PMC7090138_01
Stimulation protocol and clinical assessment.
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F1
Neuropsychological assessment was repeated 2 days before and 2 days after the stimulation protocol (Figure 1) by a trained neuropsychologist that was not involved in the conception of the study nor in the brain stimulation. The patient underwent two EBC sessions on the same days as the clinical and neuropsychological assessments (Figure 1).
EBC sessions before (A,C) and after (B,D) tDCS in the schizophrenic patient. The color code corresponds to the normalized response amplitude of the IR-reflected signal. The EBC protocol is depicted at the top of (A,B). (A,B) Each block represents the average signal over the 9 CS-US trials, for experiments respectively before (A) and after (B) tDCS. (C,D) Plots of the IR-reflected signal for each block before (C) and after (D) tDCS. Red rectangles delimit the area where CRs were detected in Figure 3 left. Notice that the unconditioned response (UR) peak amplitude and latency decreases block after block after tDCS (D), while before the tDCS the UR peak amplitude remains constant among all the blocks, and the latency shows no trend (C).
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F2
Results from the EBC assessment before and after stimulation are reported in Figures 2, 3. Before tDCS, the averaged block response amplitudes of the URs remained unchanged over the pre-tDCS session (Figure 2A), very few CRs were detected and peak latencies of averaged block signals remained constant during the overall session (Figure 3). Accordingly after tDCS, the averaged amplitude of the URs decreased from block to block (Figure 2D) while it was stable before tDCS, this progression of EBC can also be observed by monitoring the first peak latency of the responses from block to block.
Percentage of CRs and latency of the first peak progression from block to block before (red) and after (green) tDCS. Left panel: percentage of CRs from each block measured in the red rectangle indicated on Figures 2C,D. Right panel: First peak latency calculated from the data averaged in blocks in Figures 2A,C. Time zero for latency calculation corresponds to the onset of the US.
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F3
Results from the EBC assessment before and after stimulation are reported in Figures 2, 3. Before tDCS, the averaged block response amplitudes of the URs remained unchanged over the pre-tDCS session (Figure 2A), very few CRs were detected and peak latencies of averaged block signals remained constant during the overall session (Figure 3). Thus, 45 CS-US pairings were insufficient to induce EBC, at the end of this session only 43% of the trials displayed CRs (Figure 3 left). After tDCS, the patient was rapidly conditioned and reached a final value of 83% of CRs (Figure 3 left), as expected for a normal EBC session. Before tDCS it remained stable but rapidly decreased over the blocks after tDCS (Figure 3 right).