Collateral projection from the forebrain and mesopontine cholinergic neurons to whisker-related, sensory and motor regions of the rat

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• 作者：Suk K. Beak ; Eun Y. Hong ; Hyun S. Lee
• 关键词：Acetylcholine ; Vibrissae ; Sensorimotor integration ; Tract tracing
• 刊名：Brain Research
• 出版年：2010
• 出版时间：8 June 2010
• 年：2010
• 卷：1336
• 期：Complete
• 页码：30-45
• 全文大小：3158 K

文摘

The primary goal of this anatomical study was to examine in the rat whether cholinergic neurons provide axon collaterals to whisker-related, sensorimotor regions at cortical, thalamic, and brainstem levels, using a combined method of retrograde tracing and choline acetyltransferase (ChAT) immunostaining. First, when injections were made at primary sensory (S1) barrel field/primary whisker motor (M1) cortices, cholinergic neurons with dual projections were observed in the basal nucleus of Meynert (BM), mainly at middle level; the projection was almost exclusively ipsilateral (99 %  ± 0.7 % , n = 6). Second, following unilateral injections of tracers into ventroposteromedial (VPM) barreloids/ventrolateral (VL) thalamic nucleus, dual-projecting cells were observed in the mesopontine tegmental complex including the pedunculopontine tegmental (PTg) and laterodorsal tegmental (LDTg) nuclei, mainly at rostral to middle levels; the projection exhibited ipsilateral dominance, i.e., 67 %  ± 1.3 % (n = 6) for the PTg and 64 %  ± 1.2 % (n = 6) for the LDTg. Finally, when injections were made at whisker-related, principal sensory trigeminal (Pr5)/facial motor (Mo7) nuclei, a relatively small number of labeled neurons were observed in the PTg and the LDTg at middle to caudal levels; within LDTg, labeled cells occupied the ventral portion of the dorsal LDTg as well as the ventral LDTg (LDTgV). This projection exhibited contralateral preponderance, i.e., 67 %  ± 2.0 % (n = 6) for the PTg and 69 %  ± 3.2 % (n = 6) for the LDTg. Taken together, the present observations demonstrated that each division of the BM, PTg, and LDTg possessed a differential functional organization with respect to its collateral projection to whisker-related sensorimotor targets, suggesting that the cholinergic projection might play a modulatory role in vibrissal sensorimotor integration, which allows the guidance of behavioral action essential for the survival of the animal.