T neurons, a new morphological
and physiological class of spinal interneurons involved in limb
movement control:
Using intracellular recording and dye injection in vivo, we have described a new morphological and physiological class of spinal interneurons, which we call transverse interneurons, or T neurons. T neurons have dendritic trees that are extensive in the transverse plane but short rostrocaudally (A). They fire action potentials very rhythmically and at high peak rates during fictive scratching, as can be seen in raw recordings (B) and in firing rate phase histograms (C). Their membrane potential oscillations during fictive scratching are on average larger (D), and their action potentials narrower, with briefer afterhyperpolarizations, than other scratch-activated interneurons. Most T neurons are active during multiple forms of ipsilateral and contralateral fictive scratching and during ipsilateral fictive limb withdrawal. Many T neurons have axon terminal arborizations in the spinal cord ventral horn (E), suggesting that they may play important roles in limb movement control.
Using intracellular recording and dye injection in vivo, we have described a new morphological and physiological class of spinal interneurons, which we call transverse interneurons, or T neurons. T neurons have dendritic trees that are extensive in the transverse plane but short rostrocaudally (A). They fire action potentials very rhythmically and at high peak rates during fictive scratching, as can be seen in raw recordings (B) and in firing rate phase histograms (C). Their membrane potential oscillations during fictive scratching are on average larger (D), and their action potentials narrower, with briefer afterhyperpolarizations, than other scratch-activated interneurons. Most T neurons are active during multiple forms of ipsilateral and contralateral fictive scratching and during ipsilateral fictive limb withdrawal. Many T neurons have axon terminal arborizations in the spinal cord ventral horn (E), suggesting that they may play important roles in limb movement control.
(Adapted
from
Berkowitz, A., Yosten, G.L.C., and Ballard, R.M., J.
Neurophysiol. 95:2821-2831,
2006.)
Strong interactions between scratch and swim spinal cord networks |
Hyperpolarization of scratch-specialized neurons during swim |
Rhythmic activity of interneurons during two types of scratching |
Rhythmic activity of interneurons during left and right motor rhythms |