Browsing by Author "Blazing, Robin"
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Item Open Access An Avian Basal-Ganglia Forebrain Circuit Modulates the Reversal of Externally Reinforced Changes to Adult Zebra Finch Song(2017-05-20) Blazing, RobinSongbirds learn their songs through a trial and error process that shows remarkable similarities to human language learning, making them an ideal model for studying the neural substrates of vocal learning. Although adult zebra finch song is generally highly stable, a recent white noise aversive reinforcement learning paradigm has made it possible to shift the pitch of targeted song syllables. When aversive reinforcement is stopped, syllable pitch recovers to its stable baseline value over the course of several days. This recovery provides evidence that zebra finches are intrinsically motivated to match song performance to a previously memorized target version of the song. In this study, I tested the hypothesis that the lateral magnocellular nucleus of the anterior nidopallium (LMAN), a cortico-basal ganglia outflow nucleus implicated in both juvenile and externally reinforced adult learning, is necessary for intrinsically motivated pitch recovery. I drove down the fundamental frequency of targeted song syllables using white noise aversive reinforcement. I then performed bilateral electrolytic lesions of LMAN to determine whether normal pitch recovery would take place without LMAN activity. All three birds lesioned demonstrated significantly reduced recovery rates, providing convincing preliminary evidence that LMAN is implicated in song recovery. However, these results were not conclusive due to small sample size and the lack of histological data to verify lesion efficacy. Further characterization of the role of LMAN in pitch recovery could provide a valuable context for explaining phenomena associated with human language re-learning, such as how stroke victims might have difficulty recovering speech, or how adults are able access and easily re-learn elements of languages to which they were exposed during early childhood.Item Open Access Gigapixel imaging with a novel multi-camera array microscope.(eLife, 2022-12) Thomson, Eric E; Harfouche, Mark; Kim, Kanghyun; Konda, Pavan C; Seitz, Catherine W; Cooke, Colin; Xu, Shiqi; Jacobs, Whitney S; Blazing, Robin; Chen, Yang; Sharma, Sunanda; Dunn, Timothy W; Park, Jaehee; Horstmeyer, Roarke W; Naumann, Eva AThe dynamics of living organisms are organized across many spatial scales. However, current cost-effective imaging systems can measure only a subset of these scales at once. We have created a scalable multi-camera array microscope (MCAM) that enables comprehensive high-resolution recording from multiple spatial scales simultaneously, ranging from structures that approach the cellular scale to large-group behavioral dynamics. By collecting data from up to 96 cameras, we computationally generate gigapixel-scale images and movies with a field of view over hundreds of square centimeters at an optical resolution of 18 µm. This allows us to observe the behavior and fine anatomical features of numerous freely moving model organisms on multiple spatial scales, including larval zebrafish, fruit flies, nematodes, carpenter ants, and slime mold. Further, the MCAM architecture allows stereoscopic tracking of the z-position of organisms using the overlapping field of view from adjacent cameras. Overall, by removing the bottlenecks imposed by single-camera image acquisition systems, the MCAM provides a powerful platform for investigating detailed biological features and behavioral processes of small model organisms across a wide range of spatial scales.Item Embargo Investigating Cortical Readout of Temporal Codes for Olfaction(2024) Blazing, RobinIn all sensory systems, arrays of receptors respond to stimuli over both space and time. Whether and how the precise temporal pattern of receptor activation impacts the activity of downstream brain regions remains unclear. This is the case in the olfactory system, where odors activate stereotyped spatiotemporal sequences of olfactory bulb (OB) glomeruli, whose responses reflect the activity of olfactory receptor neurons. These glomeruli project to downstream piriform cortex (PCx), where ensembles of activated neurons represent the odor percept. Each odor stimulus activates a specific subset of glomeruli in a specific temporal order, leading to the hypothesis that both the identity and timing of glomerular responses convey odor information. However, the extent to which each of these response features influences cortical activity is not known.To address this question, I used patterned optogenetic stimulation to precisely and independently control the spatial and temporal dynamics of the glomeruli. I simultaneously measured cortical responses to glomerular stimulation using large-scale electrophysiological recordings of populations of PCx neurons in awake, head-fixed mice. My experiments revealed that PCx reads out the temporal pattern of “odor-like” optogenetic input sequences with millisecond precision. Using reduced stimuli to probe the computations underlying this phenomenon, I demonstrated that in addition to the identity of activated glomeruli, cortical neurons are tuned to the phase of glomerular stimulation relative to the respiration cycle. Additional circuit and experimental manipulations revealed that this tuning is gated by oscillations imposed by respiratory drive to the PCx network, and is further shaped by cortical recurrent circuits. Thus, my experiments reveal a central role for spike timing in transmitting information from the OB to PCx. Moreover, my findings provide novel insights into the computational principles and circuit mechanisms governing the readout of neural population codes.