Cognitive Neuroscience最新文献

Observation of others' actions activates motor representations in sensorimotor cortex. Although action observation in the real-world often involves multiple agents displaying varying degrees of action involvement, most lab studies on action observation studied individual actions. We recorded EEG-mu suppression over sensorimotor cortex to investigate how the multi-agent nature of observed hand/arm actions is incorporated in sensorimotor action representations. Hereto we manipulated the extent of agent involvement in dyadic interactions presented in videos. In all clips two agents were present, of which agent-1 always performed the same action, while the involvement of agent-2 differed along three levels: (1) passive and uninvolved, (2) passively involved, (3) actively involved. Additionally, a no-action condition was presented. The occurrence of these four conditions was predictable thanks to cues at the start of each trial, which allowed to study possible mu anticipation effects. Dyadic interactions in which agent-2 was actively involved resulted in increased power suppression of the mu rhythm compared to dyadic interactions in which agent-2 was passively involved. The latter did not differ from actions in which agent-2 was present but not involved. No anticipation effects were found. The results suggest that the sensorimotor representation of a dyadic interaction takes into account the simultaneously performed bodily articulations of both agents, but no evidence was found for incorporation of their static articulated postures.

This commentary makes three suggestions on Willems' neurocognitive model for understanding mixed and ambiguous emotions and morality. First, it proposes that his atheoretical approach risks unwittingly adopting theoretical and conceptual limitations implicit in reigning paradigms and overlooking the need for theoretical impetus and constraints in the development of valid constructs of targeted emotions. Second, it suggests that a dynamical systems approach to emotions provides a fruitful theory and neuro-phenomenology as a corresponding methodology. Lastly, it proposes that Willems' objective would benefit from a more systematic integration of insights from the humanities into the nature and nuances of literary (moral) emotions.

This study aimed to investigate the intra-/inter-hemispheric interactions during visual word processing, by manipulating stimulus onset asynchrony (SOA) in a primed-lateralized lexical decision task. To assess intra-/inter-hemispheric priming effects, identical prime-target pairs were presented in the same or opposite unilateral visual fields. The study found that the right visual field advantage (RVFA) was observed when Korean words were presented sequentially within hemispheres, indicating that the inherent characteristics of the two hemispheres, rather than differences in memory or linguistic aspects of lexical processing, contributed to the hemispheric asymmetry. Additionally, intra-hemispheric priming effects were symmetrical in both hemispheres, with similar increases in priming for words and nonwords from SOA 120 ms to SOA 600 ms. Furthermore, inter-hemispheric priming effects were asymmetrical, with stronger priming when stimuli were presented in a sequence of LH→RH than in RH→LH. These findings suggest that the intrinsic differences in lexical processing between the two hemispheres may be related to the asymmetric pattern of hemispheric interactions in visual word processing.

Midfrontal theta activity is crucial for attentional and cognitive control. However, its causal role in facilitating visual search, particularly from the perspective of distractor inhibition, is yet to be discovered. We applied theta band transcranial alternate current stimulation (tACS) over frontocentral regions when participants searched for targets among heterogeneous distractors with foreknowledge of distractor features. The results demonstrated improved visual search performance in the theta stimulation group compared to the active sham group. Moreover, we observed the facilitation effect of the distractor cue only in participants who exhibited larger inhibition benefits, which further confirms the role of theta stimulation in precise attentional control. Taken together, our results provide compelling causal evidence for the involvement of midfrontal theta activity in memory-guided visual search.

Over the past decades, the emerging and ever-growing body of studies in empirical aesthetics has made one thing abundantly clear: our current models and conceptualizations of emotional experiences have outlived their usefulness. How do we go from here?

Several novel ideas and suggestions were made in response to our discussion paper (Tallman et al., this issue). Careful consideration of the content and context of memory while accounting for the neuroanatomy and functional specialization of the hippocampus may reveal more consistent patterns in fMRI studies of memory consolidation. Below we address these ideas as well as issues that arise when interpreting the fMRI signal in memory consolidation studies. In addition, we describe new analyses suggested by the commentators that clarify our findings with respect to current theories.

The review by Slotnick is valuable for raising the important question of how much the hippocampal activity induced by novel stimuli is due to mechanisms for encoding into long-term memory, and how much is due to working memory. Slotnick's paper implicitly defines working memory as being equivalent to sustained activation during the late delay period. In this commentary, we suggest that cognitive neuroscientists should consider a broader range of cellular and synaptic mechanisms for maintaining information in working memory.

I propose working memory be considered, not as a process for static maintenance in a particular set of brain regions, but rather as a dynamic process unfolding to serve future needs. Brain regions such as the hippocampus, or sensory and motor regions, may be necessarily recruited during this process, depending on task demands. Information stored in working memory is thus a distributed representation reflected in the structural and functional state of multiple brain areas and the trajectory of that state over time. Recent research is discussed in support of this view.

Recent studies suggest the hippocampus is involved in working memory (WM). Slotnick (this issue) critically reviewed relevant fMRI findings and concludes WM 'does not activate the hippocampus.' We extend Slotnick's review by discussing observations from human intracranial and lesion research. These studies do suggest hippocampal contributions to WM (beyond novelty encoding), which however are difficult to capture with conventional fMRI. Still, the advent of new fMRI techniques combined with a stronger emphasis on shared hippocampal mechanisms across short- and long-term memory pave an exciting path forward.

The aim of the present discussion paper was to identify whether any fMRI studies have provided convincing evidence that the hippocampus is associated with working memory. The key outcome variable was the phase in which hippocampal activity was observed: study, early delay, late delay, and/or test. During working memory tasks, long-term memory processes can operate during the study phase, early delay phase (due to extended encoding), or test phase. Thus, working memory processes can be isolated from long-term memory processes during only the late delay period. Twenty-six working memory studies that reported hippocampal activity were systematically analyzed. Many experimental protocol and analysis parameters were considered including number of participants, stimulus type(s), number of items during the study phase, delay duration, task during the test phase, behavioral accuracy, relevant fMRI contrast(s), whether the information was novel or familiar, number of phases modeled, and whether activation timecourses were extracted. For studies that were able to identify activity in different phases, familiar information sometimes produced activity during the study phase and/or test phase, but never produced activity during the delay period. When early-delay phase and late-delay phase activity could be distinguished via modeling these phases separately or inspecting activation timecourses, novel information could additionally produce activity during the early delay phase. There was no convincing evidence of hippocampal activity during the late delay period. These results indicate that working memory does not activate the hippocampus and suggest a model of working memory where maintenance of novel information can foster long-term memory encoding.