TY - JOUR TI - Neural excitability and sensory input determine intensity perception with opposing directions in initial cortical responses AU - Stephani, Tilman AU - Hodapp, Alice AU - Jamshidi Idaji, Mina AU - Villringer, Arno AU - Nikulin, Vadim V A2 - Obleser, Jonas A2 - de Lange, Floris P A2 - Gao, Richard A2 - Weisz, Nathan VL - 10 PY - 2021 DA - 2021/10/05 SP - e67838 C1 - eLife 2021;10:e67838 DO - 10.7554/eLife.67838 UR - https://doi.org/10.7554/eLife.67838 AB - Perception of sensory information is determined by stimulus features (e.g., intensity) and instantaneous neural states (e.g., excitability). Commonly, it is assumed that both are reflected similarly in evoked brain potentials, that is, larger amplitudes are associated with a stronger percept of a stimulus. We tested this assumption in a somatosensory discrimination task in humans, simultaneously assessing (i) single-trial excitatory post-synaptic currents inferred from short-latency somatosensory evoked potentials (SEPs), (ii) pre-stimulus alpha oscillations (8–13 Hz), and (iii) peripheral nerve measures. Fluctuations of neural excitability shaped the perceived stimulus intensity already during the very first cortical response (at ~20 ms) yet demonstrating opposite neural signatures as compared to the effect of presented stimulus intensity. We reconcile this discrepancy via a common framework based on the modulation of electro-chemical membrane gradients linking neural states and responses, which calls for reconsidering conventional interpretations of brain potential magnitudes in stimulus intensity encoding. KW - somatosensory KW - EEG KW - alpha KW - oscillations KW - excitability KW - intensity perception JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -