Topographical organization of the nigrotectal projection in rat: Evidence for segregated channels

摘要: Abstract Recent evidence suggests that projections from the superior colliculus to brainstem in rat are organized into a series of anatomically segregated output channels. To understand how collicular function may be modified by basal ganglia it is important know whether particular modules can selectively influenced input substantia nigra. The purpose present study was, therefore, examine more detail topography within nigrotectal system rat. Small injections (10–50 nl) 1% solution wheatgerm agglutinin conjugated with horseradish peroxidase were made at different locations nigra and surrounding structures. A discontinuous puff-like pattern anterogradely transported label was found medial caudal parts ipsilateral intermediate layers colliculus. In contrast, rostrolateral enlargement contained greater density evenly distributed terminal label. Injection sites associated this dense oflaterally located concentrated lateral pars reticulata, while produced ventromedial reticulata. Retrograde tracing experiments fluorescent dyes True Blue Fast revealed involving consistently restricted column labelled cells dorsolateral part Comparable regions retrograde labelling ventral rostral two-thirds Both anterograde data indicated contralateral arise results suggest main projection reticulata comprises two components characterized regionally populations spatially separated zones termination. Of interest apparent close alignment between channels previously defined crossed descending Thus, contain concentration terminals specifically which project medulla spinal cord. Conversely, receive paramedian pontine medullary reticular formation. Evidence considered these largely extending nuclei via specialized for aspects head control.