Time-sensitive Prefrontal Involvement in Associating Confidence With Task Performance Illustrates Metacognitive Introspection in Monkeys

Metacognition refers to the ability to be aware of one’s own cognition. Ample evidence indicates that metacognition in the human primate is highly dissociable from cognition, specialized across domains, and subserved by distinct neural substrates. However, these aspects remain relatively understudied in macaque monkeys. In the present study, we investigated the functionality of macaque metacognition by combining a confidence proxy, hierarchical Bayesian meta-d′ computational modelling, and a single-pulse transcranial magnetic stimulation technique. We found that Brodmann area 46d (BA46d) played a critical role in supporting metacognition independent of task performance; we also found that the critical role in of this region in meta-calculation was time-sensitive. Additionally, we report that macaque metacognition is highly domain-specific with respect to memory and perception decisions. These findings carry implications for our understanding of metacognitive introspection within the primate lineage.

Temporal-sensitive prefrontal involvement in associating confidence with task performance illustrates metacognitive introspection in Old World monkeys (Macaca mulatta)

Metacognition refers to the ability to be aware of one’s own cognition. Ample evidence indicate that metacognition in the human primate is highly dissociable from cognition, specialized across domains, and subserved by distinct neural substrates. However, these aspects remain relatively understudied in the macaque monkeys. Here we investigated the functionality of macaques’ metacognition by combining a confidence proxy, hierarchical Bayesian meta-d’ computational modelling, and single-pulse transcranial magnetic stimulation technique. We found a critical role of Brodmann Area 46d (BA 46d) in supporting metacognition without implicating task performance and its critical time-sensitive role in meta-calculation. We additionally revealed that macaque metacognition is highly domain-specific with respect to memory and perception decisions. These findings carry implications for our understanding of metacognitive introspection within the primate lineage.

Interindividual variability of electric fields during transcranial temporal interference stimulation (tTIS)

Transcranial temporal interference stimulation (tTIS) is a novel non-invasive brain stimulation technique for electrical stimulation of neurons at depth. Deep brain regions are generally small in size, making precise targeting a necessity. The variability of electric fields across individual subjects resulting from the same tTIS montages is unknown so far and may be of major concern for precise tTIS targeting. Therefore, the aim of the current study is to investigate the variability of the electric fields due to tTIS across 25 subjects. To this end, the electric fields of different electrode montages consisting of two electrode pairs with different center frequencies were simulated in order to target selected regions-of-interest (ROIs) with tTIS. Moreover, we set out to compare the electric fields of tTIS with the electric fields of conventional tACS. The latter were also based on two electrode pairs, which, however, were driven in phase at a common frequency. Our results showed that the electric field strengths inside the ROIs (left hippocampus, left motor area and thalamus) during tTIS are variable on single subject level. In addition, tTIS stimulates more focally as compared to tACS with much weaker co-stimulation of cortical areas close to the stimulation electrodes. Electric fields inside the ROI were, however, comparable for both methods. Overall, our results emphasize the potential benefits of tTIS for the stimulation of deep targets, over conventional tACS. However, they also indicate a need for individualized stimulation montages to leverage the method to its fullest potential.

Efficacy of TMS and Cognitive Training in Mild Cognitive Impairment: A Pilot Study

Purpose: Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique with the potential to improve memory. Mild cognitive impairment (MCI), which still lacks a specific therapy, is a clinical syndrome associated with increased risk of dementia. This study aims to assess the effects of deep TMS (dTMS) on a group of 10 patients diagnosed with amnesic MCI. Methods: We compared the effects of TMS COG treatment (dTMS delivered with H7 helmet for ten daily sessions together with cognitive training of memory and attention), with those of COG treatment (cognitive training alone) of the same duration. Results: Neuropsychological evaluation at baseline, after TMS COG treatment, after COG treatment and at six months follow up, compared with ANOVA, revealed a significant group-by-time interaction (𝑝 = 0.05), favoring the TMS COG treatment for memory tests. The improvement was kept after six months. Other neuropsychological tests were not significantly affected by treatment. Conclusions: These findings suggest that dTMS might be effective as a therapy for MCI and probably a tool to delay cognitive deterioration.

Особенности проведения неразрушающего контроля полимерных и композиционных материалов с использованием бесконтактной ультразвуковой стимуляции и лазерного вибросканирования

Until present, air-coupled (non-contact) ultrasonic excitation has not been routinely used in nondestructive testing of polymers and composites. It is believed that, by combining this stimulation technique with high-sensitive laser vibrometry, it would be possible to ensure acceptable quality of inspection avoiding any external influence on materials to be tested. This study is devoted to analyzing an ultrasonic inspection system including a non-contact magnetostrictive transducer and sa canning laser dopler vibrometer in application to nondestructive testing of polymeric and composite materials. The use of the magnetostrictor has ensured stimulation power high enough to detect hidden defects, provided that the experimental procedure has been appropriately optimized. The radiation pattern of the magnetostrictive device has been analyzed to demonstrate peculiarities of combining such type of ultrasonic emitters with a titanium waveguide.