44 research outputs found
Shifts in Gamma PhaseâAmplitude Coupling Frequency from Theta to Alpha Over Posterior Cortex During Visual Tasks
The phase of ongoing theta (4â8 Hz) and alpha (8â12 Hz) electrophysiological oscillations is coupled to high gamma (80â150 Hz) amplitude, which suggests that low-frequency oscillations modulate local cortical activity. While this phaseâamplitude coupling (PAC) has been demonstrated in a variety of tasks and cortical regions, it has not been shown whether task demands differentially affect the regional distribution of the preferred low-frequency coupling to high gamma. To address this issue we investigated multiple-rhythm theta/alpha to high gamma PAC in two subjects with implanted subdural electrocorticographic grids. We show that high gamma amplitude couples to the theta and alpha troughs and demonstrate that, during visual tasks, alpha/high gamma coupling preferentially increases in visual cortical regions. These results suggest that low-frequency phase to high-frequency amplitude coupling is modulated by behavioral task and may reflect a mechanism for selection between communicating neuronal networks
Evaluation of Life Events in Major Depression: Assessing Negative Emotional Bias
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137243/1/cpp2033.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137243/2/cpp2033_am.pd
Worth the âEEfRTâ? The Effort Expenditure for Rewards Task as an Objective Measure of Motivation and Anhedonia
Background: Of the putative psychopathological endophenotypes in major depressive disorder (MDD), the anhedonic subtype is particularly well supported. Anhedonia is generally assumed to reflect aberrant motivation and reward responsivity. However, research has been limited by a lack of objective measures of reward motivation. We present the Effort-Expenditure for Rewards Task (EEfRT or ââeffortââ), a novel behavioral paradigm as a means of exploring effort-based decision-making in humans. Using the EEfRT, we test the hypothesis that effort-based decision-making is related to trait anhedonia. Methods/Results: 61 undergraduate students participated in the experiment. Subjects completed self-report measures of mood and trait anhedonia, and completed the EEfRT. Across multiple analyses, we found a significant inverse relationship between anhedonia and willingness to expend effort for rewards. Conclusions: These findings suggest that anhedonia is specifically associated with decreased motivation for rewards, and provide initial validation for the EEfRT as a laboratory-based behavioral measure of reward motivation and effort-base
Neuroimaging the consciousness of self: Review, and conceptual-methodological framework
We review neuroimaging research investigating self-referential processing (SRP), that is, how we respond to stimuli that reference ourselves, prefaced by a lexical-thematic analysis of words indicative of âself-feelingsâ. We consider SRP as occurring verbally (V-SRP) and non-verbally (NV-SRP), both in the controlled, âtop-downâ form of introspective and interoceptive tasks, respectively, as well as in the âbottom-upâ spontaneous or automatic form of âmind wanderingâ and âbody wanderingâ that occurs during resting state. Our review leads us to outline a conceptual and methodological framework for future SRP research that we briefly apply toward understanding certain psychological and neurological disorders symptomatically associated with abnormal SRP. Our discussion is partly guided by William Jamesâ original writings on the consciousness of self
The sexually dimorphic impact of maltreatment on cortical thickness, surface area and gyrification
CONTROL OF METALLURGICAL PROCESSES IN THE PRODUCTION OF CASTINGS OF ALUMINUM-BASED ALLOYS, USING COMPUTER ANALYSIS DATA
The mathematical models and results of classification of alloys on the basis of aluminum on the specified brand with use of parameters of the computer thermal analysis are presented
Individual EEG measures of attention, memory, and motivation predict population level TV viewership and Twitter engagement.
Television (TV) programming attracts ever-growing audiences and dominates the cultural zeitgeist. Viewership and social media engagement have become standard indices of programming success. However, accurately predicting individual episode success or future show performance using traditional metrics remains a challenge. Here we examine whether TV viewership and Twitter activity can be predicted using electroencephalography (EEG) measures, which are less affected by reporting biases and which are commonly associated with different cognitive processes. 331 participants watched an hour-long episode from one of nine prime-time shows (~36 participants per episode). Three frequency-based measures were extracted: fronto-central alpha/beta asymmetry (indexing approach motivation), fronto-central alpha/theta power (indexing attention), and fronto-central theta/gamma power (indexing memory processing). All three EEG measures and the composite EEG score significantly correlated across episode segments with the two behavioral measures of TV viewership and Twitter volume. EEG measures explained more variance than either of the behavioral metrics and mediated the relationship between the two. Attentional focus was integral for both audience retention and Twitter activity, while emotional motivation was specifically linked with social engagement and program segments with high TV viewership. These findings highlight the viability of using EEG measures to predict success of TV programming and identify cognitive processes that contribute to audience engagement with television shows
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Temporal Dynamics and Response Modulation across the Human Visual System in a Spatial Attention Task An ECoG Study
The selection of behaviorally relevant information from cluttered visual scenes (often referred to as "attention") is mediated by a cortical large-scale network consisting of areas in occipital, temporal, parietal, and frontal cortex that is organized into a functional hierarchy of feedforward and feedback pathways. In the human brain, little is known about the temporal dynamics of attentional processing from studies at the mesoscopic level of electrocorticography (ECoG), that combines millisecond temporal resolution with precise anatomical localization of recording sites. We analyzed high-frequency broadband responses (HFB) responses from 626 electrodes implanted in 8 epilepsy patients who performed a spatial attention task. Electrode locations were reconstructed using a probabilistic atlas of the human visual system. HFB responses showed high spatial selectivity and tuning, constituting ECoG response fields (RFs), within and outside the topographic visual system. In accordance with monkey physiology studies, both RF widths and onset latencies increased systematically across the visual processing hierarchy. We used the spatial specificity of HFB responses to quantitatively study spatial attention effects and their temporal dynamics to probe a hierarchical top-down model suggesting that feedback signals back propagate the visual processing hierarchy. Consistent with such a model, the strengths of attentional modulation were found to be greater and modulation latencies to be shorter in posterior parietal cortex, middle temporal cortex and ventral extrastriate cortex compared with early visual cortex. However, inconsistent with such a model, attention effects were weaker and more delayed in anterior parietal and frontal cortex.</p