I have found toxicology research that suggests that it's P10 in mice for synaptogenesis, and other research which suggests that it goes on even into the first or second month.
For neurogenesis I have that it peaks between 7 to 12 days after birth, but some sources say that it's on P7.5.
What resources are best to rely on? Thanks in advance.
Dear Tatyana,
That is a very good question. In my opinion, the answer to your question is not a very straight one due to much variation in peak synaptogenesis among species and developmental differences among neuronal pools. For example in humans it would be much later than any other species. In mice it differ say between cortical, cerebral and spinal neurons. Synaptogenesis peaks earlier at around time of birth in spinal motoneurons compared to Purkinje and pyramidal neurons. For details and references see my recent review on that. In this paper synaptogenesis in motoneurons during development is compared to pyramidal and Purkinje neurons (section 4, page 16).
best wishes, Refik
Article Emerging Roles of Filopodia and Dendritic Spines in Motoneur...
Dear Tatyana,
That is a very good question. In my opinion, the answer to your question is not a very straight one due to much variation in peak synaptogenesis among species and developmental differences among neuronal pools. For example in humans it would be much later than any other species. In mice it differ say between cortical, cerebral and spinal neurons. Synaptogenesis peaks earlier at around time of birth in spinal motoneurons compared to Purkinje and pyramidal neurons. For details and references see my recent review on that. In this paper synaptogenesis in motoneurons during development is compared to pyramidal and Purkinje neurons (section 4, page 16).
best wishes, Refik
Article Emerging Roles of Filopodia and Dendritic Spines in Motoneur...
The only problem is that most of the studies are performed in the visual cortex of rats, and as you stated in your paper, this might not be the peak of synaptogenesis in other parts of the brain, like the hippocampus. It wouldn't make sense that there would not be any cognitive processing or synaptic connections before they open their eyes? Am I right?
Oh yes you are absolutely right, synaptogenesis develops at visual cortex and auditory cortex very late in the rats after opening of the eyes or onset of hearing that is around post-natal day 9 (P9) or so in the rat. In contrast in spinal cord, synaptogenesis starts and peaks much earlier. At birth, the pups/baby needs to breath, move and find milk/food and suckle to survive, therefore synaptogenesis in spinal motoneurons starts as early as E11. Synaptogenesis for cortical synapses and cognitive processing comes at alot later stages and takes many years in humans. Central synaptogenesis for sensory systems such as olfaction and taste (gustatory) also developes before the visual and hearing systems.
best wishes, Refik