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In the face of multiple sensory streams, there may be competition for processing resources in multimodal cortical area devoted to establishing representations. In such cases, alpha oscillations may serve to maintain the relevant... more
In the face of multiple sensory streams, there may be competition for processing resources in multimodal cortical area devoted to establishing representations. In such cases, alpha oscillations may serve to maintain the relevant representations and protect them from interference, whereas theta band activity may facilitate their updating when needed. It can be hypothesized that these oscillations would differ in response to an auditory stimulus when the eyes are open or closed, as intermodal resource competition may be more prominent in the former than in the latter case. Across two studies we investigated the role of alpha and theta power in multimodal competition using an auditory task with the eyes open and closed, respectively enabling and disabling visual processing in parallel with the incoming auditory stream. In a passive listening task (Study 1a), we found alpha suppression following a pip tone with both eyes open and closed, but subsequent alpha enhancement only with closed eyes. We replicated this eyes-closed alpha enhancement in an independent sample (Study 1b). In an active auditory oddball task (Study 2), we again observed the eyes open/eyes closed alpha pattern found in Study 1 and also demonstrated that the more attentionally demanding oddball trials elicit the largest oscillatory effects. Theta power did not interact with eye status in either study. We propose a hypothesis to account for the findings in which alpha may be endemic to multimodal cortical areas in addition to visual ones.
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In the present study, we examined whether the use of partial information for response preparation depends on the utility of that partial information for meeting task demands. Using a choice/Nogo task, the utility of the partial... more
In the present study, we examined whether the use of partial information for response preparation depends on the utility of that partial information for meeting task demands. Using a choice/Nogo task, the utility of the partial information was varied by manipulating the proportion of Go relative to Nogo signals, and preliminary response preparation was indexed by the degree of lateralized readiness potential (LRP) activity on Nogo trials. The Nogo LRP was clearly present when Go probability was high (67% Go) and, to a lesser extent, when Go and Nogo signals were equiprobable. However, the Nogo LRP disappeared when the probability of a Go signal was low (25% Go). This pattern of results supports the hypothesis that response preparation will be based on partial stimulus information only when the information has significant utility in the context of the overall task requirements.
Research Interests: Psychology, Psychophysiology, Medicine, Probability, Biological Sciences, and 15 moreEvoked Potentials, Humans, Cerebral Cortex, Cues, Female, Male, Reaction Time, Partial Information, Adult, Analysis of Variance, Time Factors, Functional Laterality, Psychomotor Performance, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Neuroscience, Psychology, Electrophysiology, Motor Control, Medicine, and 15 morePathophysiology, Brain, Humans, Movement, Female, Male, Electromyography, Choice reaction time, Aged, Middle Aged, Choice Behavior, Parkinson Disease, Contingent Negative Variation, photic stimulation, and Medical and Health Sciences
Research Interests: Cognitive Science, Electrophysiology, Cognition, Electroencephalography, Medicine, and 15 moreLinear models, Humans, Cues, Female, Male, Eye Movements, Electromyography, Choice reaction time, Motor Preparation, American Psychological Association, Adult, Analysis of Variance, Choice Behavior, Contingent Negative Variation, and Functional Laterality
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Research Interests: Physics, Biomedical Engineering, Magnetic Resonance Imaging, Adolescent, Medicine, and 15 moreBrain Mapping, Humans, Female, Male, Detectors, Diagnostic Imaging, Middle Aged, Image Enhancement, Adult, Optics and Photonics, Reproducibility of Results, Optical Filters, Sensitivity and Specificity, Electrical And Electronic Engineering, and Low Pass Filters
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Research Interests: Computer Science, Physics, Magnetic Resonance Imaging, Near Infrared, Medicine, and 15 moreOptical Imaging, Brain Mapping, Humans, Female, Neuroimage, Male, Optical Properties, Adult, Hand, Light Propagation, Median Nerve, optical recording, Magnetic resonance image, Medical and Health Sciences, and Electric stimulation
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Research Interests: Psychology, Perception, Psychophysiology, Auditory Perception, Audiology, and 14 moreMedicine, Biological Sciences, Humans, Female, Male, Feedback, Latent Inhibition, Adult, Auditory evoked Potentials, Attenuation, Refractoriness, Acoustic Stimulation, Psychology and Cognitive Sciences, and Medical and Health Sciences
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This chapter discusses a series of experiments in which a pre‐cue signals which of several dimensions of an upcoming stimulus is relevant on a particular trial. The event‐related optical signal is used to follow the time course of... more
This chapter discusses a series of experiments in which a pre‐cue signals which of several dimensions of an upcoming stimulus is relevant on a particular trial. The event‐related optical signal is used to follow the time course of activity in different cortical areas after the pre‐cue. The data show two types of preparatory brain activities: (1) a domain‐general set, involving first the left middle frontal gyrus and then the lateral parietal cortex; and (2) a domain‐specific set, involving secondary sensory and motor areas of the brain. These data suggest that task preparation involves the operation of a hierarchical, top‐down system.
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Research Interests:
The broadband shape of the EEG spectrum, summarized using a 1/fxfunction, is thought to reflect the balance between excitation and inhibition in cortical regions (E:I balance). This balance is an important characteristic of neural... more
The broadband shape of the EEG spectrum, summarized using a 1/fxfunction, is thought to reflect the balance between excitation and inhibition in cortical regions (E:I balance). This balance is an important characteristic of neural circuits and could inform studies of aging, as older adults show a relative inhibitory activity deficit. Thus far, no studies have leveraged the event-related temporal dynamics of 1/fxactivity to better understand the phases of information processing, especially in the context of aging. Here, for the first time, we examined variations of this activity during the foreperiod of a cued flanker task in younger (YA) and older adults (OA), with picture cues varying in task relevance, relative novelty, and valence. We report a biphasic change in the spectral exponent (corresponding to negative slopes in log-log space) after cue presentation, independent of cue-elicited ERPs, with an initial period of increased negativity (indicating cortical inhibition, similar i...
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It is well-established that younger adults prioritize information accrued during different stages of stimulus evaluation ("early" versus "late") to optimize performance. The extent to which older adults flexibly adjust... more
It is well-established that younger adults prioritize information accrued during different stages of stimulus evaluation ("early" versus "late") to optimize performance. The extent to which older adults flexibly adjust their processing strategies, however, is largely unexplored. Twenty-four younger and twenty-four older participants completed a cued flanker task in which one of three cues, indicating the probability that a congruent array would appear (75%, 50%, or 25%), was presented on each trial. Behavioral and ERP (CNV, LRP, N2, and P3b) analyses allowed us to infer cue-driven changes in strategy selection. Results indicate that when both younger and older adults expected an incongruent array, they prioritized late, target information, resulting in a decreased susceptibility to the performance-impairing effect of distractors, extending the conclusions of Gratton et al. (1992) to older adults and supporting the claim that strategic control remains largely intact during healthy aging.
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Research Interests:
Aging is accompanied by widespread changes in brain tissue. Here, we hypothesized that head tissue opacity to near-infrared light provides information about the health status of the brain’s cortical mantle. In diffusive media such as the... more
Aging is accompanied by widespread changes in brain tissue. Here, we hypothesized that head tissue opacity to near-infrared light provides information about the health status of the brain’s cortical mantle. In diffusive media such as the head, opacity is quantified through the Effective Attenuation Coefficient (EAC), which is proportional to the geometric mean of the absorption and reduced scattering coefficients. EAC is estimated by the slope of the relationship between source–detector distance and the logarithm of the amount of light reaching the detector (optical density). We obtained EAC maps across the head in 47 adults (age range 18–75 years), using a high-density dual-wavelength optical system. We correlated regional and global EAC measures with demographic, neuropsychological, structural and functional brain data. Results indicated that EAC values averaged across wavelengths were strongly associated with age-related changes in cortical thickness, as well as functional and ne...
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Research Interests: Neuroscience, Psychology, Cognitive Science, Magnetic Resonance Imaging, Aging, and 15 moreDiffusion Tensor Imaging, Medicine, Memory, Hippocampus, Evoked Potentials, Humans, Female, Male, Aged, Middle Aged, Neuropsychologia, Fractional Anisotropy, Neurosciences, Hippocampal formation, and Neuropsychological Tests
In the first use of the event-related optical signal as a brain imaging tool for the study of long-term memory, we examined relational or associative aspects of memory, widely presumed to involve the interplay among multiple brain regions... more
In the first use of the event-related optical signal as a brain imaging tool for the study of long-term memory, we examined relational or associative aspects of memory, widely presumed to involve the interplay among multiple brain regions in representing and reactivating different elements of a given event. Here, we found that a brain region known to be involved in face processing (the posterior superior temporal sulcus) was active not only when viewing faces during the study phase but also when viewing scenes at test that, through prior learning, were associated with specific faces. These findings, demonstrating the activation of stimulus-specific cortical regions in the absence of stimuli of that type, based on learned relations, reveal cortical substrates of the reactivation of relational memories.
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Cognitive aging theories emphasize the decrease in efficiency of inhibitory processes and attention control in normal aging, which, in turn, may result in reduction of working memory function. Accordingly, some of these age-related... more
Cognitive aging theories emphasize the decrease in efficiency of inhibitory processes and attention control in normal aging, which, in turn, may result in reduction of working memory function. Accordingly, some of these age-related changes may be due to faster sensory memory decay or to inefficient filtering of irrelevant sensory information (sensory gating). Here, event-related brain potentials and the event-related optical signal were recorded in younger and older adults passively listening to tone trains. To determine whether age differentially affects decay of sensory memory templates over short intervals, trains were separated by delays of either 1 or 5 sec. To determine whether age affects the suppression of responses to unattended repeated stimuli, we evaluated the brain activity elicited by successive train stimuli. Some trains started with a shorter-duration stimulus (deviant trains). Results showed that both electrical and optical responses to tones were more persistent wi...
Research Interests: Cognitive Science, Computer Science, Electrophysiology, Audiology, Cognition, and 15 moreElectroencephalography, Cognitive Neuroscience, Comparative Study, Attentional Control, Cognitive Aging, Cognitive, Brain Mapping, Brain, Age, Aged, Adult, Age Factors, Auditory evoked Potentials, Contingent Negative Variation, and Acoustic Stimulation
. An important function of working memory is the integration of incoming information into an appropriate model of the contextual situation. We hypothesized that individual variability in working-memory function (estimated using Engle’s... more
. An important function of working memory is the integration of incoming information into an appropriate model of the contextual situation. We hypothesized that individual variability in working-memory function (estimated using Engle’s operation-span measure) may lead to differential reactivity to a changing context. We recorded event-related brain potentials (ERPs) and reaction-time measures to stimuli embedded in long stimulus series (two auditory discrimination tasks), and examined the participants’ responses in relation to how the current stimuli fit with the context generated by the previous stimuli. In both tasks, participants with low working-memory span scores showed larger brain responses as a function of variations in the local stimulus sequence than participants with high span scores. These data suggest that the low working-memory span group is more affected by the local stimulus sequence than the high span group, possibly because they are more easily swayed by ongoing changes and are therefore less capable of maintaining their attention on the overall sequence.
Research Interests: Psychology, Cognitive Psychology, Cognitive Science, Experimental Psychology, Attention, and 15 moreWorking Memory, Adolescent, Medicine, Individual Differences, Memory, Evoked Potentials, Humans, Female, Male, Reaction Time, Memory Span, Adult, Individual Difference, Neuropsychological Tests, and mass Screening
The resting-state human EEG power spectrum is dominated by alpha (8-12 Hz) and theta (4-8Hz) oscillations, and also includes non-oscillatory broadband activity inversely related to frequency (1/f activity). Gratton (2018) proposed that... more
The resting-state human EEG power spectrum is dominated by alpha (8-12 Hz) and theta (4-8Hz) oscillations, and also includes non-oscillatory broadband activity inversely related to frequency (1/f activity). Gratton (2018) proposed that alpha and theta oscillations are both related to cognitive control function, though in a complementary manner. Alpha activity is hypothesized to facilitate the maintenance of representations, such as task sets in preparation for expected task conditions. In contrast, theta activity would facilitate changes in representations, such as the updating of task sets in response to unpredicted task demands. Therefore, theta should be related to reactive control (which may prompt changes in task representations), while alpha may be more relevant to proactive control (which implies the maintenance of current task representations). Less is known about the possible relationship between 1/f activity and cognitive control, which was analyzed here in an exploratory ...
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When analyzing visual scenes, it is sometimes important to determine the relevant "grain" size. Attention control mechanisms may help direct our processing to the intended grain size. Here we used the event-related optical... more
When analyzing visual scenes, it is sometimes important to determine the relevant "grain" size. Attention control mechanisms may help direct our processing to the intended grain size. Here we used the event-related optical signal, a method possessing high temporal and spatial resolution, to examine the involvement of brain structures within the dorsal attention network (DAN) and the visual processing network (VPN) in preparation for the appropriate level of analysis. Behavioral data indicate that the small features of a hierarchical stimulus (local condition) are more difficult to process than the large features (global condition). Consistent with this finding, cues predicting a local trial were associated with greater DAN activation. This activity was bilateral but more pronounced in the left hemisphere, where it showed a frontal-to-parietal progression over time. Furthermore, the amount of DAN activation, especially in the left hemisphere and in parietal regions, was pre...
Research Interests: Cognitive Science, Computer Science, Attention, Cognitive Neuroscience, Adolescent, and 15 moreMedicine, Optical Imaging, Brain Mapping, Brain, Humans, Cues, Female, Male, Adult, Neural pathways, Neurosciences, Functional Laterality, Neuropsychological Tests, photic stimulation, and attention network
The way our brain reacts to sensory stimulation may provide important clues about higher-level cognitive function and its operation. Here we show that short-latency... more
The way our brain reacts to sensory stimulation may provide important clues about higher-level cognitive function and its operation. Here we show that short-latency (< 200 ms) sensory cortical responses elicited by visual and auditory stimuli differ dramatically between subjects with high and low working-memory span, as well as between subjects scoring high and low on a fluid intelligence test. Our findings also suggest that this link between sensory responses and complex cognitive tasks is modality specific (visual sensory measures correlate with visuo-spatial tasks whereas auditory sensory measures correlate with verbal tasks). We interpret these findings as indicating that people's effectiveness in controlling attention and gating sensory information is a critical determinant of individual differences in complex cognitive abilities.
Research Interests: Psychology, Cognitive Science, Intelligence, Auditory Perception, Cognition, and 15 moreAttention, Medicine, Evoked Potentials, Humans, Cerebral Cortex, Female, Male, Memory Span, Adult, Auditory Cortex, Neurosciences, Predictive value of tests, Acoustic Stimulation, Neuropsychological Tests, and photic stimulation
The significance of stimuli is linked not only to their nature but also to the sequential structure in which they are embedded, which gives rise to contingency rules. Humans have an extraordinary ability to extract and exploit these... more
The significance of stimuli is linked not only to their nature but also to the sequential structure in which they are embedded, which gives rise to contingency rules. Humans have an extraordinary ability to extract and exploit these rules, as exemplified by the role of grammar and syntax in language. To study the brain representations of contingency rules, we recorded ERPs and event-related optical signal (EROS; which uses near-infrared light to measure the optical changes associated with neuronal responses). We used sequences of high- and low-frequency tones varying according to three contingency rules, which were orthogonally manipulated and differed in processing requirements: A Single Repetition rule required only template matching, a Local Probability rule required relating a stimulus to its context, and a Global Probability rule could be derived through template matching or with reference to the global sequence context. ERP activity at 200–300 msec was related to the Single Re...
Research Interests: Cognitive Science, Computer Science, Acoustics, Auditory Perception, Electroencephalography, and 15 moreCognitive Neuroscience, Near Infrared, Medicine, Low Frequency, Information Processing, Brain Mapping, Brain, Humans, Female, Male, Adult, Analysis of Variance, Choice Behavior, Acoustic Stimulation, and Contextual Information
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This chapter discusses a series of experiments in which a pre‐cue signals which of several dimensions of an upcoming stimulus is relevant on a particular trial. The event‐related optical signal is used to follow the time course of... more
This chapter discusses a series of experiments in which a pre‐cue signals which of several dimensions of an upcoming stimulus is relevant on a particular trial. The event‐related optical signal is used to follow the time course of activity in different cortical areas after the pre‐cue. The data show two types of preparatory brain activities: (1) a domain‐general set, involving first the left middle frontal gyrus and then the lateral parietal cortex; and (2) a domain‐specific set, involving secondary sensory and motor areas of the brain. These data suggest that task preparation involves the operation of a hierarchical, top‐down system.
Research Interests:
Coordination between networks of brain regions is important for optimal cognitive performance, especially in attention demanding tasks. With the event-related optical signal (a measure of changes in optical scattering because of neuronal... more
Coordination between networks of brain regions is important for optimal cognitive performance, especially in attention demanding tasks. With the event-related optical signal (a measure of changes in optical scattering because of neuronal activity) we can characterize rapidly evolving network processes by examining the millisecond-scale temporal correlation of activity in distinct regions during the preparatory period of a response mode switching task. Participants received a precue indicating whether to respond vocally or manually. They then saw or heard the letter “L” or “R,” indicating a “left” or “right” response to be implemented with the appropriate response modality. We employed lagged cross-correlations to characterize the dynamic connectivity of preparatory processes. Our results confirmed coupling of frontal and parietal cortices and the trial-dependent relationship of the right frontal cortex with response preparation areas. The frontal-to-modality-specific cortex cross-co...
Research Interests: Engineering, Neuroscience, Psychology, Cognitive Science, Computer Science, and 15 moreCognitive Neuroscience, Adolescent, Medicine, Optical Imaging, Executive Function, Humans, Female, Male, Adult, Parietal Lobe, Time Factors, Neurosciences, Frontal Lobe, Psychomotor Performance, and Neuropsychological Tests
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Preterm infants (born at 24–34 weeks of gestational age) suffer from a high incidence of neurological complications. Cerebrovascular lesions (intraventricular hemorrhages, IVH, and ischemic injury) due to the immaturity of the vascular... more
Preterm infants (born at 24–34 weeks of gestational age) suffer from a high incidence of neurological complications. Cerebrovascular lesions (intraventricular hemorrhages, IVH, and ischemic injury) due to the immaturity of the vascular system and its inability to adapt to the extra-uterine environment are the major causes of adverse neurological outcomes. We investigated the feasibility of assessing cerebrovascular status in preterm infants using a novel non-invasive optical procedure, pulse-DOT, usable within the incubator. Pulse-DOT, validated in adults, provides estimates of cerebral arterial status based on optical measurements of the pulse wave. These measurements are taken with a high-density optode montage and provide accurate spatial and temporal information. We found that two pulse parameters (pulse relaxation function, PReFx, and pulse rise time, PRT) in the investigated frontotemporal region, correlated with infant’s age at recording, indexing cerebrovascular development....
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Near infrared (NIR) light has been widely used for measuring changes in hemoglobin concentration in the human brain (functional NIR spectroscopy, fNIRS). fNIRS is based on the differential measurement and estimation of absorption... more
Near infrared (NIR) light has been widely used for measuring changes in hemoglobin concentration in the human brain (functional NIR spectroscopy, fNIRS). fNIRS is based on the differential measurement and estimation of absorption perturbations, which, in turn, are based on correctly estimating the absolute parameters of light propagation. To do so, it is essential to accurately characterize the baseline optical properties of tissue (absorption and reduced scattering coefficients). However, because of the diffusive properties of the medium, separate determination of absorption and scattering across the head is challenging. The effective attenuation coefficient (EAC), which is proportional to the geometric mean of absorption and reduced scattering coefficients, can be estimated in a simpler fashion by multidistance light decay measurements. EAC mapping could be of interest for the scientific community because of its absolute information content, and because light propagation is govern...