Some visual and other connections to the cerebellum of the pigeon

Abstract

By anatomical techniques it has been shown that folia VIc-IXc of the pigeon cerebellum receive inputs from the following groups of neurons: the medial and lateral pontine nuclei, the superficial synencephalic nucleus, the medial spiriform nucleus, the inferior olive, and the deep cerebellar nuclei. From all but the last of these, the projection is mainly crossed, though the uncrossed component from the lateral pontine nucleus is not insubstantial. The input from the superficial synencephalic nucleus provides a direct pathway from the retina to the cerebellum (folia VIc, VII, VIII and IXc). Less direct visual pathways reach the cerebellum via the following routes: (i) the superficial synencephalic nucleus projects ipsilaterally to the lateral pontine nucleus and sparsely to the inferior olive; (ii) the tectum projects ipsilaterally to the lateral and medial pontine nuclei, though the latter connection is sparse. In electrophysiological experiments, the importance of the tecto-pontine component of the projection has been demonstrated by cooling the tectum while recording visual responses from the cerebellum. The visual receptive fields of pontine cells have been analysed. They vary in extent from 10 degrees to the whole monocular field. They respond best to moving targets, preferring speeds of 20 to 60 degrees/second, and are usually direction-selective.

A mosaic pattern characterizes the evolution of the avian brain

“…Based upon the analyses presented in mammals, any significant correlations are likely to be between those regions sharing the greatest interconnectivity (Barton & Harvey 2000). Specifically, we expected significant correlations between five region pairs because of the large number of connections that they share with one another: telencephalon and diencephalon; diencephalon and mesencephalon; mesencephalon and optic tectum; mesencephalon and myelencephalon; and myelencephalon and cerebellum (Clarke 1977;Bravo & Pettigrew 1981;Arends & Zeigler 1991;Wild et al 1993;Wild 1997;Husband & Shimizu 2002).…”

Topographical organization of inferior olive cells projecting to translation and rotation zones in the vestibulocerebellum of pigeons

“…12,19,20 Nuclei of the accessory optic system project to areas of the inferior olive (IO) that provide climbing fiber input to the contralateral vestibulocerebellum (VbC). 1,[6][7][8]20,33 In pigeons, the VbC consists of folium X (nodulus), the ventral lamella of folium IXc,d (ventral uvula) and the auricle (flocculus), which is the lateral extension of these folia. 18 Previous electrophysiological studies of the pigeon VbC have shown that complex-spike (CS) activity of Purkinje cells (which reflects climbing fiber activity) responds best to specific patterns of optic flow resulting from either self-translation or self-rotation.…”

A Direct Hippocampo‐Cerebellar Projection in Chicken

“…In some birds, the HRP-positive neurons were also present in the nucleus of posterior commissure (Jungherr, 1969). The distribution pattern of the labeled neurons in midbrain and diencephalon was similar to the pigeon (Clarke, 1977).…”

“…In the pons, the labeled neurons existed mainly in the pontine nuclei, and the locus ceruleus. In the midbrain and diencephalon, the HRP-positive cells were located in the red nucleus, the superfiscial synencephalic nucleus (Clarke, 1977), the medial spiriform nucleus, the nucleus ectomamillaris (Brecha et al, 1980) and the ventral part of the lateral geniculate nucleus (Clarke, 1977;Fig. 2).…”

“…This phenomenon may be involved in the spatial and nonspatial memory function of the HF, because the avian cerebellum also received afferent fibers that convey the visual (Clarke, 1977;Brecha et al, 1980), vestibular (Arends et al, 1991), spinal somatosensory (Yamamoto et al, 2001), inferior olivary (Paken et al, 2005), basis pons (Brodal et al, 1950), and even the auditory information (Whitlock, 1952;Gross, 1970) to the HF (unpublished data).…”