Moreover , the changes seen in mouse brains are not exactly the same as those observed in sids babies , in whom the serotonin receptor in question , known as 1a , is , if anything , underactive .
Muscles that are typically weak and underactive are the abdominal muscles - especially the transversus abdominis , glutes ( butt ) , lower trapezius , serratus anterior and the deep stabilizing muscles of the neck and spine ( coli and multifidus respectively ) .