Articles: biological-evolution.
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We propose that chronic spondylolytic defects at L5 are influenced by insufficient differential mediolateral distances between inferior articular facets of L4 and the superior facets of S1, which results in these structures impinging on adjacent sides of the par interarticularis during hyperlordosis. Individuals with adequate increase in interfacet distances from L4 through S1 are less likely to develop or maintain defects. ⋯ Spondylolysis is the direct result of contact pressures on both sides of the pars interarticularis resulting from inadequate separation between the inferior articular processes of L4 and the superior articular facets of S1. Individuals lacking sufficient increase in transverse interfacet dimensions in their lumbar columns are at greater risk of developing and maintaining spondylolytic defects.
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The threat simulation theory of dreaming (TST) () states that dream consciousness is essentially an ancient biological defence mechanism, evolutionarily selected for its capacity to repeatedly simulate threatening events. Threat simulation during dreaming rehearses the cognitive mechanisms required for efficient threat perception and threat avoidance, leading to increased probability of reproductive success during human evolution. One hypothesis drawn from TST is that real threatening events encountered by the individual during wakefulness should lead to an increased activation of the system, a threat simulation response, and therefore, to an increased frequency and severity of threatening events in dreams. ⋯ Our results give support for most of the predictions drawn from TST. The severely traumatized children reported a significantly greater number of dreams and their dreams included a higher number of threatening dream events. The dream threats of traumatized children were also more severe in nature than the threats of less traumatized or non-traumatized children.
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Endocannabinoid signaling, mediated by presynaptic CB1 cannabinoid receptors on neurons, is fundamental for the maintenance of synaptic plasticity by modulating neurotransmitter release from axon terminals. In the rodent basal forebrain, CB1 cannabinoid receptor-like immunoreactivity is only harbored by a subpopulation of cholinergic projection neurons. However, endocannabinoid control of cholinergic output from the substantia innominata, coincident target innervation of cholinergic and CB1 cannabinoid receptor-containing afferents, and cholinergic regulation of endocannabinoid synthesis in the hippocampus suggest a significant cholinergic-endocannabinergic interplay. ⋯ Aging did not affect either the density or layer-specific distribution of CB1 cannabinoid receptor-immunoreactive processes. We concluded that organizing principles of CB1 cannabinoid receptor-containing neurons and their terminal fields within the basal forebrain are evolutionarily conserved between rodents and prosimian primates. In contrast, the areal expansion and cytoarchitectonic differentiation of neocortical subfields in primates is associated with differential cortical patterning of CB1 cannabinoid receptor-containing subcortical and intracortical afferents.