Journal of Cognitive Neuroscience最新文献

The present study tested central predictions of our conceptual framework "distraction under competition" (DUC), including the extent to which semantic processing of emotional cues triggers competitive interactions among multiple stimuli. In situations in which stimuli compete for attentional processing resources, DUC proposes a time-delayed, biphasic process: An early feedforward gain elicited by the emotional distractor that needs to cross a certain threshold to trigger subsequent competitive interactions that results in the withdrawal of resources from a concurrent task stimulus. Competition was implemented by presenting naturalistic images in the background of a taxing foreground task. One emotional image was embedded in a stream of neutral images to trigger semantic categorization. The image stream and foreground task were frequency-tagged, thereby eliciting distinct steady-state visual evoked potentials (SSVEPs), allowing us to analyze the respective amplitude time-courses that provide temporal dynamics of the shifting of attentional resources in competitive interactions. We replicated a significant enhancement of SSVEP amplitudes for emotional pictures that was greater for pleasant compared with unpleasant pictures, commencing at about 180 msec. The SSVEP amplitude driven by the foreground task was reduced from about 300 msec after the onset of a pleasant image only. Results support the biphasic time-delayed nature of resource allocation and suggest that the initial feedforward gain evoked by salient distractors may trigger subsequent competitive interactions. Formal modeling analyses showed a better fit of a biphasic process as proposed by DUC compared with a standard model based on divisive normalization.

Variability in visual contrast detection has been linked to prestimulus alpha oscillations, yet whether modulating alpha power can causally influence perception remains unclear. In this sham-controlled, single-blinded, within-participant study, we applied transcranial alternating current stimulation (tACS) at individual alpha frequency over the occipital cortex while participants performed a near-threshold visual contrast detection task. Under sham conditions, correlation analyses indicated that higher prestimulus alpha power predicted elevated visual contrast thresholds (VCTs), particularly in the time intervals immediately preceding stimulus onset. When tACS was applied, we observed a modest and temporally selective enhancement of occipital prestimulus alpha power, primarily restricted to specific prestimulus intervals within one experimental block. Importantly, this localized alpha enhancement did not translate into corresponding improvements in visual contrast detection performance. Instead, participants' VCT remained statistically similar between sham and tACS conditions. These findings suggest that although tACS can reliably modulate alpha power, simply elevating occipital alpha amplitude may not be sufficient to alter perceptual outcomes. Factors such as the precise timing of alpha oscillations, the extent and duration of neural modulation, and the interaction with other neural or cognitive processes may be critical for producing measurable behavioral effects. Our findings underscore the nuanced relationship between alpha oscillations and perception, highlight the challenge of establishing direct causal links using neuromodulation, and emphasize the need for more comprehensive stimulation protocols, extended EEG recordings, and investigations into interactions with other confounding factors.

Our theories stemming from perception, memory, and neurology came to similar and complementary conclusions regarding the mechanism of conscious brain processes. We suggest that consciousness is the explicit memory of past events or the general cognitive capacity to simulate events, whether used to consciously remember the past, experience the present, or imagine the future. Perceptual mechanisms may represent an ongoing, editable, "best estimate" of our past, present, and future. In fact, at milliseconds to seconds timescales, there may be no hard boundary between perception and memory. We view conscious perceptions, decisions, and actions as simulations of prior unconscious sensations, decisions, and actions. As consciousness is the simulation/explicit memory of past events, the neural correlates of consciousness may therefore be the neural correlates of simulation/explicit memory. Because the default mode network, along with the frontoparietal control and salience networks, is critical for simulation/explicit memory, it is likely critical for normal consciousness. Each aspect of consciousness (e.g., visual, auditory, decision-making) may have its own neural correlate. Lastly, by combining our three theories, our synthesis can shed light on conscious perceptions, decisions, and actions in timescales ranging from subsecond to seconds, minutes, days, months, and years.

Many people have experienced being so engrossed in an activity that they lost awareness of their surroundings, had difficulty stopping the activity, and found their perception of time condensed. This experience is known colloquially as hyperfocus. There is a small but quickly growing body of peer-reviewed research on hyperfocus. Most of this research is dependent upon self-report measures with little consideration given to the neurocognitive mechanisms responsible for hyperfocus. To advance hyperfocus research, this nascent field must move beyond self-report to uncover the neurocognitive mechanisms underlying this not-uncommon experience. On the basis of the reported phenomenology of hyperfocus, we propose that this experience frequently stems from a fracturing of prefrontal control hierarchies, which reduces the ability of higher-order contextual information to govern the contents of thought and action. More precisely, we propose that diminished functioning of fronto-striatal-thalamic loops, brought about by changes in the ascending arousal system, leads to a decoupling of intermediate-level contextual information (e.g., the activity one is hyperfocusing on) from the regulation of higher-order contexts.

N,N-dimethyltryptamine (DMT) is a fast-acting psychedelic drug that induces a radical reorganization of conscious contents and brain dynamics. However, our understanding of how brain dynamics support psychedelic-induced conscious states remains unclear. We therefore present a repeated-measures dose-dependent study of the subjective and neural dynamics induced through DMT under naturalistic conditions. Nineteen participants received either a 20-mg or a 40-mg dose of freebase DMT across two sessions in a blinded, counterbalanced order. Electroencephalography data and time-resolved measures of subjective experience (Temporal Experience Tracing) were collected. Both doses of DMT induced rapid changes in experience dimensions, with the 40-mg dose inducing more extreme visual hallucinations and emotionally intense experiences. A variety of neural features were computed on the electroencephalography data, with oscillatory alpha power and permutation entropy most strongly associated with continuous subjective experience dimensions. Strikingly, Lempel-Ziv complexity, previously hailed as a robust correlate of subjective experiences within the psychedelic state, yielded the weakest associations. These findings suggest that the relationship between neural complexity and phenomenology in psychedelic states is less clear than originally hypothesized.

Extensive research shows that charitable framing (gain vs. loss) shapes donation intentions. However, questions persist concerning how emotional context interacts with framing effects to impact both donation intentions and subsequent evaluations of outcomes. The present study combined electroencephalography and multivariate pattern analysis to investigate neural responses to gain- and loss-framed charitable appeals under neutral and negative emotions. Behaviorally, negative emotions reversed the charitable framing effect observed under a neutral emotional context, as gain-framed appeals elicited a greater donation intention than loss-framed appeals. Neurologically, during the donation stage, donation proposals following gain-framed (vs. loss-framed) appeals under a negative context produced larger N2 and P3 amplitudes. Multivariate pattern analysis demonstrated robust decoding of framing types from electroencephalography signals throughout early to late processing stages, independent of whether the emotional context was neutral or negative. In the feedback stage, the FRN effect (larger FRN for negative feedback than positive feedback) was absent in gain-framed conditions but emerged in loss-framed conditions under a negative emotional context. Time-frequency analysis confirmed that framing effects on outcome evaluation are emotion sensitive. The current findings extend previous research by demonstrating that the charitable framing effect on donation behavior and outcome evaluation depends on the emotional context.

Transitive inference (TI) is a cognitive process in which decisions are guided by internal representations of abstract relationships. Although the mechanisms underlying transitive learning have been well studied, the dynamics of the decision-making process during learning and inference remain less clearly understood. In this study, we investigated whether a modeling framework traditionally applied to perceptual decision-making-the drift diffusion model (DDM)-can account for performance in a TI transfer task involving rapid decisions that deviate from standard accuracy and response time (RT) patterns. We trained six macaque monkeys on a TI transfer task, in which they learned the implied order of a novel list of seven images in each behavioral session, indicating their decisions with saccadic eye movements or reaching movements. Consistent learning of the list structure was achieved within 200-300 trials per session. Behavioral performance exhibited a symbolic distance effect, with accuracy increasing as the ordinal distance between items grew. Notably, RTs remained relatively stable across learning, despite improvements in accuracy. We applied a generalized DDM implementation (PyDDM) [Shinn, M., Lam, N. H., & Murray, J. D. A flexible framework for simulating and fitting generalized drift-diffusion models. eLife, 9, e56938, 2020] to jointly fit accuracy and RT data. Model fits were achieved by incorporating both an increasing evidence accumulation rate and a collapsing decision bound, successfully capturing the RT distribution shapes observed during learning. Learning and transfer were fit by varying drift rate with little change in other parameters. Eye and reaching movements showed similar dynamics, with the difference in RT accounted for mainly by nondecision time. Our results highlight a distinct dynamical regime of the DDM framework, extending its applicability to cognitive domains involving symbolic reasoning and serial relational learning.

Humans possess a remarkable ability to recognize visual objects with high fidelity, supported by complex neural mechanisms underlying memory retrieval. ERP studies have identified two key neural signatures of recognition memory: the parietal old/new effect and the frontal old/new effect. Despite extensive research on these ERP components, the extent to which these components reflect distinct memory processes remains debated. In the present study, we investigated how repetitive learning modulates these ERP components. Participants repeatedly studied a fixed list of 32 real-world images across up to five study-test repetitions while EEG was recorded. In addition, a separate set size 1 condition served as a proxy for working memory. Our results showed that with increased repetitions, the parietal old/new effect exhibited enhanced amplitude and earlier peak latency, reflecting more efficient retrieval of well-learned memories. In contrast, the frontal old/new effect remained unchanged in both amplitude and timing. These findings suggest that the parietal old/new effect is a sensitive neural marker of learning-related changes in long-term memory representations, whereas the frontal effect is less influenced by repetition. In addition, despite similarly high accuracy between the well-practiced set size 32 condition and the set size 1 working memory condition, both parietal and frontal old/new effects peaked significantly earlier for set size 1, suggesting that access to working memory is substantially faster than even well-practiced long-term memory. Together, our results highlight the unique role of the parietal old/new effect, but not the frontal old/new effect, in repetitive learning, despite both components being important for successful recognition of learned visual stimuli.