Distinct and dementia-related synaptopathy in the hippocampus after military blast exposures.

Explosive shockwaves, and other types of blast exposures, are linked to injuries commonly associated with military service and to an increased risk for the onset of dementia. Neurological complications following a blast injury, including depression, anxiety, and memory problems, often persist even when brain damage is undetectable. Here, hippocampal explants were exposed to the explosive 1,3,5-trinitro-1,3,5-triazinane (RDX) to identify indicators of blast-induced changes within important neuronal circuitries. Highly controlled detonations of small, 1.7-gram RDX spherical charges reduced synaptic markers known to be downregulated in cognitive disorders, but without causing overt neuronal loss or astroglial responses. In the absence of neuromorphological alterations, levels of synaptophysin, GluA1, and synapsin IIb were significantly diminished within 24 hr, and these synaptic components exhibited progressive reductions following blast exposure as compared to their stable maintenance in control explants. In contrast, labeling of the synapsin IIa isoform remained unaltered, while neuropilar staining of other markers decreased, including synapsin IIb and neural cell adhesion molecule (NCAM) isoforms, along with evidence of NCAM proteolytic breakdown. NCAM180 displayed a distinct decline after the RDX blasts, whereas NCAM140 and NCAM120 exhibited smaller or no deterioration, respectively. Interestingly, the extent of synaptic marker reduction correlated with AT8-positive tau levels, with tau pathology stochastically found in CA1 neurons and their dendrites. The decline in synaptic components was also reflected in the size of evoked postsynaptic currents recorded from CA1 pyramidals, which exhibited a severe and selective reduction. The identified indicators of blast-mediated synaptopathy point to the need for early biomarkers of explosives altering synaptic integrity with links to dementia risk, to advance strategies for both cognitive health and therapeutic monitoring.

Hominin-carnivore interactions during the Chinese Early Paleolithic: taphonomic perspectives from Xujiayao.

The ability of archaic Homo sapiens to survive in more northerly latitudes was contingent on securing a regular source of animal fat and protein. We present a taphonomic study that examines how successful these hominins were at acquiring these food sources during the latter part of the Early Paleolithic in Northeast Asia. This study focuses on the long bone midshaft surface modifications observed on the faunal remains from Xujiayao, a middle-late Pleistocene open-air site located at 40 degrees latitude in the western Nihewan Basin, northern China. The faunal assemblage is dominated by equid remains. Analysis of the percussion, tooth, and cut mark frequencies on the long bone midshafts demonstrates that the Xujiayao hominins had primary access to high utility (meat-bearing and marrow-rich) long bones. Investigation of the dual-patterned (tooth-marked and butchery-marked) bone fragments suggests that hominins were under little pressure from competing carnivores to abandon their kills. The lack of significant differences between the size of fragments with only percussion-marks and those with only tooth-marks supports these findings. Fragmentation ratios indicate that forelimbs were more intensively processed than hind limbs. Based on the water rounding and abrasion data, the Xujiayao assemblage is likely of autochthonous origin. Since the age of Xujiayao is still in question, we can only conclude that archaic Homo sapiens were successful predators of large game in Northeast Asia some time during the latter part of the Early Paleolithic.

Middle Pleistocene handaxes from the Korean Peninsula.

We present four biface assemblages from an archaeologically poorly known region of the Old World: Middle Pleistocene Korea. The handaxes are derived from a series of Middle Pleistocene localities in the Imjin/Hantan River Basins (IHRB) in Korea. The best known of these localities is Chongokni, although a number of equally important sites in the IHRB have been discovered and excavated over the course of the past two decades (e.g., Kumpari, Chuwoli, and Kawoli). Reanalysis of the age of the Chongokni deposits suggests a hominin occupation between 350-300 ka. Comparative study of the IHRB handaxes with the well-known bifacial implements from Olorgesailie (Kenya) and Hunsgi-Baichbal (India) indicates that the often-noted "thick" trait of the East Asian handaxes differs at a statistical level across the various regions of the Old World. The finds from the IHRB sites, and the Chinese sites of Bose and Dingcun that contain handaxes-like implement, question the validity of the Movius Line sensu stricto. However, why East Asian Middle Pleistocene hominins did not consistently produce more refined bifaces across broader regional and/or temporal facies, remains open to question. Thus, the absence of similar sites in wider areas of Early and Middle Pleistocene East Asia suggests that the Movius Line sensu lato is still supportable and warrants additional detailed cross comparative studies of the stone toolkits east and west of the line.