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Hub AI
Synaptogenesis AI simulator
(@Synaptogenesis_simulator)
Hub AI
Synaptogenesis AI simulator
(@Synaptogenesis_simulator)
Synaptogenesis
Synaptogenesis is the formation of synapses between neurons in the nervous system. Although it occurs throughout a healthy person's lifespan, an explosion of synapse formation occurs during early brain development, known as exuberant synaptogenesis. Synaptogenesis is particularly important during an individual's critical period, during which there is a certain degree of synaptic pruning due to competition for neural growth factors by neurons and synapses. Processes that are not used, or inhibited during their critical period will fail to develop normally later on in life.[further explanation needed]
Brain growth and development begins during gestation and into the postnatal period. Brain development can be divided into stages including: neurogenesis, differentiation, proliferation, migration, synaptogenesis, gliogenesis and myelination, and apoptosis and synaptic pruning. Synaptogenesis occurs in the third trimester during gestation as well as the first two years postnatal. During neuron differentiation, growth cones that extend off the tip of each axon act as the site for elongation of each axon. These growth cones find signal molecules which act as guidance cues and form synapses. Connections formed between neurites may be random or selective.
Exuberant synaptogenesis is characterized by a few characteristics. First, it involves the formation of long axonal projections, and an overproduction of small axonal branches, synapses, and dendritic branches and/or spines. Throughout this process, many of these structures may be maintained or eventually eliminated. Elimination may occur by neuronal death or selective deletion.
Developmental exuberance may occur macro- or microscopically. Macroscopic exuberance occurs when transient projections are formed between macroscopic regions in the brain. In comparison, microscopic exuberance occurs when transient structures involved in communication between neurons forms.
What specific molecules and chemical signals are involved in synaptogenesis has yet to be fully understood. Some evidence posits that transcription factors are heavily involved in directing where axons and dendrites form synapses before and after synaptogenesis. The main study focusing on this involved motor neurons of C.elegans. In this study, researchers found that knockout animals without the gene, unc-4 have motor defects specifically with moving backwards. This gene is necessary for the Prd-like homeodomain transcription factor. These animals also had abnormal synaptic specificity indicating that this transcription factor is likely involved in determining where and how synapses are formed.
Other studies found that this transcription factor was involved in synaptic strength. In this study, it was found that the unc-4 pathway negatively regulates ceh-12, a gene involved in regulating synaptic choice.
Guidance cues are essential for nervous system development as well as synaptic maintenance and remodeling. Guidance cues--attractive or repulsive--are sensed by growth cones. Expression of guidance cue genes is mediated at the transcriptional, post-transcriptional, translational, and post-translational levels.
Most guidance cues converge onto various families of small GTPases which go back and forth from active to inactive forms. There are a multitude of signaling pathways involved in this process but the key ones involve netrins (NTNs) and fibronectin leucine-rich repeat transmembrane proteins (FLRTs), the Slit family, semamorphins (SEMA), ephrin, non-canonical genes (morphogens, chemokines, growth factors), and RTN4 receptors.
Synaptogenesis
Synaptogenesis is the formation of synapses between neurons in the nervous system. Although it occurs throughout a healthy person's lifespan, an explosion of synapse formation occurs during early brain development, known as exuberant synaptogenesis. Synaptogenesis is particularly important during an individual's critical period, during which there is a certain degree of synaptic pruning due to competition for neural growth factors by neurons and synapses. Processes that are not used, or inhibited during their critical period will fail to develop normally later on in life.[further explanation needed]
Brain growth and development begins during gestation and into the postnatal period. Brain development can be divided into stages including: neurogenesis, differentiation, proliferation, migration, synaptogenesis, gliogenesis and myelination, and apoptosis and synaptic pruning. Synaptogenesis occurs in the third trimester during gestation as well as the first two years postnatal. During neuron differentiation, growth cones that extend off the tip of each axon act as the site for elongation of each axon. These growth cones find signal molecules which act as guidance cues and form synapses. Connections formed between neurites may be random or selective.
Exuberant synaptogenesis is characterized by a few characteristics. First, it involves the formation of long axonal projections, and an overproduction of small axonal branches, synapses, and dendritic branches and/or spines. Throughout this process, many of these structures may be maintained or eventually eliminated. Elimination may occur by neuronal death or selective deletion.
Developmental exuberance may occur macro- or microscopically. Macroscopic exuberance occurs when transient projections are formed between macroscopic regions in the brain. In comparison, microscopic exuberance occurs when transient structures involved in communication between neurons forms.
What specific molecules and chemical signals are involved in synaptogenesis has yet to be fully understood. Some evidence posits that transcription factors are heavily involved in directing where axons and dendrites form synapses before and after synaptogenesis. The main study focusing on this involved motor neurons of C.elegans. In this study, researchers found that knockout animals without the gene, unc-4 have motor defects specifically with moving backwards. This gene is necessary for the Prd-like homeodomain transcription factor. These animals also had abnormal synaptic specificity indicating that this transcription factor is likely involved in determining where and how synapses are formed.
Other studies found that this transcription factor was involved in synaptic strength. In this study, it was found that the unc-4 pathway negatively regulates ceh-12, a gene involved in regulating synaptic choice.
Guidance cues are essential for nervous system development as well as synaptic maintenance and remodeling. Guidance cues--attractive or repulsive--are sensed by growth cones. Expression of guidance cue genes is mediated at the transcriptional, post-transcriptional, translational, and post-translational levels.
Most guidance cues converge onto various families of small GTPases which go back and forth from active to inactive forms. There are a multitude of signaling pathways involved in this process but the key ones involve netrins (NTNs) and fibronectin leucine-rich repeat transmembrane proteins (FLRTs), the Slit family, semamorphins (SEMA), ephrin, non-canonical genes (morphogens, chemokines, growth factors), and RTN4 receptors.