Helmeke C, Poeggel G, Braun K
Leibniz Institute for Neurobiology, 39008 Magdeburg, Germany.
Neuroscience. 2001;104(4):927-31. doi: 10.1016/s0306-4522(01)00201-9.
It appears likely that, in analogy to the synaptic development of sensory and motor cortices, which critically depends on sensory or motor stimulation (Rosenzweig and Bennett, 1996), the synaptic development of limbic cortical regions are modulated by early postnatal cognitive and emotional experiences. The very first postnatal experience, which takes place in a confined and stable familial environment, is the interaction of the newborn individual with the parents and siblings (Gray, 1958). The aim of this quantitative morphological study was to analyze the impact of different degrees of juvenile emotional experience on the synaptic development in a limbic cortical area, the dorsal anterior cingulate cortex, a region which is involved in the perception and regulation of emotions. We study the precocious trumpet-tailed rat (Octodon degus) as the animal model, because, like human babies, this species is born with functional visual and acoustic systems and the pups are therefore capable of detecting even subtle environmental changes immediately after birth (Reynolds and Wright, 1979; Poeggel and Braun, 1996; Braun et al., 2000; Ovtscharoff and Braun, 2001). The results demonstrate that already a subtle disturbance of the familial environment such as handling induced significantly elevated spine densities on the basal dendrites of layer III cortical pyramidal neurons. More severe disturbances of the emotional environment, such as periodic parental deprivation with or without subsequent chronic social isolation, resulted in an elevation of spine densities of similar magnitude as seen after handling and in addition, altered spine densities confined to specific dendritic segments were observed in these groups. These observations unveil the remarkable sensitivity of the dorsal anterior cingulate cortex towards environmental influences and behavioral experiences during phases of postnatal development. The behavioral consequences of these experience-induced synaptic changes still need to be analyzed further to assess if they are beneficial or detrimental to the animals cognitive and emotional capacities in later life.
与感觉和运动皮层的突触发育类似，感觉和运动皮层的突触发育严重依赖于感觉或运动刺激（罗森茨韦格和贝内特，1996年），边缘皮质区域的突触发育可能受到出生后早期认知和情感体验的调节。出生后的首次体验发生在有限且稳定的家庭环境中，即新生儿个体与父母和兄弟姐妹的互动（格雷，1958年）。这项定量形态学研究的目的是分析不同程度的幼年情感体验对边缘皮质区域——背侧前扣带回皮质（参与情绪感知和调节的区域）突触发育的影响。我们将早熟的喇叭尾鼠（八齿鼠）作为动物模型进行研究，因为该物种与人类婴儿一样，出生时视觉和听觉系统就已具备功能，幼崽因此能够在出生后立即察觉到即使是细微的环境变化（雷诺兹和赖特，1979年；波格尔和布劳恩，1996年；布劳恩等人，2000年；奥夫查罗夫和布劳恩，2001年）。结果表明，即使是像处理这样对家庭环境的细微干扰，也会导致III层皮质锥体细胞基底树突上的棘密度显著升高。更严重的情感环境干扰，如周期性的父母剥夺（无论有无随后的长期社会隔离），导致棘密度升高，幅度与处理后相似，此外，在这些组中还观察到局限于特定树突节段的棘密度改变。这些观察结果揭示了背侧前扣带回皮质在出生后发育阶段对环境影响和行为体验具有显著的敏感性。这些由经验引起的突触变化的行为后果仍需进一步分析，以评估它们对动物后期生活中的认知和情感能力是有益还是有害。
