We can only conjecture that either GABAergic VTA cells, or glutamate corelease from DA cell synapses, may convey the oscillatory input to PFC. Nonetheless, the study by Fujisawa and Buzsáki (2011) paves the way for future experiments centered on these themes. “
“More than 2,000 years ago the Chinese advanced the concept of Yin and Yang to help explain the progressive and regressive forces that operate during life. As depicted in the Taiji diagram, Yin and Yang are interdependent, interconnected, and transformable. Today, this ancient theory still provides a useful conceptual framework for viewing the

dynamic relationship between progressive and regressive events during neural development and maintenance. see more Here we describe how this principle applies to multiple organizational levels of the nervous system: from circuits, to cells, to molecules (Figure 1A). Neural circuit formation involves many progressive events including neural stem cell proliferation, axon and dendrite outgrowth, and synapse formation. Later in development, however, regressive events such as cell death, axon pruning, and synapse elimination further refine the precise pattern of connectivity needed for proper function of the mature circuitry. Neuron death and synapse loss also occur under pathophysiological conditions such as amyotrophic lateral sclerosis and Alzheimer’s disease, for example (Vanderhaeghen ABT-737 molecular weight and Cheng, 2010). Unfortunately,

the counterforces that might offset the degeneration of neural circuits seem to be far less robust in the adult than the embryonic nervous system of higher vertebrates, creating a major clinical challenge (Giger et al., 2010). Progressive and regressive events also apply to the attractive and repulsive forces that guide growing axons (O’Donnell et al., 2009). Some cellular targets express attractive cues, which promote the assembly of cytoskeletal networks within growth cones, leading to axonal turning and extension, whereas other others targets express repulsive cues that cause cytoskeleton

disassembly. Interestingly, the signaling pathways that cause axon attraction and repulsion are transformable when levels of cyclic nucleotides and Ca2+ are altered (Hong et al., 2000, Höpker et al., 1999 and Nishiyama et al., 2003). In fact, the responsiveness of axons to guidance signals often changes over their course of growth. Long axons typically navigate using a series of intermediate targets. For each intermediate target, the axon is first attracted then switches its response upon arrival and becomes repelled, allowing it to move on to the next leg of its journey (Tessier-Lavigne and Goodman, 1996 and Yu and Bargmann, 2001). At a molecular level, the synthesis and degradation of proteins can likewise be viewed as progressive and regressive processes. Accordingly, it is easy to understand how the synthesis of new proteins is critical for cell proliferation, the specification of neuronal identity, and axonal extension.