The Visual Scene Network and Hippocampus Represent Spatial Boundary Structures for Temporal Episodic Memory Organization.

Crossing a spatial boundary such as a doorway plays an important role in the temporal organization of episodic memory. However, despite the wealth of evidence showing that visual boundary structures in scenes affect our representation of space, no studies have tested the possibility that they also function as event boundaries even without active navigation. In this study, we used a nonnavigational scene-based memory task that required participants to remember a sequence of objects moving to various baskets in a scene. In the boundary condition, there was a freestanding boundary in the middle of the room, low enough to see the rest of the room beyond it. We found that the additional boundary within the scene was sufficient to trigger a larger response in the cortical visual scene network, the hippocampus, and their coordinated activity. These results suggest that active navigation across a spatial boundary such as a doorway into another room is not necessary to form an event boundary and that a visual representation of boundaries is sufficient to influence the organization of a hippocampal episodic memory.

Wearable functional near-infrared spectroscopy for measuring dissociable activation dynamics of prefrontal cortex subregions during working memory.

The prefrontal cortex (PFC) has been extensively studied in relation to various cognitive abilities, including executive function, attention, and memory. Nevertheless, there is a gap in our scientific knowledge regarding the functionally dissociable neural dynamics across the PFC during a cognitive task and their individual differences in performance. Here, we explored this possibility using a delayed match-to-sample (DMTS) working memory (WM) task using NIRSIT, a high-density, wireless, wearable functional near-infrared spectroscopy (fNIRS) system. First, upon presentation of the sample stimulus, we observed an immediate signal increase in the ventral (orbitofrontal) region of the anterior PFC, followed by activity in the dorsolateral PFC. After the DMTS test stimulus appeared, the orbitofrontal cortex activated once again, while the rest of the PFC showed overall disengagement. Individuals with higher accuracy showed earlier and sustained activation of the PFC across the trial. Furthermore, higher network efficiency and functional connectivity in the PFC were correlated with individual WM performance. Our study sheds new light on the dynamics of PFC subregional activity during a cognitive task and its potential applicability in explaining individual differences in experimental, educational, or clinical populations. PRACTITIONER POINTS: Wearable functional near-infrared spectroscopy (fNIRS) captured dissociable temporal dynamics across prefrontal subregions during a delayed match-to-sample task. Anterior regions of the orbitofrontal cortex (OFC) activated first during the delay period, followed by the dorsolateral prefrontal cortex (PFC). PFC disengaged overall after the delay, but the OFC reactivated to the test stimulus. Earlier and sustained activation of PFC was associated with better accuracy. Functional connectivity and network efficiency also varied with task performance.

Behavioral evidence for memory replay of video episodes in the macaque.

Humans recall the past by replaying fragments of events temporally. Here, we demonstrate a similar effect in macaques. We trained six rhesus monkeys with a temporal-order judgement (TOJ) task and collected 5000 TOJ trials. In each trial, the monkeys watched a naturalistic video of about 10 s comprising two across-context clips, and after a 2 s delay, performed TOJ between two frames from the video. The data are suggestive of a non-linear, time-compressed forward memory replay mechanism in the macaque. In contrast with humans, such compression of replay is, however, not sophisticated enough to allow these monkeys to skip over irrelevant information by compressing the encoded video globally. We also reveal that the monkeys detect event contextual boundaries, and that such detection facilitates recall by increasing the rate of information accumulation. Demonstration of a time-compressed, forward replay-like pattern in the macaque provides insights into the evolution of episodic memory in our lineage.

Syntheses and biological evaluation of new fluoroquinolone antibacterials containing chiral oxiimino pyrrolidine.

The design and syntheses of new fluoroquinolone antibacterial agents having pyrrolidine ring at C-7 position are described. The pyrrolidine ring is optically active and possesses methyloxime functional group. Two of them have excellent in vitro antibacterial activities and pharmacokinetic profiles.

Divergent syntheses of all possible optically active regioisomers of myo-inositol tris- and tetrakisphosphates.

Since the discovery of D-myo-inositol 1,4,5-trisphosphate, which plays a pivotal role as a second messenger in transmembrane signaling, the scope of the phosphoinositide-based signaling processes has been continually expanding. However, the clear understanding of the molecular signal transduction mechanisms including the functions of newly found IP(n) is still lacking. As a continuing effort to our previously reported syntheses of all possible 39 optically inactive regioisomers of myo-inositol phosphates (IP(n); n = 1-6), we synthesized all possible optically active regioisomers of myo-IP(3) and myo-IP(4) using chiral IBz(3)s and IBz(2)s, respectively. A series of procedures involving CRL-catalyzed enzymatic resolution of racemic 1,2:5,6-di-O-isopropylidene-myo-inositol and base-catalyzed benzoyl migration in tri- and dibenzoyl-isopropylidene-myo-inositol afforded eight enantiomeric pairs of IBz(3) and six enantiomeric pairs of IBz(2), respectively. Phosphorylation of these intermediates by the phosphitylation and oxidation procedure gave the target products.