Laboratory of Neurophysiology, Department of Medicine, University of Patras, Rion, Greece.
Int J Dev Biol. 2022;66(1-2-3):285-296. doi: 10.1387/ijdb.210191cp.
Brain aging is associated with alterations in the behavioral capacity to process information, due to mechanisms that are still largely unclear. Short-term neuronal activity dynamics are basic properties of local brain networks profoundly involved in neural information processing. In this study, we investigated the properties of short-term changes in excitatory synaptic transmission and neuronal excitation in the CA1 field of dorsal and ventral hippocampal slices from young adult and old rats. We found that short-term synaptic plasticity (i.e. short-term dynamics of input to CA1 circuit) does not significantly differ between young and old dorsal or ventral hippocampus. However, short-term dynamics of hippocampal output differ markedly between young and old rats. Notably, age-dependent alterations in short-term neuronal dynamics were detected mainly in the dorsal hippocampus. Thus, the dorsal hippocampus of young rats can detect and facilitate transmission of 1-30 Hz input and depress transmission of higher-frequency input. In contrast, the old dorsal hippocampus appears unable to transmit information in a frequency-dependent discriminatory manner. Furthermore, the amplification of steady-state output at frequencies < 40 Hz is considerably lower in the old than the young dorsal hippocampus. The old ventral hippocampus did not show major alterations in short-term processing of neural information, though under conditions of intense afferent activation, neuronal output of the ventral hippocampus is depressed at steady-state more in old than in young rats. These results suggest that aging is accompanied by alterations in neural information processing mainly in the dorsal hippocampus, which displays a narrower dynamic range of frequency-dependent transient changes in neuronal activity in old compared with young adult rats. These alterations in short-term dynamics may relate to deficits in processing ongoing activity seen in old individuals.
大脑老化与信息处理能力的行为改变有关，其机制尚不清楚。短期神经元活动动态是局部脑网络的基本特性，这些网络在神经信息处理中起着至关重要的作用。在这项研究中，我们研究了来自年轻成年和老年大鼠背侧和腹侧海马切片中兴奋性突触传递和神经元兴奋的短期变化的特性。我们发现，短期突触可塑性（即 CA1 回路输入的短期动态）在年轻和老年背侧或腹侧海马体之间没有显著差异。然而，海马体输出的短期动力学在年轻和老年大鼠之间存在明显差异。值得注意的是，短期神经元动力学的年龄依赖性改变主要在背侧海马体中检测到。因此，年轻大鼠的背侧海马体可以检测并促进 1-30 Hz 输入的传递，并抑制更高频率输入的传递。相比之下，老年背侧海马体似乎无法以频率依赖的方式进行信息传递。此外，在年轻的背侧海马体中，<40 Hz 的稳态输出的放大明显低于老年背侧海马体。老年腹侧海马体在神经信息的短期处理中没有显示出主要变化，尽管在强烈的传入激活下，老年大鼠的腹侧海马体的神经元输出在稳态下比年轻大鼠更容易受到抑制。这些结果表明，随着年龄的增长，主要在背侧海马体中伴随着神经信息处理的改变，与年轻成年大鼠相比，老年大鼠的神经元活动的频率依赖性瞬态变化的动态范围更窄。这些短期动力学的改变可能与老年个体中观察到的持续活动处理缺陷有关。
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