Cellular and network properties in the functioning of the nervous system: from central pattern generators to cognition

Evidence for the presence and functioning of the spinal generator for ejaculation in the neonatal male rat

“…14 Studies on embryonic and neonatal animals have shown that the organisation of CPGs is genetically determined and their operation does not importantly depend on experience. 5 Besides, it has been demonstrated that the future adult motor patterngenerating neural circuitry will be present early in development awaiting the appearance of appropriate activating commands. 4 Present results show that in neonatal male rats, the spinal generator for ejaculation is functional at early postnatal stages, and suggest that the oxytocinergic spinal system, certainly among others, plays an important role in its expression.…”

“…4 Besides, studies on embryonic and neonatal animals have shown that the organisation of the CPGs is genetically determined and their operation does not depend on experience. 5 Thus, a criterion to further establish that a given rhythmic motor response is under the control of a CPG would be to provide evidence for its existence early during development. On these bases, rhythmic motor patterns under the control of CPGs that become active at late developmental stages, such as puberty or adulthood, should also be present early in development and be capable of producing the innate rhythmic motor behaviour at those early stages.…”

Role of genital sensory information in the control of the functioning of the spinal generator for ejaculation

“…[1][2][3][4] CPGs are neural networks that generate the basic pattern of motor outputs in animals lacking a cerebral cortex 2 or in the absence of peripheral sensory feedback. [1][2][3] Neurons from the CPG underlying fictive movements are pacemakers whose endogenous rhythmic activity is under the influence of conditional factors such as chemical signals or its command sensory inputs. 3 It has been proposed that the close interaction between sensory signals and CPGs accounts for the crucial effects of a certain kind of stimuli upon rhythmic behaviour such as the rhythmic alternation of extensor and flexor muscle bursts in one leg in cats.…”

“…[1][2][3] Neurons from the CPG underlying fictive movements are pacemakers whose endogenous rhythmic activity is under the influence of conditional factors such as chemical signals or its command sensory inputs. 3 It has been proposed that the close interaction between sensory signals and CPGs accounts for the crucial effects of a certain kind of stimuli upon rhythmic behaviour such as the rhythmic alternation of extensor and flexor muscle bursts in one leg in cats. 1 Besides, it has been demonstrated that the sensory input-CPG connections account for the conditional oscillation in motor pattern-generating networks 5 and that strong continuous stimuli delivered to CPGs could effectively freeze them so that they would stop producing any rhythmic output.…”

“…7 Thus, rhythmogenic networks for movements are highly susceptible to external inputs which pace pattern generation by exerting an important modulatory influence. 1,3,4,6,7 Spinal cord transection at T6 level allows the expression of a rhythmic motor pattern in the perineal genital muscles, which coincides with the potent expulsion of urethral contents. 8,9 This response appears at 3-min intervals, suggesting the existence of an instrinsic spinal rhythm controlling its expression.…”