Absence of Whisker-Related Pattern Formation in Mice with NMDA Receptors Lacking Coincidence Detection Properties and Calcium Signaling

Precise refinement of synaptic connectivity is the result of activity-dependent mechanisms in which coincidence-dependent calcium signaling by NMDA receptors (NMDARs) under control of the voltage-dependent Mg2+ block might play a special role. In the developing rodent trigeminal system, the pattern of synaptic connections between whisker-specific inputs and their target cells in the brainstem is refined to form functionally and morphologically distinct units (barrelettes). To test the role of NMDA receptor signaling in this process, we introduced the N598R mutation into the native NR1 gene. This leads to the expression of functional NMDARs that are Mg2+ insensitive and Ca2+impermeable. Newborn mice expressing exclusively NR1 N598R-containing NMDARs do not show any whisker-related patterning in the brainstem, whereas the topographic projection of trigeminal afferents and gross brain morphology appear normal. Furthermore, the NR1 N598R mutation does not affect expression levels of NMDAR subunits and other important neurotransmitter receptors. Our results show that coincidence detection by, and/or Ca2+ permeability of, NMDARs is necessary for the development of somatotopic maps in the brainstem and suggest that highly specific signaling underlies synaptic refinement

Pharmacologically induced motor patterns in the suboesophageal ganglion of the locust

Pharmacologically-induced motor patterns were studied in the locust suboesophageal ganglion. This model system comprises a complex pattern-generating network extending over several neuromeres. Strict coordination of motor patterns of different neuromeres is typical for mouthpart motor patterns making them a uniquely true in vitro model of complex behaviour. Spectral analysis of time series was used as a powerful tool for the evaluation of long time series for the first time in the analysis of pattern generation. It was shown that similar but not identical motor patterns are induced in the same system upon induction with pilocarpine and IBMX. Most prominent are the higher regularity and frequency of the motor pattern induced with IBMX. The new pharmacological tool allowed a study of the synaptic input to motoneurones and neurosecretory cells. This analysis showed that the input to efferent neurones is more complex than the spiking pattern recorded from them. Following hints given by the nature of the drugs known to induce motor patterns, questions on the transmitters involved in pattern generation were addressed. It was shown for the first time that the NO/cGMP signalling pathway is involved in mandibular pattern generation. The NO/cGMP pathway appears to act independently from the muscarinic pathway. Both sources and targets of NO were detected in histological preparations

Pharmacologically induced motor patterns in the suboesophageal ganglion of the locust

Pharmacologically-induced motor patterns were studied in the locust suboesophageal ganglion. This model system comprises a complex pattern-generating network extending over several neuromeres. Strict coordination of motor patterns of different neuromeres is typical for mouthpart motor patterns making them a uniquely true in vitro model of complex behaviour. Spectral analysis of time series was used as a powerful tool for the evaluation of long time series for the first time in the analysis of pattern generation. It was shown that similar but not identical motor patterns are induced in the same system upon induction with pilocarpine and IBMX. Most prominent are the higher regularity and frequency of the motor pattern induced with IBMX. The new pharmacological tool allowed a study of the synaptic input to motoneurones and neurosecretory cells. This analysis showed that the input to efferent neurones is more complex than the spiking pattern recorded from them. Following hints given by the nature of the drugs known to induce motor patterns, questions on the transmitters involved in pattern generation were addressed. It was shown for the first time that the NO/cGMP signalling pathway is involved in mandibular pattern generation. The NO/cGMP pathway appears to act independently from the muscarinic pathway. Both sources and targets of NO were detected in histological preparations

De infinitis sectionibus conicis methodo nova geometrice delineandis ...

auctore Georgius Henricus Ras

Zwischen Dianenwall und Vasenwall

ZWISCHEN DIANENWALL UND VASENWALL Zwischen Dianenwall und Vasenwall / Rast, Georg (Rights reserved) ( -

Kiri G. S. Bayer'ile

Rast, Georg Heinrich, 1695-1726, saksa matemaatikBayer, Gottlieb (Theophil) Siegfried, 1694-1738, orientalist, prof. Königsbergis ja Peterburis, Peterburi TA liigeSoovitab G. J. Kehri. Küsib arvamust Leibnitzi väidete koht