Projections from the medial column of the inferior olive to different classes of rotation-sensitive Purkinje cells in the flocculus of pigeons

In the flocculus of pigeons, as in other species, there are two major types of Purkinje cell responses to rotational optokinetic stimuli. One type prefers rotation about the vertical axis (VA neurons) whereas the other prefers rotation about an horizontal axis oriented at 135° ipsilateral azimuth (H-135 neurons). In this study, we injected the retrograde tracer cholera toxin subunit B into the VA and H-135 zones in attempt to determine the origin of inferior olive inputs. We found that VA and H-135 zones received input from the caudal and rostral margins of the medial column of the inferior olive, respectively. There is a similar pattern of connectivity in mammalian species.