span class='st'>"bert"</span>, <span class='st'>"surf"</span><span class='op'>)</span>
   <span class='va'>file</span> <span class='op'>=</span> <span class='fu'><a href='https://rdrr.io/r/base/file.path.html'>file.path</a></span><span class='op'>(</span><span class='va'>bert_dir</span>, <span class='st'>"lh.thickness"</span><span class='op'>)</span>
   <span class='va'>fid</span> <span class='op'>=</span> <span class='fu'><a href='https://rdrr.io/r/base/connections.html'>file</a></span><span class='op'>(</