Cerebral cortex最新文献

Previous studies have shown that individuals with internet gaming disorder (IGD) and tobacco use disorder (TUD) represent nonsubstance and substance-related addictions, respectively. Identifying neuroimaging differences is essential for detecting and intervening in these disorders. 44 IGD participants, 73 TUD participants, and 33 healthy controls (HCs) were scanned with resting-state fMRI (rs-fMRI). We used independent component analysis (ICA) to identify regions of interest and compared the functional connectivity between groups using a false discovery rate correction. Rs-fMRI revealed increased functional connectivity in the precuneus cortex, left postcentral gyrus, and right superior frontal gyrus in the dorsal attention network (DAN) in the IGD group in contrast to HC group. In the TUD group, increased functional connectivity was observed in the superior frontal gyrus, supplementary motor cortex, right precentral gyrus, cingulate gyrus, anterior division, postcentral gyrus, thalamus r, and thalamus I. In contrast, decreased functional connectivity was observed in the right lateral occipital cortex (the inferior and superior division), right occipital fusiform gyrus, and the right occipital pole. Our results indicate distinct alterations in the DAN associated with IGD and TUD, suggesting divergent mechanisms in behavioral versus substance-related addictions.

Metacognition enables adaptive behavior through the self-evaluation of our cognitions. An unresolved question is whether metacognition relies on domain-general or domain-specific mechanisms. The domain-general account proposes that shared prefrontal resources support metacognition across all cognitive functions. This predicts that metacognitive abilities should correlate across cognitive tasks and show uniform age-related decline, as aging would affect this shared system. However, behavioral results show inconsistent cross-domain correlations and age-related decline, often confounded by methodological differences between tasks. The neural oscillations supporting metacognition also remain unclear, though electroencephalography (EEG) studies suggest theta oscillations as a potential mechanism in specific domains. No study has compared both behavioral and oscillatory patterns across domains using matched tasks. We addressed this by recording EEG from younger and older-adults during matched perceptual and visual short-term memory tasks. Despite equivalent task performance, aging selectively impaired metacognition in perception and not memory, revealing behavioral decoupling between domains. This dissociation was mirrored in oscillatory dynamics. Younger adults showed stronger occipital theta-synchronization supporting perceptual metacognition, while older adults engaged compensatory frontal beta-desynchronization. During memory, older adults' metacognition was supported by occipital alpha-desynchronization. These findings reveal the domain-specific oscillatory mechanisms supporting metacognition, each tuned to computational demands of the cognitive domain and age-group.

Using diffusion-weighted imaging, we quantified the microstructure of U-shaped fiber bundles connecting the primary motor and somatosensory cortices in chimpanzees. We tested for sex and age effects, lateralization, and associations with manual and orofacial motor functions. Manual skills were assessed with a tool-use task; orofacial communication was assessed by individual variation in attention-getting sound production. Chimpanzees showed population-level leftward asymmetries in fractional anisotropy in U-fibers connecting central and inferior cortices, especially in females. Age was inversely associated with radial, axial, and mean diffusivity in these bundles. Right-handed motor skill was linked to stronger leftward fractional anisotropy asymmetries in superior regions. In contrast, more frequent attention-getting sound production was associated with increased leftward asymmetries in inferior regions. These findings show that different motor functions in chimpanzees are linked to region-specific variation in U-fiber integrity along the dorsal-ventral axis, aligning with previous representations of the chimpanzee motor "homunculus." The observed association between orofacial skill and leftward asymmetry in inferior sensorimotor regions suggests a potential preadaptation for the lateralized speech functions found in modern humans.

Memory decline (MD) has become a critical issue affecting personal life and societal function, especially spatial memory plays a central role in daily life. Transcranial direct current stimulation (tDCS) has been demonstrated as an efficient neural modulation for memory, however its effects on spatial memory and underlying mechanism remain unclear. This study proposes a spatial matching paradigm with a 2-back principle to explore the enhancement of the tDCS on spatial memory. Three conditions of pre-tDCS, short-tDCS, and long-tDCS accompanied with event-related potential, brain network and behavioral data are applied to investigate the effect. Results show that the tDCS enhances the P300 components in prefrontal and parietal regions, with significantly higher amplitudes and shorter latencies than pre-tDCS. The brain network connectivity also increases as well as the subjects respond more accurately and quickly. Moreover, females exhibit greater changes in P3 amplitude and mean potential area than males, suggesting higher sensitivity to the tDCS. These findings indicate that the tDCS could enhance memory by increasing cortical excitability and neural efficiency and this study provides valuable insights into the neural mechanisms behind the enhanced memory function of the tDCS and introduces a novel framework for its evaluation.

Retrieval-induced forgetting is a phenomenon whereby retrieving certain memories can impair the recall of related information. We tested the hypothesis that inhibitory mechanisms play a pivotal role in retrieval-induced forgetting, applying transcranial magnetic stimulation to the dorsolateral prefrontal cortex, an area involved in inhibitory control, while participants retrieved memory associations. Participants learned a series of word pairs, then completed an interference task where they learned directly conflicting associations, or semantically related associates. A train of transcranial magnetic stimulation pulses was applied to the right dorsolateral prefrontal cortex (Experiment 1) or the left dorsolateral prefrontal cortex (Experiment 2) during retrieval of the interfering pairs, beginning 200 ms after stimulus onset. Participants showed robust retrieval-induced forgetting for the original pairs after retrieving conflicting associations, which was reduced when transcranial magnetic stimulation was applied to the right dorsolateral prefrontal cortex compared with a control brain site. This effect was specific to conflicting memories and did not extend to semantically related interference, indicating the right dorsolateral prefrontal cortex's critical role in inhibitory processes during retrieval. Transcranial magnetic stimulation administered to the homologous left dorsolateral prefrontal cortex had no effect on forgetting. These findings provide strong evidence for the involvement of the right dorsolateral prefrontal cortex in managing retrieval competition within an early time window (200 to 533 ms) and highlight its importance in memory control.

Stimuli associated with a response can prime the motor system for action. While these action tendencies can be advantageous, reducing the demands of routine decisions and actions, they can be counter-productive when goals change. It is therefore important to understand how automatic motor preparation is brought under control. We used transcranial magnetic stimulation (TMS) to investigate the neurophysiological signatures of conditioned action tendencies in the motor system. Participants were trained to respond to target images appearing in a stream of other images. We then delivered TMS to the primary motor cortex to measure motor-evoked potentials (MEPs) as an index of cortico spinal excitability (CSE). Critically, participants were instructed to withhold the previously trained response to target cues. Despite this, the target cues increased CSE shortly before the timepoint at which a response would have typically been made (median RT). This was followed by distinct CSE suppression at later timepoints. TMS also triggered a motor response that may have otherwise been withheld in a time-sensitive manner. These results provide new evidence about the time-course of action tendencies triggered by conditioned cues and suggest that cue-elicited elevation of CSE is reined in when task goals change.

Slow waves are the main oscillatory activity during non-rapid eye movement sleep, playing a crucial role in synaptic homeostasis, memory consolidation, and cortical network regulation. In urethane-anesthetized rodents, frequently used in long-term potentiation experiments in vivo, brain activity alternates between a deactivated state, dominated by slow waves, and an activated state characterized by faster oscillations. However, the interplay between synaptic plasticity and slow wave dynamics within these fluctuating brain states remains unclear. Here, we investigated whether long-term potentiation in the hippocampal-medial prefrontal cortex (CA1-mPFC) circuit, critical for memory processing, modulates cortical slow wave dynamics during urethane anesthesia. Electrical stimulation of CA1 robustly evoked a transient (50 to 200 ms) event of population silence (down states) in the medial prefrontal cortex, which emerged after the typical evoked field post-synaptic potential, and was consistently associated with a slow waves. Importantly, long-term potentiation induction significantly enhanced the CA1-evoked medial prefrontal cortex down states and slowed spontaneous cortical slow wave oscillations, without altering the activated/deactivated brain state proportion. Our findings provide direct evidence of an interaction between synaptic plasticity and cortical slow wave dynamics, laying the groundwork for future studies on the underlying mechanisms of state-dependent synaptic homeostasis.

Inhibitory control takes multiple forms, including proactive slowing, a strategic delay of responses, and reactive inhibition, the cancelation of an initiated response. How these processes adapt across sensory modalities and their neural mechanisms remains unclear. This cross-sectional study tested whether proactive slowing and reactive inhibition are adaptable across sensory modalities and supported by shared and distinct neural adaptations. We recruited 23 athletes and 21 age-matched controls. Participants performed a choice-reaction task, requiring rapid response selection, and a stop-signal task, requiring occasional cancelation of initiated responses. Proactive slowing and reactive inhibition were assessed across visual, auditory, and somatosensory modalities. Proactive slowing was measured by anticipatory response slowing, and reactive inhibition by stop-signal reaction time. Event-related potentials (ERPs) were recorded to examine neural processing. Athletes exhibited greater proactive slowing and reactive inhibition than controls across all modalities. ERP analyses revealed that proactive slowing was associated with greater N2 and smaller P3 amplitudes in athletes, suggesting enhanced early conflict monitoring and reduced reliance on later attentional control. Athletes showed greater N2 amplitudes for reactive inhibition, indicating superior stimulus-driven inhibition, similar to proactive slowing. These findings provide novel evidence that both proactive slowing and reactive inhibition adapt across sensory modalities, accompanied by neural changes that are partly shared (N2) and partly distinct (P3).

The subjective experience of mental effort is critical for adaptive cognitive control, yet its neural and computational underpinnings remain elusive. Here, we combine hierarchical drift-diffusion modeling and EEG to investigate how trial-by-trial fluctuations in both preparatory and task-related neural activity shape subjective effort ratings. Participants performed an arithmetic task of variable difficulty, choosing task difficulty in advance, which allowed us to isolate neural signatures of preparation (contingent negative variation) and task engagement (P3 amplitude). Computational modeling revealed that participants adjusted decision boundaries based on anticipated difficulty, reflecting heightened caution. Critically, subjective effort ratings tracked this increased caution, likely reflecting the cost of additional accumulation. EEG analyses showed that while subjective effort was sensitive to the P3 amplitude, indicating exerted effort during task performance, it was insensitive to preparatory CNV activity. Our findings offer novel insights into the computations underlying subjective effort, proposing a selective role for exerted, but not preparatory activity.