Efferent connections of the claustrum to the posterior thalamic and pretectal region in the rat

Abstract

Injection of the fluorescent retrograde tracers Fast Blue and Diamidino Yellow in the posterior thalamic and anterior pretectal region of rats resulted in significant retrograde neuronal labeling of the ipsilateral claustrum. The labeled cell bodies were especially abundant in the central third of the claustrum, while the rostral and caudal portions of the nucleus contained only few fluorescing cells. Thus, in addition to the major reciprocal connections of the claustrum with the cerebral cortex, a substantial number of claustral neurons project to the posterior thalamic and anterior pretectal region. Unlike the cortico-claustrocortical loop, this connection appears to be only ipsilateral.