Review Article – Article Example
Article Review- “Individual neurons dissociated from rat Suprachiasmatic Nucleus express independently phased circadian firing rhythms”
The researchers investigated the role of the circadian clock in the suprachiasmatic nucleus (SCN) in timing diverse behavioral, endocrine and neuronal rhythms (Welsh 697). Neonatal rat cells containing SCN were cultured and action potential was recorded from individual SCN neurons for days or weeks, thereby revealing prominent circadian rhythms in firing rate. The researchers also observed that circadian rhythms expressed by neuron cells in the same culture were not synchronized. The researchers were able to establish that SCN contain autonomous single cell circadian oscillators but the synapses formed in vitro are insufficient for synchrony.
The purpose of the study is to monitor the long-term firing of circadian firing rhythms from multiple individual SCN neurons in parallel, in a dissociated culture system in which cell interactions can be manipulated and individual rhythmic cells are accessible for further detailed study. There is sufficient background information on the role of spontaneous circadian rhythms in neuronal firing rate from populations of SCN neuron either as multiple-unit recordings or as ensemble averages of many brief single-unit recordings. The existence of population rhythms implies that there is communication in circadian phase information in SCN neurons.
SCN neurons expressing circadian firing rhythms exhibited very regular short-term firing
patterns, especially close to their circadian peaks. The same clock cell could express different short-term firing patterns with each varying circadian phase similar to those reported for cells in SCN slices. Simultaneous recordings of multiple cells revealed that the phases of circadian firing rhythms varied widely among cells in the same culture. This finding proved that the activity of SCN cells was not synchronized. The first research question posed would be the role of the circadian clock in neuronal firing. Secondly, the possibility of functional coupling of the circadian clock in SCN cells.
Welsh,David, Diomedes Logothetis, Markus Meister and Steven Reppert. Individual Neurons Dissociated from Rat Suprachiasmatic Nucleus Express Independently Phased Circadian Firing Rhythms. Neuron. 14(1995):697-706.