Figure 5
From: Sparsened neuronal activity in an optogenetically activated olfactory glomerulus
Compact distributions of light-activated glomerular layer interneurons. (A1) Frame subtractions showing a 7250 glomerulus activated with 0.16 mW vs. 8.8 mW laser stimuli. A stronger target signal and additional cell responses (red arrows) are visible in the 8.8 mW stimulation condition. The scale bar in the left panel applies to both images. (A2) Averaged calcium signals recorded from the neuropil during strong and weak laser stimulation. The signals were normalized by dividing each trace from pairs of strong laser and weak laser trials with the fluorescence signal during the response evoked by the strong laser stimulus. Dashed lines indicate standard deviations. (A3) The calcium signal amplitude in the neuropil of the target glomerulus was significantly larger in the 8.8 mW stimulus condition (normalized as in A2). (B1) More interneurons responded to 8.8 mW laser stimulation; the size of their responses also increased (B2–3). Calcium signals were averaged and normalized as described for A2. (B4) Analysis of interneurons that respond to 0.16 mW laser stimuli: the responses are organized based on what interneurons do in comparison to the 8.8 mW stimulus condition. (C1) Three-dimensional reconstructions of a 7250 glomerulus stimulated with 0.16 mW (pink, left panel) and 8.8 mW (red, right panel): more cells are recruited during strong stimulation and they cluster mainly near the target glomerulus (green). (C2) Frequency distribution showing the distances of interneuron responses from the border of the target glomerulus. Approximately 80% of cells are located within 20μm from the target for both laser stimulation intensities.
