Items on GUI's that run code do so via simple, straightforward, function calls called "callbacks". You may call those functions independently.
The arguments to those functions normally includes a list/structure of all of the handles to items on the GUI, and some event data (e.g. what key you pressed), you may need to supply those to the function as an argument.
Using the handles of the items on the GUI, you can change what the GUI says and does using "set"
eg.
set( handles.checkbox45,'value',0) % This would unchecks whatever checkbox "handles.checkbox45" refers to.
