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Fig. 5 | BMC Biology

Fig. 5

From: Suprachiasmatic nucleus-dependent and independent outputs driving rhythmic activity in hypothalamic and thalamic neurons

Fig. 5

Inhibitory SCN input is associated with circadian firing patterns with peak activity during the night or early day. a Schematic of the recording/stimulation configuration for long-term monitoring of neural activity in SCN target regions of VIP+/cre; Ai32+/− slices (left) and proportions of cells responding to optogenetic/electrical stimulation (n.r. indicates no response). b, c Spontaneous firing rates of representative neurons that were inhibited (b) or activated (c) by electrical stimulation of the SCN region, from slices prepared during early (upper panels) or late (lower panels) projected day. Rightmost cells from b were also inhibited by SCN optogenetic stimulation (VIPIn). d Proportions of neurons with inhibition, activation or no response to SCN electrical stimulation (n = 54, 35 and 651 respectively) that displayed evidence of circadian variation. Data analysed by χ2 test. e Mean ± SEM duration of firing rate peak (left), 24 h average (mid) and peak-trough amplitude for rhythmic neurons showing inhibition, activation or no response to SCN electrical stimulation (n = 45, 25 and 566 respectively). Data analysed by mixed-effects linear model (left: F2,628 = 0.61, P = 0.55; mid: F2,625 = 0.63, P = 0.53; right: F2,624 = 0.72, P = 0.49). f Mean ± SEM normalised, peak-aligned, 24 h firing profiles for populations in e. g Rayleigh vector plots showing distributions of peak times for rhythmic neurons (outer histogram smoothed with Gaussian, SD = 15 min; individual neurons represented by inner dots). Lower panels show cells counts in 6 h bins, compared against a uniform distribution by χ2 test. hk As in dg but for VIPIn cells (n = 17/18 classed as rhythmic) vs. those showing inhibitory responses to electrical stimulation only (non-VIPIn; n = 35/43 rhythmic), data in i analysed by mixed-effects linear model (left: F1,43.6 = 0.002, P = 0.97; mid: F1,47.1 = 2.22, P = 0.14; right: F1,44.5 = 4.65, P = 0.04). l Mean ± SEM normalised firing rate of the populations in ik as a function of projected Zeitgeber time. Raw data values used for statistical analysis can be found in Additional file 8.

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