Figure 1. Influence of bdnf gene mutation on central respiratory output.

A, central respiratory activity was recorded in vitro on the first (P0.5) and fifth (P4.5) postnatal day from the C4 ventral root in wild-type (+/+), bdnf heterozygous (+/-) and bdnf knockout (-/-) brainstem–spinal cord preparations. A markedly lower frequency of respiratory discharges in bdnf mutants compared with wild-type controls was apparent at both ages tested. At both ages, the preparations of different genotypes were derived from littermates. B, bulbospinal transection (arrow) abolished respiratory activity recorded from the C4 ventral root. This recording was made from the same P0.5 wild-type preparation shown in A.