Reduction in Noise Correlation is Associated with Improved Behavioural Performance

Background: Visual perception constitutes the dominant method by which we process our environment, yet the neuronal substrates that underlie visual perception in the brain are not well understood. Noise correla- tion, defined as the correlation in non-stimulus evoked activity between neurons, has been shown to impact both encoding and decoding processes of visual stimuli. We wanted to determine whether changes in noise correlation can predict behavioural performance in a coherent motion-detection task. Methods: Two macaque monkeys (Macaca mulatta) were trained in a coherent motion-detection task, where they learned to fixate on a screen and anticipate the onset of a motion coherence stimulus. During this task, spike activity from pairs of neurons of the middle temporal area (area MT) were recorded and data was analyzed using MATLAB. Specifically, we examined noise correlation as a function of time and success rate in the task. Results: We found a decrease in the correlation in activity between neurons in area MT prior to the onset of the motion coherence stimulus. This decrease was accompanied by improved behavioural performance in the motion coherence-detection task. Limitations: The activity in pairs of neurons may not accurately represent overall activity in a population of neurons. In addition, control experiments to better assess the nature of the common input that leads to a reduction in noise correlation were not conducted. Conclusions: Despite these limitations, we have shown that a reduction in noise correlation prior to stimulus onset is accompanied by improved behavioural performance, suggesting that noise correlation may be a critical parameter that can aid in our understanding of how visual perception occurs in the brain.