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Background: Progressive difficulty in performing everyday functional activities is a key diagnostic feature of dementia syndromes. However, not much is known about the neural signature of functional decline, particularly during the very early stages of dementia. Early intervention before overt impairment is observed offers the best hope of reducing the burdens of Alzheimer disease (AD) and other dementias. However, to justify early intervention, those at risk need to be detected earlier and more accurately. The decline in complex daily function (CdF) such as managing medications has been reported to precede impairment in basic activities of daily living (eg, eating and dressing). Objective: Our goal is to establish the neural signature of decline in CdF during the preclinical dementia period. Methods: Gait is central to many CdF and community-based activities. Hence, to elucidate the neural signature of CdF, we validated a novel electroencephalographic approach to measuring gait-related brain activation while participants perform complex gait-based functional tasks. We hypothesize that dementia-related pathology during the preclinical period activates a unique gait-related electroencephalographic (grEEG) pattern that predicts a subsequent decline in CdF. Results: We provide preliminary findings showing that older adults reporting CdF limitations can be characterized by a unique gait-related neural signature: weaker sensorimotor and stronger motor control activation. This subsample also had smaller brain volume and white matter hyperintensities in regions affected early by dementia and engaged in less physical exercise. We propose a prospective observational cohort study in cognitively unimpaired older adults with and without subclinical AD (plasma amyloid-β) and vascular (white matter hyperintensities) pathologies. We aim to (1) establish the unique grEEG activation as the neural signature and predictor of decline in CdF during the preclinical dementia period; (2) determine associations between dementia-related pathologies and incidence of the neural signature of CdF; and (3) establish associations between a dementia risk factor, physical inactivity, and the neural signature of CdF. Conclusions: By establishing the clinical relevance and biological basis of the neural signature of CdF decline, we aim to improve prediction during the preclinical stages of ADs and other dementias. Our approach has important research and translational implications because grEEG protocols are relatively inexpensive and portable, and predicting CdF decline may have real-world benefits. International Registered Report Identifier (IRRID): DERR1-10.2196/56726 [ABSTRACT FROM AUTHOR]

Identification of novel, non-invasive, non-cognitive based markers of Alzheimer's disease (AD) and related dementias are a global priority. Growing evidence suggests that Alzheimer's pathology manifests in sensory association areas well before appearing in neural regions involved in higher-order cognitive functions, such as memory. Previous investigations have not comprehensively examined the interplay of sensory, cognitive, and motor dysfunction with relation to AD progression. The ability to successfully integrate multisensory information across multiple sensory modalities is a vital aspect of everyday functioning and mobility. Our research suggests that multisensory integration, specifically visual-somatosensory integration (VSI), could be used as a novel marker for preclinical AD given previously reported associations with important motor (balance, gait, and falls) and cognitive (attention) outcomes in aging. While the adverse effect of dementia and cognitive impairment on the relationship between multisensory functioning and motor outcomes has been highlighted, the underlying functional and neuroanatomical networks are still unknown. In what follows we detail the protocol for our study, named The VSI Study, which is strategically designed to determine whether preclinical AD is associated with neural disruptions in subcortical and cortical areas that concurrently modulate multisensory, cognitive, and motor functions resulting in mobility decline. In this longitudinal observational study, a total of 208 community-dwelling older adults with and without preclinical AD will be recruited and monitored yearly. Our experimental design affords assessment of multisensory integration as a new behavioral marker for preclinical AD; identification of functional neural networks involved in the intersection of sensory, motor, and cognitive functioning; and determination of the impact of early AD on future mobility declines, including incident falls. Results of The VSI Study will guide future development of innovative multisensory-based interventions aimed at preventing disability and optimizing independence in pathological aging. [ABSTRACT FROM AUTHOR]

Advances in Mobile Brain/Body Imaging (MoBI) technology allows for real‐time measurements of human brain dynamics during every day, natural, real‐life situations. This special issue Time to Move brings together a collection of experimental papers, targeted reviews and opinion articles that lay out the latest MoBI findings. A wide range of topics across different fields are covered including art, athletics, virtual reality, and mobility. What unites these diverse topics is the common goal to enhance and restore human abilities by reaching a better understanding on how cognition is implemented by the brain‐body relationship. The breadth and novelty of paradigms and findings reported here positions MoBI as a new frontier in the field of human cognitive neuroscience. [ABSTRACT FROM AUTHOR]

Behavioral findings suggest that aging alters the involvement of cortical sensorimotor mechanisms in postural control. However, corresponding accounts of the underlying neural mechanisms remain sparse, especially the extent to which these mechanisms are affected during more demanding tasks. Here, we set out to elucidate cortical correlates of altered postural stability in younger and older adults. 3D body motion tracking and high‐density electroencephalography (EEG) were measured while 14 young adults (mean age = 24 years, 43% women) and 14 older adults (mean age = 77 years, 50% women) performed a continuous balance task under four different conditions. Manipulations were applied to the base of support (either regular or tandem (heel‐to‐toe) stance) and visual input (either static visual field or dynamic optic flow). Standing in tandem, the more challenging position, resulted in increased sway for both age groups, but for the older adults, only this effect was exacerbated when combined with optic flow compared to the static visual display. These changes in stability were accompanied by neuro‐oscillatory modulations localized to midfrontal and parietal regions. A cluster of electro‐cortical sources localized to the supplementary motor area showed a large increase in theta spectral power (4–7 Hz) during tandem stance, and this modulation was much more pronounced for the younger group. Additionally, the older group displayed widespread mu (8–12 Hz) and beta (13–30 Hz) suppression as balance tasks placed more demands on postural control, especially during tandem stance. These findings may have substantial utility in identifying early cortical correlates of balance impairments in otherwise healthy older adults. [ABSTRACT FROM AUTHOR]

During navigation of complex environments, the brain must continuously adapt to both external demands, such as fluctuating sensory inputs, and internal demands, such as engagement in a cognitively demanding task. Previous studies have demonstrated changes in behavior and gait with increased sensory and cognitive load, but the underlying cortical mechanisms remain largely unknown. In the present study, in a mobile brain/body imaging (MoBI) approach, 16 young adults walked on a treadmill with high-density EEG while 3-dimensional (3D) motion capture tracked kinematics of the head and feet. Visual load was manipulated with the presentation of optic flow with and without continuous mediolateral perturbations. The effects of cognitive load were assessed by the performance of a go/no-go task on half of the blocks. During increased sensory load, participants walked with shorter and wider strides, which may indicate a more restrained pattern of gait. Interestingly, cognitive task engagement attenuated these effects of sensory load on gait. Using an independent component analysis and dipole-fitting approach, we found that cautious gait was accompanied by neuro-oscillatory modulations localized to frontal (supplementary motor area, anterior cingulate cortex) and parietal (inferior parietal lobule, precuneus) areas. Our results show suppression in alpha/mu (8-12 Hz) and beta (13-30 Hz) rhythms, suggesting enhanced activation of these regions with unreliable sensory inputs. These findings provide insight into the neural correlates of gait adaptation and may be particularly relevant to older adults who are less able to adjust to ongoing cognitive and sensory demands while walking. [ABSTRACT FROM AUTHOR]

Several structural brain abnormalities have been associated with aggression in patients with schizophrenia. However, little is known about shared and distinct abnormalities underlying aggression in these subjects and non-psychotic violent individuals. We applied a region-of-interest volumetric analysis of the amygdala, hippocampus, and thalamus bilaterally, as well as whole brain and ventricular volumes to investigate violent (n = 37) and non-violent chronic patients (n = 26) with schizophrenia, non-psychotic violent (n = 24) as well as healthy control subjects (n = 24). Shared and distinct volumetric abnormalities were probed by analysis of variance with the factors violence (non-violent versus violent) and diagnosis (non-psychotic versus psychotic), adjusted for substance abuse, age, academic achievement and negative psychotic symptoms. Patients showed elevated vCSF volume, smaller left hippocampus and smaller left thalamus volumes. This was particularly the case for non-violent individuals diagnosed with schizophrenia. Furthermore, patients had reduction in right thalamus size. With regard to left amygdala, we found an interaction between violence and diagnosis. More specifically, we report a double dissociation with smaller amygdala size linked to violence in non-psychotic individuals, while for psychotic patients smaller size was linked to non-violence. Importantly, the double dissociation appeared to be mostly driven by substance abuse. Overall, we found widespread morphometric abnormalities in subcortical regions in schizophrenia. No evidence for shared volumetric abnormalities in individuals with a history of violence was found. Finally, left amygdala abnormalities in non-psychotic violent individuals were largely accounted for by substance abuse. This might be an indication that the association between amygdala reduction and violence is mediated by substance abuse. Our results indicate the importance of structural abnormalities in aggressive individuals. [ABSTRACT FROM AUTHOR]

We assessed the role of alpha-band oscillatory activity during a task-switching design that required participants to switch between an auditory and a visual task, while task-relevant audiovisual inputs were simultaneously presented. Instructional cues informed participants which task to perform on a given trial and we assessed alpha-band power in the short 1.35-s period intervening between the cue and the task-imperative stimuli, on the premise that attentional biasing mechanisms would be deployed to resolve competition between the auditory and visual inputs. Prior work had shown that alpha-band activity was differentially deployed depending on the modality of the cued task. Here, we asked whether this activity would, in turn, be differentially deployed depending on whether participants had just made a switch of task or were being asked to simply repeat the task. It is well established that performance speed and accuracy are poorer on switch than on repeat trials. Here, however, the use of instructional cues completely mitigated these classic switch-costs. Measures of alpha-band synchronisation and desynchronisation showed that there was indeed greater and earlier differential deployment of alpha-band activity on switch vs. repeat trials. Contrary to our hypothesis, this differential effect was entirely due to changes in the amount of desynchronisation observed during switch and repeat trials of the visual task, with more desynchronisation over both posterior and frontal scalp regions during switch-visual trials. These data imply that particularly vigorous, and essentially fully effective, anticipatory biasing mechanisms resolved the competition between competing auditory and visual inputs when a rapid switch of task was required. [ABSTRACT FROM AUTHOR]

Individuals with schizophrenia are more prone to violent behaviors than the general population. It is increasingly recognized that processing of emotionally valenced stimuli is impaired in schizophrenia, a deficit that may play a role in aggressive behavior. Our goal was to establish whether patients with a history of violence would show more severe deficits in processing emotionally valenced inputs than non-violent patients. Using event-related potentials, we measured how early during processing of emotional valence, evidence of aberrant function was observed. A total of 42 schizophrenia patients (21 with history of violence; 21 without) and 28 healthy controls were tested. Participants performed an inhibitory control task, making speeded responses to pictorial stimuli. Pictures occasionally repeated twice and participants withheld responses to these repeats. Valenced pictures from the International Affective Picture System were presented. Results in controls showed modulations during the earliest phases of sensory processing (<100 ms) for negatively valenced pictures. A cascade of modulations ensued, involving sensory and perceptual processing stages. In contrast, neither schizophrenia group showed early differentiation. Non-violent patients showed earliest modulations beginning ∼150 ms. For violent patients, however, earliest modulations were further delayed and highly attenuated. The current study reveals sensory–perceptual processing dysfunction for negatively valenced inputs, which is particularly pronounced in aggressive patients. [ABSTRACT FROM AUTHOR]

High-density electrical mapping of event-related potentials was used to investigate the neural processes that permit some elderly subjects to preserve high levels of executive functioning. Two possibilities pertain: (1) high-performance in elderly subjects is underpinned by similar processing mechanisms to those seen in young adults; that is, these individuals display minimal functional decay across the lifespan, or (2) preserved function relies on successfully recruiting and amplifying control processes to compensate for normal sensory-perceptual decline with age. Fifteen young and nineteen elderly participants, the latter split into groups of high and low performers, regularly alternated between a letter and a number categorization task, switching between tasks every third trial (AAA-BBB-AAA...). This allowed for interrogation of performance during switch, repeat, and preparatory pre-switch trials. Robust effects of age were observed in both frontal and parietal components of the task-switching network. Greatest differences originated over prefrontal regions, with elderly subjects generating amplified, earlier, and more differentiated patterns of activity. This prefrontal amplification was evident only in high-performing (HP) elderly, and was strongest on pre-switch trials when participants prepared for an upcoming task-switch. Analysis of the early transient and late sustained activity using topographic analyses and source localization collectively supported a unique and elaborated pattern of activity across frontal and parietal scalp in HP-elderly, wholly different to that seen in both young and low-performing elderly. On this basis, we propose that preserved executive function in HP-elderly is driven by large-scale recruitment and enhancement of prefrontal cortical mechanisms. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Segregation of auditory inputs into meaningful acoustic groups is a key element of auditory scene analysis. Previously, we showed that two interwoven sets of tones differing widely along multiple feature dimensions (duration, pitch and location) were pre-attentively separated into different groups, and that tones separated in this manner did not elicit the mismatch negativity component with respect to each other. Grouping was studied with human subjects using a stimulus rate too slow to induce streaming. Here, we varied the separation of tone sequences along a single feature dimension, i.e. frequency. Frequency differences were either 24 Hz (small) or 1054 Hz (large). Two relatively slow stimulus rates were used (2.7 or 1 tone/s) to explicitly investigate grouping outside the so-called ‘streaming effect’, which requires rates of about 4 tones/s or faster. Two tones were presented in a quasi-random manner with embedded trains of one to four identical tones in a row. Deviants were defined as frequency switches after trains of four identical tones. Mismatch negativity was only elicited for small frequency switches at the slower stimulation rate. The data indicate that pre-attentive grouping of tones occurred when the frequency difference that separated them was large, regardless of stimulation rate. For small frequency differences, inputs were only grouped separately when the stimulation rate was relatively fast. [ABSTRACT FROM AUTHOR]

To promote preattenive grouping of two sets of tones, one set of tones with a combination of frequency and ear of delivery was intermixed with another set of tones with a different combination of frequency and ear of delivery. The ERPs elicited by tones delivered to one ear that were preceded by three or four tones delivered in a row to the other ear were associated with an enhanced N1, due to the changes in frequency and ear of delivery with respect to the immediately preceding tones. However, no mismatch negativity (MMN) was obtained, even though these tones differed from the previious tones on the two dimensions of frequency and ear of delivery. The data were interpreted to signify that preattentively grouped sets of tones do not elicit MMN with respect to one another. This implies that once acoustic input has been preattentively grouped, the MMN system is dedicated to detecting changes that occur within but not between preattentively grouped stimuli. [ABSTRACT FROM AUTHOR]