Ficarella Stefania C, Battelli Lorella
Center for Mind/Brain Sciences, University of Trento, 38068 Rovereto, Italy; Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Corso Bettini 31, 38068 Rovereto (TN), Italy; Laboratoire de Neuroscience Cognitives (LNC), Aix-Marseille Université, 3 Place Victor Hugo, 13331 Marseille, France.
Center for Neuroscience and Cognitive Systems@UniTn, Istituto Italiano di Tecnologia, Corso Bettini 31, 38068 Rovereto (TN), Italy; Berenson-Allen Center for Noninvasive Brain Stimulation and Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, 02215 Massachusetts, USA.
Brain Stimul. 2017 May-Jun;10(3):596-603. doi: 10.1016/j.brs.2016.12.009. Epub 2016 Dec 19.
Action inhibition is a complex decision process that can be triggered by external factors (exogenous) or internal decisions (endogenous). While the neuronal underpinnings of exogenous action inhibition have been extensively investigated, less is known about the brain areas responsible for endogenous action inhibition.
We used inhibitory repetitive transcranial magnetic stimulation (rTMS) to test the causal role of two brain areas, the left dorsal fronto-median Cortex (dFMC) and the right Inferior Frontal Cortex (rIFC) in exogenous and endogenous action inhibition.
The exogenous condition was a modified version of the Go/NoGo paradigm, where a green stimulus served as a cue to perform an action (a button press, Exogenous-Go), while a magenta stimulus indicated that action should be withhold (Exogenous-NoGo). Crucially, for the endogenous condition we psychophysically generated a shade of colour that participants randomly categorized as green or magenta. This unique stimulus, randomly intermixed with green and magenta stimuli, forced participants to perform an endogenous (internally-driven) choice to either execute or inhibit the action.
In the endogenous condition, at baseline participants executed the action on half the trials; however, after 1-Hz rTMS over the dFMC they responded significantly more frequently, indicating a reduced response inhibition. The effect was selective for the dFMC stimulation and sustained in time. Moreover, no significant effects were found in the exogenous condition.
These results support the causal role of the left dFMC in endogenous action inhibition and, more generally, the notion of separate brain circuits for endogenous and exogenous action inhibition.
动作抑制是一个复杂的决策过程，可由外部因素（外源性）或内部决策（内源性）触发。虽然外源性动作抑制的神经基础已得到广泛研究，但对于负责内源性动作抑制的脑区了解较少。
我们使用抑制性重复经颅磁刺激（rTMS）来测试两个脑区，即左侧背侧额中回皮质（dFMC）和右侧额下回皮质（rIFC）在外源性和内源性动作抑制中的因果作用。
外源性条件是Go/NoGo范式的修改版本，其中绿色刺激作为执行动作（按下按钮，外源性Go）的提示，而品红色刺激表示应抑制动作（外源性NoGo）。至关重要的是，对于内源性条件，我们通过心理物理学方法生成一种颜色阴影，参与者将其随机分类为绿色或品红色。这种独特的刺激与绿色和品红色刺激随机混合，迫使参与者做出内源性（内部驱动）选择，以执行或抑制动作。
在内源性条件下，在基线时参与者在一半的试验中执行动作；然而，在对dFMC进行1赫兹rTMS刺激后，他们的反应频率显著增加，表明反应抑制降低。该效应对于dFMC刺激具有选择性且随时间持续。此外，在外源性条件下未发现显著影响。
这些结果支持左侧dFMC在内源性动作抑制中的因果作用，更普遍地说，支持内源性和外源性动作抑制存在独立脑回路的观点。
