Motion along the mental number line reveals shared representations for numerosity and space.

Perception of number and space are tightly intertwined. It has been proposed that this is due to 'cortical recycling', where numerosity processing takes over circuits originally processing space. Do such 'recycled' circuits retain their original functionality? Here, we investigate interactions between numerosity and motion direction, two functions that both localize to parietal cortex. We describe a new phenomenon in which visual motion direction adapts nonsymbolic numerosity perception, giving rise to a repulsive aftereffect: motion to the left adapts small numbers, leading to overestimation of numerosity, while motion to the right adapts large numbers, resulting in underestimation. The reference frame of this effect is spatiotopic. Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. 'Cortical recycling' thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains.

Wolf spider envenomation.

Although wolf spider venom has been implicated in necrotic arachnidism without acceptably documented verification, limited, prospectively collected data demonstrate a lack of cutaneous necrosis. The infrequent nature of exposure and inherent difficulty in confirming wolf spider bites in humans makes it challenging to study such envenomations. We present the case of a 20 year-old man with confirmed exposure to the wolf spider who developed cutaneous erythema with ulceration following the bite. There was no evidence of skin necrosis. He was treated with aggressive wound care and systemic antibiotics for wound infection, with subsequent resolution of symptoms. This case adds to the limited knowledge regarding wolf spider envenomations and describes the clinical effects and management of wolf spider envenomation.

Recurrence of primary headache disorders after emergency department discharge: frequency and predictors of poor pain and functional outcomes.

STUDY OBJECTIVE: We determine the frequency of moderate or severe headache during the first 24 hours after an emergency department (ED) visit for a primary headache disorder (such as migraine or tension-type headache), determine the burden of headache during the 3 months after the ED visit, and identify predictors of poor pain and functional outcomes after ED discharge for each of these periods. METHODS: In this prospective cohort study, we enrolled headache patients during their initial ED visit, interviewed them by using a standardized questionnaire, and followed them by telephone 24 hours and 3 months after ED discharge. Two emergency physicians classified all headaches according to criteria established by the International Headache Society, using a valid questionnaire and a reproducible technique. RESULTS: During an 18-month period, we enrolled 309 primary headache disorder patients in the cohort. The most common primary headache diagnoses assigned to patients were migraine, tension-type headache, and unclassifiable recurrent headache disorder. We successfully obtained follow-up in 94% of patients 24 hours after ED discharge and in 94% 3 months after ED discharge. Moderate or severe headache was present within 24 hours of ED discharge in 31% (95% confidence interval [CI] 25% to 38%) of migraine patients, 19% (95% CI 9% to 36%) of tension-type headache patients, and 27% (95% CI 18% to 38%) of the unclassifiable headache patients. Multiple functionally impairing headaches occurred during the 3 months after ED discharge in 37% of migraine patients (95% CI 30% to 44%), 38% of tension-type headache patients (95% CI 23% to 54%), and 26% of the unclassifiable headache patients (95% CI 17% to 37). After multivariate adjustment, independent predictors of poor 24-hour outcomes were severe baseline pain, baseline nausea, screening positive for depression, and longer duration of headache; the independent predictor of poor 3-month outcomes was Medicaid insurance. CONCLUSION: Regardless of type of primary headache disorder, ED headache patients frequently experience pain and functional impairment during the hours and months after discharge.