Congruent representation of visual and acoustic space in the superior colliculus of the echolocating bat Phyllostomus discolor.

The midbrain superior colliculus (SC) commonly features a retinotopic representation of visual space in its superficial layers, which is congruent with maps formed by multisensory neurons and motor neurons in its deep layers. Information flow between layers is suggested to enable the SC to mediate goal-directed orienting movements. While most mammals strongly rely on vision for orienting, some species such as echolocating bats have developed alternative strategies, which raises the question how sensory maps are organized in these animals. We probed the visual system of the echolocating bat Phyllostomus discolor and found that binocular high acuity vision is frontally oriented and thus aligned with the biosonar system, whereas monocular visual fields cover a large area of peripheral space. For the first time in echolocating bats, we could show that in contrast with other mammals, visual processing is restricted to the superficial layers of the SC. The topographic representation of visual space, however, followed the general mammalian pattern. In addition, we found a clear topographic representation of sound azimuth in the deeper collicular layers, which was congruent with the superficial visual space map and with a previously documented map of orienting movements. Especially for bats navigating at high speed in densely structured environments, it is vitally important to transfer and coordinate spatial information between sensors and motor systems. Here, we demonstrate first evidence for the existence of congruent maps of sensory space in the bat SC that might serve to generate a unified representation of the environment to guide motor actions.

Chronic recurrent multifocal osteomyelitis: what is it and how should it be treated?

BACKGROUND: Chronic recurrent multifocal osteomyelitis (CRMO) is the most severe form of chronic nonbacterial osteomyelitis. In children and adolescents, chronic nonbacterial osteomyelitis predominantly affects the metaphyses of the long bones, but lesions can occur at any site in the skeleton. Other organs (the skin, eyes, gastrointestinal tract and lungs) can also be affected. Clinical diagnosis is often difficult because the symptoms and course of disease vary significantly. We present a 10-year-old girl diagnosed with CRMO involving several vertebrae, the femur and the metatarsus. INVESTIGATIONS: Physical examination, abdominal ultra sonography, conventional X-ray, MRI, technetium bone scan, esophagogastroduodenoscopy, colonoscopy, tests for HLA-B27 and thiopurine methyltransferase, polymerase chain reaction and thoracic vertebral bone biopsies. DIAGNOSIS: CRMO and Crohn's disease. MANAGEMENT: The patient's condition improved whilst being treated with NSAIDs for 3 months; however, the patient had an allergic skin reaction to this therapy. Treatment was switched to sulfasalazine, accompanied by 3 weeks of therapy using oral prednisone, but sulfasalazine was discontinued 2 months later because the patient exhibited a minor elevation in the levels of liver enzymes. The patient was free of musculoskeletal symptoms for 6 months, at which time she started to complain again about pain in her back and bowel. Multimodal therapy, consisting of mesasalazine, corticosteroids (budesonide) and azathioprine, induced clinical remission of Crohn's disease.

Sex differences in cortisol response to noxious stress.

OBJECTIVES: Evidence has accumulated that men and women show different responses to noxious stimuli, with women exhibiting greater sensitivity to pain than men. Data concerning sex differences in cortisol response patterns have revealed inconsistent results so far. The purpose of the present study was to examine sex differences in subjective pain and cortisol response to a noxious stressor. METHODS: Seventy-six subjects (39 male and 37 female) were investigated by a modification of the cold pressor test that consisted of intermittent immersion of the hand into ice water (plunge test, PT). The PT was conducted twice, in consecutive trials, to guarantee a sufficient exposure to the noxious stressor for eliciting cortisol responses. In each trial, tolerance time and pain ratings visual analog scale (VAS) were assessed. Seven saliva samples (c1-c7) were collected to determine cortisol levels at baseline (c1-c2), directly before (c3) and 20 minutes after noxious stress (c4), and during recovery period (c5-c7). RESULTS: We found no significant sex differences in tolerance time in trial 1, but highly significant differences in tolerance time in trial 2, with higher tolerance times in men. No significant sex differences were found for the VAS ratings of pain intensity and unpleasantness in the 2 trials. In contrast, a significantly larger cortisol increase in men was observed compared with women. Analysis of covariance revealed that this result could not be attributed to sex differences in cortisol level at baseline and in tolerance time. DISCUSSION: The present study demonstrates that men show a larger cortisol response to a noxious stressor than women that is not attributable to sex differences in subjective pain. The conclusion of a causal relation between larger cortisol responses and higher pain tolerance thresholds in men is tempting but yet speculative.