134 Pharmacological activation of cannabinoid (CB1) receptors can also impair the proper timing between place cells without affecting the spatial tuning of the hippocampal cells. Despite the intact hippocampal spatial map, the animal under the influence of cannabinoid cannot solve a spatial memory task, presumably because the downstream reader networks of hippocampal neurons cannot decode the time-jittered spikes.135 The above examples from work on the hippocampus demonstrate that representation of multiple time scales is a fundamental feature of cortical function. Similar coding strategies may support the emergence of “grid cells”136 (neurons
found Inhibitors,research,lifescience,medical to be active not only in particular places in the environment but occupying an array of places which are regularly spaced in a grid of equilateral triangles) in the entorhinal cortex14,137-140 and other complex functions in the prefrontal cortex and other structures.141-144 Temporal compression is also at play while the network is not receiving
Inhibitors,research,lifescience,medical Inhibitors,research,lifescience,medical new sensory input, or is “offline.” As described earlier, “place cells” are neurons which fire when the animal is physically in certain places in the environment and in the waking animal. During behavioral pauses just before an animal runs across an environment, the sequence of anticipated place cell firings during the animal’s future run Inhibitors,research,lifescience,medical are “preplayed” in a compressed manner during sharp wave -ripple (SPW-R) events which last 80-150 ms.104 They are also “replayed” after reaching the end of the run but this time in selleck reverse sequence, as if the path is retracted.145,146 Such compressed replay is also routinely observed in non-REM sleep.147,148 The bidirectional re-enactment of temporal sequences Inhibitors,research,lifescience,medical during SPW-Rs
is critical for memory consolidation64,66,149-154 and may also contribute to creative associations in the subsequent waking episodes.155,156 Similar time-compressed off-line replay of waking activity has been also documented in the neocortex80,157-161 and striatum,162,163 suggesting that multiple time-scale representation is a general phenomenon in the brain. Thus, neuronal oscillations organize the spiking activity of multiple neurons in a number of manners, which appear to allow for prediction, recall, consolidation, and creative Cilengitide association. Furthermore, this appears to be a phenomenon utilized more broadly than by only the spatial processing system and may underlie a great deal of selleck products efficient neural information handling. Oscillations can promote both spike synchrony and asynchrony Oscillations and synchrony are often used synonymously and an often-expressed objection against the utility of network oscillations is that rhythmically discharging neurons are predictable and synchronized spikes are largely redundant.