Evolution and fear-fainting

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Combat and Warfare in the Early Paleolithic and Medically Unexplained Musculo-Facial Pain in the 21st Century War Veterns and Active-Duty Military Personnel

In a series of recent articles, we suggest that family dentists, military dentists and psychiatrists with expertise in posttraumatic stress disorder (especially in the Veterans Health Administration) are likely to see an increased number of patients with symptomatic jaw-clenching and early stages of tooth- grinding (Bracha et al., 2005). Returning warfighters and other returnees from military deployment may be especially at risk for high rates of clenching- induced masticatory muscle disorders at early stages of incisor grinding. The literature we have recently reviewed strongly supports the conclusion that clenching and grinding may primarily be a manifestation of experiencing extreme fear or severe chronic distress (respectively). We have recently reviewed the clinical and paleoanthropological literature and have noted that ancestral warfare and ancestral combat, in the early Paleolithic Environment of Evolutionary Adaptedness (EEA) may be a neglected factor explaining the conservation of the archaic trait of bite-muscle strengthening. We have hypothesized that among ancestral warriors, jaw clenching may have rapidly strengthened the two primary muscles involved in biting, the masseter muscles and the much larger temporalis muscles. The strengthening of these muscles may have served the purpose of enabling a stronger, deeper, and therefore more lethal, defensive bite for early Paleolithic humans. The neuroevolutionary perspective presented here may be novel to many dentists. However, it may be useful in patient education and in preventing progression from jaw-clenching to chronic facial pain

Hirschsprung disease in the U.S. associated Pacific Islands: more common than expected.

INTRODUCTION: Tripler Army Medical Center (TAMC) in Honolulu, Hawaii, is uniquely situated to serve patients from the United States Associated Pacific Islands (USAPIs) through the congressionally funded Pacific Island Health Care Project (PIHCP). Because of time differences and distance, a web-based store-and-forward consultation and referral network was established using the internet to more efficiently and economically facilitate patient care. Using both electronic and hard copy records, we sought to establish the incidence of Hirschsprung Disease (HD) in children from the USAPI and contrast it to that of the developed world. METHODS: PIHCP website records as well as all the inpatient and outpatient medical records of patients referred to TAMC fortreatment of HD from 1994 to 2002 were reviewed. A diagnosis of HD was confirmed in all cases with full thickness biopsy. Incidence figures for HD are based on this review and on the birth rates for these islands from the International Data Base of the U.S. Bureau of the Census. RESULTS: There were 14 cases of short-segment HD referred over a nine year study period. Nine patients came from the Federated States of Micronesia (FSM) with an average annual incidence of 1:3190, which is 1.5 to 2 times the reported incidence in Western nations. Remarkably, seven of these nine were from Pohnpei State, capital of the FSM (annual incidence of 1:1370 or3-5 times that in the West). Three patients came from the Republic of the Marshall Islands (RMI), and two came from American Samoa (AS). There were no reported consanguineous marriages, associated syndromes, or complications of surgery. CONCLUSION: HD was found to be up to 2-3 times more common among people from the FSM than has been reported in the developed world. Given the limitations of providing care and obtaining data from all the USAPls with a population that is spread over a massive expanse of ocean larger than the continental United States, this incidence is likely an underestimation of HD among Pacific Islanders. A secure web-based referral network developed in 1998 has been invaluable in collecting epidemiologic data from these islands as well as in providing health care workers in the USAPI with an efficient and inexpensive means to seek consultation from specialists and sub-specialists at a major tertiary care medical facility

Reevaluating the Management of Chronic Temporomandibular Pain Are We Treating PTSD with Debridement and Lavage?

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Spike-Timing Precision and Neuronal Synchrony Are Enhanced by an Interaction between Synaptic Inhibition and Membrane Oscillations in the Amygdala

The basolateral complex of the amygdala (BLA) is a critical component of the neural circuit regulating fear learning. During fear learning and recall, the amygdala and other brain regions, including the hippocampus and prefrontal cortex, exhibit phase-locked oscillations in the high delta/low theta frequency band (∼2–6 Hz) that have been shown to contribute to the learning process. Network oscillations are commonly generated by inhibitory synaptic input that coordinates action potentials in groups of neurons. In the rat BLA, principal neurons spontaneously receive synchronized, inhibitory input in the form of compound, rhythmic, inhibitory postsynaptic potentials (IPSPs), likely originating from burst-firing parvalbumin interneurons. Here we investigated the role of compound IPSPs in the rat and rhesus macaque BLA in regulating action potential synchrony and spike-timing precision. Furthermore, because principal neurons exhibit intrinsic oscillatory properties and resonance between 4 and 5 Hz, in the same frequency band observed during fear, we investigated whether compound IPSPs and intrinsic oscillations interact to promote rhythmic activity in the BLA at this frequency. Using whole-cell patch clamp in brain slices, we demonstrate that compound IPSPs, which occur spontaneously and are synchronized across principal neurons in both the rat and primate BLA, significantly improve spike-timing precision in BLA principal neurons for a window of ∼300 ms following each IPSP. We also show that compound IPSPs coordinate the firing of pairs of BLA principal neurons, and significantly improve spike synchrony for a window of ∼130 ms. Compound IPSPs enhance a 5 Hz calcium-dependent membrane potential oscillation (MPO) in these neurons, likely contributing to the improvement in spike-timing precision and synchronization of spiking. Activation of the cAMP-PKA signaling cascade enhanced the MPO, and inhibition of this cascade blocked the MPO. We discuss these results in the context of spike-timing dependent plasticity and modulation by neurotransmitters important for fear learning, such as dopamine

Rare and low-frequency coding variants alter human adult height

Height is a highly heritable, classic polygenic trait with ~700 common associated variants identified so far through genome - wide association studies . Here , we report 83 height - associated coding variants with lower minor allele frequenc ies ( range of 0.1 - 4.8% ) and effects of up to 2 16 cm /allele ( e.g. in IHH , STC2 , AR and CRISPLD2 ) , >10 times the average effect of common variants . In functional follow - up studies, rare height - increasing alleles of STC2 (+1 - 2 cm/allele) compromise d proteolytic inhibition of PAPP - A and increased cleavage of IGFBP - 4 in vitro , resulting in higher bioavailability of insulin - like growth factors . The se 83 height - associated variants overlap genes mutated in monogenic growth disorders and highlight new biological candidates ( e.g. ADAMTS3, IL11RA, NOX4 ) and pathways ( e.g . proteoglycan/ glycosaminoglycan synthesis ) involved in growth . Our results demonstrate that sufficiently large sample sizes can uncover rare and low - frequency variants of moderate to large effect associated with polygenic human phenotypes , and that these variants implicate relevant genes and pathways