Journal: Journal of Neuroscience

Article Title: Spatial Organization of Neuronal Population Responses in Layer 2/3 of Rat Barrel Cortex

doi: 10.1523/jneurosci.2210-07.2007

Figure Lengend Snippet: Figure 1. Sensory-evoked calcium transients in identified E1 barrel column. A, Left, Craniotomy over somatosensory cortex. Middleleft,IntrinsicopticalsignalafterstimulationofE1whiskershowingtheresulting“spot.”Theoutlineofthedarkestpixelsis overlaid in both images indicating the position of E1 barrel column. Middle right, Close-up view of the E1 area from a low- resolution two-photon image. Barrel field outlines obtained from cytochrome c staining are overlaid. Note the pipette tip on the right side. Right, L2/3 neurons (green) and astrocytes (yellow) stained with calcium indicator and sulforhodamine 101, respec- tively,intheE1areaandthesurroundingtissue.AneuronwithintheE1barrelborder(red)wastargetedwithapatchelectrodefor cell-attachedrecording.B,CalciummeasurementfromapopulationofneuronsfromadifferentexperimentthaninA(scalebar, 30 m). Fluorescence traces from five simultaneously recorded PW-related L2/3 neurons showing spontaneous (blue asterisks) and sensory-evoked (red arrowheads) calcium transients. Calcium transients were classified as sensory evoked if the initial fluorescence rise and peak occurred within 200 ms after either the onset (away from resting position) or the offset (return to resting position) of the whisker deflection. Note that not all whisker deflections evoke calcium transients. Yellow bars indicate stimulation periods. An example calcium transient associated with offset stimulation is shown on expanded timescale. C, Simul- taneous cell-attached (CA) recording and fluorescence measurement from the L2/3 neuron from the E1 area shown in B. A spontaneous(blueasterisks)andastimulus-evoked(redarrowhead)spikeandtheirassociatedcalciumtransientsareexpanded in the bottom. The spontaneous spike fell outside the 200 ms time windows used to classify spikes as onset (window a) or offset response (window b). D, Electrically (top, ePSTH) and optically (bottom, oPSTH) determined PSTH for the same neuron and the sametrials.Onlyfivefalsepositivesresultedfor16mincontinuousimagingand231stimuliinthisexperiment.Arrowsdepictbins that contain responses to whisker stimulation.

Article Snippet: Twophoton imaging was performed using a custom-built two-photon laserscanning microscope (excitation wavelength, 870 nm; laser model Mira 900-F laser; Verdi-10 pump; Coherent, Santa Clara, CA).

Techniques: Staining, Transferring, Fluorescence, Whisker Assay