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(So does running) Ketamine reverses neural changes underlying depression-related behaviors in mice: Study sheds light on the neural mechanisms underlying remission of depression -- ScienceDaily

Researchers took high-resolution images of dendritic spines in the prefrontal cortex of mice before and after they experienced a stressor. Dendritic spines are protrusions in the part of neurons that receive communication input from other neurons. The researchers found that mice displaying behaviors related to depression had increased elimination of, and decreased formation of, dendritic spines in their prefrontal cortex compared with mice not exposed to a stressor. This finding replicates prior studies linking the emergence of behaviors related to depression in mice with dendritic spine loss. In addition to the effects on dendritic spines, stress reduced the functional connectivity and simultaneous activity of neurons in the prefrontal cortex of mice. This reduction in connectivity and activity was associated with behaviors related to depression in response to stressors. Liston's group then found that ketamine treatment rapidly restored functional connectivity and ensemble activity of neurons and eliminated behaviors related to depression

The Brain Learns Completely Differently than We've Assumed Since the 20th Century - Neuroscience News

The newly suggested learning scenario indicates that learning occurs in a few dendrites that are in much closer proximity to the neuron, as opposed to the previous notion. “Does it make sense to measure the quality of air we breathe via many tiny, distant satellite sensors at the elevation of a skyscraper, or by using one or several sensors in close proximity to the nose? Similarly, it is more efficient for the neuron to estimate its incoming signals close to its computational unit, the neuron,” says Kanter. Hebb’s theory has been so deeply rooted in the scientific world for 70 years that no one has ever proposed such a different approach. Moreover, synapses and dendrites are connected to the neuron in a series, so the exact localized site of the learning process seemed irrelevant. Another important finding of the study is that weak synapses, previously assumed to be insignificant even though they comprise the majority of our brain, play an important role in the dynamics of our brain. They induce oscillations of the learning parameters rather than pushing them to unrealistic fixed extremes, as suggested in the current synaptic learning scenario.