Boussaoud Driss, Tanné-Gariépy Judith, Wannier Thierry, Rouiller Eric M
Institut de Neurosciences Cognitives de la Méditerranée, INCM, UMR 6193, CNRS, Université de la Méditerranée, 31 Ch. Joseph Aiguier, 13402 Marseille Cedex 20, France.
BMC Neurosci. 2005 Nov 25;6:67. doi: 10.1186/1471-2202-6-67.
The lateral premotor cortex plays a crucial role in visually guided limb movements. It is divided into two main regions, the dorsal (PMd) and ventral (PMv) areas, which are in turn subdivided into functionally and anatomically distinct rostral (PMd-r and PMv-r) and caudal (PMd-c and PMv-c) sub-regions. We analyzed the callosal inputs to these premotor subdivisions following 23 injections of retrograde tracers in eight macaque monkeys. In each monkey, 2-4 distinct tracers were injected in different areas allowing direct comparisons of callosal connectivity in the same brain.
Based on large injections covering the entire extent of the corresponding PM area, we found that each area is strongly connected with its counterpart in the opposite hemisphere. Callosal connectivity with the other premotor areas, the primary motor cortex, prefrontal cortex and somatosensory cortex varied from one area to another. The most extensive callosal inputs terminate in PMd-r and PMd-c, with PMd-r strongly connected with prefrontal cortex. Callosal inputs to PMv-c are more extensive than those to PMv-r, whose connections are restricted to its counterpart area. Quantitative analysis of labelled cells confirms these general findings, and allows an assessment of the relative strength of callosal inputs.
PMd-r and PMv-r receive their strongest callosal inputs from their respective counterpart areas, whereas PMd-c and PMv-c receive strong inputs from heterotopic areas as well (namely from PMd-r and PMv-r, respectively). Finally, PMd-r stands out as the lateral premotor area with the strongest inputs from the prefrontal cortex, and only the PMd-c and PMv-c receive weak callosal inputs from M1.
外侧运动前皮层在视觉引导的肢体运动中起关键作用。它分为两个主要区域，即背侧（PMd）和腹侧（PMv）区，这两个区域又进一步细分为功能和解剖学上不同的吻侧（PMd-r和PMv-r）和尾侧（PMd-c和PMv-c）子区域。我们在八只猕猴中进行了23次逆行示踪剂注射，分析了这些运动前子区域的胼胝体输入。在每只猴子中，在不同区域注射2-4种不同的示踪剂，以便在同一大脑中直接比较胼胝体连接性。
基于覆盖相应PM区域整个范围的大量注射，我们发现每个区域与其对侧半球的对应区域紧密相连。与其他运动前区、初级运动皮层、前额叶皮层和体感皮层的胼胝体连接因区域而异。最广泛的胼胝体输入终止于PMd-r和PMd-c，其中PMd-r与前额叶皮层紧密相连。PMv-c的胼胝体输入比PMv-r的更广泛，PMv-r的连接仅限于其对应区域。对标记细胞的定量分析证实了这些一般发现，并允许评估胼胝体输入的相对强度。
PMd-r和PMv-r从各自的对应区域接收最强的胼胝体输入，而PMd-c和PMv-c也从异位区域接收强输入（分别来自PMd-r和PMv-r）。最后，PMd-r作为外侧运动前区，从前额叶皮层接收最强的输入，并且只有PMd-c和PMv-c从M1接收较弱的胼胝体输入。
