The projections from the claustrum to the cerebral cortex in the rat were examined by means of retrogradely transported fluorescent tracers Fast Blue (FB) and Diamidino Yellow dihydrochloride (DY), injected in the prefrontal, motor, somatosensory, auditory, and visual fields. In all cases, substantial numbers of retrogradely labeled neurons were observed in the ipsilateral and moderate to scant numbers in the contralateral claustrum insulare. Symmetrical bilateral injections of FB and DY as well as simultaneous injections of the tracers in the motor and visual cortex of the same hemisphere revealed no double-labeled neurons in the claustrum. The following conclusions may be drawn: The claustral projections to the motor, somatosensory, and visual cortex are prominent. The projection to the prefrontal cortex is less substantial and that to the auditory cortex is relatively modest. The claustrocortical connections lack the clear-cut topographic pattern of the thalamic nuclei but are, to some degree, preferentially arranged, albeit with considerable overlapping of the subpopulations of corticopetal neurons, a coarse anteroposterior topographic distribution appears to exist also in rodents. Neurons contributing to the claustrocortical connection project either ipsilaterally or contralaterally but not bilaterally. Projections to different cortical fields of one hemisphere also originate from separate claustral neurons.

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Reviews and critical articles covering the entire field of normal anatomy (cytology, histology, cyto-and histochemistry, electron microscopy, macroscopy, experimental morphology and embryology and comparative anatomy) are published in Advances in Anatomy, Embryology and Cell Biology. Papers dealing with anthropology and clinical morphology that aim to encourage cooperation between anatomy and related disciplines will also be accepted. Papers are normally commissioned. Original papers and communications may be submitted and will be considered for publication provided they meet the requirements of a review article and thus fit into the scope of "Advances". English language is preferred. It is a fundamental condition that submitted manuscripts have not been and will not simultaneously be submitted or published elsewhere. With the acceptance of a manuscript for publication, the publisher acquires full and exclusive copyright for all languages and countries.

The orexinergic system interacts with several functional states of emotions, stress, hunger, wakefulness and behavioral arousal through four pathways originating in the lateral hypothalamus (LH). Hundreds of orexinergic efferents have been described by tracing studies and direct immunohistochemistry of orexin in the forebrain, olfactory regions, hippocampus, amygdala, septum, basal ganglia, thalamus, hypothalamus, brain stem and spinal cord. Most of these tracing studies investigated the whole orexinergic projection to all regions of the intracranial part of the CNS. To identify the orexinergic efferents at the subnuclear level of resolution, we focussed on the orexinergic target in the amygdala, which is substantially involved in the LH output and contributes mostly to the functional outcome of the orexinergic system and the basal ganglia. Immunohistochemical identification of axonal orexin A and orexin B in male adult rats has been performed on serial sections. In the extended amygdala many new orexinergic targets were found in the anterior amygdaloid area (dense), anterior cortical nucleus (moderate), amygdalostriatal transition region (moderate), basolateral regions (moderate), basomedial nucleus (moderate), several bed nucleus of the stria terminals regions (few to dense), central amygdaloid subdivisions (dense), posteromedial cortical nucleus (moderate) and medial amygdaloid subnuclei (dense). Furthermore, the entopeduncular nucleus has been newly identified as another target for orexinergic fibers with a high density. These results suggest that subdivisions and subnuclei of the extended amygdala are specific targets of the orexinergic system.