Introduction: Sufi Texts in Translation

This special issue of the Journal of Sufi Studies attempts to make the case that the act of translation is best seen as a recurrent activity necessitated by the various changes that inform the interpretation of Sufi texts on the one hand, and the languages and cultures that receive them on the other. The nine Sufi texts featured in this collection illustrate the diversity of genres and variety of languages in which they have been written, thereby pointing up the distinctive hermeneutic potentials of translation theory and practice when these texts are rendered by experts into modern European languages, particularly English and French.

Recurrent Activity from Active Asteroid (248370) 2005 QN173: A Main-belt Comet

We present archival observations of main-belt asteroid (248370) 2005 QN173 (also designated 433P) that demonstrate this recently discovered active asteroid (a body with a dynamically asteroidal orbit displaying a tail or coma) has had at least one additional apparition of activity near perihelion during a prior orbit. We discovered evidence of this second activity epoch in an image captured 2016 July 22 with the DECam on the 4 m Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. As of this writing, (248370) 2005 QN173 is just the eighth active asteroid demonstrated to undergo recurrent activity near perihelion. Our analyses demonstrate (248370) 2005 QN173 is likely a member of the active asteroid subset known as main-belt comets, a group of objects that orbit in the main asteroid belt that exhibit activity that is specifically driven by sublimation. We implement an activity detection technique, wedge photometry, that has the potential to detect tails in images of solar system objects and quantify their agreement with computed antisolar and antimotion vectors normally associated with observed tail directions. We present a catalog and an image gallery of archival observations. The object will soon become unobservable as it passes behind the Sun as seen from Earth, and when it again becomes visible (late 2022) it will be farther than 3 au from the Sun. Our findings suggest (248370) 2005 QN173 is most active interior to 2.7 au (0.3 au from perihelion), so we encourage the community to observe and study this special object before 2021 December.

Visual Thalamocortical Mechanisms of Waking State Dependent Activity and Alpha Oscillations

SummaryThe brain exhibits distinct patterns of recurrent activity closely related to the behavioral state of the animal. The neural mechanisms that underlie state-dependent activity in the awake animal are incompletely understood. Here, we demonstrate that two types of state-dependent activity - rapid arousal/movement related signals and a 3-5 Hz alpha-like rhythm - in the primary visual cortex (V1) of mice strongly correlate with activity in the visual thalamus. Inactivation of V1 does not interrupt arousal/movement related signals in most visual thalamic neurons, but it abolishes the 3-5 Hz oscillation. Silencing of the visual thalamus similarly eradicates the alpha-like rhythm and perturbs arousal/movement-related activation in V1. Finally, we observed that whisker movement or locomotion is not required for rapid increases in cortical activation. Our results indicate that thalamocortical interactions together with cell-intrinsic properties of thalamocortical cells play a crucial role in shaping state-dependent activity in V1 of the awake animal.HighlightsWhisker movements correlate with rapid synaptic activation in V1 and visual thalamusSilencing of V1 does not abolish movement related activation in most dLGN or LP cellsSilencing of visual thalamus strongly reduces movement related activation in V1Thalamocortical interactions generate state-dependent alpha frequency oscillationVisual thalamic cells exhibit LTS firing during alpha oscillation in the awake mouse

Transient and layer-specific reduction in neocortical PV inhibition during sensory association learning

Sensory and motor learning reorganizes neocortical circuitry, particularly manifested in the strength of excitatory synapses. Prior studies suggest reduced inhibition can facilitate glutamatergic synapse plasticity during learning, but the role of specific inhibitory neurons in this process has not been well-documented. Here we investigate whether inhibition from parvalbumin (PV)-expressing neurons is altered in primary somatosensory cortex in mice trained in a whisker-based reward-association task. Anatomical and electrophysiological analyses show PV input to L2/3, but not L5, pyramidal (Pyr) neurons is rapidly suppressed during early stages of sensory training, effects that are reversed after longer training periods. Importantly, sensory stimulation without reward does not alter PV-mediated inhibition. Computational modeling indicates that reduced PV inhibition in L2/3 selectively enables an increase in translaminar recurrent activity, also observed during SAT. PV disinhibition in superficial layers of the neocortex may be one of the earliest changes in learning-dependent rewiring of the cortical column.Impact statementTactile learning is associated with reduced PV inhibition in superficial layers of somatosensory cortex. Modeling studies suggest that PV disinhibition can support prolonged recurrent activity initiated by thalamic input.

Recurrent activity-induced headache associated with posttraumatic dural adhesion of the middle meningeal artery: A case report

Background The middle meningeal artery is surrounded by a plexus of afferent fibers shown to be involved in the progression of some forms of headache, especially migraine. Posttraumatic headache disorders sharing characteristics with migraine and involving the middle meningeal artery are not readily available in the literature. Case description This report describes a posttraumatic headache disorder in a middle-aged woman in which the causative factor proved to be a pathology of the left middle meningeal artery that resulted from trauma. Her pain could be triggered by moderate accelerative changes, occurring in the left frontotemporal region, and shared characteristics with migraine. Resection of a portion of the left middle meningeal artery has completely eliminated her pain syndrome. Conclusion This case further elucidates associations between the middle meningeal artery and headache. The presentation of posttraumatic headache sharing characteristics with migraine should suggest the possibility of a middle meningeal artery abnormality.

Beyond appearance: An unusual manifestation of isolated oral secondary syphilis

Syphilis is a sexually acquired chronic infection caused by Treponema pallidum and is characterized by a variety of clinical manifestations. The secondary stage of the disease results from the hematogenous and lymphatic dissemination of treponemes after a few weeks or months, and it is characterized by recurrent activity of the disease, with muco-cutaneous as well as systemic manifestations. Mucosal lesions range from small, superficial ulcers that resemble painless aphthae to large gray plaques, and they are generally associated with systemic manifestations of the disease. The exclusive asymptomatic oral localization not associated with general manifestations is uncommon but may actually be unrecognized and under-reported. We report a case of isolated oral manifestation as the unique presentation of secondary syphilis.

Propagation of spike timing and firing rate in feedforward networks reconstituted in vitro

The manner in which information is transferred and transformed across brain regions is yet unclear. Theoretical analyses of idealized feedforward networks suggest that several conditions have to be satisfied in order for activity to propagate faithfully across layers. Verifying these concepts experimentally in networks has not been possible owing to the vast number of variables that must be controlled. Here, we culture cortical neurons in a chamber with sequentially connected compartments, optogenetically stimulate individual neurons in the first layer with high spatiotemporal resolution, and monitor the subthreshold and suprathreshold potentials in subsequent layers. In the first layer, a brief stimulus with different temporal precisions resulted in the modulation of the firing rate. This temporal to rate transformation was propagated to other layers as a sustained response, thereby preserving rate information. This novel mode of propagation occurred in the balanced excitatory-inhibitory regime and is mediated by NMDA-mediated synapses activated by recurrent activity.

A population of gap junction-coupled neurons drives recurrent network activity in a developing visual circuit

In many regions of the vertebrate brain, microcircuits generate local recurrent activity that aids in the processing and encoding of incoming afferent inputs. Local recurrent activity can amplify, filter, and temporally and spatially parse out incoming input. Determining how these microcircuits function is of great interest because it provides glimpses into fundamental processes underlying brain computation. Within the Xenopus tadpole optic tectum, deep layer neurons display robust recurrent activity. Although the development and plasticity of this local recurrent activity has been well described, the underlying microcircuitry is not well understood. Here, using a whole brain preparation that allows for whole cell recording from neurons of the superficial tectal layers, we identified a physiologically distinct population of excitatory neurons that are gap junctionally coupled and through this coupling gate local recurrent network activity. Our findings provide a novel role for neuronal coupling among excitatory interneurons in the temporal processing of visual stimuli.