Transient and frequency-dependent conductivity measurements on excised brain-tissue lesions from epilepsy patients indicate that sodium cations are the predominant charge carriers. The transient conductivity ultimately vanishes as ions encounter blockages. The initial and final values of the transient conductivity correspond to the high-frequency and low-frequency limits of the frequency-dependent conductivity, respectively. Carrier dynamics determines the conductivity between these limits. Typically, the conductivity rises monotonically with increasing frequency. By contrast, when pathology examinations found exceptionally disorganized excised tissue, the conductivity falls with increasing frequency as it approaches its high-frequency limit. To analyze these measurements, excised tissues are modeled as mixtures of "normal" tissue within which sodium cations can diffuse and "abnormal" tissue within which sodium cations are trapped. The decrease in the conductivity with increasing frequency indicates the predominance of trapping. The high-frequency conductivity decreases as the rate with which carriers are liberated from traps decreases. A relatively low conductivity results when most sodium cations remain trapped in "abnormal" brain tissue, while few move within "normal" brain tissue. Thus, the high densities of sodium nuclei observed by 23Na-MRI in epilepsy patients' lesions are consistent with the low densities of diffusing sodium cations inferred from conductivity measurements of excised lesions.

中文翻译：

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了解人类癫痫脑组织的钠阳离子电导率。

对癫痫患者切除的脑组织病变的瞬态和频率依赖性电导率测量表明，钠阳离子是主要的电荷载体。随着离子遇到阻塞，瞬态电导率最终消失。瞬态电导率的初始值和最终值分别对应于与频率相关的电导率的高频和低频极限。载流子动力学决定了这些极限之间的电导率。通常，电导率随频率增加而单调增加。相反，当病理检查发现切除的组织异常混乱时，电导率会随着频率的升高而降低，因为它接近其高频极限。为了分析这些测量结果，将切除的组织建模为“正常”组织的混合物 钠阳离子可以在其中扩散的组织和钠离子被困在其中的“异常”组织。电导率随频率的增加而降低表明存在陷阱。高频电导率随着载流子从阱中释放的速率降低而降低。当大多数钠阳离子仍被困在“异常”的脑组织中，而很少一部分在“正常”的脑组织内移动时，则电导率相对较低。因此，通过23Na-MRI在癫痫患者的病变中观察到的高密度的钠核与从切除的病变的电导率测量推断出的低扩散的钠阳离子的密度一致。电导率随频率的增加而降低表明存在陷阱。高频电导率随着载流子从阱中释放的速率降低而降低。当大多数钠阳离子仍被困在“异常”的脑组织中，而很少一部分在“正常”的脑组织内移动时，则电导率相对较低。因此，通过23Na-MRI在癫痫患者的病变中观察到的高密度的钠核与从切除的病变的电导率测量推断出的低扩散的钠阳离子的密度一致。电导率随频率的增加而降低表明存在陷阱。高频电导率随着载流子从阱中释放的速率降低而降低。当大多数钠阳离子仍被困在“异常”的脑组织中，而很少一部分在“正常”的脑组织内移动时，则电导率相对较低。因此，通过23Na-MRI在癫痫患者的病变中观察到的高密度的钠核与从切除的病变的电导率测量推断出的低扩散的钠阳离子的密度一致。当大多数钠阳离子仍被困在“异常”的脑组织中，而很少一部分在“正常”的脑组织内移动时，则电导率相对较低。因此，通过23Na-MRI在癫痫患者的病变中观察到的高密度的钠核与从切除的病变的电导率测量推断出的低扩散的钠阳离子的密度一致。当大多数钠阳离子仍被困在“异常”的脑组织中，而很少一部分在“正常”的脑组织内移动时，则电导率相对较低。因此，通过23Na-MRI在癫痫患者的病变中观察到的高密度的钠核与从切除的病变的电导率测量推断出的低扩散的钠阳离子的密度一致。