Neural consequences of binaural beat stimulation on auditory sentence comprehension: an EEG study.

A growing literature has shown that binaural beat (BB)-generated by dichotic presentation of slightly mismatched pure tones-improves cognition. We recently found that BB stimulation of either beta (18 Hz) or gamma (40 Hz) frequencies enhanced auditory sentence comprehension. Here, we used electroencephalography (EEG) to characterize neural oscillations pertaining to the enhanced linguistic operations following BB stimulation. Sixty healthy young adults were randomly assigned to one of three listening groups: 18-Hz BB, 40-Hz BB, or pure-tone baseline, all embedded in music. After listening to the sound for 10 min (stimulation phase), participants underwent an auditory sentence comprehension task involving spoken sentences that contained either an object or subject relative clause (task phase). During the stimulation phase, 18-Hz BB yielded increased EEG power in a beta frequency range, while 40-Hz BB did not. During the task phase, only the 18-Hz BB resulted in significantly higher accuracy and faster response times compared with the baseline, especially on syntactically more complex object-relative sentences. The behavioral improvement by 18-Hz BB was accompanied by attenuated beta power difference between object- and subject-relative sentences. Altogether, our findings demonstrate beta oscillations as a neural correlate of improved syntactic operation following BB stimulation.

Neural correlates of confusability in recognition of morphologically complex Korean words.

When people confuse and reject a non-word that is created by switching two adjacent letters from an actual word, is called the transposition confusability effect (TCE). The TCE is known to occur at the very early stages of visual word recognition with such unit exchange as letters or syllables, but little is known about the brain mechanisms of TCE. In this study, we examined the neural correlates of TCE and the effect of a morpheme boundary placement on TCE. We manipulated the placement of a morpheme boundary by exchanging places of two syllables embedded in Korean morphologically complex words made up of lexical morpheme and grammatical morpheme. In the two experimental conditions, the transposition syllable within-boundary condition (TSW) involved exchanging two syllables within the same morpheme, whereas the across-boundary condition (TSA) involved the exchange of syllables across the stem and grammatical morpheme boundary. During fMRI, participants performed the lexical decision task. Behavioral results revealed that the TCE was found in TSW condition, and the morpheme boundary, which is manipulated in TSA, modulated the TCE. In the fMRI results, TCE induced activation in the left inferior parietal lobe (IPL) and intraparietal sulcus (IPS). The IPS activation was specific to a TCE and its strength of activation was associated with task performance. Furthermore, two functional networks were involved in the TCE: the central executive network and the dorsal attention network. Morpheme boundary modulation suppressed the TCE by recruiting the prefrontal and temporal regions, which are the key regions involved in semantic processing. Our findings propose the role of the dorsal visual pathway in syllable position processing and that its interaction with other higher cognitive systems is modulated by the morphological boundary in the early phases of visual word recognition.

Anti-inflammatory activity of a methanol extract from Ardisia tinctoria on mouse macrophages and paw edema.

Ardisia tinctoria (AT) is a plant of the Myrsinaceae family. No studies on its anti-inflammatory effects have yet been reported. This study investigated the anti-inflammatory activity of AT. A non-cytotoxic methanol extract of AT inhibited the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), leading to significantly reduced levels of nitric oxide (NO) and prostaglandin E2 (PGE2) and of two proteins regulated by these, interleukin-1ß (IL-1ß) and IL-6, in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The thickness of paw edema induced in vivo in mice by carrageenan administration was effectively reduced by the AT extract. Translocation of the nuclear factor-κB (NF-κB) subunit 65 (p65) into the nucleus and phosphorylation of mitogen-activated protein kinase kinase (MEK) and extracellular signal-related kinase (ERK) were inhibited by the AT extract. Our results indicated that a methanol extract of AT downregulates the inflammatory response by blocking phosphorylation of MEK and ERK and activation of NF-κB. To the best of our knowledge, this is the first study of anti-inflammatory effects of an AT extract, and demonstrates its potential in the treatment of inflammatory diseases.