Development of coordinated movement in chicks: I. Temporal analysis of hindlimb muscle synergies at embryonic days 9 and 10

Self Cite

Bradley NS, Ryu YU, Lin J. Fast locomotor burst generation in late stage embryonic motility. J Neurophysiol 99: 1733-1742, 2008. First published February 13, 2008 doi:10.1152/jn.01393.2007. We examined muscle burst patterns and burst frequencies for a distinct form of repetitive leg movement recently identified in chick embryos at embryonic day (E)18 that had not been previously studied. The aim was to determine if burst frequencies during repetitive leg movements were indicative of a rhythm burst generator and if maturing muscle afferent mechanisms could modulate the rhythm. Electromyographic recordings synchronized with video were performed in ovo during spontaneous movement at E15, E18, and E20. Multiple leg muscles were rhythmically active during repetitive leg movements at E18 and E20. Rhythmic activity was present at E15 but less well formed. The ankle dorsi flexor, tibialis anterior, was the most reliably rhythmic muscle because extensor muscles frequently dropped out. Tibialis anterior burst frequencies ranged from 1 to 12 Hz, similar to frequencies during fast locomotor burst generation in lamprey. The distribution in burst frequencies at E18 was greatest at lower frequencies and similar to locomotor data in hatchlings. Relative distributions were more variable at E20 and shifted toward faster frequencies. The shell wall anterior to the leg was removed in some experiments to determine if environmental constraints associated with growth contributed to frequency distributions. Wall removal had minimal impact at E18. E20 embryos extended their foot outside the egg, during which faster frequencies were observed. Our findings provide evidence that embryonic motility in chick may be controlled by a fast locomotor burst generator by E15 and that modulation by proprioceptors may emerge between E18 and E20.

Section: Age-related Changes In Rlmsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fast Locomotor Burst Generation in Late Stage Embryonic Motility

Bradley

Ryu²,

Lin³

2008

Self Cite

“…In future studies, it should be equally possible to inhibit neuronal activity in peripheral axons using light-driven chloride or proton pumps (Arrenberg et al 2009;Chow et al 2010). Importantly, we have shown that tonic activation of motor neurons innervating flexor muscles can disrupt normal extension of the leg.…”

Section: Discussionmentioning

confidence: 99%

“…Since embryonic motility has been well-described on E9 (Bradley and Bekoff 1990;Sharp et al 1999;Sharp and Bekoff 2001), we chose to examine light-evoked movement more carefully at this age. Brief (ϳ1-s) pulses of light centered over the thigh and presented between episodes of spontaneous movement produced flexions of the leg that were very reproducible when presented with a period Ͼ0.5 Hz.…”

Section: Embryonic Movement Evoked By Chief Activationmentioning

confidence: 99%

Optogenetic regulation of leg movement in midstage chick embryos through peripheral nerve stimulation

Sharp

Fromherz²

2011

Numerous disorders that affect proper development, including the structure and function of the nervous system, are associated with altered embryonic movement. Ongoing challenges are to understand in detail how embryonic movement is generated and to understand better the connection between proper movement and normal nervous system function. Controlled manipulation of embryonic limb movement and neuronal activity to assess short- and long-term outcomes can be difficult. Optogenetics is a powerful new approach to modulate neuronal activity in vivo. In this study, we have used an optogenetics approach to activate peripheral motor axons and thus alter leg motility in the embryonic chick. We used electroporation of a transposon-based expression system to produce ChIEF, a channelrhodopsin-2 variant, in the lumbosacral spinal cord of chick embryos. The transposon-based system allows for stable incorporation of transgenes into the genomic DNA of recipient cells. ChIEF protein is detectable within 24 h of electroporation, largely membrane-localized, and found throughout embryonic development in both central and peripheral processes. The optical clarity of thin embryonic tissue allows detailed innervation patterns of ChIEF-containing motor axons to be visualized in the living embryo in ovo, and pulses of blue light delivered to the thigh can elicit stereotyped flexures of the leg when the embryo is at rest. Continuous illumination can disrupt full extension of the leg during spontaneous movements. Therefore, our results establish an optogenetics approach to alter normal peripheral axon function and to probe the role of movement and neuronal activity in sensorimotor development throughout embryogenesis.

“…1999) and muscle discharge (Bekoff et al 1975;Bradley and Bekoff 1990;Ryu and Bradley 2009) have been accomplished in acute preparation of freely moving chicken embryos across much of embryogenesis. These types of studies have given rise to a description of how motor activity is altered during development (Bekoff 2001;Bradley 2001;Sharp and Bekoff 2001), but still lacking is an understanding of the relationship of muscle activity to force production by the limb and how this may be regulated by sensory feedback.…”

mentioning

confidence: 99%

A system for the determination of planar force vectors from spontaneously active chicken embryos

Sharp

Cain

Pakiraih

et al. 2014

Sharp AA, Cain BW, Pakiraih J, Williams JL. A system for the determination of planar force vectors from spontaneously active chicken embryos. J Neurophysiol 112: 2349 -2356. First published August 20, 2014 doi:10.1152/jn.00423.2014.-Generally, a combination of kinematic, electromyographic (EMG), and force measurements are used to understand how an organism generates and controls movement. The chicken embryo has been a very useful model system for understanding the early stages of embryonic motility in vertebrates. Unfortunately, the size and delicate nature of embryos makes studies of motility during embryogenesis very challenging. Both kinematic and EMG recordings have been achieved in embryonic chickens, but two-dimensional force vector recordings have not. Here, we describe a dual-axis system for measuring force generated by the leg of embryonic chickens. The system employs two strain gauges to measure planar forces oriented with the plane of motion of the leg. This system responds to forces according to the principles of Pythagorean geometry, which allows a simple computational program to determine the force vector (magnitude and direction) generated during spontaneous motor activity. The system is able to determine force vectors for forces Ͼ0.5 mN accurately and allows for simultaneous kinematic and EMG recordings. This sensitivity is sufficient for force vector measurements encompassing most embryonic leg movements in midstage chicken embryos allowing for a more complete understanding of embryonic motility. Variations on this system are discussed to enable nonideal or alternative sensor arrangements and to allow for translation of this approach to other delicate model systems. force vector; strain gauge; 2D; chicken embryo; kinematics RESEARCH ON THE CHICKEN EMBRYO has provided a wealth of information on the development of motor circuitry (Bekoff et al. 1975;Kastanenka and Landmesser 2013;O'Donovan and Landmesser 1987;O'Donovan et al. 2008) and behavior (Bradley 2001;Bradley et al. 2005;Sharp et al. 1999) that is especially relevant to limbed terrestrial animals. The chicken has been particularly important due to the capacity for direct observation and manipulation of the embryo throughout embryogenesis, which is arguably more challenging with mammalian fetuses (e.g., Brumley and Robinson 2010). Motor studies on chicken embryos present technical challenges that are unique compared with juvenile and adult limbed animals such as relatively small size and an aquatic environment. Nonetheless, quantitative studies of leg movement (Bradley 2001;Bradley et al. 2005;Ryu and Bradley 2009;