Fasciculus retroflexus

Fig. 5. The plate illustrates the ventral midbrain tegmentum as illustrated in the atlas of the rat brain of Swanson (1992), at levels approximately equivalent to those shown in Fig. 4. B and D are images of Nissl-stained sections. Abbreviations CLI, central linear nucleus of the raphe cpd, cerebral peduncle DGlb, dentate gyrus, lateral blade EW, Edinger-Westphal nucleus fr, fasciculus retroflexus hf, hippocampal fixure IF, interfascicular...

Interestingly, experimental chronic amphetamine and cocaine administration induces degeneration confined to the lateral habenula and its main output pathway, the fasciculus retroflexus (reviewed by Ellison, 1994). The habenula is the key relay in the descending dorsal diencephalic system, consisting of stria medullaris, habenula and fasciculus retroflexus, which links the limbic forebrain and the basal ganglia with lower diencephalic and mesencephalic centers (see for review Ellison, 1994). Dopaminergic dysfunction in this circuit could be implicated in psychiatric diseases including schizophrenia (Ellison, 1994). 

Abbreviations Al = primary auditory area ac = anterior commissure Acc = accumbens nucleus AON = anterior olfactory nucleus BF = barrel field BLA = basolateral nucleus of the amygdala CAl = cornu ammonis 1 CA3 = cornu ammonis 3 cc = corpus callosum Cg = cingulate area CPu = caudate-putamen DCb = deep cerebellar nuclei DCo = dorsal cochlear nucleus DG = dentate gyrus DMV = dorsal motor nucleus of the vagus nerve ECu = external cuneate nucleus EP = external plexiform layer ER = entorhinal cortex f = fornix Fa = facial nucleus fa = facial nerve fr = fasciculus retroflexus G1 = glomerular layer GPe = (external segment of the)... 

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