Nguyen Hoang Nam, Huppé-Gourgues Frédéric, Vaucher Elvire
Laboratoire de Neurobiologie de la Cognition Visuelle, École D'optométrie, Université de Montréal Montréal, QC, Canada.
Front Syst Neurosci. 2015 Feb 9;9:1. doi: 10.3389/fnsys.2015.00001. eCollection 2015.
The medial prefrontal cortex (mPFC) exerts top-down control of primary visual cortex (V1) activity. As there is no direct neuronal projection from mPFC to V1, this functional connection may use an indirect route, i.e., via basalo-cortical cholinergic projections. The cholinergic projections to V1 originate from neurons in the horizontal limb of the diagonal band of Broca (HDB), which receive neuronal projections from the ventral part of the mPFC, composed of prelimbic (PrL) and infralimbic cortices (IL). Therefore, the objective of this study was to determine whether electrical stimulation of mice mPFC subregions activate (1) V1 neurons; and (2) HDB cholinergic neurons, suggesting that the HDB serves as a relay point in the mPFC-V1 interaction. Neuronal activation was quantified using c-Fos immunocytochemistry or thallium autometallography for each V1 layer using automated particle analysis tools and optical density measurement. Stimulation of IL and PrL induced significantly higher c-Fos expression or thallium labeling in layers II/III and V of V1 in the stimulated hemisphere only. A HDB cholinergic neuron-specific lesion by saporin administration reduced IL-induced c-Fos expression in layers II/III of V1 but not in layer V. However, there was no c-Fos expression or thallium labeling in the HDB neurons, suggesting that this area was not activated by IL stimulation. Stimulation of another mPFC subarea, the anterior cingulate cortex (AC), which is involved in attention and receives input from V1, activated neither V1 nor HDB. The present results indicate that IL and PrL, but not AC, stimulation activates V1 with the minor involvement of the HDB cholinergic projections. These results suggest a functional link between the ventral mPFC and V1, but this function is only marginally supported by HDB cholinergic neurons and may involve other brain regions.
内侧前额叶皮质(mPFC)对初级视觉皮质(V1)的活动施加自上而下的控制。由于mPFC与V1之间没有直接的神经元投射,这种功能连接可能通过间接途径实现,即通过基底-皮质胆碱能投射。向V1的胆碱能投射起源于布罗卡斜带水平支(HDB)中的神经元,这些神经元接收来自mPFC腹侧部分(由前边缘皮质(PrL)和边缘下皮质(IL)组成)的神经元投射。因此,本研究的目的是确定电刺激小鼠mPFC亚区域是否会激活:(1)V1神经元;以及(2)HDB胆碱能神经元,这表明HDB在mPFC-V1相互作用中充当中继点。使用c-Fos免疫细胞化学或铊自动金属显影术,通过自动颗粒分析工具和光密度测量对每个V1层的神经元激活进行定量。刺激IL和PrL仅在受刺激半球的V1的II/III层和V层中诱导出显著更高的c-Fos表达或铊标记。通过注射皂草素对HDB胆碱能神经元进行特异性损伤,可降低IL诱导的V1的II/III层而非V层中的c-Fos表达。然而,HDB神经元中没有c-Fos表达或铊标记,这表明该区域未被IL刺激激活。刺激mPFC的另一个亚区域,即参与注意力并接收来自V1输入的前扣带回皮质(AC),既未激活V1也未激活HDB。目前的结果表明,刺激IL和PrL而非AC可激活V1,且HDB胆碱能投射仅起次要作用。这些结果表明腹侧mPFC与V1之间存在功能联系,但这种功能仅在一定程度上由HDB胆碱能神经元支持,可能还涉及其他脑区。