ABSTRACT
BACKGROUND: Chondrodysplasia punctata (CDP) describes skeletal dysplasia secondary to a variety of genetic underpinnings characterized by cartilaginous stippling from abnormal calcium deposition during endochondral bone formation. Approximately 20%-38% of patients with CDP have cervical spine abnormalities, resulting in stenosis and cord compression. However, approaches to management differ among patients. OBSERVATIONS: The authors present an 18-year-old male with a known history of CDP and cervical kyphosis with worsening paresthesias and increased spasticity. Imaging confirmed dysplastic C4 and C5 vertebra with focal kyphosis, bony retropulsion, spinal cord compression, and myelomalacia. To treat the stenosis and deformity, the patient underwent C4 and C5 vertebrectomies with C3 to C6 anterior fusion with resolution of symptoms. LESSONS: Despite many CDP patients having cervical deformities with spinal cord compression and associated neurological symptoms, there is a paucity of data on surgical management and outcomes. There are only scattered reports, and most authors recommend initial conservative management because of the high risk of operative morbidity and mortality secondary to comorbidities. When surgery is performed, long-term follow-up is recommended because of the high rates of progression of deformity, requiring subsequent operations. The authors hope that their experience adds to the literature describing the surgical management of cervical deformities in these patients.
ABSTRACT
The brain has evolved different approaches to solve problems, but the mechanisms that determine which approach to take remain unclear. One possibility is that control progresses from simpler processes, such as associative learning, to more complex ones, such as relational reasoning, when the simpler ones prove inadequate. Alternatively, control could be based on competition between the processes. To test between these possibilities, we posed the support problem to rhesus monkeys using a tool-use paradigm, in which subjects could pull an object (the tool) toward themselves to obtain an otherwise out-of-reach goal item. We initially provided one problem exemplar as a choice: for the correct option, a food item placed on the support tool; for the incorrect option, the food item placed off the tool. Perceptual cues were also correlated with outcome: e.g., red, triangular tool correct, blue, rectangular tool incorrect. Although the monkeys simply needed to touch the tool to register a response, they immediately pulled it, reflecting a relational reasoning process between themselves and another object (Rself-other), rather than an associative one between the arbitrary touch response and reward (Aresp-reward). Probe testing then showed that all four monkeys used a conjunction of perceptual features to select the correct option, reflecting an associative process between stimuli and reward (Astim-reward). We then added a second problem exemplar and subsequent testing revealed that the monkeys switched to using the on/off relationship, reflecting a relational reasoning process between two objects (Rother-other). Because behavior appeared to reflect Rself-other rather than Aresp-reward, and Astim-reward prior to Rother-other, our results suggest that cognitive processes are selected via competitive control dynamics.
