Sino Biological provides a range of tools for studying many aspects of nervous system function, including axon guidance, synaptic transmission, neurodegeneration, neural stem cell, and more.
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Neuroscience is the scientific study of the nervous system. Current neuroscience is not only a branch of biology, it involves many others disciplines such as psychology, philosophy, mathematics, medicine, physics, and computer science. Current neuroscience research activities can be roughly categorized into the following major branches, including molecular and cellular neuroscience, developmental neuroscience, neural engineering, neurology, psychiatry, systems neuroscience, behavioral neuroscience, cognitive neuroscience, neuroimaging, neurolinguistics, theoretical neuroscience, and computational neuroscience, etc. Therefore, the term neurobiology is more accurate than neuroscience when refers specifically to the biology of the nervous system.
There are approximately 100 billion neurons in human brains, which constitute the basic structural and functional units of the nervous system. Neurons transmit information by electrical and chemical signaling, and they connect to each other to form neural networks. A typical neuron possesses a cell body (often called the soma), dendrites, and an axon.
Axon guidance is the process by which axons extend to reach their correct targets. Axons often follow very precise paths in the nervous system, and axon guidance is important in neural development. Axons are guided along specific pathways by attractive and repulsive cues in the extracellular environment. At the growing tip of axons, a highly motile structure, called growth cone, contains receptors that recognize these guidance cues and activate various signaling molecules to regulate the cytoskeleton. Genetic and biochemical studies have led to the identification of highly conserved families of guidance molecules, including Ephrins, Netrins, Semaphorins and Slits.
The key to neural function is the synaptic signaling process, which is partly electrical and partly chemical. Synaptic signals to other neurons are transmitted by the axon; signals from other neurons are received by the soma and dendrites. Synapses can be excitatory or inhibitory and will either increase or decrease activity in the target neuron. The electrical synapses are direct, electrically-conductive junctions between cells. In a chemical synapse, the process of synaptic transmission is as follows: when an action potential reaches the axon terminal, it opens voltage-gated calcium channels, allowing calcium ions to enter the terminal. Calcium causes synaptic vesicles filled with neurotransmitter molecules to fuse with the membrane, releasing their contents into the synaptic cleft. The neurotransmitters diffuse across the synaptic cleft and activate receptors on the postsynaptic neuron. The human brain contains about 100 trillion synapses; each neuron may have thousands of input synaptic connections. It is the complex integration of these synaptic signals that controls all of the body functions including learning, memory, sensory integration, motor coordination, and emotional responses.
Neurons of the adult brain do not generally undergo cell division, and usually cannot be replaced after being lost, although there are a few known exceptions. It is hypothesized that neurogenesis in the adult brain originates from neural stem cells (NSCs). Neural stem cells are multipotent stem cells that are capable of self-renewing and differentiating into the three main central nervous system (CNS) lineages: neurons, astrocytes, and oligodendrocytes. Neural stem cells were first isolated from the neurogenic areas of adult mice brain tissue by Reynolds and Weiss in 1992. Since then, neural stem cells have been isolated from various areas of the adult brain, including non-neurogenic areas, such as the spinal cord, and from various species including human. Neural stem cells undergo proliferative symmetric and asymmetric divisions to replenish themselves and to produce intermediate neural progenitors (INPs), respectively. Intermediate neural progenitors, which reside next to the ventricular zone in the subventricular zone (SVZ), are thought to produce a majority of cortical neurons. Neurons are also produced by neural stem cells undergoing neurogenic asymmetric divisions. Thus, a balance of symmetric and asymmetric neural stem cell divisions regulates the number of neural stem cells, intermediate neural progenitors and produced neurons, and is critical for defining the adult brain.
Neurotrophic factors comprise a broad family of secreted proteins that exert survival-promoting, growth promoting, and trophic actions on neuronal cells. Neurotrophic factors are essential for keeping neurons alive and properly connected. During development, these factors play a critical role in nourishing the neurons in the spinal cord that connect to the muscle cells to prevent the death of the nerve cell. In addition, neurotrophic factors regulate growth of neurons, associated metabolic functions such as protein synthesis, and the ability of the neuron to make the neurotransmitters that carry chemical signals which allow the neuron to communicate with other neurons or with other targets. Disruption of neurotrophic factor signalling is a characteristic of many central and peripheral nervous system disorders.
The progressive loss of structure and function of neurons is referred to as neurodegeneration. Neurodegenerative diseases constitute one of the major challenges of modern medicine, including Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, Lyme disease, Parkinson's disease, and so on. These diseases are relatively common and often highly debilitating. However, the mechanisms responsible for their pathologies are poorly understood, and there are currently no effective preventative therapies. Advances in our understanding of the molecular mechanisms underlying nervous system dysfunction are critical for the development of effective treatments. Recent research on the genetic pathways leading to pathology with animal models (mice and Drosophila) begun to identify molecular mechanisms underlying neurodegenerative disorders.