Swallowing Preparation and Execution: Insights from a Delayed-Response Functional Magnetic Resonance Imaging (fMRI) Study.

The present study sought to elucidate the functional contributions of sub-regions of the swallowing neural network in swallowing preparation and swallowing motor execution. Seven healthy volunteers participated in a delayed-response, go, no-go functional magnetic resonance imaging study involving four semi-randomly ordered activation tasks: (i) "prepare to swallow," (ii) "voluntary saliva swallow," (iii) "do not prepare to swallow," and (iv) "do not swallow." Results indicated that brain activation was significantly greater during swallowing preparation, than during swallowing execution, within the rostral and intermediate anterior cingulate cortex bilaterally, premotor cortex (left > right hemisphere), pericentral cortex (left > right hemisphere), and within several subcortical nuclei including the bilateral thalamus, caudate, and putamen. In contrast, activation within the bilateral insula and the left dorsolateral pericentral cortex was significantly greater in relation to swallowing execution, compared with swallowing preparation. Still other regions, including a more inferior ventrolateral pericentral area, and adjoining Brodmann area 43 bilaterally, and the supplementary motor area, were activated in relation to both swallowing preparation and execution. These findings support the view that the preparation, and subsequent execution, of swallowing are mediated by a cascading pattern of activity within the sub-regions of the bilateral swallowing neural network.

Occurrences of yawn and swallow are temporally related.

Yawning is a stereotyped motor behavior characterized by deep inhalation and associated dilation of the respiratory tract, pronounced jaw opening, and facial grimacing. The frequency of spontaneous yawning varies over the diurnal cycle, peaking after waking and before sleep. Yawning can also be elicited by seeing or hearing another yawn, or by thinking about yawning, a phenomenon known as "contagious yawning". Yawning is mediated by a distributed network of brainstem and supratentorial brain regions, the components of which are shared with other airway behaviors including respiration, swallowing, and mastication. Nevertheless, the possibility of behavioral coordination between yawning and other brainstem-mediated functions has not been examined. Here we show, with a double-blind methodology, a greater-than-fivefold increase in rest (saliva) swallowing rate during the 10-s period immediately following contagious yawning elicited in 14 adult humans through the viewing of videotaped yawn stimuli. Sixty-five percent of yawns were followed by a swallow within 10 s and swallows accounted for 26 % of all behaviors produced during this post-yawn period. This novel finding of a tight temporal coupling between yawning and swallowing provides preliminary evidence that yawning and swallowing are physiologically related, thus extending current models of upper airway physiology and neurophysiology. Moreover, our finding suggests the possibility that yawning plays a role in eliciting rest swallowing, a view not considered in previous theories of yawning. As such, the present demonstration of a temporal association between yawning and swallowing motivates a re-examination of the longstanding question, "Why do we yawn?".

Prevention of venous thromboembolism in pregnant patients with a history of venous thromboembolic disease: A retrospective cohort study.

BACKGROUND: Optimal prophylactic strategies in pregnant women with a history of venous thromboembolism (VTE) are unknown. PATIENTS AND METHODS: We conducted a retrospective cohort study of consecutive pregnant patients with a previous VTE history. Patients were followed until 6 weeks postpartum. Patients with a previous unprovoked event (including antepartum VTE) received antenatal prophylaxis, mostly with low dose low molecular weight heparin (LMWH). All patients received prophylaxis for six weeks after delivery. RESULTS: We included a total of 199 pregnancies in 142 women. Of these, 147 pregnancies occurred in women with unprovoked or estrogen-related VTE history and 52 pregnancies in women with provoked VTE. There were 8 recurrences in 199 pregnancies (4%; 95%CI: 2.05-7.73), of which 5 were antepartum recurrences (2.5%; 95%CI 1.08-5.75) and 3 were postpartum (1.5%; 95% CI 0.51-4.34). In the unprovoked VTE group there were 7 recurrences (4.7%; 95%CI: 2.32-9.50), whereas in the provoked VTE group there was 1 (1.9%; 95%CI: 0.34-10.12). There was one major bleeding event in a patient not receiving LMWH secondary to placental abruption. CONCLUSION: This study suggests that the use of prophylactic doses of LMWH during pregnancy and puerperium, as described in this study, results in low occurrence of ante- and postpartum VTE recurrences in patients with previous VTE. Further studies are required to confirm this observation.

Considerations of a Dual-systems Model of Cognitive Development and Risky Driving.

The dual-systems model of adolescent risk-taking postulates that risk-taking during adolescence partially results from an imbalance in the development of the executive and the socio-emotional cognitive systems. While supported by behavioral and neuroanatomical data, translational research linking the model with real-world driving or laboratory driving simulation is sparse. This paper discusses the model as it relates to adolescent driving and reviews empirical studies that have applied it in a driving-specific context. While, the studies reviewed provided partial support, each lacked a critical component necessary to fully test the model. Thus, a strong test has yet to be implemented; however, the dual-systems model holds promise for advancing the understanding of teen driving risk and guiding applications for prevention and policy.