In:
eLife, eLife Sciences Publications, Ltd, Vol. 4 ( 2015-10-14)
Abstract:
Although there are many different movements an animal can make with its limbs—from reaching to walking—they all basically involve two sets of muscles that act as opposing levers around each joint. ‘Flexor’ muscles contract to bend the limb, and ‘extensor’ muscles contract to extend the limb. When an animal is walking these two sets of muscles contract repeatedly, one after the other. Inhibitory neurons in the spinal cord coordinate these walking movements by preventing the flexor or extensor muscles from contracting at the same time. In 2014, researchers discovered that two groups of inhibitory neurons, known as the V1 and V2b interneurons, are essential for this alternating pattern of flexing and extending of the limbs of newborn mice. However, these experiments were not able to assess the particular contribution that the V1 and V2b neurons each make to limb movements. Now, Britz et al.—including several of the researchers involved in the 2014 study—have used a sophisticated genetic technique in mice to investigate the role that each group of neurons plays separately. This involved introducing a gene into either the V1 or V2b neurons that makes them susceptible to being killed with the diphtheria toxin. Injecting the mice with diphtheria toxin selectively removed these cells from the regions of the spinal cord that controls hindlimb movements. Britz et al. found that removing either group of neurons prevented the mice from walking normally. Eliminating the V1 neurons caused extreme flexing of the hindlimbs, revealing that the V1 neurons are needed to extend the limb by inhibiting the motor neurons that contract the flexor muscles. In contrast, the loss of V2b neurons caused exaggerated hindlimb extension, indicating that the V2b neurons inhibit the motor neurons that innervate extensor muscles. Both the V1 and V2b groups of neurons contain a wide range of different cell types. Future studies will therefore need to explore how these different cells are involved in coordinating the motions involved in walking.
Type of Medium:
Online Resource
ISSN:
2050-084X
DOI:
10.7554/eLife.04718.001
DOI:
10.7554/eLife.04718.002
DOI:
10.7554/eLife.04718.003
DOI:
10.7554/eLife.04718.004
DOI:
10.7554/eLife.04718.005
DOI:
10.7554/eLife.04718.006
DOI:
10.7554/eLife.04718.007
DOI:
10.7554/eLife.04718.008
DOI:
10.7554/eLife.04718.009
DOI:
10.7554/eLife.04718.010
DOI:
10.7554/eLife.04718.011
DOI:
10.7554/eLife.04718.012
DOI:
10.7554/eLife.04718.015
DOI:
10.7554/eLife.04718.013
DOI:
10.7554/eLife.04718.014
DOI:
10.7554/eLife.04718.016
DOI:
10.7554/eLife.04718.017
Language:
English
Publisher:
eLife Sciences Publications, Ltd
Publication Date:
2015
detail.hit.zdb_id:
2687154-3