Basic nervous systems types: one or many?

TY - CHAP

T1 - Basic nervous systems types: one or many?

AU - Hirth, Frank

AU - Reichert, H

PY - 2007/1/1

Y1 - 2007/1/1

N2 - Based on classical neuroanatomy, the bilaterians have been divided into two major groups: the Gastroneuralia, such as arthropods and annelids, characterized by a ventral central nervous system (CNS) and the Notoneuralia, such as chordates, characterized by a dorsal CNS. In contrast, molecular genetic studies based on the expression and function of conserved developmental control genes in neurogenesis have revealed striking similarities in the developmental organization of the brain in animals as diverse as flies and mammals. Comparison of the expression, function, and regulation of genes and genetic networks involved in anteroposterior, dorsoventral, and midline patterning of the insect and vertebrate CNS suggests that orthologous genes were already involved in neural specification in a common ancestor, indicating that insect and vertebrate brains evolved from an ancestral urbilaterian brain. The notion that the brains of diverse animal groups are homologous is supported by molecular genetic data that evoke the hypothesis of a dorsoventral body and neuraxis inversion in animal evolution and revive the historic debate about a common Bauplan underlying development in bilaterians. Whereas the evolutionary occurrence and mode of nervous system centralization are still debated, available data suggest that one ancestral and complex nervous system type was at the origin of bilaterian CNS evolution.

AB - Based on classical neuroanatomy, the bilaterians have been divided into two major groups: the Gastroneuralia, such as arthropods and annelids, characterized by a ventral central nervous system (CNS) and the Notoneuralia, such as chordates, characterized by a dorsal CNS. In contrast, molecular genetic studies based on the expression and function of conserved developmental control genes in neurogenesis have revealed striking similarities in the developmental organization of the brain in animals as diverse as flies and mammals. Comparison of the expression, function, and regulation of genes and genetic networks involved in anteroposterior, dorsoventral, and midline patterning of the insect and vertebrate CNS suggests that orthologous genes were already involved in neural specification in a common ancestor, indicating that insect and vertebrate brains evolved from an ancestral urbilaterian brain. The notion that the brains of diverse animal groups are homologous is supported by molecular genetic data that evoke the hypothesis of a dorsoventral body and neuraxis inversion in animal evolution and revive the historic debate about a common Bauplan underlying development in bilaterians. Whereas the evolutionary occurrence and mode of nervous system centralization are still debated, available data suggest that one ancestral and complex nervous system type was at the origin of bilaterian CNS evolution.

U2 - 10.1016/B0-12-370878-8/00107-5

DO - 10.1016/B0-12-370878-8/00107-5

M3 - Chapter

SN - 978-0-12-370878-6

VL - 1

SP - 55

EP - 72

BT - Evolution of Nervous Systems

A2 - Bullock, T

A2 - Krubitzer, L

A2 - Preuss, T

A2 - Rubenstein, J

A2 - Strausfeld, N

A2 - Streidter, G

PB - Academic Press

CY - London, San Diego

ER -