Limb Movements During Embryonic Development in the Chick: Evidence for a Continuum in Limb Motor Control Antecedent to Locomotion

Bradley, Nina S.; Solanki, Dhara; Zhao, Dawn

doi:10.1152/jn.00804.2005

Cited by 20 publications

(29 citation statements)

References 55 publications

(51 reference statements)

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“…Conceivably, needed primitives might be built into the CNS and its development by evolution. Early experience in utero or in ovo during critical periods might then further shape the modularity (Schouenborg, 2002(Schouenborg, , 2004Bradley et al, 2005). This would support early motor functions and could "seed" subsequent motor learning, thus helping, for example,, the wildebeest calf to walk almost de novo and to rapidly learn agile movements.…”

Section: Discussionmentioning

confidence: 99%

A Neural Basis for Motor Primitives in the Spinal Cord

Hart

Giszter²

2010

J. Neurosci.

241

194

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Motor primitives and modularity may be important in biological movement control. However, their neural basis is not understood. To investigate this, we recorded 302 neurons, making multielectrode recordings in the spinal cord gray of spinalized frogs, at 400, 800, and 1200 m depth, at the L2/L3 segment border. Simultaneous muscle activity recordings were used with independent components analysis to infer premotor drive patterns. Neurons were divided into groups based on motor pattern modulation and sensory responses, depth recorded, and behavior. The 187 motor pattern modulated neurons recorded comprised 14 cutaneous neurons and 28 proprioceptive neurons at 400 m in the dorsal horn, 131 intermediate zone interneurons from ϳ800 m depth without sensory responses, and 14 motoneuron-like neurons at ϳ1200 m. We examined all such neurons during spinal behaviors. Mutual information measures showed that cutaneous neurons and intermediate zone neurons were related better to premotor drives than to individual muscle activity. In contrast, proprioceptive-related neurons and ventral horn neurons divided evenly. For 46 of the intermediate zone interneurons, we found significant postspike facilitation effects on muscle responses using spike-triggered averages representing short-latency postspike facilitations to multiple motor pools. Furthermore, these postspike facilitations matched significantly in both their patterns and strengths with the weighting parameters of individual primitives extracted statistically, although both were initially obtained without reference to one another. Our data show that sets of dedicated interneurons may organize individual spinal primitives. These may be a key to understanding motor development, motor learning, recovery after CNS injury, and evolution of motor behaviors.

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Section: Discussionmentioning

confidence: 99%

A Neural Basis for Motor Primitives in the Spinal Cord

Hart

Giszter²

2010

J. Neurosci.

241

194

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“…Measurements were made between ED5 and ED11 and were not made after ED11 since from this period onwards the movements of the embryo can be constrained by the space in the shell (Sharp et al, 1999), which would lead to the introduction of another variable to the experiments. Additionally, the number of limb movements appears to peak around this period (ED11-12) before declining dramatically by ED15 (Bradley, 1999;Bradley et al, 2005).…”

Section: Temperature and Embryonic Movementmentioning

confidence: 96%

In ovotemperature manipulation influences embryonic motility and growth of limb tissues in the chick (Gallus gallus)

Hammond

Simbi

Stickland

2007

Journal of Experimental Biology

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SUMMARY The chick embryo, developing in the egg, is an ideal system in which to investigate the effects of incubation environment on the development of the embryo. We show that raising the temperature of the eggs by just one degree,from 37.5°C to 38.5°C, during embryonic days (ED) 4–7 causes profound changes in development. We demonstrate that embryonic movement is significantly increased in the chicks raised at 38.5°C both during the period in which they are at the higher temperature but also 4 days after their return to the control temperature. Concomitant with this increase in embryonic activity, the embryos raised at higher temperature grow to significantly heavier weights and exhibit significantly longer leg bones (tibia and tarsus)than the controls from ED12 onwards, although mineralization occurs normally. Additionally, the number of leg myonuclei is increased from ED12 in the embryos raised at the higher temperature. This is likely to promote greater leg muscle growth later in development, which may provide postural stability to the chicks posthatch. These changes are similar to those seen when drugs are injected to increase embryonic activity. We therefore believe that the increased embryonic activity provides a mechanism that can explain the increased growth of leg muscle and bone seen when the eggs are incubated for 3 days at higher temperature.

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“…Yet by E9, leg movements are produced by alternating flexor/extensor muscle activity and coupled joint rotations at the hip, knee, and ankle at frequencies of 0.2-2 Hz (Bekoff 1976;Bradley and Bekoff 1990;Chambers et al 1995). The muscle patterns and coupled rotations of hip and knee persist up through hatching, suggesting they are controlled by a pattern generating network (Bekoff 1976(Bekoff , 1992Bradley 1999Bradley , 2001Bradley et al 2005;Sharp et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Fast Locomotor Burst Generation in Late Stage Embryonic Motility

Bradley

Ryu²,

Lin³

2008

Journal of Neurophysiology

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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.

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Limb Movements During Embryonic Development in the Chick: Evidence for a Continuum in Limb Motor Control Antecedent to Locomotion

Cited by 20 publications

References 55 publications

A Neural Basis for Motor Primitives in the Spinal Cord

A Neural Basis for Motor Primitives in the Spinal Cord

In ovotemperature manipulation influences embryonic motility and growth of limb tissues in the chick (Gallus gallus)

Fast Locomotor Burst Generation in Late Stage Embryonic Motility

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