In vivo study of left-right differences of the rodent hippocampus

虽然大脑的左右不对称在普通人群中是众所周知的，但其生理意义仍不清楚。为了研究动物体验对脑不对称性的影响，我们记录了丰富环境饲养大鼠(ENR)和隔离环境饲养大鼠(ISO)大鼠双侧海马区的局部场电位。我们发现，在ENR饲养的大鼠中，伽马振荡的功率往往比在ISO饲养的大鼠更大。这种经验依赖的伽马增强在不同受试者的右侧海马区始终更大，与右侧海马区突触密度的侧化增加相一致。此外，ENR组的大脑半球间一致性在伽马频率下显著增强。这些结果表明，ENR增强通过突触的重组形成了功能性的左右不对称的海马环路。

Though left-right asymmetry of the brain is well known among the general population, the physiological meanings remain unclear. To investigate how animal experience influence on brain asymmetry, we recorded local field potentials of rat hippocampi bilaterally from rat reared in enriched environment (ENR) and those reared in isolated condition (ISO). We found that the power of gamma oscillations tends to be greater in rats reared in ENR than those reared in an ISO. This experience-dependent gamma enhancement is consistently larger in the right hippocampus across subjects, coinciding with a lateralized increase of synaptic density in the right hippocampus. Moreover, interhemispheric coherence in ENR group is significantly elevated at the gamma frequency. These results suggest that ENR rearing sculpts the functional left-right asymmetry of hippocampal circuits by reorganization of synapses.