imread(fullfile(pathname, filename))
Is it really the case that you want to get a directory listing of files whose names start with "Dataset 1" followed by any number of characters with a .tif extension? Such as Dataset 1July-20-1969_eagle.tif ? Or are you wanting to look inside a folder named Dataset 1 for all .tif files?
I really recommend you get into the habit of using fullfile()
