Ketamine disrupts naturalistic coding of working memory in primate lateral prefrontal cortex networks

Ketamine is a dissociative anesthetic drug, which has more recently emerged as a rapid-acting antidepressant. When acutely administered at subanesthetic doses, ketamine causes cognitive deficits like those observed in patients with schizophrenia, including impaired working memory. Although these effects have been linked to ketamine’s action as an N-methyl-D-aspartate receptor antagonist, it is unclear how synaptic alterations translate into changes in brain microcircuit function that ultimately influence cognition. Here, we administered ketamine to rhesus monkeys during a spatial working memory task set in a naturalistic virtual environment. Ketamine induced transient working memory deficits while sparing perceptual and motor skills. Working memory deficits were accompanied by decreased responses of fast spiking inhibitory interneurons and increased responses of broad spiking excitatory neurons in the lateral prefrontal cortex. This translated into a decrease in neuronal tuning and information encoded by neuronal populations about remembered locations. Our results demonstrate that ketamine differentially affects neuronal types in the neocortex; thus, it perturbs the excitation inhibition balance within prefrontal microcircuits and ultimately leads to selective working memory deficits.

Mineral associations and Mo-W ore types of the Slepaya Zalezh' orebody at Tyrnyauz deposit

Slepaya Zalezh is the largest ore body of the Tyrnyauz Mo-W deposit. It is the priority object on the renewal of its operation. A dissemination of molibdoscheelite, scheelite and molibdenite, controling ore concentrations, is confined to metasomatic rocks of the productive stage, laid on skarns, near-skarn rocks, hornfelses and marbles. The types of the ores are divided accordingly of ratio in them of different facies of ore-bearing metasomatic and initial rocks, which is a working out mass of ore. 7 types of the ores are divided and maped on the ore body vertical projection. Aposkarn ores predominate clearly in the I and II types, accordingly laid over endo- (substituting hornfelses) or exo- (apomarble) skarns. In the III type there are ores laid over endo-skarns and near-skarn rocks in equal parts. Relative to it the type IV contain less of of near-skarn rocks, but more of hornfelses. Ores replacing exo-skarns and to a lesser degree (up to 25%) – marbles dominate in the V type. The type VI is an intermediate one between the types III and IV. In the type VII all initial rocks are presented. Every of the types has a stable mineral and chemical composition inherited from the initial rocks. The ores of the specific type have convenient simple distinguishing features for a hand sorting of specimens, samples, and a preliminary ore separation. The types of ores have narrow change limits in size and form of ore mineral grains and their intergrowthes, percentage of minerals harmful for the flotation. Minor differences in contents of the useful components of each ore type offer possibilities of their selective working off and burdening. Mapping results contain data of the distribution of accompany sorts of mineral resources: garnet and wollastonite in the skarns and productive metasomatic rocks, pyroxene-plagioclase near-skarn rocks and hydrothermal alterated rocks with Cu, Au and other mineralization.

Selective Working Memory Disables Inhibition of Visual Features

Recent research suggests that information held in working memory can facilitate subsequent attentional processing. Here, we explore the negative corollary of this conception: Under which circumstances does information in working memory disrupt subsequent processing? Seventy participants performed visual discriminations in a dual-task paradigm. They were asked to judge colors or shapes in an online attention task under three different working-memory conditions: Same, Switch, or Unknown. In the Same condition, participants selectively maintained one visual feature in working memory, from the same dimension as in the online attention task. In the Switch condition, participants selectively maintained one visual feature in working memory, but had to focus on another visual dimension in the online attention task. In the Unknown condition, participants could not predict which visual feature would be relevant for the working-memory task. We found that irrelevant features in the online attention task were particularly difficult to ignore in the Switch condition, that is, when the irrelevant features belong to a visual dimension that is simultaneously prioritized in selective working memory. The findings are consistent with accounts in terms of neural overlap between working-memory and attention circuits, and suggest that mechanisms of selection, rather than resource limitations, critically determine the extent of visual interference.