Pattern formation and rhythm generation in the ventral respiratory group.

摘要: 1. There is increasing evidence that the kernel of rhythm-generating circuitry for breathing located within a discrete subregion column respiratory neurons ventrolateral medulla referred to as ventral group (VRG). It less clear how this rhythm transformed into precise patterns appearing on varied motor outflows. 2. Two different approaches were used test whether subregions VRG have distinct roles in or pattern generation. In one, clusters activated inactivated by pressure injection small volumes neuroactive agents activate inactivate groups and resulting effects determined. The underlying assumption was if are generated subregions, then we should be able identify regions where activation predominantly alters with little effect other altered rhythm. 3. Based phrenic nerve responses an excitatory amino acid (DL-homocysteate), divided four subdivisions arranged along rostrocaudal axis. Injections three rostral elicited changes both pattern. From caudal included: (i) bradypnoea region, roughly associated Botzinger complex; (ii) dysrhythmia/tachypnoea area, pre-Botzinger complex (PBC); (iii) second area; and, most caudally, (iv) region from which no detectable change output elicited. 4. approach, unilateral lesions one subregion, PBC, Breuer-Hering reflex Activation lung inflation shortens inspiration lengthens expiration (TE). 5. Unilateral PBC attenuated lengthening TE, but did not baseline 6. These findings consistent concept functionally homogenous, consists rostrocaudally subregions. Neurons so-called appear dominant role Nevertheless, contribute Thus, at least anatomical level resolvable injection, there appears significant overlap generating