Journal of Cognitive Neuroscience最新文献

Visual working memory is a core cognitive function that allows active storage of task-relevant visual information. Contrary to the common assumption that the capacity of this system is fixed with respect to a single feature dimension, recent research has shown that working memory performance for a simple visual feature-color-is improved when this feature is encoded as part of a real-world object relative to an unrecognizable scrambled object. Using EEG (n = 24), we here demonstrate that this performance benefit is supported by increased neural engagement during the retention period, as indexed by enlarged contralateral delay activity during maintenance. Furthermore, the pattern of neural activity across parietal-occipital electrodes was more stable across time, suggesting that real-world objects may support more robust memory representations. Finally, we report a novel fronto-central ERP that distinguishes between real-world objects and scrambled objects during encoding and maintenance processes. Overall, our results demonstrate that active visual working memory capacity for simple features is not fixed but can expand depending on what context these features are encoded in.

To navigate social environments, people make inferences and predictions about other minds (e.g., their beliefs, preferences, intentions), an ability known as mentalizing. Although the neural basis of mentalizing has been studied extensively, the cognitive processes that support it have been challenging to characterize. One hypothesis is that particular mentalizing processes, subserved by particular brain regions, support inferences about particular categories of mental content (e.g., beliefs or preferences) with defined boundaries. An alternative hypothesis is that apparent categorical distinctions arise from variability along continuous, underlying dimensions. Here, we report evidence that regions of the brain's mentalizing network, including medial prefrontal cortex (MPFC) and Right TPJ, show diverging sensitivity to the underlying dimension of transience, that is, how temporary or enduring the state is that one attributes to another person. During fMRI scanning, participants received information about others and inferred their stable or transient beliefs or preferences in a 2 × 2 design. Overall, the Right TPJ, Left TPJ, and posterior cingulate were more engaged during inferences about transient than stable mental content, whereas dorsal, middle, and ventral MPFCs were more engaged during inferences about stable than transient mental content. Findings support suggestions that MPFC and Right TPJ make dissociable contributions to mentalizing and show that differences in the transience of the mental content under consideration, not only the categorical type of mental content itself, contributes importantly to this dissociation. Results contribute to scientific understanding of the structure of human social cognition, with implications for conceptualizations of atypical social thinking.

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.