The primary afferent pathway of extracular muscle proprioception in the pigeon

Trigeminal disynaptic circuit mediating corneal afferent input to m. depressor palpebrae inferioris motoneurons in the pigeon (Columba livia)

“…Thus, corneal inputs to CuE in the pigeon could be involved in oculomotor control, as are the extraocular proprioceptive inputs shown by Knox and Donaldson (1993), to modify the vestibulo-ocular reflex. The pathway thought to mediate this control was suggested by Hayman et al (1995) to originate in the CuE and terminate in the vestibular nuclei via relays in the inferior olive and cerebellum. Perhaps the converse situation also holds, i.e., one in which extraocular proprioceptive inputs, as well as corneal inputs, are involved in the control of lower eyelid motility via the direct projection of CuE to Vd.…”

“…Inputs to accessory abducens motoneurons, which innervate the two muscles controlling the nictitating membrane, M. quadratus and M. pyramidalis (Isomura, 1973;Labandeira-Garcia et al, 1987;Hayman et al, 1995), have not been definitely identified, but the present study suggests that, unlike the case in the lizard Veranus, Acc does not receive a direct projection from corneal afferents (Barbas-Henry and Wouterlood, 1988). Nevertheless, in view of the short delay and rapid action of the membrane, there seems likely to be a disynaptic link between neurons in corneal afferentrecipient regions of the lower brainstem and accessory abducens motoneurons.…”

“…This cluster is situated immediately caudal and dorsolateral to the caudal pole of the accessory abducens nucleus (Acc) that contains motoneurons innervating the two muscles effecting nictitation (Labandeira-Garcia et al, 1987;Hayman et al, 1995), but whether cells in this or any other corneal afferent-recipient region of the TBNC project upon Acc will need to be examined in future studies. The present data indicate that Acc does not receive a projection from exactly the same region that projects upon Vd.…”

“…In birds, although the cornea is known to be densely innervated, as it is in mammals (Bee, 1982), the central projections of corneal afferents, as distinct from the full complement of trigeminal primary afferents, have not specifically been determined (Dubbeldam and Karten, 1978;Wild and Zeigler, 1996), and therefore the links with either Vd or nictitation motoneurons (Labendeira-Garcia et al, 1988;Evinger, 1988;Hayman et al, 1995) are not known. The present study is concerned with the former of these two links, namely that between the recipient of corneal afferents and Vd, the nucleus innervating M. depressor palpebrae inferioris.…”

Somatotopic Organization of Primary Afferent Perikarya of the Guinea-pig Extraocular Muscles in the Trigeminal Ganglion: a Post-mortem DiI-tracing Study

“…Primary afferent perikarya of extraocular muscles (EOMs) are localized within the ophthalmic part of the TG in pigeon (Hayman, Donaldson and Donaldson, 1995), rat (Daunicht, 1983 ;Daunicht, Jaworski and Eckmiller, 1985), guinea-pig (Aigner, Lukas and Mayr, 1993), cat (Alvarado-Mallart et al, 1975 ;Porter and Spencer, 1982 ;Bortolami et al, 1987 ;Buisseret-Delmas and Buisseret, 1990 ;Porter and Donaldson, 1991), lamb (Manni, Palmieri and Marini, 1972 ;Bortolami et al, 1979Bortolami et al, , 1987, pig (Bortolami et al, 1987), calf (Manni, Desde and Palmer, 1970) and monkey (Porter, Guthrie and Sparks, 1983). These primary afferents from the oculomotor nerves form a certain population of ganglion cells with a special course of development during fetal life.…”