Freund Nadja, Güntürkün Onur, Manns Martina
Biopsychology, Institute of Cognitive Neuroscience, Faculty of Psychology, Ruhr-University Bochum, Universitaetsstr. 150, GAFO 05/623, 44780 Bochum, Germany.
Brain Res Bull. 2008 Mar 18;75(2-4):491-3. doi: 10.1016/j.brainresbull.2007.10.031. Epub 2007 Nov 20.
In pigeons, the tectofugal system is functionally as well as structurally lateralized. So for example the right nucleus rotundus is less modulated by right forebrain influences than the left nucleus rotundus by the left ones. This functional lateralization pattern may depend on a dynamic balance between left and right tectal processing. Apart from inhibitory interactions at tectal level, suppressive influences might directly affect rotundal neurons by GABAergic input from a cluster of nuclei, the bed nuclei of the tecto-thalamic tract. A major afferent of these nuclei is the side branch of the tectorotundal projection which is of bilateral origin and which is involved in the regulation of ipsilateral as well as bilateral visual processing. Hence, an important role of the bed nuclei could be the interhemispheric communication and in turn the mediation of functional asymmetries. In a first step to unravel asymmetric influences of these nuclei, the present study investigated if the largest of the bed nuclei, the nucleus subpretectalis displays morphological asymmetries in the pigeon. We found that the nucleus subpretectalis in fact exhibits asymmetric cell sizes with larger cell bodies on the left side. This asymmetrical pattern was not present in dark-incubated animals indicating that cell size asymmetries within nucleus subpretectalis are induced by asymmetric photic stimulation during embryonic development.
在鸽子中，顶盖离中系统在功能和结构上都存在侧化现象。例如，右侧圆核受右前脑影响的调节程度低于左侧圆核受左前脑影响的调节程度。这种功能侧化模式可能取决于左右顶盖处理之间的动态平衡。除了顶盖水平的抑制性相互作用外，抑制性影响可能通过来自一群核团（顶盖 - 丘脑束的床核）的GABA能输入直接影响圆核神经元。这些核团的主要传入纤维是顶盖 - 圆核投射的侧支，其起源于双侧，参与同侧以及双侧视觉处理的调节。因此，床核的一个重要作用可能是半球间的通信，进而介导功能不对称。作为揭示这些核团不对称影响的第一步，本研究调查了鸽子中最大的床核——顶盖前核是否存在形态不对称。我们发现，顶盖前核实际上表现出细胞大小不对称，左侧的细胞体更大。这种不对称模式在黑暗孵化的动物中不存在，这表明顶盖前核内的细胞大小不对称是由胚胎发育期间不对称的光刺激诱导的。
