An online adaptive screening procedure for selective neuronal responses

BACKGROUND A common problem in neurophysiology is to identify stimuli that elicit neuronal responses in a given brain region. Particularly in situations where electrode positions are fixed, this can be a time-consuming task that requires presentation of a large number of stimuli. Such a screening for response-eliciting stimuli is employed, e.g., as a standard procedure to identify 'concept cells' in the human medial temporal lobe. NEW METHOD Our new method evaluates neuronal responses to stimuli online during a screening session, which allows us to successively exclude stimuli that do not evoke a response. Using this method, we can screen a larger number of stimuli which in turn increases the chances of finding responsive neurons and renders time-consuming offline analysis unnecessary. RESULTS Our method enabled us to present 30% more stimuli in the same period of time with additional presentations of the most promising candidate stimuli. Our online method ran smoothly on a standard computer and network. COMPARISON WITH AN EXISTING METHOD To analyze how our online screening procedure performs in comparison to an established offline method, we used the Wave_Clus software package. We did not observe any major drawbacks in our method, but a much higher efficiency and analysis speed. CONCLUSIONS By transitioning from a traditional offline screening procedure to our new online method, we substantially increased the number of visual stimuli presented in a given time period. This allows to identify more response-eliciting stimuli, which forms the basis to better address a great number of questions in cognitive neuroscience.