Fig. 3: Cluster analysis of DMN ensembles enables hypothesis generation and suggests experimental tests.
From: Connectome-constrained networks predict neural activity across the fly visual system
We clustered 50 DMNs after carrying out nonlinear dimensionality reduction of their responses to naturalistic scenes for each cell type, and aimed to identify whether clusters correspond to qualitatively different tuning mechanisms. a, Responses of T4c cells exhibit three clusters, two with ON-motion direction selectivity (circular and triangular marker) and one (square marker) without. b, T4c tuning in the three clusters. Circular marker: upwards tuning (cluster with lowest average task error 5.297; black: known tuning of T4c). Triangular marker: downwards (5.316 error). Square marker: no motion tuning (5.357 error). c, Schematic of corresponding ON-motion detection pathway. d, Connectivity of major input elements to T4c. Blue and red colour: putative hyper- and depolarizing inputs. Saturation: average number of input synapses for each offset location. e, Tuning properties within each cluster reveal dependencies between T4 tuning and that of Mi4 and Mi9 cells in the ensemble: switching Mi4 (known ON-contrast selective) and Mi9 (known OFF-contrast selective) contrast preferences results in directionally opposite motion-tuning solutions in T4. DMNs in first cluster (T4c in DMN upwards tuned, circle) exhibit ON-selectivity for Mi1, Tm3, Mi4 and CT1(M10), and OFF-selectivity for Mi9. For ON-motion stimuli, in these DMNs T4c receives central depolarizing input from Mi1 and Tm3 and dorsal hyperpolarizing input from Mi4 and CT1(M10).
