Neural correlates of implicit knowledge about statistical regularities

In this study, we examined the neural correlates of implicit knowledge about statistical regularities of temporal order and item chunks using functional magnetic resonance imaging (fMRI). In a familiarization scan, participants viewed a stream of scenes consisting of structured (i.e., three scenes were always presented in the same order) and random triplets. In the subsequent test scan, participants were required to detect a target scene. Test sequences included both forward order of scenes presented during the familiarization scan and backward order of scenes (i.e., reverse order of forward scenes). Behavioral results showed a learning effect of temporal order in the forward condition and scene chunks in the backward condition. fMRI data from the familiarization scan showed the difference of activations between the structured and random blocks in the left posterior cingulate cortex including the retrosplenial cortex. More important, in the test scan, we observed brain activities in the left parietal lobe when participants detected target scenes on temporal order information. In contrast, the left precuneus activated when participants detected target scenes based on scene chunks. Our findings help clarify the brain mechanisms of implicit knowledge about acquired regularities

The limited contribution of early visual cortex in visual working memory for surface roughness

Are visual representations in the human early visual cortex necessary for visual working memory (VWM)? Previous studies suggest that VWM is underpinned by distributed representations across several brain regions, including the early visual cortex. Notably, in these studies, participants had to memorize images under consistent visual conditions. However, in our daily lives, we must retain the essential visual properties of objects despite changes in illumination or viewpoint. The role of brain regions—particularly the early visual cortices—in these situations remains unclear. The present study investigated whether the early visual cortex was essential for achieving stable VWM. Focusing on VWM for object surface properties, we conducted fMRI experiments, while male and female participants performed a delayed roughness discrimination task in which sample and probe spheres were presented under varying illumination. By applying multi-voxel pattern analysis to brain activity in regions of interest, we found that the ventral visual cortex and intraparietal sulcus were involved in roughness VWM under changing illumination conditions. In contrast, VWM was not supported as robustly by the early visual cortex. These findings show that visual representations in the early visual cortex alone are insufficient for the robust roughness VWM representation required during changes in illumination

A connectionist account of ontological boundary shifting

Abstract. Previous research on children's categorizations has suggested that children use perceptual and conceptual knowledge to generalize object names. Especially, the relation between ontological categories and linguistic categories appears to be a critical cue to learning object categories. However, its underlying mechanism remains unclear. In this paper, we propose a connectionist model that can acquire ontological knowledge by learning linguistic categories of entities. The results suggest that linguistic cues help children attend to specific perceptual properties

An intestinal bacterial metabolite (M1) of ginseng protopanaxadiol saponins inhibits tumor-induced neovascularization

The present study demonstrated that an intestinal bacterial metabolite (M1) of protopanaxadiol-type ginsenosides significantly inhibited the growth of implanted tumor and the intrahepatic metastasis by the implantation of a small fragment of colon 26-L5 tumor into the liver when it was administered orally. These findings indicates that M1 was effective for the inhibition of the growth and metastasis of colon26-L5 cells in addition to lung metastasis of B16-BL6 melanoma cells as have been reported previously. The conditioned medium of colon 26-L5 cellS (CM-L5) induced in vitro tube formation of hepatic sinusoidal endothelial (HSE) cells on Matrigel-coated substrates, which is considered to be an important step in the processes of tumor angiogenesis. \u27This activity of CML5 was abrogated by noncytotoxic concentrations of M1 in a concentration-dependent manner. Similarly, M1 eliminated the ability of CM-L5 to promote the migration of HSE cells concentration-dependently. These findings indicate that M1-induced inhibition of tumor growth and intrahepatic metastasis may be partly related to the suppression of tumor angiogenic responses including capillary tube formation and migration of HSE cells. 本研究では,薬用人参(Panax ginseng C.A.MEYER)のprotopanaxadiol-type ginsenosidesの主要な腸内細菌代謝物M1の経口投与は,マウス結腸癌colon 26-L5細胞の腫瘍小片を肝へ直接移植した後の移植部位での増殖と肝内移転に対して有意に抑制効果を示すことを明らかにした。この結果は,B16-BL6メラノーマ細胞による肺転移を抑制した以前の報告と同様に,co1on 26-L5細胞に対しても有効であることが示された。肝類洞内度細胞(HSE細胞)をマトリゲルをコートした基質上で,colon 26-L5細胞の培養上清(CM-L5)とともに培養すると,腫瘍血管新生の週程における重要なステップのひとつである,内度細胞の菅腔形成を誘導した。CM-L5による菅形成能は,細胞傷害性を示さない濃度範囲のM1により,濃度依存的に抑制された。同様に,CM-L5によるHSE細胞の移動能の亢進を,M1は濃度に依存して抑制した。以上,M1による結腸癌の肝における増殖及び肝内転移の抑制は,内度細胞の骨腔形成及ぴ移動能を含む血管新生反応の抑制と部分的に関係していることが示唆された

Chemopreventive effects and anti-tumorigenic mechanisms of Actinidia arguta, known as sarunashi in Japan toward 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)- induced lung tumorigenesis in a/J mouse

Background Previously, we reported the inhibitory effect of Actinidia arguta juice, known as sarunashi juice (sar-j) in Japan, on mutagenesis, inflammation, and mouse skin tumorigenesis. The components of A. arguta responsible for the anti-mutagenic effects were identified to be water-soluble, heat-labile phenolic compounds. We proposed isoquercetin (isoQ) as a candidate anticarcinogenic component. In this study, we sought to investigate the chemopreventive effects of A. arguta juice and isoQ on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice, and identify the possible mechanisms underlying the anti-tumorigenic effects of A. arguta. Results The number of tumor nodules per mouse lung in the group injected with NNK and administered A. arguta juice orally was significantly lower than that in the group injected with NNK only. Oral administration of isoQ also reduced the number of nodules in the mouse lungs. As expected, the mutagenicity of NNK and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) detected using S. typhimurium TA1535 decreased in the presence of sar-j. However, NNK and MNNG mutagenicity detected using S. typhimurium YG7108, a strain lacking the O6-methylguanine DNA methyltransferases (ogtST and adaST) did not decrease in the presence of sar-j suggesting that sar-j may mediate its antimutagenic effect by enhancing the DNA damage repair by ogtST and adaST. Phosphorylation of Akt, with or without epidermal growth factor stimulation, in A549 cells was significantly decreased following sar-j and isoQ treatment, indicating that components in sar-j including isoQ suppressed the PI3K/AKT signaling pathways. Conclusions Sar-j and isoQ reduced NNK-induced lung tumorigenesis. Sar-j targets both the initiation and growth/progression steps during carcinogenesis, specifically via anti-mutagenesis, stimulation of alkyl DNA adduct repair, and suppression of Akt-mediated growth signaling. IsoQ might contribute in part to the biological effects of sar-j via suppression of Akt phosphorylation, but it may not be the main active ingredient

Open monitoring meditation reduces the involvement of brain regions related to memory function

洞察瞑想時に自伝的記憶関連脳領域間の結合性が低下することを発見 --今この瞬間に生じている経験にありのままに気づくことの神経基盤--. 京都大学プレスリリース. 2018-07-05.Mindfulness meditation consists of focused attention meditation (FAM) and open monitoring meditation (OMM), both of which reduce activation of the default mode network (DMN) and mind-wandering. Although it is known that FAM requires intentional focused attention, the mechanisms of OMM remain largely unknown. To investigate this, we examined striatal functional connectivity in 17 experienced meditators (mean total practice hours = 920.6) during pre-resting, meditation, and post-resting states comparing OMM with FAM, using functional magnetic resonance imaging. Both FAM and OMM reduced functional connectivity between the striatum and posterior cingulate cortex, which is a core hub region of the DMN. Furthermore, OMM reduced functional connectivity of the ventral striatum with both the visual cortex related to intentional focused attention in the attentional network and retrosplenial cortex related to memory function in the DMN. In contrast, FAM increased functional connectivity in these regions. Our findings suggest that OMM reduces intentional focused attention and increases detachment from autobiographical memory. This detachment may play an important role in non-judgmental and non-reactive attitude during OMM. These findings provide new insights into the mechanisms underlying the contribution of OMM to well-being and happiness

Two solanesyl diphosphate synthases with different subcellular localizations and their respective physiological roles in Oryza sativa

Long chain prenyl diphosphates are crucial biosynthetic precursors of ubiquinone (UQ) in many organisms, ranging from bacteria to humans, as well as precursors of plastoquinone in photosynthetic organisms. The cloning and characterization of two solanesyl diphosphate synthase genes, OsSPS1 and OsSPS2, in Oryza sativa is reported here. OsSPS1 was highly expressed in root tissue whereas OsSPS2 was found to be high in both leaves and roots. Enzymatic characterization using recombinant proteins showed that both OsSPS1 and OsSPS2 could produce solanesyl diphosphates as their final product, while OsSPS1 showed stronger activity than OsSPS2. However, an important biological difference was observed between the two genes: OsSPS1 complemented the yeast coq1 disruptant, which does not form UQ, whereas OsSPS2 only very weakly complemented the growth defect of the coq1 mutant. HPLC analyses showed that both OsSPS1 and OsSPS2 yeast transformants produced UQ9 instead of UQ6, which is the native yeast UQ. According to the complementation study, the UQ9 levels in OsSPS2 transformants were much lower than that of OsSPS1. Green fluorescent protein fusion analyses showed that OsSPS1 localized to mitochondria, while OsSPS2 localized to plastids. This suggests that OsSPS1 is involved in the supply of solanesyl diphosphate for ubiquinone-9 biosynthesis in mitochondria, whereas OsSPS2 is involved in providing solanesyl diphosphate for plastoquinone-9 formation. These findings indicate that O. sativa has a different mechanism for the supply of isoprenoid precursors in UQ biosynthesis from Arabidopsis thaliana, in which SPS1 provides a prenyl moiety for UQ9 at the endoplasmic reticulum