  The standard state space model is widely believed to account for the
cerebellar computation in motor adaptation tasks [1]. Here we show that several
recent experiments [2-4] where the visual feedback is irrelevant to the motor
response challenge the standard model. Furthermore, we propose a new model that
accounts for the the results presented in [2-4]. According to this new model,
learning and forgetting are coupled and are error size dependent. We also show
that under reasonable assumptions, our proposed model is the only model that
accounts for both the classical adaptation paradigm as well as the recent
experiments [2-4].
