Local generation of theta-frequency EEG activity in the parasubiculum
Local generation of theta-frequency EEG activity in the parasubiculum
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DOI：
10.1152/jn.01306.2006
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发表时间：
2007-06-01
影响因子：
2.5
通讯作者：
Chapman, C. Andrew
中科院分区：
文献类型：
--
作者：
Glasgow, Stephen D.;Chapman, C. Andrew
副耻骨是海马结构的一个主要组成部分，它接受来自CA1区、丘脑前部和内侧隔的输入，并主要投射到嗅内皮层的第二层。海马频率脑电图（EEG）活动与感觉运动整合、空间导航和记忆功能相关。本研究的目的是确定θ是否也在副耻骨内局部产生，而不是从邻近结构产生。在尿素麻醉的大鼠中，利用消除体积传导活动影响的可移动双极电极的差分记录，证明了副胛浅层和深层之间的θ波活动的相位反转。阿托品使副丘θ消失，并与CA1区辐射层/空隙层分子中的θ相合。然后使用脑切片的全细胞电流钳记录来确定是否部分由第二层神经元的膜电位振荡产生眼旁波。当使用电流注入将细胞保持在接近阈值电压时，大多数第二层神经元（包括四个假定的中间神经元）发生膜电位振荡。当浴液温度从22℃升高到32℃时，振荡频率从3.2 Hz增加到6.1 Hz，且振荡在快速嗜离子性谷氨酸能和gaba能突触传递阻滞剂存在时持续存在。因此，振荡可能是由固有的、电压相关的离子电导产生的。这些结果表明，θ波场活动是在副耻骨内局部产生的，并且由局部抑制输入同步的固有膜电位振荡可能有助于这种活动的产生。
The parasubiculum is a major component of the hippocampal formation that receives inputs from the CA1 region, anterior thalamus, and medial septum and that projects primarily to layer II of the entorhinal cortex. Hippocampal theta-frequency (4-12 Hz) electroencephalographic ( EEG) activity has been correlated with sensorimotor integration, spatial navigation, and memory functions. The present study was aimed at determining if theta is also generated locally within the parasubiculum versus volume conducted from adjacent structures. In urethan-anesthetized rats, the phase-reversal of theta activity between superficial and deep layers of the parasubiculum was demonstrated using differential recordings from movable bipolar electrodes that eliminate the influence of volume-conducted activity. Parasubicular theta was abolished by atropine, and was in phase with theta in stratum radiatum/lacunosum-moleculare of the CA1 region. Whole cell current-clamp recordings in brain slices were then used to determine if parasubicular theta may be generated in part by membrane potential oscillations in layer II neurons. Membrane potential oscillations occurred in most layer II neurons, including four putative interneurons, when cells were held at near-threshold voltages using current injection. The frequency of oscillations increased from 3.2 to 6.1 Hz when bath temperature was raised from 22 to 32 degrees C, and oscillations persisted in the presence of blockers of fast ionotropic glutamatergic and GABAergic synaptic transmission. Oscillations are therefore likely generated by intrinsic, voltage-dependent ionic conductances. These results indicate that theta field activity is generated locally within the parasubiculum and that intrinsic membrane potential oscillations, synchronized by local inhibitory inputs, may contribute to the generation of this activity.