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Origins of the Brain: Complex Synapses Drove Brain Evolution
http://www. physorg. com/ news132152252. html
June 08, 2008
One of the greatest challenges in science is understanding the design principles and origins of the human brain. New research has shed light on the evolutionary origins of the brain and how it evolved into such a complex structure.
This study suggests that it is not just size that provides greater brainpower, but also increasingly complex molecular processing of neural signals during evolution, which allowed animals to develop more sophisticated behaviors.
The research demonstrates that there were two waves of increased complexity in the structure of neural connections, which may have been the driving forces enabling the evolution of complex brains—including our own. The foundational building blocks evolved before larger brains.
Current thinking holds that the protein components of neural connections—called synapses—are largely similar across most animals, from humble worms to humans, and that it is the increase in the number of synapses in larger animals that makes more complex thinking possible.
"Our simplistic view that 'more neurons' alone explains 'more brainpower' is not supported by our study," said Professor Seth Grant, head of the Genes to Cognition Programme at the Wellcome Trust Sanger Institute and leader of the study. "While much research has focused on the number of neurons, none has examined the molecular composition of neural connections. We found significant differences in the number of proteins in neural connections across different species."
"We studied about 600 proteins found in mammalian synapses and were surprised to find that only 50% of these are present in invertebrate synapses, and about 25% in single-celled organisms, which obviously lack a brain."
Synapses are the connections between neurons, where electrical signals from one cell are transmitted to the next through a series of biochemical exchanges. However, synapses are not just welded junctions but miniature processors that give the nervous system its capacity for learning and memory.
Remarkably, this study shows that some proteins involved in signaling, learning, and memory at synapses can be found in yeast, where they function in responding to environmental signals, such as stress from nutrient deprivation or changes in temperature.
"This set of proteins found in single-celled organisms represents an ancient or 'proto-synapse' involved in simple behaviors," Professor Grant continued. "This set of proteins was embellished by additional new proteins as invertebrates and vertebrates evolved, enabling these animals to develop more complex behaviors."
"The number and complexity of proteins at synapses first exploded when multicellular animals emerged, around a billion years ago. A second wave occurred with the appearance of vertebrates, approximately 500 million years ago."
One of the team's key achievements was the first isolation of synaptic proteins from the brain of a fly, demonstrating that invertebrates possess a simpler set of proteins compared to vertebrates.What is most important for understanding human thought is that they discovered the expansion of proteins occurring in vertebrates provides a pool of proteins that can be used to construct different parts of the brain into complex regions, such as the cortex, cerebellum, and spinal cord.
Due to the evolution of molecular complexes, "large" synapses emerged before large brains. It may be these molecular evolutionary events that allowed the evolution of the large brains found in humans, primates, and other vertebrates.
In ethological studies of animals, mutations disrupting synaptic genes support this conclusion: the synaptic proteins that evolved in vertebrates enabled the emergence of a broader range of behaviors, including those involving the highest mental functions.
For example, a "vertebrate innovation" gene called SAP102 is necessary for a mouse to adjust its learning strategy when solving maze challenges. When humans lack this gene, it can lead to certain forms of mental disorders.
"The molecular evolution of synapses is akin to the evolution of computer chips—increased complexity gives them more power, and the animals with the most powerful chips are capable of the most," Professor Grant continued.
Simple invertebrate species exhibit basic forms of learning based on synapses composed of simple molecules, while complex mammalian species display a wider range of learning types based on synapses composed of highly complex molecules. (Omitted)
These new findings will be crucial for understanding the normal functioning of the human brain and have direct relevance to disease research. Professor Grant's team has recently identified gene evolution involved in human cognitive impairment and modeled these deficiencies in mice. (Omitted)
Source: http:/ / only- perception. blogs……/ 2008/ 06/ blog- post_8239. html
Study: Complex Synapses Drive Brain Evolution
http://www. physorg. com/ news132152252. html
June 08, 2008
One of the greatest challenges in science is understanding the design principles and origins of the human brain. New research has shed light on the evolutionary origins of the brain and how it evolved into such a complex structure.
This study suggests that it is not just size that provides greater brainpower, but also increasingly complex molecular processing of neural signals during evolution, which allowed animals to develop more sophisticated behaviors.
The research demonstrates that there were two waves of increased complexity in the structure of neural connections, which may have been the driving forces enabling the evolution of complex brains—including our own. The foundational building blocks evolved before larger brains.
Current thinking holds that the protein components of neural connections—called synapses—are largely similar across most animals, from humble worms to humans, and that it is the increase in the number of synapses in larger animals that makes more complex thinking possible.
"Our simplistic view that 'more neurons' alone explains 'more brainpower' is not supported by our study," said Professor Seth Grant, head of the Genes to Cognition Programme at the Wellcome Trust Sanger Institute and leader of the study. "While much research has focused on the number of neurons, none has examined the molecular composition of neural connections. We found significant differences in the number of proteins in neural connections across different species."
"We studied about 600 proteins found in mammalian synapses and were surprised to find that only 50% of these are present in invertebrate synapses, and about 25% in single-celled organisms, which obviously lack a brain."
Synapses are the connections between neurons, where electrical signals from one cell are transmitted to the next through a series of biochemical exchanges. However, synapses are not just welded junctions but miniature processors that give the nervous system its capacity for learning and memory.
Remarkably, this study shows that some proteins involved in signaling, learning, and memory at synapses can be found in yeast, where they function in responding to environmental signals, such as stress from nutrient deprivation or changes in temperature.
"This set of proteins found in single-celled organisms represents an ancient or 'proto-synapse' involved in simple behaviors," Professor Grant continued. "This set of proteins was embellished by additional new proteins as invertebrates and vertebrates evolved, enabling these animals to develop more complex behaviors."
"The number and complexity of proteins at synapses first exploded when multicellular animals emerged, around a billion years ago. A second wave occurred with the appearance of vertebrates, approximately 500 million years ago."
One of the team's key achievements was the first isolation of synaptic proteins from the brain of a fly, demonstrating that invertebrates possess a simpler set of proteins compared to vertebrates.What is most important for understanding human thought is that they discovered the expansion of proteins occurring in vertebrates provides a pool of proteins that can be used to construct different parts of the brain into complex regions, such as the cortex, cerebellum, and spinal cord.
Due to the evolution of molecular complexes, "large" synapses emerged before large brains. It may be these molecular evolutionary events that allowed the evolution of the large brains found in humans, primates, and other vertebrates.
In ethological studies of animals, mutations disrupting synaptic genes support this conclusion: the synaptic proteins that evolved in vertebrates enabled the emergence of a broader range of behaviors, including those involving the highest mental functions.
For example, a "vertebrate innovation" gene called SAP102 is necessary for a mouse to adjust its learning strategy when solving maze challenges. When humans lack this gene, it can lead to certain forms of mental disorders.
"The molecular evolution of synapses is akin to the evolution of computer chips—increased complexity gives them more power, and the animals with the most powerful chips are capable of the most," Professor Grant continued.
Simple invertebrate species exhibit basic forms of learning based on synapses composed of simple molecules, while complex mammalian species display a wider range of learning types based on synapses composed of highly complex molecules. (Omitted)
These new findings will be crucial for understanding the normal functioning of the human brain and have direct relevance to disease research. Professor Grant's team has recently identified gene evolution involved in human cognitive impairment and modeled these deficiencies in mice. (Omitted)
Source: http:/ / only- perception. blogs……/ 2008/ 06/ blog- post_8239. html