Here is the timetable for buses between Yudanaka Station and Shiga Kogen:
It is somewhat complicated. The upper table shows buses from Oku-Shiga-Kogen to Yudanaka and from Yudanaka to Yokoteyama, as well as buses directly operating between Oku-Shiga-Kogen and Yudanaka. The lower table shows the buses in the opposite direction.
湯田中駅 means Yudanaka Station. It is listed with two columns in the middle of both tables. The first column shows arrival times, the second departure times.
上林温泉口 means Kanbayahsi Onsen Guchi. It is the closest bus stop to the trail that leads to the monkey park
And on both sides of the timetable are multiple bus stops in the Shiga Kogen area. Where in Shiga Kogen are you planning to travel?
There is also another bus line that operates between Yudanaka Station and Kanbayashi Onsen:
The buses with a black triangle don't operate on weekends and national holidays.
Finally, there are direct buses between Nagano Station and Shiga Kogen:
長野駅東口 means Nagano Station (East Exit)
The above linked timetables will be in effect from December 8, 2012. Different timetables are in effect until December 7.