Neurotransmission

Synaptotagmins are trafficked to distinct subcellular domains including the postsynaptic compartment. Adolfsen, B. et al. J Cell. Biol. 166, 249–260 (2004)

Synaptotagmin 1 (SYT1) is an abundant synaptic protein and has been implicated in neurotransmission. The authors characterized the subcellular localization of other SYT proteins. They show that SYT4 is localized at the post-synapstic compartment, SYT12 and SYT14 are expressed at low levels presynaptically, SYTα and SYTβ are present in some neurosecretory cells, and SYT7 is not detectable at synapses. Overexpression of SYT4 and SYT7 cannot rescue the defects in neurotransmission in SYT1-deficient neurons.

Regeneration

P2X7 receptor inhibition improves recovery after spinal cord injury Wang, X. et al. Nature Med. 10, 821–827 (2004)

This study shows that high levels of ATP are released after spinal cord injury and can lead to secondary damage. ATP also acts as an excitatory neurotransmitter in spinal cord neurons and results in high-frequency spiking and cell death. The effects of ATP can be blocked by antagonists of the P2X7 receptors, oxidised-ATP (OxATP) and piridoxalphosphate-6-azophenyl-2'-4'-disulphonic acid (PPADS). OxATP and PPADS can reduce cell death and significantly improve functional recovery after spinal cord injury.

Stem cells

Telomere shortening and chromosomal instability abrogates proliferation of adult but not embryonic neural stem cells. Ferrón, S. et al. Development 131, 4059–4070 (2004)

Chromosome integrity is important for cell survival and proliferation. Ferrón et al. show that proliferation of adult neural stem cells (NSCs) from the subventricular zone of telomerase-deficient mice is impaired both in vitro and in vivo. By contrast, embryonic NSCs proliferate extensively despite their shortened telomeres, severe chromosome abnormalities and increased p53 expression.

Motion detection

Neurons compute internal models of the physical laws of motion. Angelaki, D. E. et al. Nature 430, 560–564 (2004)

The CNS needs to differentiate various types of motion that generate similar sensory signals. The authors proposed an equation of motion, which states that the neural estimate of the inertial acceleration along the y-axis can be approximated by a linear superposition of the net acceleration signal sensed by the otoliths and an internal estimate of the y-axis gravitational acceleration. The firing rates of the vestibular nuclei and the rostral fastigial nucleus were consistent with their predictions, indicating that these neurons might carry out the computations to detect motion and orientation.