br Developmental changes in metaplasticity align with hippoc

Developmental changes in metaplasticity align with hippocampal maturation The hippocampus is required for contextual learning in rats and mice. This statement is derived predominantly from hippocampal lesion studies involving contextual learning and memory tasks such as spatial navigation to a goal (Morris, 1984; Sutherland et al., 1983) spontaneous alternation (Douglas and Isaacson, 1965; Douglas, 1972), contextual fear conditioning (Phillips and LeDoux, 1992; Kim and Fanselow, 1992), and object-place-context recognition (Langston and Wood, 2010). Many of these h2 receptor antagonist same behavior tasks have been applied to investigate the maturational time course of hippocampal integrity (Albani et al., 2014). While spontaneous alternation, contextual fear conditioning, and spatial learning and memory appear to mature at the end of the third postnatal week (Douglas et al., 1973; Rudy et al., 1987; Paylor et al., 1992; Rudy and Morledge, 1994; Pugh and Rudy, 1996; Dumas, 2005), performance in object-place-context conditioning does not reach adult levels until after 1 month of age (Langston and Lyon, 2013). Thus, the metaplastic alterations at SC-CA1 synapses described above occur at the same developmental stage when most forms of hippocampal-dependent learning and memory first come “on line.” Neural discharge events in the hippocampus also suggest involvement in sequence learning. While the animal remains motionless on a testing surface, pyramidal neurons in area CA1 display transient extra-field discharge events that replay the animal\'s prior path (Foster and Wilson, 2006; Diba and Buzsáki, 2007; Wu and Foster, 2014) and pre-play the animal\'s future trajectory (“look ahead”) (Johnson and Redish, 2007; Diba and Buzsáki, 2007; Pfeiffer and Foster, 2013). There are no developmental studies on these phenomena. However, it is reasonable to suspect that maturation of neural encoding and decoding of trajectories at least partially limits the behavioral emergence of spatial navigation at 3 weeks of age. How might the metaplastic changes at hippocampal synapses regulate the emergence of trajectory encoding/decoding and spatial navigation? Each alteration in synaptic function described above may contribute independently to the behavioral change. Brief examples are provided below.
Conclusion
Conflict of interest statement
Acknowledgments This work was supported by the Thomas and Kate Miller Jeffress Memorial Trust Fund (J-904) as well as the Krasnow Institute for Advanced Study and the College of Science at George Mason University.