Supranormal orientation selectivity of visual neurons in orientation-restricted animals

Altered sensory experience in early life often leads to remarkable adaptations so that humans and animals can make the best use of the available information in a particular environment. By restricting visual input to a limited range of orientations in young animals, this investigation shows that stimulus selectivity, e.g., the sharpness of tuning of single neurons in the primary visual cortex, is modified to match a particular environment. Specifically, neurons tuned to an experienced orientation in orientation-restricted animals show sharper orientation tuning than neurons in normal animals, whereas the opposite was true for neurons tuned to non-experienced orientations. This sharpened tuning appears to be due to elongated receptive fields. Our results demonstrate that restricted sensory experiences can sculpt the supranormal functions of single neurons tailored for a particular environment. The above findings, in addition to the minimal population response to orientations close to the experienced one, agree with the predictions of a sparse coding hypothesis in which information is represented efficiently by a small number of activated neurons. This suggests that early brain areas adopt an efficient strategy for coding information even when animals are raised in a severely limited visual environment where sensory inputs have an unnatural statistical structure

Suppression of fibrosis in human pterygium fibroblasts by butyrate and phenylbutyrate

AIM: To evaluate the antifibrogenic effects of butyrate or phenylbutyrate, a chemical derivative of butyrate, in human pterygium fibroblasts. METHODS: Human pterygium fibroblasts obtained from patient pterygium tissue were treated with butyrate or phenylbutyrate for 48h. Expression of α-smooth muscle actin, collagen I, collagen III and matrix metalloproteinase-1 mRNA was measured by quantitative real-time reverse transcription polymerase chain reaction, and acetylated histone was evaluated by Western blotting. RESULTS: Butyrate inhibited α-smooth muscle actin, type III collagen and matrix metalloproteinase-1 expressions, and phenylbutyrate inhibited types I and III collagen and matrix metalloproteinase-1 expressions without changing cell viability as well as both of these increased histone acetylation. These results suggested that butyrate and phenylbutyrate suppress fibrosis through a mechanism involving histone deacetylase inhibitor. CONCLUSION: This indicates that butyrate or phenylbutyrate have antifibrogenic effects in human pterygium fibroblasts and could be novel types of prophylactic and/or therapeutic drugs for pterygium, especially phenylbutyrate, which does not have the unpleasant smell associated with butyrate

P1-28: Supranormal Orientation Selectivity of Visual Neurons in Orientation-Restricted Animals

Altered sensory experience in early life often leads to remarkable adaptations in humans and animals. Consistent with this, previous studies have reported that restricting visual inputs in young animals can make drastic long-lasting changes in the early sensory areas of their brains. Typically, the majority of sensory neurons are allocated to stimulus features to which the animals were exposed. However, if that is the only change, it will make the sensory encoding highly redundant with many neurons signaling the same features. Are there additional changes, heretofore unnoticed, to functional properties of single neurons in such adaptation processes? Here we show that stimulus selectivities like the sharpness of tuning of single neurons in the primary visual cortex are modified to match a particular environment that has a restricted range of orientations. Specifically, we found in orientation-restricted animals that neurons tuned to an experienced orientation show sharper orientation tuning than neurons in normal animals, whereas the opposite was true for neurons tuned to non-experienced orientations. The sharpened tuning appears to be due to elongated receptive fields. Additionally, quality of signals such as the signal-to-noise ratio can be improved by averaging the activities of a population of neurons unless the same noise source is shared. Correlation of noise shared across neurons in the orientation-restricted animals was comparable to that in normal animals, confirming the potential for such improvements. Our results demonstrate that restricted sensory experiences can sculpt the supranormal functions of neurons tailored for a particular environment

Performance of plasma Aβ42/40, measured using a fully automated immunoassay, across a broad patient population in identifying amyloid status

Abstract Background Plasma biomarkers have emerged as promising screening tools for Alzheimer’s disease (AD) because of their potential to detect amyloid β (Aβ) accumulation in the brain. One such candidate is the plasma Aβ42/40 ratio (Aβ42/40). Unlike previous research that used traditional immunoassay, recent studies that measured plasma Aβ42/40 using fully automated platforms reported promising results. However, its utility should be confirmed using a broader patient population, focusing on the potential for early detection. Methods We recruited 174 participants, including healthy controls (HC) and patients with clinical diagnoses of AD, frontotemporal lobar degeneration, dementia with Lewy bodies/Parkinson’s disease, mild cognitive impairment (MCI), and others, from a university memory clinic. We examined the performance of plasma Aβ42/40, measured using the fully automated high-sensitivity chemiluminescence enzyme (HISCL) immunoassay, in detecting amyloid-positron emission tomography (PET)-derived Aβ pathology. We also compared its performance with that of Simoa-based plasma phosphorylated tau at residue 181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light (NfL). Results Using the best cut-off derived from the Youden Index, plasma Aβ42/40 yielded an area under the receiver operating characteristic curve (AUC) of 0.949 in distinguishing visually assessed 18F-Florbetaben amyloid PET positivity. The plasma Aβ42/40 had a significantly superior AUC than p-tau181, GFAP, and NfL in the 167 participants with measurements for all four biomarkers. Next, we analyzed 99 participants, including only the HC and those with MCI, and discovered that plasma Aβ42/40 outperformed the other plasma biomarkers, suggesting its ability to detect early amyloid accumulation. Using the Centiloid scale (CL), Spearman’s rank correlation coefficient between plasma Aβ42/40 and CL was -0.767. Among the 15 participants falling within the CL values indicative of potential future amyloid accumulation (CL between 13.5 and 35.7), plasma Aβ42/40 categorized 61.5% (8/13) as Aβ-positive, whereas visual assessment of amyloid PET identified 20% (3/15) as positive. Conclusion Plasma Aβ42/40 measured using the fully automated HISCL platform showed excellent performance in identifying Aβ accumulation in the brain in a well-characterized cohort. This equipment may be useful for screening amyloid pathology because it has the potential to detect early amyloid pathology and is readily applied in clinical settings