Seelke Adele M H, Perkeybile Allison M, Grunewald Rebecca, Bales Karen L, Krubitzer Leah A
Center for Neuroscience, University of California Davis, Davis, California, 95618.
Department of Psychology, University of California Davis, Davis, California, 95616.
J Comp Neurol. 2016 Feb 15;524(3):564-77. doi: 10.1002/cne.23837. Epub 2015 Jul 18.
Early-life sensory experiences have a profound effect on brain organization, connectivity, and subsequent behavior. In most mammals, the earliest sensory inputs are delivered to the developing brain through tactile contact with the parents, especially the mother. Prairie voles (Microtus ochrogaster) are monogamous and, like humans, are biparental. Within the normal prairie vole population, both the type and the amount of interactions, particularly tactile contact, that parents have with their offspring vary. The question is whether these early and pervasive differences in tactile stimulation and social experience between parent and offspring are manifest in differences in cortical organization and connectivity. To address this question, we examined the cortical and callosal connections of the primary somatosensory area (S1) in high-contact (HC) and low-contact (LC) offspring using neuroanatomical tracing techniques. Injection sites within S1 were matched so that direct comparisons between these two groups could be made. We observed several important differences between these groups. The first was that HC offspring had a greater density of intrinsic connections within S1 compared with LC offspring. Additionally, HC offspring had a more restricted pattern of ipsilateral connections, whereas LC offspring had dense connections with areas of parietal and frontal cortex that were more widespread. Finally, LC offspring had a broader distribution of callosal connections than HC offspring and a significantly higher percentage of labeled callosal neurons. This study is the first to examine individual differences in cortical connections and suggests that individual differences in cortical connections may be related to natural differences in parental rearing styles associated with tactile contact.
早期的感官体验对大脑组织、连接性及后续行为有着深远影响。在大多数哺乳动物中,最早的感官输入是通过与父母,尤其是母亲的触觉接触传递给发育中的大脑的。草原田鼠(Microtus ochrogaster)是一夫一妻制的,并且像人类一样,是双亲抚养后代。在正常的草原田鼠群体中,父母与后代之间互动的类型和数量,尤其是触觉接触,各不相同。问题在于,父母与后代之间在触觉刺激和社交体验方面这些早期且普遍存在的差异是否会体现在皮质组织和连接性的差异上。为了解决这个问题,我们使用神经解剖追踪技术,研究了高接触(HC)和低接触(LC)后代的初级体感区(S1)的皮质和胼胝体连接。S1内的注射部位相互匹配,以便能够对这两组进行直接比较。我们观察到了这两组之间的几个重要差异。第一个差异是,与LC后代相比,HC后代在S1内具有更高密度的内在连接。此外,HC后代同侧连接的模式更为局限,而LC后代与顶叶和额叶皮质区域的连接更为密集且分布更广。最后,LC后代胼胝体连接的分布比HC后代更广泛,且标记的胼胝体神经元的百分比显著更高。这项研究首次考察了皮质连接中的个体差异,并表明皮质连接中的个体差异可能与与触觉接触相关的父母养育方式的自然差异有关。