Intratelencephalic projections of the visual wulst in pigeons (Columba livia)

Abstract

The visual wulst is the telencephalic target of the thalamofugal visual pathway of birds, and thus the avian equivalent of the striate cortex of mammals. The anterograde tracer Phaseolus vulgaris leucoagglutinin was used to follow the intratelencephalic connections of the major constituents of the visual wulst in pigeons. In particular, efferent pathways from the granular layer (Intercalated nucleus of the hyperstriatum accessorium, IHA), supragranular layer (hyperstriatum accessorium, HA), and infragranular layers (hyperstriatum intercalatus superior and/or hyperstriatum dorsale, HIS/HD) were investigated. These efferent projections were confirmed by injections of the retrograde tracer cholera toxin subunit B into their terminal fields. When a deposit of the anterograde tracer was centered in IHA, which receives the visual thalamic input, efferent fibers were seen mainly dorsomedially to IHA. When a deposit of the anterograde tracer was centered in HA, efferent fibers were seen to extend mainly in three directions: 1) medially to the tractus septomesencephalicus, which sends projections to extratelencephalic visual nuclei: 2) ventrolaterally to the lateral portion of the neostriatum frontale, where there were also labeled cells after the retrograde tracer was injected in HA; and 3) ventromedially to the paleostriatal complex, which is the avian equivalent of the mammalian caudale, 5) neostriatum intermedium, 6) archistriatum intermedium, and 7) hyperstriatum laterale. Finally, HIS/HD have projections predominantly to HA and the dorsocaudal telencephalon (area corticoidea dorsolateralis and area parahippocampalis), as well as relatively minor projections to the areas which also receive projections from HA. No anterogradely labeled fibers were seen in the tractus septomesencephalicus following the tracer injections in HIS/HD. These results indicate that the visual information from the granular layer is distributed via the supragranular layer HA to multiple areas within the telencephalon, such as the neostriatum frontale and paleostriatal complex. In addition, HA is the source of an extratelencephalic projection via the tractus septomesencephalicus. Thus, the avian supragranular layer HA contains neurons which are the source of both intratelencephalic and extratelencephalic projections, whereas neurons of the mammalian cortex are segregated into two distinct layers, supragranular and infragranular layers, based on the targets of their projections. The findings are further discussed and compared to the mammalian striate cortex.

Dominant Vertical Orientation Processing without Clustered Maps: Early Visual Brain Dynamics Imaged with Voltage-Sensitive Dye in the Pigeon Visual Wulst

“…The observed spread most likely reflected arborizations connecting the input pseudolamina (IHA) to HA (Shimizu et al, 1995). The maximal speed of spread measured along posterior-anterior axis was ϳ0.1 m/s (N ϭ 9) at threshold level (p Ͻ 0.01) (Fig.…”

Revised nomenclature for avian telencephalon and some related brainstem nuclei

“…7A-D; Kä llén, 1953;Wä chtler, 1985;Brauth et al, 1986;Wä chtler and Ebinger, 1989;Csillag et al, 1993;Hodos, 1993;Shimizu et al, 1995;Husband and Shimizu, 1999;Denisenko-Nehrbass et al, 2000;Medina and Reiner, 2000;Sun and Reiner, 2000;Wada et al, 2001). The option approved by the Forum was to replace the term hyperstriatum in the various layers of Wulst with the term hyperpallium, to replace HV with mesopallium, and to replace neostriatum with nidopallium.…”

“…The HA gives rise to the extratelencephalic, as well as some intratelencephalic, projections of the Wulst Wild, 1992;Shimizu et al, 1995;Veenman et al, 1995b;Kröer and Gü nẗrkü n, 1999;Williams, 1999, 2000). The Forum decided to replace "accessorium" with "apicale" because of the evolutionary or functional subordination to other parts of the hyperpallium implied by the term "acccessorium."…”

Spatial contrast sensitivity of birds

“…In addition, the eagle function (Reymond and Wolfe, 1981) and the kestrel function (Hirsch, 1982) are each comprised of data from a single subject only. This paucity of data is rather surprising considering the substantial literature that exists on the optics, anatomy, physiology, and histochemistry of the eye, the retina, and the central visual system of birds (Karten, 1969;Karten et al, 1973;Shimizu, Cox, and Karten, 1995;Hodos and Erichsen, 1990;Holden, 1980;Bagnoli, 1984;Wang, Jiang, and Frost, 1993), including a number of studies that have been carried out on their visual acuity (Hodos and Leibowitz, 1976;Hodos, et al, 1991a;Gaffney and Hodos, 2003;Güntürkün and Hahmann, 1994;Hahmann and Güntürkün, 1993;Schmid and Wildsoet, 1998;Porciatti, et al, 1991;Hirsch, 1982;Reymond and Wolfe, 1981;Reymond, 1987;Martin and Gordon, 1974;Fite, 1973;Fite and RosenfieldWessels, 1975;Fox, et al, 1976;Dabrowska, 1975;Blough, 1971; Orders combined. Since a great deal of diversity is found in avian visual morphology, specialized for various econiches, it would not be surprising to find avian species that had contrast sensitivities currently considered to be in the mammalian range.…”