Right Hemisphere Lateralization in Neural Connectivity Within Fronto-Parietal Networks in Non-human Primates During a Visual Reaching Task

A fronto-parietal network, comprised of the posterior parietal cortex (PPC) and the dorsal premotor cortex (PMd) has been proposed to be involved in planning and guiding movement. However, the issue of how the network is expressed across the bilateral cortical area according to the effector's side remains unclear. In this study, we tested these questions using electrocorticographic (ECoG) recordings in non-human primates and using a simple visual guided reaching task that induced a left or right hand response based on relevant cues provided for the task. The findings indicate that right hemisphere lateralized network patterns in which the right PMd was strongly coordinated with bilateral PPC immediately after presentation of the movement cue occurred, while the coherence with the left PMd was not enhanced. No difference was found in the coherence pattern between the effector's side (left hand or right hand), but the strength of coherence was different, in that animals showed a higher coherence in the right hand response compared to the left. Our data support that right lateralization in long-range phase synchrony in the 10–20 Hz low beta band is involved in motor preparation stage, irrespective of the upcoming effector's side

Supplementation With Whey Peptide Rich in β-Lactolin Improves Cognitive Performance in Healthy Older Adults: A Randomized, Double-Blind, Placebo-Controlled Study

Epidemiological reports showed that consumptions of fermented dairy products are beneficial for cognitive decline in elderly. Our previous preclinical studies have demonstrated that intakes of whey peptide rich in the β-lactolin [β-lactopeptide of glycine-thereonine-tryptophan-tyrosine (GTWY)] improve memory and attention by regulating monoamine system, and clinical study using neuropsychological test suggested that consumptions with GTWY-rich whey peptide enhance cognitive performance associated with the frontal cortex activity. However, corresponding interventional studies in humans are limited. Objectives: to evaluate the effects of the whey peptide on cognitive functions in healthy older adults using a randomized, double-blinded, placebo-controlled trial design. 114 healthy subjects aged 50–75 were supplemented with the whey peptide or placebo for 12 weeks, and changes in cognitive function were assessed using neuropsychological tests at weeks 0, 6, and 12 of the intervention. Neuropsychological tests included assessments for memory functions (subtests from Wechsler memory scale-revised, standard verbal paired-associate learning test, and recognition memory test for faces), assessments for attention (cancelation and detection tests), and assessments for general cognitive functions (repeatable battery for assessments of neuropsychological status). Cerebral blood flow was also assessed using near-infrared spectroscopy (NIRS) after 6 weeks of intervention. This study was registered on the 19 November, 2017 in the database of the University Hospital Medical Information Network (UMIN) prior to enrollment of subjects (Registration No. UMIN000030461: https://www.umin.ac.jp/ctr/index-j.htm). In the whey peptide group, visual paired-associates I and visual cancelation tests were significantly improved compared with those in the placebo group at weeks 6 and 12 of the intervention, respectively. Visuospatial and constructional scores of the repeatable battery for assessments of neuropsychological status and standard verbal paired-associate learning tests (S-PA) also tended to be improved by the intervention at week 12. Daily intakes of GTWY-rich whey peptide show beneficial effects on cognitive performance, especially associative learning memory and control of attention, in healthy older adults and might prevent age-related cognitive declines

Attention and Functional Connectivity in Survivors of Childhood Brain Tumors

To study potential hyperactivity and hyperconnectivity based on the latent resource hypothesis, this study assessed functional connectivity in survivors of childhood brain tumors compared to their healthy peers during an attention task using psychophysiological interaction (PPI) analyses and evaluated for a relationship with performance. Twenty-three survivors and 23 healthy controls completed a letter n-back task in the scanner. An empirically-based seed was placed in the parietal lobe, a theoretical seed was placed in the hippocampus, and a control seed was placed in the occipital lobe. Differences in both performance and functional connectivity networks from each seed emerged between groups, with some findings supporting the latent resource hypothesis and other networks showing compensatory function in survivors. Attention networks, phonological networks, and executive function networks were all found to differ between controls and survivors

Variations of response time in a selective attention task are linked to variations of functional connectivity in the attentional network.

International audienceAlthough variations of response time (RT) within a particular experimental condition are typically ignored, they may sometimes reflect meaningful changes in the efficiency of cognitive and neural processes. In the present study, we investigated whether trial-by-trial variations of response time (RT) in a cross-modal selective attention task were associated with variations of functional connectivity between brain regions that are thought to underlie attention. Sixteen healthy young adults performed an audiovisual selective attention task, which involved attending to a relevant visual letter while ignoring an irrelevant auditory letter, as we recorded their brain activity using functional magnetic resonance imaging (fMRI). In line with predictions, variations of RT were associated with variations of functional connectivity between the anterior cingulate cortex and various other brain regions that are posited to underlie attentional control, such as the right dorsolateral prefrontal cortex and bilateral regions of the posterior parietal cortex. They were also linked to variations of functional connectivity between anatomically early and anatomically late regions of the relevant-modality visual cortex whose communication is thought to be modulated by attentional control processes. By revealing that variations of RT in a selective attention task are linked to variations of functional connectivity in the attentional network, the present findings suggest that variations of attention may contribute to trial-by-trial fluctuations of behavioral performance

Information-theoretic Bounded Rationality: Timing Laws and Cognitive Costs Emerge from Rational Bounds on Information Coding and Transmission

University of Minnesota Ph.D. dissertation. October 2019. Major: Psychology. Advisors: Paul Schrater, Maria Gini. 1 computer file (PDF); xi, 164 pages.Cognitive models are used to characterize and understand task performance in humans. Human behavior often deviates from predictions made by models that assume perfect rationality. Imposing constraints on cognitive resources, time, and/or information, while still assuming optimal function within those bounds, produces better characterizations of behavior. However, many of the proposed constraints and costs are ad-hoc and are not derived from fundamental limitations on computation. We suggest that behavioral performance is limited by the necessity of encoding and transmitting information about the world in the brain. Encoding information imposes a set of intrinsic bounds, defined by signal power, noise power, and knowledge of environmental statistics, that can be understood and quantified using concepts from information theory. In this dissertation, we investigate the patterns of behavior that should arise if cognition is subject to these bounds. Using an information transmission mechanism built using stochastic processes and Bayesian inference, we show that known `laws' of human behavior, including the Hick-Hyman law and the Power Law of Learning, are direct consequences of unavoidable limitations on the efficiency of information transmission. By instantiating constraints on information transmission in a working system, we are able to quantify transmission costs induced by task performance. This provides a unifying and principled explanation of cognitive costs and mental effort: effort arises in tasks that require expensive information transmission and is reduced through practice as learned task statistics are exploited to improve efficiency. To test the extent to which humans exploit task statistics to improve efficiency, we measured behavior on a version of the N-back task modified to include a predictable structure in target responses. We found that human data closely matches model predictions, suggesting that humans integrate information about both task structure and past images to produce responses. This finding is an experimental validation of our model, and suggests that the N-back task is more complex than is normally assumed. In sum, we show that treating cognition as a process constrained by fundamental bounds on information transmission provides a unified explanation of a wide range of behavioral phenomena

Cortical and psychophysiological effects of sensory modulation on attentional switching during exercise

The present research programme sought to further understanding of the neurophysiological mechanisms that underlie the effects of music on exercise. Five original experiments were conducted using a wide range of psychophysical, psychological, physiological, and psychophysiological techniques. The results of the first study indicated that music partially reallocates attention towards task-unrelated thoughts (i.e., external dissociation), suppresses the amplitude of low-frequency waves in the brain, and enhances task performance. The findings of the second study indicated that music can have a negative effect if delivered during the execution of highly-demanding cognitive-motor tasks. In such instances, the right parietal regions of the brain activate in response to the presence of auditory distractors and prevent task performance from being compromised. The third study shed new light on the neural control of working muscles and indicated that music has the potential to reduce the frequency of electrical outputs emitted to the musculature and reduce the communication between the central motor command and adjacent regions. The fourth study of this research programme was conducted in an ecologically valid environment, wherein participants walked at self-paced speeds in the presence of different auditory stimuli. The results of the fourth study indicated that music elicits more positive affective responses and up-regulates beta waves to a greater degree than no-music conditions. Finally, the fifth study of this thesis made use of functional magnetic resonance imaging to explore the brain regions that activate in response to exercise and music. The results of this final study revealed that the left inferior frontal gyrus is highly active when individuals execute part-body exercises with music. The present research programme provides a neurophysiological basis for the use of music in exercise settings. The findings presented herein support the use of music as a valuable tool to explore more complex psychophysiological phenomena such as attention, affect, and fatigue.Brazilian Government (Coordination for the Improvement of Higher Education Personnel [CAPES]

Information Processing Speed in Ageing: Is it task dependent?

Evidence indicates that information processing speed slows as age increases and disproportionately so with impaired cognition and various neurodegenerative diseases such as Alzheimer’s disease. The new DSM-5 criteria for neuro-cognitive disorders state that measuring information processing speed associated with attentional function should be included within dementia diagnosis. However, what is not clarified is that outcome variability can occur, in part, as a result of methodological factors i.e. type of attention-related test/ attentional function and by person-related factors such as sex and education. In addition, there appears to be a dichotomy between the types of tests used within research studies and clinical settings which should be addressed [Haworth et al, 2016].The aim of the research presented in this thesis was to investigate how using different tests of attentional function in similar groups of young and older adults may affect the outcome measure of information processing speed (RT) and its variability (IIV). Part of this aim was to determine whether the number of trials may influence performance i.e. RT, IIV and accuracy (number of errors). Another aim was to determine whether result outcome is affected similarly across tests by a variety of person-related factors i.e. sex, education, objective cognitive measures and particularly previously un-tested factors of subjective memory function and perceived test difficulty which may help determine whether subjective feelings are associated with slower and more variable information processing speed and may influence study outcome.The first study [Chapter 2] comprised of a visual search test commonly used in research as a sensitive measure of ageing upon RT and IIV and attentional shifting, yet not examined particularly in relation to subjective memory function and perceived test difficulty. Results indicated that information processing speed was significantly slowed in older compared to younger adults and attentional shifting was poorer in older adults. There was no relationship with subjective memory function whereas the influence of sex, education and perceived test difficulty were dependent on the condition and age.In the second, larger study including the Trail Making Test (TMT), Simple reaction time (RT) test, Choice RT test and Multi-Item Localization test (MILO) [Chapters 3- 5], the results indicated that in all tests older adults were significantly slower and more variable than young adults at group level. Person-related factors were influential depending on the test used. Subjective memory function and education were only influential within conditions of the MILO and perceived test difficulty influential in Trails B and Choice RT. Large effect sizes in visual search, MILO and the Choice RT suggested they were most sensitive to ageing effects. In conclusion, we speculate which attentional tests may be more useful in research and than those already used in clinical settings i.e. TMT and highlight the need to take into consideration different factors depending on the attentional test used so as not to misinterpret normal levels of information processing speed in ostensibly healthy aging