Hello, I'm Keren, a doctoral student conducting my first MRI scans and using SPM. I've encountered an issue and would appreciate some help. My motor task involves two conditions: in the first condition, the subject needs to reach a stimulus at a fixed location, and in the second condition, the subject needs to reach with their finger to a stimulus at an unknown location. When comparing each condition to rest, I observe activity in expected areas like the motor and visual cortex. However, when I contrast the condition with the unknown location against the known one, I'm seeing activity in various brain regions, including the Ventricles.. Does anyone have ideas why I am getting this result (which is consistent across most subjects) and what I can do to correct my mistake? I thought that perhaps the betas in both conditions are negative, leading to the display of brain activity in the ventricles .(not sure if this is logical). Does anyone know how I can add a condition in the SPM GUI that shows the contrast of activity in the first condition less activity in the second condition but only shows positive betas, it means? Thank you very much.