Induction of excitatory brain state governs plastic functional changes in visual cortical topology

Adult visual plasticity underlying local remodeling of the cortical circuitry in vivo appears to be associated with a spatiotemporal pattern of strongly increased spontaneous and evoked activity of populations of cells. Here we review and discuss pioneering work by us and others about principles of plasticity in the adult visual cortex, starting with our study which showed that a confined lesion in the cat retina causes increased excitability in the affected region in the primary visual cortex accompanied by fine-tuned restructuring of neuronal function. The underlying remodeling processes was further visualized with voltage-sensitive dye (VSD) imaging that allowed a direct tracking of retinal lesion-induced reorganization across horizontal cortical circuitries. Nowadays, application of noninvasive stimulation methods pursues the idea further of increased cortical excitability along with decreased inhibition as key factors for the induction of adult cortical plasticity. We used high-frequency transcranial magnetic stimulation (TMS), for the first time in combination with VSD optical imaging, and provided evidence that TMS-amplified excitability across large pools of neurons forms the basis for noninvasively targeting reorganization of orientation maps in the visual cortex. Our review has been compiled on the basis of these four own studies, which we discuss in the context of historical developments in the field of visual cortical plasticity and the current state of the literature. Overall, we suggest markers of LTP-like cortical changes at mesoscopic population level as a main driving force for the induction of visual plasticity in the adult. Elevations in excitability that predispose towards cortical plasticity are most likely a common property of all cortical modalities. Thus, interventions that increase cortical excitability are a promising starting point to drive perceptual and potentially motor learning in therapeutic applications.

Toxoplasma Retinochoroiditis with Chorioretinal Neovascularization in a Young Patient

We present a pediatric case to highlight the clinical appearance and management of choroidal neovascularization in the setting of active toxoplasma retinochoroiditis (TRC). A 17-year-old female presented with 2 days of blurry vision in her left eye. Retinal examination demonstrated a pigmented chorioretinal lesion with associated subretinal fluid, vessel sheathing, and adjacent intraretinal hemorrhage. She was diagnosed with active choroidal neovascularization and successful treatment with bevacizumab revealed an underlying active toxoplasmosis lesion. Choroidal neovascularization may rarely present during an acute case of TRC. Dual therapy with anti-vascular endothelial growth factor antibody and anti-parasitic agents leads to improved visual outcomes.

Optical coherence tomography features of retinal lesions in Chinese patients with endogenous Candida endophthalmitis

Background

To evaluate the optical coherence tomography (OCT) features of retinal lesions in Chinese patients with endogenous Candida endophthalmitis (ECE).

Methods

We performed a retrospective review of patients diagnosed with ECE at one medical center. The medical records of the patients including predisposing risk factors, treatment and visual acuity were reviewed. And we focused on the analysis of OCT images of retinal lesions before and after treatment.

Results

A total of 16 Chinese patients (22 eyes) were included in this study. The most frequent predisposing risk factors were intravenous use of corticosteroids or antibiotics, lithotripsy for urinary calculi, and diabetes. After treatment, visual acuity was improved in 13 (59.1%) of the 22 eyes, and remained the same in the other 9 (40.9%) eyes. Pre-treatment OCT images obtained at presentation were available for 17 of the 22 eyes. Four types of the OCT manifestations of retinal lesions were identified: type 1 (subretinal macular lesions), type 2 (lesions are located in the inner retinal layer), type 3 (lesions involve the full-thickness retina and accompanied with macular edema), type 4 (sub-inner limiting membrane lesions). Pre-treatment OCT imaging of the 17 eyes revealed five as type 1, four as type 2, six as type 3, and two as type 4. After treatment, OCT images revealed epiretinal membrane and subretinal fibrosis as the most common post-treatment complications of ECE. Epiretinal membrane was detected in 2/4 type 2 lesions, in 4/6 type 3 lesions, and in 1/2 type 4 lesions, while subretinal fibrosis was mainly seen in type 1 lesions (4/5). Among the types, visual prognosis was best in eyes with type 2 lesions.

Conclusions

In this case series, the OCT manifestations of retinal lesions in ECE could be classified into four types. The post-treatment OCT manifestations were different in four types of lesions. We preliminarily found that the OCT morphology of retinal lesions was associated with the visual prognosis of ECE.