Neural Correlates of the Difference between Working Memory Speed and Simple Sensorimotor Speed: An fMRI Study

The difference between the speed of simple cognitive processes and the speed of complex cognitive processes has various psychological correlates. However, the neural correlates of this difference have not yet been investigated. In this study, we focused on working memory (WM) for typical complex cognitive processes. Functional magnetic resonance imaging data were acquired during the performance of an N-back task, which is a measure of WM for typical complex cognitive processes. In our N-back task, task speed and memory load were varied to identify the neural correlates responsible for the difference between the speed of simple cognitive processes (estimated from the 0-back task) and the speed of WM. Our findings showed that this difference was characterized by the increased activation in the right dorsolateral prefrontal cortex (DLPFC) and the increased functional interaction between the right DLPFC and right superior parietal lobe. Furthermore, the local gray matter volume of the right DLPFC was correlated with participants' accuracy during fast WM tasks, which in turn correlated with a psychometric measure of participants' intelligence. Our findings indicate that the right DLPFC and its related network are responsible for the execution of the fast cognitive processes involved in WM. Identified neural bases may underlie the psychometric differences between the speed with which subjects perform simple cognitive tasks and the speed with which subjects perform more complex cognitive tasks, and explain the previous traditional psychological findings

Brain Training Game Improves Executive Functions and Processing Speed in the Elderly: A Randomized Controlled Trial

The beneficial effects of brain training games are expected to transfer to other cognitive functions, but these beneficial effects are poorly understood. Here we investigate the impact of the brain training game (Brain Age) on cognitive functions in the elderly.Thirty-two elderly volunteers were recruited through an advertisement in the local newspaper and randomly assigned to either of two game groups (Brain Age, Tetris). This study was completed by 14 of the 16 members in the Brain Age group and 14 of the 16 members in the Tetris group. To maximize the benefit of the interventions, all participants were non-gamers who reported playing less than one hour of video games per week over the past 2 years. Participants in both the Brain Age and the Tetris groups played their game for about 15 minutes per day, at least 5 days per week, for 4 weeks. Each group played for a total of about 20 days. Measures of the cognitive functions were conducted before and after training. Measures of the cognitive functions fell into four categories (global cognitive status, executive functions, attention, and processing speed). Results showed that the effects of the brain training game were transferred to executive functions and to processing speed. However, the brain training game showed no transfer effect on any global cognitive status nor attention.Our results showed that playing Brain Age for 4 weeks could lead to improve cognitive functions (executive functions and processing speed) in the elderly. This result indicated that there is a possibility which the elderly could improve executive functions and processing speed in short term training. The results need replication in large samples. Long-term effects and relevance for every-day functioning remain uncertain as yet.UMIN Clinical Trial Registry 000002825

The neural bases for valuing social equality

The neural basis of how humans value and pursue social equality has become a major topic in social neuroscience research. Although recent studies have identified a set of brain regions and possible mechanisms that are involved in the neural processing of equality of outcome between individuals, how the human brain processes equality of opportunity remains unknown. In this review article, first we describe the importance of the distinction between equality of outcome and equality of opportunity, which has been emphasized in philosophy and economics. Next, we discuss possible approaches for empirical characterization of human valuation of equality of opportunity vs. equality of outcome. Understanding how these two concepts are distinct and interact with each other may provide a better explanation of complex human behaviors concerning fairness and social equality

Superior Temporal Activity for the Retrieval Process of Auditory-Word Associations

Previous neuroimaging studies have reported that learning multisensory associations involves the superior temporal regions (Tanabe et al, 2005). However, the neural mechanisms underlying the retrieval of multi-sensory associations were unclear. This functional MRI (fMRI) study investigated brain activations during the retrieval of multi-sensory associations. Eighteen right-handed college-aged Japanese participants learned associations between meaningless pictures and words (Vw), meaningless sounds and words (Aw), and meaningless sounds and visual words (W). During fMRI scanning, participants were presented with old and new words and were required to judge whether the words were included in the conditions of Vw, Aw, W or New. We found that the left superior temporal region showed greater activity during the retrieval of words learned in Aw than in Vw, whereas no region showed greater activity for the Vw condition versus the Aw condition (k > 10, p < .001, uncorrected). Taken together, the left superior temporal region could play an essential role in the retrieval process of auditory-word associations

An fMRI Investigation into the Effects of Ketogenic Medium-Chain Triglycerides on Cognitive Function in Elderly Adults: A Pilot Study

Evidence suggests that oral intake of medium-chain triglycerides (MCTs), which promote the production of ketone bodies, may improve cognitive functions in elderly people; however, the underlying brain mechanisms remain elusive. We tested the hypothesis that cognitive improvement accompanies physiological changes in the brain and reflects the use of ketone bodies as an extra energy source. To this end, by using functional magnetic resonance imaging, cerebral blood oxygenation level-dependent (BOLD) signals were measured while 20 healthy elderly subjects (14 females and 6 males; mean age: 65.7 ± 3.9 years) were engaged in executive function tasks (N-back and Go-Nogo) after ingesting a single MCT meal (Ketonformula®) or placebo meal in a randomized, double-blind placebo-controlled design (UMIN000031539). Morphological characteristics of the brain were also examined in relation to the effects of an MCT meal. The MCT meal improved N-back task performance, and this was prominent in subjects who had reduced grey matter volume in the dorsolateral prefrontal cortex (DLPFC), a region known to promote executive functions. When the participants were dichotomized into high/low level groups of global cognitive function at baseline, the high group showed improved N-back task performance, while the low group showed improved Go-Nogo task performance. This was accompanied by decreased BOLD signals in the DLPFC, indicative of the consumption of ketone bodies as an extra energy source

The Neural Basis of Event Simulation: An fMRI Study

<div><p>Event simulation (ES) is the situational inference process in which perceived event features such as objects, agents, and actions are associated in the brain to represent the whole situation. ES provides a common basis for various cognitive processes, such as perceptual prediction, situational understanding/prediction, and social cognition (such as mentalizing/trait inference). Here, functional magnetic resonance imaging was used to elucidate the neural substrates underlying important subdivisions within ES. First, the study investigated whether ES depends on different neural substrates when it is conducted explicitly and implicitly. Second, the existence of neural substrates specific to the future-prediction component of ES was assessed. Subjects were shown contextually related object pictures implying a situation and performed several picture–word-matching tasks. By varying task goals, subjects were made to infer the implied situation implicitly/explicitly or predict the future consequence of that situation. The results indicate that, whereas implicit ES activated the lateral prefrontal cortex and medial/lateral parietal cortex, explicit ES activated the medial prefrontal cortex, posterior cingulate cortex, and medial/lateral temporal cortex. Additionally, the left temporoparietal junction plays an important role in the future-prediction component of ES. These findings enrich our understanding of the neural substrates of the implicit/explicit/predictive aspects of ES-related cognitive processes.</p></div

Schematic depiction of a trial for each task and condition.

<p>In the Object task (cue “Same?”), the subject answered whether one of the three objects presented was congruent with the subsequently presented target word (i.e., object name). Three objects presented in the Con condition were contextually unrelated, and those in the Imp condition were contextually related and indicated a situation. In the Situation task (cue “Situation?”), the subject answered whether the target word was properly depicting the situation indicated by the object pictures. In the Future-prediction task (cue “After this?”), the subject answered whether the target word was properly depicting possible future events of the indicated situation.</p

Activation areas specific to the implicit and explicit event simulation (ES) processes.

<p>All voxels except for the regions described below are significant at a statistical threshold of <i>p</i><0.001, corrected to <i>p</i><0.05 for multiple comparisons using the cluster size, assuming the whole brain as the search volume. The result of the left parahippocampal cortex in the explicit ES process is thresholded at <i>p</i><0.001 (uncorrected). Error bars indicate standard deviations (SDs). IPL: inferior parietal lobule. PCC: posterior cingulate cortex. RSC: retrosplenial cortex. R: right. L: left. The coordinates in the Montreal Neurological Institute (MNI) standard space are indicated.</p