3/30/2023 0 Comments Philip songbird![]() Apparently, disruption of the intratelencephalic pathways causes disturbance of motor performance through these projections to the premotor system. In previous sections it was already mentioned that this fiber system has projections to, among other areas, the medial spiriform nucleus (a relay to the cerebellar cortex) and to the premotor systems of the jaw, tongue, and neck system ( Figure 10 ). The archistriatum can be subdivided into several parts one of these is considered a sensorimotor region and is source of one of the large descending systems, the occipitomesencephalic tract (Zeier and Karten, 1971). Sometimes this intratelencephalic circuit is called a “feeding circuit” (e.g., Dubbeldam, 1985). Comparable effects can be found after disruption of the trigeminoarchistriatal pathway: feeding behavior deficits were found after bilateral damage to the ascending sensory trigeminal system ( Zeigler and Karten, 1973). Interruption of the visual circuit (e.g., bilateral ablation of the lateral neostriatum) causes a visuomotor deficit during feeding in pigeons: birds can still direct their peck, but have difficulties with grasping and ingesting grains ( Jäger, 1990). Such circuits have been described for the visual system (Ritchie, 1979) and the trigeminal system ( Figure 11 Wild et al., 1985 Dubbeldam and Visser, 1987) and can be considered to be sensorimotor circuits. Each of these sensory centers is, via relays in the neostriatum and hyperstriatum ventrale, connected with the archistriatum, a region in the temporal pole of the telencephalon. basalis (tactile sense head region), the ectostriatum of the visual system, and field L of the auditory system (see Chapters 1– Chapter 2). The neostriatum embraces telencephalic end stations of ascending sensory systems-the nucleus trigeminalis prosencephali or n. The archistriatum is one of the regions derived from the dorsal ventricular ridge, other parts are the neostriatum and hyperstriatum ventrale ( Figure 9). DUBBELDAM, in Sturkie's Avian Physiology (Fifth Edition), 2000 B Archistriatum and Occipitomesencephalic Tract However, little is as yet known about the anatomical connections among these regions in hummingbirds. A study of the expression of the immediate early gene ZENK in hummingbirds after vocalization revealed a set of circumscribed telencephalic nuclei in locations similar to those of the vocal control nuclei of songbirds and parrots ( Jarvis et al., 2000). In addition to songbirds and parrots, at least some hummingbirds (family Trochilidae of order Apodiformes) appear capable of learning complex vocalizations ( Baptista and Schuchmann, 1990). The parrot AFP also incorporates an oval nucleus of the anterior MO which, unlike its oscine counterpart, has known connections to other vocal control nuclei ( Striedter, 1994 Durand et al., 1997). Furthermore, parrots have a group of structures comparable to the songbird AFP, including a region of medial striatum containing sparsely distributed aspiny neurons that project directly to the dorsal thalamus ( Striedter, 1994). This arcopallial nucleus receives input from a part of the nidopallium, the central nucleus of the lateral nidopallium (NLC), analogous to the oscine HVC ( Paton et al., 1981). Like songbirds, parrots have an arcopallial nucleus, the central nucleus of the anterior arcopallium (AAC), that directly innervates syringeal motor neurons and brainstem respiratory circuits ( Paton et al., 1981). Parrots also have an interconnected set of telencephalic vocal control centers bearing considerable resemblance to the oscine song system ( Figure 2 ). Parrots (order Psittaciformes) are famous for their vocal mimicry, with abilities ranging from the relatively modest (but still quite accomplished) budgerigar ( Farabaugh and Dooling, 1996) to the African grey parrot capable of learning more than 70 English words ( Pepperberg, 2002). Oscines may be the most extensively studied vocal learners among birds, but they are not the only avian group that learns vocalizations.
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