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This article presents an analysis of the impact of functional neuroimaging studies (positron emission tomography, PET) in asymmetric hearing loss based on the clinical expertise obtained from a group of 21 patients. In these patients, PET studies are performed at rest and after auditory stimulation in order to measure the increase in brain activity in the ipsi- and contralateral cortex, providing supporting evidence to recommend a specific treatment and the side to implant. In conclusion, PET is a useful tool for selected cases in which information on the metabolic status of the auditory pathway can drive the decision regarding the treatment of the most appropriate ear. However, in view of our small sample, further research is needed to confirm our results in this topic.

The cat ventral oral pontine reticular nucleus (vRPO) is responsible for the generation and maintenance of rapid eye movement (REM) sleep. Hypothalamic neurons containing the peptide hypocretin-1 (also called orexin-A) which will be herewith defined as orexinergic (Orx) neurons, occupy a preeminent place in the integration and stabilization of arousal networks as well as in the physiopathology of narcolepsy/cataplexy. In the previous investigations, low-volume and dose microinjections of hypocretin-1 in cat vRPO produced a specific and significant suppression of REM sleep. The aim of this study is to map the hypothalamic Orx neurons that project to the vRPO and suppress REM sleep generation in the cat. Five adult cats received microinjections of the retrograde tracer cholera toxin (CTb) into the vRPO. Brains were processed employing both CTb staining and antiorexin-A immunocytochemistry techniques. A large number of double-labeled neurons (Orx-CTb) intermingled with the single CTb-positive and single Orx neurons were detected in the ipsilateral lateral, perifornical, dorsal, anterior, perimammillothalamic, and posterior hypothalamic areas but were very scarce in the paraventricular, dorsomedial, ventromedial, and periventricular hypothalamic nuclei. A considerable number of double-labeled neurons were also observed in both the dorsal and the lateral hypothalamic areas in the contralateral hypothalamus. Our results suggest that the widely distributed Orx neuronal hypothalamic groups could physiologically inhibit REM sleep generation in vRPO. Anat Rec, 296:815-821, 2013. V C 2013 Wiley Periodicals, Inc.

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