Circuits #1 and #3 are on one leg of the circuit breaker box and Circuits #2 and #4 are on the other leg of the circuit breaker box.
12-13-10: Puerto
Puerto,
Most if not all electrical panels made in, at least, the last 25 years have the odd number breaker space on the left hand side of the panel and the even numbers on the right hand side.
If that is the case for your panel then 1 & 2 are connected to Line 1 (leg). 3 & 4 are connected to Line 2.
You can verify at the receptacles with a volt meter. (See above post.)
Line 1 and line 2 alternate down each side of the panel.
Are you sure you have (4) dedicated branch circuits an not (4) separate circuits?
Dedicated branch circuits have their own hot, neutral, and equipment grounding conductor.
Where as for a single phase electrical panel found in most houses two separate branch circuits can share a neutral and equipment ground. In this case the two hot conductors must be install on opposite Lines, (legs).
Did you install the 4 circuits or did you hire an electrician? Were 4 dedicated branch circuits installed?
Example, four 12-2 W/ground Romex (NM-B) or two 12-3 W/grd Romex?