Critical period for activity-dependent elimination of corticospinal synapses in vitro
Section snippets
Organotypic slice culture
Details are given elsewhere (Takuma et al., 2002). In brief, coronal slices (400 μm) of sensorimotor cortex and axial slices (400 μm) of the cervical cord from P0 Wister rats were sectioned, and the forelimb areas of the cortex excised from each section with a razor blade. The cortical and spinal cord slices were placed on collagen-coated membranes (Transwell-Col, 3.0 μm pore; Costar, Cambridge, MA, USA); then serum-free, hormone-supplemented medium (Dulbecco’s modified essential medium/Ham’s
Results
Corticospinal synapse fEPSPs were recorded along a 100 μm-interval lattice in the spinal gray matter. Representative recordings of fEPSPs are shown in Fig. 1 and the averaged amplitudes of each points are shown in Fig. 2. Normalized, average fEPSP amplitudes were plotted at five medio-lateral points (Fig. 3b) for quantitative analysis of the dorso-ventral gradient of synapse formation.
Discussion
Previously, we found that corticospinal synapses first are formed diffusely in an in vitro slice coculture system after which synapses in the ventral part are eliminated. Moreover, synapse elimination was activity- and NMDA-dependent: it is blocked by the NMDA blocker, APV. Here we showed that the APV effect is irreversible for at least the length of culture. When APV was removed from the medium after 11 DIV, ventral synapses no longer were eliminated, at least up to 21 DIV. Furthermore, APV
Acknowledgments
This work was supported by Ministry of Education, Culture, Sports, Science & Technology of Japan, Grant-in-Aid 15300137 (M.S.), Grant-in-Aid for Research on Priority Areas 15016097 (M.S.), and by the Mitsubishi Foundation (M.S.). We thank Dr. H. Takagi for his help with the statistical analysis.
References (28)
- et al.
Critical periods during sensory development
Curr Opin Neurobiol
(2000) - et al.
Developmental sequence in the origin of descending spinal pathwaysstudies using retrograde transport techniques in the North American opossum (Didelphis virginiana)
Brain Res Dev
(1984) - et al.
Selective elimination of transient corticospinal projections in the rat cervical spinal cord gray matter
Brain Res Dev
(1994) - et al.
Mouse somatosensory cortexalterations in the barrelfield following receptor injury at different early postnatal ages
Neuroscience
(1981) Corticospinal tract regrowth
Prog Neurobiol
(1997)- et al.
Development, critical period plasticity, and adult reorganizations of mammalian somatosensory systems
Curr Opin Neurobiol
(1994) - et al.
Axon elimination in the developing corticospinal tract of the rat
Brain Res
(1988) - et al.
In vitro formation of corticospinal synapses in an organotypic slice culture
Neuroscience
(2002) - et al.
Selective stabilization of developing synapses as a mechanism for the specification of neuronal networks
Nature
(1976) - et al.
Patterned activity, synaptic convergence and the NMDA receptors in developing visual pathways
Annu Rev Neurosci
(1990)
On the development of the pyramidal tract in the rat: I. The morphology of the growth zone
Anat Embryol Berl
A quantitative analysis of the development of the pyramidal tract in the cervical spinal cord in the rat
Anat Embryol Berl
Critical period regulation
Annu Rev Neurosci
The period of susceptibility to the physiological effects of unilateral eye closure in kittens
J Physiol
Cited by (14)
Lack of adenylate cyclase 1 (AC1): Consequences on corticospinal tract development and on locomotor recovery after spinal cord injury
2014, Brain ResearchCitation Excerpt :Indeed, in the cerebral cortex, neuronal programmed cell death occurs during the first postnatal week in rodents as revealed by histological analysis (Heumann et al., 1978; Heumann and Leuba, 1983; Ferrer et al., 1992; Voyvodic, 1996) and labeling of apoptotic DNA fragmentation (Spreafico et al., 1995; Verney et al., 2000), whereas the refinement process occurs during the second and the third postnatal weeks (Luo and O'Leary, 2005). Furthermore, studies in developing rats suggested that synapse elimination is induced by axon branch elimination rather than neuronal cell death (Takuma et al., 2002; Ohno et al., 2004; Ohno and Sakurai, 2005; Kamiyama et al., 2006). Altogether, our results suggest that the absence of AC1 has an impact not only on sensory system but also in motor system wiring, in agreement with previous observations of fasciculation defects of motor spinal neurons (Haupt et al., 2010).
Corticospinal Development
2009, Encyclopedia of NeuroscienceMolecular mechanisms of axon guidance in the developing corticospinal tract
2008, Progress in NeurobiologyOptical and electrophysiological recordings of corticospinal synaptic activity and its developmental change in in vitro rat slice co-cultures
2007, NeuroscienceCitation Excerpt :Furthermore, both the spatial distribution of CS-terminal activity and the CS-synaptic responses correlated well with the distribution of anterogradely labeled CS-axon terminals (Fig. 5). Taken together, these findings validate our use of fEPSPs as an index of synapse formation (Takuma et al., 2002; Ohno et al., 2004; Ohno and Sakurai, 2005). The correlation between CS fibers and optEPSPs also suggests that optEPSPs reliably reflect CS-synaptic responses, and that CS fibers were effectively activated by the cortical stimulation we used.
Chapter 3 Development of the corticospinal system and spinal motor circuits
2007, Handbook of Clinical Neurology