Instituto de Neurociencias UMH-CSIC (Alicante), Avenida Santiago Ramón y Cajal s.n., 03550, Spain.
Sci Adv. 2023 Dec;9(48):eadi3728. doi: 10.1126/sciadv.adi3728. Epub 2023 Nov 29.
Barrel cortex integrates contra- and ipsilateral whiskers' inputs. While contralateral inputs depend on the thalamocortical innervation, ipsilateral ones are thought to rely on callosal axons. These are more abundant in the barrel cortex region bordering with S2 and containing the row A-whiskers representation, the row lying nearest to the facial midline. Here, we ask what role this callosal axonal arrangement plays in ipsilateral tactile signaling. We found that novel object exploration with ipsilateral whiskers confines c-Fos expression within the highly callosal subregion. Targeting this area with in vivo patch-clamp recordings revealed neurons with uniquely strong ipsilateral responses dependent on the corpus callosum, as assessed by tetrodotoxin silencing and by optogenetic activation of the contralateral hemisphere. Still, in this area, stimulation of contra- or ipsilateral row A-whiskers evoked an indistinguishable response in some neurons, mostly located in layers 5/6, indicating their involvement in the midline representation of the whiskers' sensory space.
桶状皮层整合了对侧和同侧胡须的输入。虽然对侧输入依赖于丘脑皮质神经支配，但同侧输入被认为依赖于胼胝体轴突。这些轴突在与 S2 接壤的桶状皮层区域中更为丰富，包含了 A 排胡须的代表区域，该区域最靠近面部中线。在这里，我们想知道这种胼胝体轴突排列在同侧触觉信号传递中扮演了什么角色。我们发现，用同侧胡须进行新物体探索会将 c-Fos 表达局限在高度胼胝体的亚区。通过在体贴片钳记录来靶向这个区域，揭示了神经元具有独特的强同侧反应，这依赖于胼胝体，如通过河豚毒素沉默和对侧半球的光遗传学激活来评估。尽管如此，在这个区域中，刺激 A 排对侧或同侧胡须会在一些神经元中引起无法区分的反应，这些神经元主要位于第 5/6 层，表明它们参与了胡须感觉空间的中线代表。
