Nucleus accumbens-linked executive control networks mediating reversal learning in tree shrew brain

DEAR EDITOR,Cognitive flexibility is crucial for animal survival but is frequently impaired in neuropsychiatric disorders.Although many brain structures and functional networks are involved in cognitive flexibility,the neural mechanisms underlying cooperation among specific functional networks remain unclear from a global perspective.In this study,[^(18)F]-fluorodeoxyglucose positron emission tomography(FDG-PET)was performed on 19 male tree shrews after four different visual discrimination tasks,including baseline,learning expert(LE),reversal naive(RN),and reversal expert(RE).

Lessons learned from a young man with recurrent metastasis parathyroid carcinoma with failed combination treatment

Parathyroid carcinoma is an extremely rare malignant tumor,composed primarily of vacuolated principal cells,but may also be composed of eosinophils.The exact etiology and pathogenesis of parathyroid carcinoma is unknown,and head and neck radiation exposure,chronic stimulation from renal failure,and familial syndromes can lead to the development of parathyroid carcinoma.Most parathyroid carcinoma is difficult to distinguish from benign HPT and is often diagnosed only when there is a recurrence of hypercalcemia several years later,which can manifest as weight loss,extreme fatigue,anorexia,and muscle atrophy.At present,surgical resection remains the primary treatment.In this case,the patient underwent initial surgery for primary hyperparathyroidism and was subsequently diagnosed with parathyroid carcinoma.During the 8 years of follow-up,the patient underwent 7 surgeries in combination with radiation therapy,chemotherapy and targeted medications.Although the neck tumor was cured,the patient died of complications related to hypercalcemia.We will review the literature on the combination of surgery,radiotherapy,chemotherapy,and targeted drug therapy in order to improve the diagnosis and treatment of parathyroid carcinoma.