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ow do "micro-changes" in the brain drive the formation of learning and memory
In the brain, microscopic changes—particularly changes in dendritic spines—play a critical role in driving learning and memory formation. Dendritic spines are small membrane protrusions on the dendrites of neurons that typically receive input from individual axons at synapses and serve as a place to store synaptic strength, helping to transmit electrical signals to the neuron's cell body.
The presence of dendritic spines not only provides the structural basis for memory storage and synaptic transmission, but also increases the number of possible connections between neurons.
The structural features of dendritic spines make them an integral component of the learning process. Each neuron's dendrites can carry hundreds to thousands of dendritic spines, and these tiny structures are constantly changing in response to external stimuli. Improving the shape and size of dendritic spines is thought to be closely related to the strength of learning and memory.
Structure and function of dendritic spines
Dendritic spines typically consist of a swollen head and a thin neck connected to the dendrite trunk. Depending on their shape, dendritic spines can be divided into types such as "slender", "stubby", "mushroom" and "forked". The variability of these structures is thought to be related to the strength and stage of maturation of the synapses.
The shape and volume of dendritic spines correlate with the strength and maturity of different synaptic connections, according to electron microscopy studies.
Studies have shown that most active neurons, such as pyramidal neurons in the cortex, medium spiny neurons in the striatum, and Purkinje cells in the cerebellum, are distributed with dendritic spines. Especially in the pyramidal neurons of the hippocampus and cerebral cortex, each neuron may receive tens of thousands of stimuli from other neurons.
Dendritic spine dynamics and learning
The synaptic plasticity of dendritic spines is the reason why they can respond quickly to stimuli, and this process is mainly regulated by the cytoskeleton. Dendritic spines are rich in F-actin, which enables them to rapidly change shape, directly affecting their electrophysiological properties. For example, when micro-deformations in dendritic spines are associated with the storage of a memory during learning, the stability of this deformation plays an important role in the learning outcome.
If the shape and size of dendritic spines continue to change, this may lead to loss of information.
The function of dendritic spines is not only demonstrated in their connections with other neurons, but also in their influence on learning and memory. The generation and adjustment of dendritic spines during learning changes with different experiences, and these changes may affect the maintenance and retrieval ability of the memory.
Molecular pathways and dendritic spine plasticity
When the morphology of dendritic spines changes, molecular pathways such as Rho GTPases are activated, which play a crucial role in the formation, maturation and plasticity of dendritic spines. For example, activation of RhoA and Cdc42 leads to an increase in the volume of dendritic spines, making synaptic connections stronger and more durable. These changes not only directly affect neuronal function, but also have profound consequences for the persistence of learning and memory.
Structural changes in dendritic spines affect not only synaptic plasticity but also the efficiency of information processing.
For example, during the process of learning new skills, the stabilization and proliferation of dendritic spines are important indicators of this process. The effects of environmental stimuli on dendritic spines show that these tiny structures can not only reorganize neural networks by adding new structures or changing their shape, but also affect the formation and retention of long-term memories.
The association between dendritic spines and memory formation
The plasticity of dendritic spines and their role in learning and memory are gaining increasing attention. The study showed that both the number and volume of dendritic spines change significantly during learning. Compared with youth, dendritic spines in adults show different patterns in both number and stability, which may also affect the stability of memory and the long-term maintenance of learning ability.
Dendritic spine dynamics during learning may serve as an important mechanism for maintaining long-term memory.
At the same time, the existing research results on age-related cognitive decline and its connection with changes in dendritic spines further reveal the importance of the health and function of dendritic spines to overall brain function. We can't help but wonder, how can we further promote the health of dendritic spines, and whether this can improve our learning and memory abilities?
