Comparative Vertebrate Neuroanatomy

A Dissociation of Motion and Spatial-Pattern Vision in the Avian Telencephalon: Implications for the Evolution of “Visual Streams”

“…These two telencephalic pathways are present in all terrestrial amniotes, and the similarity in their basic connectivity, neurochemistry, and response properties across classes suggest that they can be traced to a common ancestor, and both pathways are necessary for normal visual function (Karten and Shimizu, 1989;Karten, 1991, 1993;Butler and Hodos, 1996;Shimizu and Bowers, 1999). In contrast to mammals, the thalamofugal pathway is rather underdeveloped in aves, particularly lateral-eyed species (Shimizu and Karten, 1991;Butler and Hodos, 1996;Bischof and Watanabe, 1997), and reptiles (for review, see Macphail, 1982;Husband and Shimizu, 2001). Behavioral studies have failed to find a clear role for this pathway in normal vision in these animals (Hodos et al, 1984).…”

“…For example, although the avian visual wulst is thought to be the homolog of mammalian visual cortex (Medina and Reiner, 2000), lesions to the visual wulst result in only minor impairments in visual tasks (Hodos et al, 1984). Furthermore, in birds, it appears that the tectofugal pathway is highly developed compared with the thalamofugal pathway, but the opposite is true in primates (Macphail, 1982;Karten and Shimizu, 1989;Butler and Hodos, 1996;Husband and Shimizu, 2001). …”

“…The nRT projects to a telencephalic structure, the ectostriatum (Ec) , which is possibly homologous to the thalamo-recipient cells in mammalian extrastriate cortices (Karten and Shimizu, 1989;Butler and Hodos, 1996;Shimizu and Bowers, 1999). The nRT-Ec projection is topographic: the caudal and rostral Ec receive input from subnuclei in the caudal and rostral nRT, respectively (Benowitz and Karten, 1976;Nixdorf and Bischof, 1982).…”

Characterization of novel GPCR gene coding locus in amphioxus genome: Gene structure, expression, and phylogenetic analysis with implications for its involvement in chemoreception

“…From the evolutionary biological point of view, divergence and enlargement of the repertoire of ORs may therefore possibly result in the expansion of the sensory world of the organisms. Since the pallium of agnathans consists of an olfactory-dominated paleocortex (e.g., Northcutt and Puzdrowski, 1988;Butler and Hodos, 1996), the evolutionary history of this flexible and dynamic system in relation to a large-scale genomic duplication (Holland, 1998;Panopoulou et al, 2002), which is thought to have taken place in a lineage leading to the vertebrates, is of great interest. Although recent molecular as well as anatomical findings indicate the presence of amphioxus counterparts of the vertebrate diencephalon and hindbrain (Lacalli, 2001;Wada and Satoh, 2001;Mazet and Shimeld, 2002), there is not yet convincing evidence for the presence of any integrative center in amphioxus like the telencephalon and cerebellum of vertebrates.…”

The effects of stress on the dorsal raphe nucleus of the reticular formation and its role in the aetiology of disparate medical and neuropsychiatric disorders

“…The reticular (Latin reticulum, small net or mesh) formation of the brain stem of vertebrates has roles in a constellation of seemingly diverse functions, including: coordination of the movements of the head and body via stimulation and inhibition of voluntary movements and reflex movements; respiration; blood pressure; sensory gating, including in respect of pain; psychological processes such as arousal and attention; sleep and dreaming; and muscle tone (1). An important component of the vertebrate reticular formation is the raphe (Greek rhaphé, seam) group (accordance to the Olszewski-Brodal nomenclature).…”