Odour detection in children and young people with profound intellectual and multiple disabilities.

BACKGROUND: Olfaction provides information on very important dimensions of the environment; however the olfactory abilities of children and young people with profound intellectual and multiple disabilities (PIMD) remain largely unknown. This within-subjects study explores olfactory detection abilities in children with PIMD. METHOD: Twenty-two children and young people with PIMD (7-18 years) were presented with 18 medium intensity odours and an odourless control stimulus. Odorants were presented one by one in a randomised order. The neutral stimulus was presented prior to each odorant. Participants' responses were measured using 21 behavioural indicators. RESULTS: Results show that participants make a clear distinction between odorous and neutral conditions, between food and non-food, and between pleasant and unpleasant odours. The detection abilities are manifested by several behaviours, in particular by the duration of the head alignment on the odorant. CONCLUSIONS: This study shows that participants detect the stimuli and act differently depending on the category.

One hundred years of phase polymorphism research in locusts.

One hundred years ago in 1921, Sir Boris Uvarov recognized that two locust species are one species but appearing in two different phases, a solitarious and a gregarious phase. As locust swarms are still a big problem affecting millions of people, basic research has tried to understand the causes for the transition between phases. This phenomenon of phase polymorphism, now called polyphenism, is a very complex multifactorial process and this short review will draw attention to this important aspect of insect research.

Spinal interleukin-6 contributes to central sensitisation and persistent pain hypersensitivity in a model of juvenile idiopathic arthritis.

Pain is the most debilitating symptom in juvenile idiopathic arthritis. As pain correlates poorly to the extent of joint pathology, therapies that control joint inflammation are often inadequate as analgesics. We test the hypothesis that juvenile joint inflammation leads to sensitisation of nociceptive circuits in the central nervous system, which is maintained by cytokine expression in the spinal cord. Here, transient joint inflammation was induced in postnatal day (P)21 and P40 male Sprague-Dawley rats with a single intra-articular ankle injection of complete Freund's adjuvant. Hindpaw mechanical pain sensitivity was assessed using von Frey hair and weight bearing tests. Spinal neuron activity was measured using in vivo extracellular recording and immunohistochemistry. Joint and spinal dorsal horn TNFα, IL1ß and IL6 protein expression was quantified using western blotting. We observed greater mechanical hyperalgesia following joint inflammation in P21 compared to P40 rats, despite comparable duration of swelling and joint inflammatory cytokine levels. This is mirrored by spinal neuron hypersensitivity, which also outlasted the duration of active joint inflammation. The cytokine profile in the spinal cord differed at the two ages: prolonged upregulation of spinal IL6 was observed in P21, but not P40 rats. Finally, spinal application of anti-IL-6 antibody (30 ng) reduced the mechanical hyperalgesia and neuronal activation. Our results indicate that persistent upregulation of pro-inflammatory cytokines in the spinal dorsal horn is associated with neuronal sensitisation and mechanical hyperalgesia in juvenile rats, beyond the progress of joint pathology. In addition, we provide proof of concept that spinal IL6 is a key target for treating persistent pain in JIA.

The role of carbon dioxide in nematode behaviour and physiology.

Carbon dioxide (CO2) is an important sensory cue for many animals, including both parasitic and free-living nematodes. Many nematodes show context-dependent, experience-dependent and/or life-stage-dependent behavioural responses to CO2, suggesting that CO2 plays crucial roles throughout the nematode life cycle in multiple ethological contexts. Nematodes also show a wide range of physiological responses to CO2. Here, we review the diverse responses of parasitic and free-living nematodes to CO2. We also discuss the molecular, cellular and neural circuit mechanisms that mediate CO2 detection in nematodes, and that drive context-dependent and experience-dependent responses of nematodes to CO2.

Invade or die: behaviours and biochemical mechanisms that drive skin penetration in Strongyloides and other skin-penetrating nematodes.

Skin-penetrating nematodes, including the human threadworm Strongyloides stercoralis and hookworms in the genera Necator and Ancylostoma, are gastrointestinal parasites that are a major cause of neglected tropical disease in low-resource settings worldwide. These parasites infect hosts as soil-dwelling infective larvae that navigate towards hosts using host-emitted sensory cues such as odorants and body heat. Upon host contact, they invade the host by penetrating through the skin. The process of skin penetration is critical for successful parasitism but remains poorly understood and understudied. Here, we review current knowledge of skin-penetration behaviour and its underlying mechanisms in the human parasite S. stercoralis, the closely related rat parasite Strongyloides ratti, and other skin-penetrating nematodes such as hookworms. We also highlight important directions for future investigations into this underexplored process and discuss how recent advances in molecular genetic and genomic tools for Strongyloides species will enable mechanistic investigations of skin penetration and other essential parasitic behaviours in future studies. This article is part of the Theo Murphy meeting issue 'Strongyloides: omics to worm-free populations'.

Olfactive short-term habituation in children and young people with profound intellectual and multiple disabilities.

BACKGROUND: Despite its importance for learning, the existence of the habituation process and its characteristics in people with profound intellectual and multiple disabilities (PIMD) remains understudied. Habituation is, however, considered the simplest form of learning, and a significant neuroadaptive mechanism. Even though habituation occurs in all sensory modalities, the olfactory system is where it manifests itself very visibly. AIM: This study explores the olfactory short-term habituation abilities of children and young people with PIMD. METHOD: Twenty children and young people with PIMD (7-18 years) were presented six times successively with a 30-second habituating olfactory stimulus. The interstimulus interval was 15 s. A new odour was presented on the seventh trial. The scenario was carried out two times with two pairs of stimuli. The participants' head alignment duration on the odour was measured. RESULTS: Seventeen participants out of 20 manifested a decline in response, which reached about 50 % between the first and sixth presentation of the habituation odour. All habituators also showed a distinctive response when exposed to a novel odour. The participants who did not habituate showed a strong, non-fluctuating response to the stimulus throughout the presentations. Three participants only habituated to one of the two habituation stimuli. CONCLUSION AND IMPLICATIONS: The results raise theoretical, scientific, and practical issues. They question the factors explaining olfactory habituation mechanisms, namely the stimulus properties and the severity of impairment, reveal the need for points of comparison for interpreting this population's responses, and point to the consequences of stimuli repetition and or variety in therapeutic or educational settings for these individuals' learning and cognitive functioning.