combine INSERT... VALUES and INSERT... SELECT

[eykanal]

I have the following rather complex select statement which I suspect is not possible:

insert into study_sessions
(timeslot , visitnumber , behav_fmri , participant_id )
values
(now(), 1,behav,%s)
select participant_id as %s from participants where user_id='3' and study_id='3';

I'm not sure what the syntax should be, hence it probably makes no sense now. Basically, I want to insert a bunch of values, along with an INSERT... SELECT (the %s entry) based on a value in a different table. I tried doing it as a subquery:

insert into study_sessions
(timeslot , visitnumber , behav_fmri , participant_id )
values
(now(), 1,behav,
(select participant_id from participants where user_id='3' and study_id='3'));

but that didn't work either. If anyone knows how to get either of these working, I'd be most appreciative. Thanks!