Department of ELT, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran.
Brain and Language Lab, Vienna Cognitive Science Hub, University of Vienna, Vienna, Austria.
Sci Rep. 2024 Nov 25;14(1):29151. doi: 10.1038/s41598-024-79955-2.
We assessed simultaneous bilinguals and monolinguals on inhibitory control and episodic memory, and assessed their grey matter volumes in brain regions known to be involved in language processing, executive control and memory. Bilinguals outperformed monolinguals on episodic memory, and performance on the memory and inhibition tasks were correlated, only in the bilingual group. This suggests that the bilingualism-related benefits on memory are related to individual differences in executive control. We found larger grey matter volumes in bilinguals in left pars opercularis and in bilateral SFG, caudate nuclei, and parasubiculum. Episodic memory performance was correlated with volumes of bilateral posterior hippocampi, again only in the bilinguals, again suggesting that bilingualism may be driving this effect. Finally, we found positive structural covariance between the volumes of the bilateral parasubiculum and that of important components of the executive control network. We provide a novel, mechanistic explanation accounting for observed behavioural advantage and brain structural differences: bilingualism may boost the prefrontal cortex-hippocampal neural circuitry commonly underlying both executive control and memory, via cascade and reverberant effects, leading to synergistic benefits in both cognitive domains. This new framework has important implications for protective effects on cognition and brain health in relation to second language learning.
我们评估了同时掌握双语和单语的个体的抑制控制和情景记忆能力，并评估了他们大脑中与语言处理、执行控制和记忆相关的区域的灰质体积。双语者在情景记忆方面的表现优于单语者，并且只有在双语者中，记忆和抑制任务的表现才相关。这表明，与双语相关的记忆益处与执行控制的个体差异有关。我们发现双语者的左侧额下回和双侧额上回、尾状核和副隔区的灰质体积更大。情景记忆表现与双侧后海马体的体积相关，同样只在双语者中，这再次表明双语可能是造成这种影响的原因。最后，我们发现双侧副隔区的体积与执行控制网络的重要组成部分之间存在正的结构协方差。我们提供了一个新颖的、机械的解释，解释了观察到的行为优势和大脑结构差异：双语可能通过级联和回响效应，增强了共同支持执行控制和记忆的前额叶皮层-海马神经回路，从而在两个认知领域都带来协同的益处。这个新框架对于与第二语言学习相关的认知和大脑健康的保护效应具有重要意义。
