The motor function of the spinal cord requires the computation of the local neuronal circuits within the same segments as well as the long-range coordination of different spinal levels. Implicated players in this process are the propriospinal neurons (PPNs) that project their axons across different levels of the spinal cord. However, their cellular, molecular, and functional properties remain u...

I have explored the chick sympathetic system as a model for the study of specific synapse formation by examining the pattern of ganglion cell innervation by preganglionic axons in 2 different ganglia. Using intracellular recording and HRP labeling techniques, the innervation of the 12th and 15th cervical ganglia (C12 and C15) was examined. Sympathetic ganglion cells of the chick are innervated ...

Timing of oscillatory activity along the longitudinal body axis is critical for locomotion in the lamprey and other elongated animals. In the lamprey spinal locomotor central pattern generator (CPG), intersegmental coordination is thought to arise from the pattern of extensive connections made by propriospinal interneurons. However, the mechanisms responsible for intersegmental coordination rem...

Functional resistance to graded hypotensive ischemia of various segments of the somatosensory pathway was determined in anesthetized cats by repeated concurrent recordings of regional blood flow measured by hydrogen clearance, and evoked potentials (EPs), of dorsal horn of lumbar spinal cord and cerebral cortex. During normal resting CNS blood flow (CBF), there were significant successive reduc...

Many laboratories have reported the successful regeneration of neurons across damaged portions of the spinal cord. Associated improvements in hindlimb locomotor movements have been attributed to the formation of functional neuronal connections with the locomotor central pattern generator (CPG). However, regenerating axons generally extend no more than 10 mm caudal to the lesion sites, terminati...

Many laboratories have reported the successful regeneration of neurons across damaged portions of the spinal cord. Associated improvements in hindlimb locomotor movements have been attributed to the formation of functional neuronal connections with the locomotor central pattern generator (CPG). But regenerating axons generally extend no more than 10mm caudal to the lesion sites, terminating abo...

For a complete adult spinal rat to regain some weight-bearing stepping capability, it appears that a sequence of specific proprioceptive inputs that are similar, but not identical, from step to step must be generated over repetitive step cycles. Furthermore, these cycles must include the activation of specific neural circuits that are intrinsic to the lumbosacral spinal cord segments. For these...

Tissue transplantation methods, previously used to study neural development, myelination and inherited disorders of myelin can be applied also to the investigation of repair and regeneration in the mammalian CNS. The elongation of axons from injured peripheral nerve of CNS has been studied in adult mice and rats by observing the growth of axons into PNS or CNS tissue grafts. Following spinal co...

The effects of eliminating or decreasing neuromuscular activity on the expression of neurotrophins and associated molecules in the spinal cord and subsequent effects on spinal cord plasticity were determined. Spinal cord isolation (SI), which eliminates any supraspinal and peripheral monosynaptic input to the lumbar region but maintains the motoneuron-muscle connectivity, decreased the levels o...