Correct formula for MixedModels, lme4

Dear statistics experts,
I am using MixedModels.jl in Julia with this formula:

f2 = @formula(fmri~AMP+SLP+aSLP+(0+AMP|session)+(0+SLP|session)+(0+aSLP|session));

The toolbox in Julia is from Douglas Bates und the formula specification should be similar to lme4. My experiment includes 20 subjects with 4 recordings each. It
assumes a common slope across all subjects and sessions.
I think the model needs to be changed. I think it would be better to model a common slope for each subject (across the 4 recordings) but keep the session-specific intercept. How would the new model need to be specified?
Thank you, Enrico