Temporal Processing in the Visual Cortex of the Awake and Anesthetized Rat

Evoked response latencies of the LFP and single units followed from the awake state to anesthesia. A, Example traces from one experiment in awake and anesthesia showing the typical LFP signature following stimulus onset. B, Box plot of the latency of the stimulus onset to the trough and peak of the LFP signature *1.5 SD of the mean (n = 17). C, Comparison of the time between trough and peak in each condition. D, Comparison of amplitude (mV) of troughs and peaks in each condition. E, Top, Average stimulus-evoked LFP in awake and anesthesia across all experiments (n = 25 in nine animals). Error bars indicate SEM. Bottom, Morlet wavelet of LFP activity following visual stimulation in the awake and anesthetized animals. F, Stimulus evoked firing rates (top) and raster plots (bottom) of all trials in all units in each state. One line represents one trial (96 trials per unit). Trials are ranked according to awake firing rates from high to low rate from (bottom up) for each anesthetic. G, PSTH of evoked firing rates for all units followed between the awake and anesthetized state (error bars, SEM). H, PSTH of normalized firing rates spanning the time period of the average peak of evoked activity. I, Scatterplot showing latency (ms) to the first peak evoked response for all units in awake and anesthesia. Red dotted line indicates regression. J, Box plot comparing bins of first peak max responses and first peak onset for all units between awake and anesthesia (n = 262,130). K, Frequency distribution of the awake-anesthesia difference in latency for each unit. L, Box plot showing first peak latency for units in three anesthetic regimes (Iso/Dor n = 133, Iso n = 71, Ket/Xyl n = 47).

Temporal structure parameters, pairwise correlations and CV, of units followed between states. A, Pair-wise CC matrix for an example population (8 units) in both states. B, Box plot showing the CC for all pairwise correlations in awake, anesthesia and recovery (n = 733 cell-pairs). C, Scatter plot of pair-wise CC for pairs of neurons in the awake and anesthetized state (n = 1046). Black line indicates regression. D, Box plot showing the CCs during stimulus-evoked and spontaneous activity for all units. E, left panel, Example LFP trace with a typical burst suppression (BuS) pattern and no burst suppression (non-BuS). Right panel, Box plot showing CCs for pairs in sessions dominated by burst suppression (n = 276) compared with non-BS sessions (n = 210). F, Box plot showing the CCs for cell-pairs in three different anesthetic regimes: Isoflurane (n = 371), Ketamine/Xylazine (n = 246), and Isoflurane/Dormicum (n = 436). G, Scatter plot of the CV for single units in the awake and anesthetized state (n = 218). H, Box plot of the awake-anesthetized CV difference for units in each anesthetic regime (Iso n = 56, Iso/Dor n = 118, Ket/Xyl n = 44).

Temporal sequences within unit ensembles followed between states. A, Top panel, Description of MSL measure. Left, Raster plot of two representative units firing with different MSL to visual stimuli. Right, illustration of sequence representation for MSL measure. Bottom panels, MSL (red dots) for units within ensembles, sorted by their ranked sequence (MSL) in the other session. Gray indicates activity normalized between 0 and 1 (awake-awake, n = 88; awake-anesthesia, n = 82; anesthesia-anesthesia, n = 78). B, top panel, Illustration of the quantification of the single trial rank measure. Bottom panels, Histograms of single trial rank CCs. MSLs for individual stimuli presentations are rank correlated with the mean latency response across many stimuli presentations from a separate experimental session (awake-awake, n = 604; awake-anesthesia, n = 596; anesthesia-anesthesia, n = 294). Yellow outline indicates shuffled data. C, top panel, The rank-by-rank measure is described. Bottom panel, Line graph showing the CCs from the rank-by-rank measure for the individual populations (n = 8 populations). D, Single trial rank correlations for the sessile-movement (n = 352) and movement-anesthesia (n = 402) comparisons. E, Single trial rank correlations for the awake-anesthesia and anesthesia-anesthesia comparisons for three different anesthetic regimes: Isoflurane, isoflurane-Dormicum, and Ketamine/Xylazine. F, Example populations, from the three anesthetic regimes (Iso n = 15 units, Ket/Xyl n = 19, Iso-Dor n = 8).

Responses to visual stimuli of different spatial frequencies between awake and anesthesia (A–G). A, The possible position of the awake rats in the recording box gives a theoretical range of spatial frequencies of the stimuli. The maximum and minimum size of cycles considering varied distance to screen is plotted and show that overlap is restricted to one spatial frequency group. B, Average normalized firing rates for all units in each spatial frequency (n = 68). Error bars indicate SEM. Firing rates normalized by scaling between 0 and 1. C, Number of units responding maximally to each spatial frequency in awake and anesthesia. D, left panel, Comparison of normalized activity in awake and anesthesia during visual stimuli with low spatial frequencies (0.02 and 0.04 c/d) for units preferring a low spatial frequency stimuli in the awake state (n = 75). Right panel, Same for units preferring high spatial frequencies of visual stimuli in awake (0.16 and 0.3 c/d; n = 75). E, PSTH for an example unit during visual stimuli with a low spatial frequency (top panel) and a high spatial frequency (bottom panel) in the awake state and during anesthesia. F, Scatterplot of evoked latencies for the lowest spatial frequency (0.02 c/d) and the highest spatial frequency (0.3 c/d) for the awake state (left panel) and during anesthesia (right panel). G, Box plot of first peak latencies for units under five different spatial frequencies during awake and anesthesia. Responses to visual stimuli of different temporal frequencies between awake and anesthesia (H–J). H, Average normalized firing rates for all units in each temporal frequency. I, Number of units responding maximally to each temporal frequency in awake and anesthesia. J, Box plot of first peak latencies for units under visual stimulation with three different temporal frequencies during awake and anesthesia. Error bars indicate SEM. Firing rates normalized by scaling between 0 and 1.