Lesion-induced sprouting promotes neurophysiological integration of septal and entorhinal inputs to granule cells in the dentate gyrus of rats

Axonal sprouting of dentate gyrus (DG) afferents after entorhinal cortex (EC) lesion is a model preparation to assess lesion-induced functional reorganization in a denervated target structure. Following a unilateral EC lesion, the surviving contralateral entorhinal projection, termed the crossed temporodentate pathway (CTD), and the heterotypic septal input to the DG, the septodentate pathway (SD), undergo extensive axonal sprouting. We explored whether EC lesion alters the capacity of the SD pathway to influence CTD-evoked granule cell excitability in the DG. We recorded extracellular field excitatory postsynaptic potentials (fEPSPs) after CTD stimulation alone and paired SD-CTD stimulation. Male rats were given unilateral EC lesions or sham operations; evoked fEPSPs in the DG were recorded at 4-, 15-, and 90-days post-entorhinal lesion to assess functional reorganization of the CTD and SD pathways. We found significantly increased fEPSP amplitudes in cases with unilateral lesions compared to sham-operates at 15- and 90-days post lesion. Within each time point, paired SD-CTD stimulation resulted in significantly depressed fEPSP amplitudes compared to amplitudes evoked after CTD stimulation alone and this effect was solely seen in cases with EC lesion. In cases where granule cell discharge was observed, SD stimulation increased discharge amplitude elicited by the CTD stimulation at 90-days postlesion. These findings demonstrate that synaptic remodeling following unilateral cortical lesion results in a synergistic interaction between two established hippocampal afferents that is not seen in uninjured brains. This work may be important for models of neurodegenerative disease and neural injury that target these structures and associated hippocampal circuitry.

Ocular adnexal phenotype and management of a patient with mosaic expression of a mutation in TWIST2

Ablepharon-macrostomia syndrome (AMS) and Barber-Say syndrome (BSS) are congenital ectodermal dysplasias associated with mutations in the TWIST2 gene. Among the ophthalmic anomalies that occur in these syndromes, underdevelopment of the anterior lamella of the eyelid is a defining feature. Reports of mosaic expression of TWIST2 mutations are extremely rare, with only five confirmed or suspected cases described to date. Mosaic expression of TWIST2 variants is correlated with a less severe phenotype than that reported for the typical expression of TWIST2 variants associated with BSS or AMS. Abnormal development of the anterior lamella appears to be a common feature in all cases of AMS with mosaic expression. Here, we describe the phenotype of a patient with mosaic expression of a TWIST2 mutation that is typically associated with AMS. We additionally describe the surgical approach employed in the treatment of this patient.

Blunderbuss: Ocular and Orbital Injuries Due to Muzzle-Loading Firearms

PURPOSE

Injury to the eye and/or orbital and adnexal structures associated with antiquated muzzle-loading firearms has not, to our knowledge, been characterized with the exception of a single case report.

METHODS

A retrospective chart review of 7 patients treated at Vanderbilt University Medical Center from 2003 to 2017 who sustained traumatic injuries to the ocular and/or orbital structures secondary to the discharge of muzzle-loading firearms. The study was approved by the Vanderbilt Institutional Review Board.

RESULTS

In 6/7 cases, injuries occurred secondary to the muzzle-loading firearm exploding due to dysfunction or misuse. Foreign material deriving from the firearm was retained in 3/7 patients. Initial examination of the orbit and adnexa revealed 5/7 individuals sustaining orbital fractures and 6/7 with facial lacerations (including 2 with eyelid lacerations); none had evidence of a lacrimal duct injury. Three patients suffered globe injuries (1 closed-globe and 2 open-globe). Visual acuity at last follow-up was ≥20/20 in 12/14 eyes examined. Surgical intervention was required in the treatment of 4/7 individuals (including 3/7 requiring intervention for sustained orbital fractures). No individuals were wearing eye protection at the time of injury. All individuals survived their injuries.

CONCLUSIONS

The operation of muzzle-loading firearms poses a unique risk of injury to the operator. The resultant injuries in this case series were primarily due to the explosion of the firearm, which subsequently appear similar to orbital and ocular blast injuries caused by explosive weapons. Orbital injuries and more potentially more devastating ocular injuries may have been prevented by protective eyewear.

Blastic Transformation of a Mantle Cell Lymphoma Presenting as an Enlarging Unilateral Orbital Mass

Mantle cell lymphoma (MCL) is an uncommon form of non-Hodgkin lymphoma predominantly affecting male individuals of advanced age. Approximately 1-9% of cases of lymphoma affecting the orbital and ocular adnexal regions are attributed to MCL. We describe the case of a 65-year-old man with a 24-year history of MCL with initial remission followed by multiple relapses who presented with acute-onset binocular diplopia and proptosis of the left eye. Subsequent imaging demonstrated a new left superior orbital mass. Biopsy of the mass revealed two clonally related, yet distinct cellular components demonstrating the classical mantle cell morphology and large cells that appeared to have transformed to the blastoid variant of MCL. Transformation of classical MCL to the blastoid variant of MCL is rare, with few reports in the literature. The blastoid variant of MCL tends to be aggressive and associated with a poor prognosis. The case we describe represents perhaps the first report of MCL transformation observed in the orbit.

Perceptual training enhances temporal acuity for multisensory speech

The temporal relationship between auditory and visual cues is a fundamental feature in the determination of whether these signals will be integrated. The window of perceived simultaneity (TBW) is a construct that describes the epoch of time during which asynchronous auditory and visual stimuli are likely to be perceptually bound. Recently, a number of studies have demonstrated the capacity for perceptual training to enhance temporal acuity for audiovisual stimuli (i.e., narrow the TBW). These studies, however, have only examined multisensory perceptual learning that develops in response to feedback that is provided when making judgments on simple, low-level audiovisual stimuli (i.e., flashes and beeps). Here we sought to determine if perceptual training was capable of altering temporal acuity for audiovisual speech. Furthermore, we also explored whether perceptual training with simple or complex audiovisual stimuli generalized across levels of stimulus complexity. Using a simultaneity judgment (SJ) task, we measured individuals' temporal acuity (as estimated by the TBW) prior to, immediately following, and one week after four consecutive days of perceptual training. We report that temporal acuity for audiovisual speech stimuli is enhanced following perceptual training using speech stimuli. Additionally, we find that changes in temporal acuity following perceptual training do not generalize across the levels of stimulus complexity in this study. Overall, the results suggest that perceptual training is capable of enhancing temporal acuity for audiovisual speech in adults, and that the dynamics of the changes in temporal acuity following perceptual training differ between simple audiovisual stimuli and more complex audiovisual speech stimuli.

Atypical rapid audio-visual temporal recalibration in autism spectrum disorders

Changes in sensory and multisensory function are increasingly recognized as a common phenotypic characteristic of Autism Spectrum Disorders (ASD). Furthermore, much recent evidence suggests that sensory disturbances likely play an important role in contributing to social communication weaknesses-one of the core diagnostic features of ASD. An established sensory disturbance observed in ASD is reduced audiovisual temporal acuity. In the current study, we substantially extend these explorations of multisensory temporal function within the framework that an inability to rapidly recalibrate to changes in audiovisual temporal relations may play an important and under-recognized role in ASD. In the paradigm, we present ASD and typically developing (TD) children and adolescents with asynchronous audiovisual stimuli of varying levels of complexity and ask them to perform a simultaneity judgment (SJ). In the critical analysis, we test audiovisual temporal processing on trial t as a condition of trial t - 1. The results demonstrate that individuals with ASD fail to rapidly recalibrate to audiovisual asynchronies in an equivalent manner to their TD counterparts for simple and non-linguistic stimuli (i.e., flashes and beeps, hand-held tools), but exhibit comparable rapid recalibration for speech stimuli. These results are discussed in terms of prior work showing a speech-specific deficit in audiovisual temporal function in ASD, and in light of current theories of autism focusing on sensory noise and stability of perceptual representations. Autism Res 2017, 10: 121-129. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Deficient proactive interference of eyeblink conditioning in Wistar-Kyoto rats

Wistar-Kyoto (WKY) rats exhibit behavioral inhibition and model anxiety vulnerability. Although WKY rats exhibit faster active avoidance acquisition, simple associative learning or the influence of proactive interference (PI) has not been adequately assessed in this strain. Therefore, we assessed eyeblink conditioning and PI in WKY and outbred Sprague-Dawley (SD) rats. Rats were pre-exposed to either the experimental context, the conditioned stimulus (CS), the unconditional stimulus (US), or the CS & US in an explicitly unpaired (EUP) manner, to examine latent inhibition (LI), US pre-exposure effect, or learned irrelevance (LIRR), respectively. Immediately following pre-exposures, rats were trained in a delay-type paradigm (500 ms CS coterminating with a 10-ms US) for one session. During training SD rats exhibited LI and inhibition from US pre-exposures without evidence of LIRR. PI was less evident in WKY rats; LI was absent in WKY rats. Even in the context of reduced PI to CS-alone and US-alone pre-exposures, LIRR was not apparent in WKY rats. The more normal acquisition rates exhibited by WKY rats, under conditions which degrade performance in SD rats, increases the overall likelihood for WKY rats to acquire defensive responses. Enhanced acquisition of defensive responses is a means by which anxiety vulnerability (e.g., behavioral inhibition) is translated to anxiety psychopathology.