Hi all,

 

    Does anybody have a clue why beta values are negative in many brain regons?

 

    In our experiment, there are multiple events in a trial (ev1: 1s; ev2: 1s; ev3: 6s), and the jittered ITI between trials was between 1~7 s. In our GLM, we modeled the onset of each event and their durations, with the jitters as implicit baseline in the model. However, we found negative beta values in many brain regions, including anterior insula (AI), dmPFC, vmPFC and precuneus. For AI and dmPFC, there are positive values in some conditions; whereas for vmPFC and precuneus, values are negative in all conditions. What possible mistakes in the data analysis could lead to such activation patterns?

 

Best,

Chunliang