= Tutorial 12: Explore the average response = ''Authors: Francois Tadel, Elizabeth Bock, Sylvain Baillet'' <> From continuous tutorials: == Online filter == As introduced in the previous tutorials, you can add an online visualization filter to make the traces and the topographies look smoother. We suggest in this case a low-pass filter at 120Hz, because it shows very smooth traces, but all the waves we are interested in are still clearly visible in the MEG time series figure. {{http://neuroimage.usc.edu/brainstorm/Tutorials/TutRawAvg?action=AttachFile&do=get&target=onlineFilter.gif|onlineFilter.gif|class="attachment"}} == Explore the average == Open the time series for the "'''Avg: left'''". Then press '''Control+T''', to see on the side a spatial topography at the current time point. Then observe what is happening between 0ms and 100ms. Start at 0ms and play it like a movie using the arrow keys left and right, to follow the brain activity millisecond by millisecond: * '''16 ms''': First response, the sensory information reaches the right somatosensory cortex (S1) * '''30 ms''': Stronger and more focal activity in the same region, but with a source oriented in the opposite direction (S1) * '''60 ms''': Activity appearing progressively in a more lateral region (S1 + S2) * '''70 ms''': Activity in the same area in the left hemisphere (S2 left + S2 right) {{http://neuroimage.usc.edu/brainstorm/Tutorials/TutRawAvg?action=AttachFile&do=get&target=avg16.gif|avg16.gif|class="attachment"}} {{http://neuroimage.usc.edu/brainstorm/Tutorials/TutRawAvg?action=AttachFile&do=get&target=avg30.gif|avg30.gif|class="attachment"}} {{http://neuroimage.usc.edu/brainstorm/Tutorials/TutRawAvg?action=AttachFile&do=get&target=avg60.gif|avg60.gif|class="attachment"}} {{http://neuroimage.usc.edu/brainstorm/Tutorials/TutRawAvg?action=AttachFile&do=get&target=avg70.gif|avg70.gif|class="attachment"}} <> <>