Harper M S, Wallace M N
Department of Biomedical Sciences, Marischal College, University of Aberdeen, Scotland, UK.
J Anat. 1995 Apr;186 ( Pt 2)(Pt 2):373-82.
Histochemical methods were used to assess the distribution of 4 neurotransmitters thought to be involved in cortical plasticity. They were measured in the primary auditory cortex of the ferret from just before the onset of hearing. Acetylcholinesterase staining was strongest in layers I, IV and VI and there was a gradual increase in the amount of staining from postnatal day (PND) 21 through to adulthood. Serotonin fibres were located mainly in layers I-III and their density increased gradually over the same time period. Noradrenergic fibres were sparsely scattered throughout the cortex but their density and distribution showed little change over the age range studied. Dopaminergic fibres were densest in layers V and VI at all ages. However, there was a transient doubling in their density that started round about the onset of hearing at PND 28, peaked at PND 35 and had returned to baseline levels by 2 wk later. This transient peak in density did not occur in the adjacent suprasylvian gyrus and did not appear to be a general phenomenon. The local transient increase in dopaminergic fibres implies that they may have an important role during a short period in auditory cortical development. This role may involve modifying the cortical circuitry that is involved in analysing the input from the auditory periphery.
采用组织化学方法评估了4种被认为与皮质可塑性有关的神经递质的分布情况。这些神经递质是在雪貂听力开始前的初级听觉皮层中进行测量的。乙酰胆碱酯酶染色在I层、IV层和VI层最强，从出生后第21天（PND）到成年，染色量逐渐增加。5-羟色胺纤维主要位于I-III层，在同一时期其密度逐渐增加。去甲肾上腺素能纤维稀疏地散布于整个皮层，但在研究的年龄范围内，其密度和分布变化不大。多巴胺能纤维在各年龄段的V层和VI层最为密集。然而，其密度在PND 28左右听力开始时出现短暂翻倍，在PND 35达到峰值，2周后恢复到基线水平。这种密度的短暂峰值在相邻的上薛氏回中并未出现，似乎也不是一种普遍现象。多巴胺能纤维的局部短暂增加表明它们可能在听觉皮层发育的短时间内发挥重要作用。这一作用可能涉及修改参与分析来自听觉外周输入的皮质回路。
