity propagate in three dimensions through the nuclear avian brain

“…In anesthetized and spontaneously sleeping male finches, neurons in nuclei of the forebrain song system exhibit spontaneous bursts of activity [46,47]. Bursts in one nuclei often precede bursts in another distantly located nuclei, raising the possibility that this sequential activity is involved in processing song-related information [48,49].…”

Sensory response in host and engrafted astrocytes of adult brain in Vivo

“…Graber et al have shown that the elevation in Ca 2+ concentration in astrocytes is induced by auditory stimulation in the HVC, a cortical motor area (Graber et al, ). The function of HVC astrocytic sensory responses is unknown.…”