Studies using specific biomarkers associated with developing neurons have been used to support the idea of adult neurogenesis in humans. There have been two proposed sites of adult neurogenesis in humans, one in the olfactory bulb and the other in the hippocampus. It has not been convincingly demonstrated in humans. Since then, neurogenesis has been able to be discovered in birds and other small mammals. This view continued until Josef Altman was able to find evidence of neurogenesis in adult rats. Studies by Ramon Cajal had failed to find any evidence of new neuron development in adults, which led to his ‘harsh decree’ that there were no new neurons after the development of the brain stopped. Homeostatic plasticity: Mechanisms that maintain homeostasis of the synaptic network over time.Īs research continues to grow, these concepts will flesh out more of how synaptic plasticity can influence learning and aid in regaining function in the brain.Īdult neurogenesis: Adult neurogenesis is the concept that the brain continues to make new neurons. The theory of synaptic plasticity has also grown to include more of the evolving complexity of synaptic communication. ![]() Aging and neurodegenerative diseases have been associated with a decrease of neuromodulators and may contribute to a reduction in the ability of synaptic plasticity. This enhances the synapse over time in accordance with the idea by Konorski and Hebb. Synaptic plasticity can be positively influenced by several things, including, but not exclusively, exercise, the environment, repetition of tasks, motivation, neuromodulators (such as dopamine), and medications/drugs. What is theorized to occur is that when the presynaptic neuron stimulates the postsynaptic neuron, the postsynaptic neuron responds by adding more neurotransmitter receptors, which lowers the threshold that is needed to be stimulated by the presynaptic neuron. As the postsynaptic potential continued for a much longer time than expected, they termed this long-term potentiation. First discovered in 1973 by Bliss and Lomo while studying the rabbit hippocampus, repetitive stimulation of presynaptic fibers resulted in high responses of granule cells of postsynaptic neurons. This is best expressed with the concept of long-term potentiation. Synaptic plasticity: Synaptic plasticity is the ability to make experience-dependent long-lasting changes in the strength of neuronal connections. ġ) Neuronal Regeneration/Collateral Sprouting ![]() This theory claims that society is responsible for motivating the proper individuals to fill certain positions and to reward the individuals so they maintain a desire to fulfill occupational duties.Weeks to months afterward: The brain continues to remodel itself via axonal sprouting and further reorganization around the damage. Structural functionalism views society on a large scale and pays little attention to the individual in society or personal development. ![]() These systems also exhibit control of the environment and the tendency to change the systems. These systems are self-reliant and exhibit control of boundaries between individuals and the whole. Tasks and responsibilities are divided amongst members of society to maintain balance and each individual or social unit must work together to create efficiency in the system. Each social system or unit maintains a boundary with external environments and conflict between social units with other systems or external environments require adaptation. Each part of the social system has an impact upon other parts of the system and can determine the form other systems take.
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