Fig. 2: Optogenetic manipulation of time and intensity perception.
From: Direct contribution of the sensory cortex to the judgment of stimulus duration
a Left: EYFP-ChR2(H134R)-injected brain with optical fiber surrounded by electrode array. Middle: custom-built multisite drivable optrode array. Upper right: coronal section of EYFP-ChR2(H134R) injection site (green) counterstained with Anti-Vglut2 primary antibody (red). Lower right: traces of two vS1 single-neurons. In the EYFP-ChR2-injected rat 465 nm illumination (blue bar, 500 ms) excited the neuron while in the eNpHR3.0-injected rat 620 nm illumination (red bar, 250 ms) inhibited the neuron. b Left and middle: compared to no-light condition (black), photoexcitation (blue) and photoinhibition (red) during stimulus 2 yielded, respectively, an increased and decreased likelihood of judging T2 > T1. Statistical significance in the middle panels of (b–e) is evaluated by resampling (one-sided permutation test, 1000x), subtracting at each iteration the averaged percentage of choice (excluding easy trials) between the respective condition pair (see Methods). p-values labels are *p < 0.05; **p < 0.01; ns for p > 0.05. Exact values are: Chr2 vs eNpHR3.0, p < 0.001, Chr2 vs control, p = 0.003, eNpHR3.0 vs control, p = 0.009. Right: two signatures of curve shift, percent of trials judged T2 > T1 irrespective of stimulus duration (ordinate) and point of subjective equality (PSE) (abscissa), measured with bootstrap resampling (1000×). A support vector machine classifier quantifies data separation by classification error. c Left and middle: excitation during stimulus 2 (blue) compared to stimulus 1 (green). Green vs blue difference significant, p = 0.005. Left vibrissae were intact but are omitted in all sketches. SEM across individual rats indicated as error bars. Statistics derived across n = 5 rats, examined over 113 independent experiments. d Left: control condition with external LED (465 nm) illuminated above the rat with same wavelength and timing as optogenetic light delivery in photoexcitation trials. Middle: light-on during stimulus 2, compared to stimulus 1 (green) revealed no duration perceptual bias in relation to visual cues (p = 0.09). SEM across individual rats indicated as error bars. Statistics derived across n = 6 rats, examined over 202 independent experiments. e. Same as c, but for intensity rats (p < 0.001). Statistics derived across n = 3 rats, examined over 37 independent experiments. Source data are provided as a Source Data file.
