Science posts

See science posts on page 49 below.

    • 2014
    • Lars Marstaller et al
    • High Gamma Oscillations in Medial Temporal Lobe during Overt Production of Speech and Gestures
    • The study of the production of co-speech gestures (CSGs), i.e., meaningful hand movements that often accompany speech during everyday discourse, provides an important opportunity to investigate the integration of language, action, and memory because of the semantic overlap between gesture movements and speech content. Behavioral studies of CSGs and speech suggest that they have a common base in memory and predict that overt production of both speech and CSGs would be preceded by neural activity related to memory processes. However, to date the neural correlates and timing of CSG production are still largely unknown. In the current study, we addressed these questions with magnetoencephalography and a semantic association paradigm in which participants overtly produced speech or gesture responses that were either meaningfully related to a stimulus or not. Using spectral and beamforming analyses to investigate the neural activity preceding the responses, we found a desynchronization in ..
    • 2014
    • Kerstin Irlbacher et al
    • Mechanisms and neuronal networks involved in reactive and proactive cognitive control of interference in working memory
    • Cognitive control can be reactive or proactive in nature. Reactive control mechanisms, which support the resolution of interference, start after its onset. Conversely, proactive control involves the anticipation and prevention of interference prior to its occurrence. The interrelation of both types of cognitive control is currently under debate: Are they mediated by different neuronal networks? Or are there neuronal structures that have the potential to act in a proactive as well as in a reactive manner? This review illustrates the way in which integrating knowledge gathered from behavioral studies, functional imaging, and human electroencephalography proves useful in answering these questions. We focus on studies that investigate interference resolution at the level of working memory representations. In summary, different mechanisms are instrumental in supporting reactive and proactive control. Distinct neuronal networks are involved, though some brain regions, especially pre-SMA..
    • 2007
    • Derek Evan Nee et al
    • Interference resolution: Insights from a meta-analysis of neuroimaging tasks
    • A quantitative meta-analysis was performed on 47 neuroimaging studies involving tasks purported to require the resolution of interference. The tasks included the Stroop, flanker, go/no-go, stimulus-response compatibility, Simon, and stop signal tasks. Peak density-based analyses of these combined tasks reveal that the anterior cingulate cortex, dorsolateral prefrontal cortex, inferior frontal gyrus, posterior parietal cortex, and anterior insula may be important sites for the detection and/or resolution of interference. Individual task analyses reveal differential patterns of activation among the tasks. We propose that the drawing of distinctions among the processing stages at which interference may be resolved may explain regional activation differences. Our analyses suggest that resolution processes acting upon stimulus encoding, response selection, and response execution may recruit different neural regions.
    • 2000
    • Mark D'Esposito et al
    • Prefrontal cortical contributions to working memory: evidence from event-related fMRI studies
    • Working memory refers to the short-term retention of information that is no longer accessible in the environment, and the manipulation of this information, for subsequent use in guiding behavior. In this review, we will present data from a series of event-related functional magnetic-resonance-imaging (fMRI) studies of delayed-response tasks that were designed to investigate the role of different regions of the prefrontal cortex (PFC) during different working-memory component processes. From these data, we conclude that: (1) lateral PFC is anatomically organized according to the types of cognitive operations that one performs when attempting to temporarily maintain and manipulate information; and (2) consistent with the picture that has emerged from the monkey electrophysiological literature, human lateral PFC is involved in several encoding- and response-related processes as well as mnemonic and nonmnemonic processes that are engaged during the temporary maintenance of information. T..
    • 2009
    • Melina R. Uncapher et al
    • Posterior parietal cortex and episodic encoding: Insights from fMRI subsequent memory effects and dual-attention theory
    • The formation of episodic memories—memories for life events—is affected by attention during event processing. A leading neurobiological model of attention posits two separate yet interacting systems that depend on distinct regions in lateral posterior parietal cortex (PPC). From this dual-attention perspective, dorsal PPC is thought to support the goal-directed allocation of attention, whereas ventral PPC is thought to support reflexive orienting to information that automatically captures attention. To advance understanding of how parietal mechanisms may impact event encoding, we review functional MRI studies that document the relationship between lateral PPC activation during encoding and subsequent memory performance (e.g., later remembering or forgetting). This review reveals that (a) encoding-related activity is frequently observed in human lateral PPC, (b) increased activation in dorsal PPC is associated with later memory success, and (c) increased activation in ventral PPC pred..
    • 2007
    • Unsworth, Nash et al
    • The nature of individual differences in working memory capacity: Active maintenance in primary memory and controlled search from secondary memory
    • Studies examining individual differences in working memory capacity have suggested that individuals with low working memory capacities demonstrate impaired performance on a variety of attention and memory tasks compared with individuals with high working memory capacities. This working memory limitation can be conceived of as arising from 2 components: a dynamic attention component (primary memory) and a probabilistic cue-dependent search component (secondary memory). This framework is used to examine previous individual differences studies of working memory capacity, and new evidence is examined on the basis of predictions of the framework to performance on immediate free recall. It is suggested that individual differences in working memory capacity are partially due to the ability to maintain information accessible in primary memory and the ability to search for information from secondary memory.
    • 2007
    • Robert S. Blumenfeld et al
    • Prefrontal Cortex and Long-Term Memory Encoding: An Integrative Review of Findings from Neuropsychology and Neuroimaging
    • Recent findings have led to a growing appreciation of the role of the lateral prefrontal cortex (PFC) in episodic long-term memory (LTM). Here, the authors will review results from neuropsychological and neuroimaging studies of humans and present a framework to explain how different regions of the PFC contribute to successful LTM formation. Central to this framework is the idea that different regions within the PFC implement different control processes that augment memory by enhancing or attenuating memory for certain aspects of a particular item or event. Evidence reviewed here suggests that ventrolateral regions of the PFC contribute to the ability to select goal-relevant item information, and that this processing strengthens the representation of goal-relevant features of items during LTM encoding. Dorsolateral regions of the PFC may contribute to the ability to organize multiple pieces of information in working memory, thereby enhancing memory for associations among items in LTM...
    • 2000
    • Roberto Cabeza et al
    • Imaging Cognition II: An Empirical Review of 275 PET and fMRI Studies
    • Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have been extensively used to explore the functional neuroanatomy of cognitive functions. Here we review 275 PET and fMRI studies of attention (sustained, selective, Stroop, orientation, divided), perception (object, face, space/motion, smell), imagery (object, space/ motion), language (written/spoken word recognition, spoken/ no spoken response), working memory (verbal/numeric, object, spatial, problem solving), semantic memory retrieval (categorization, generation), episodic memory encoding (verbal, object, spatial), episodic memory retrieval (verbal, nonverbal, success, effort, mode, context), priming (perceptual, conceptual), and procedural memory (conditioning, motor, and nonmotor skill learning). To identify consistent activation patterns associated with these cognitive operations, data from 412 contrasts were summarized at the level of cortical Brodmann's areas, insula, thalamus, medial-tempora..
    • 2010
    • Christopher R. Madan et al
    • The influence of item properties on association-memory
    • Word properties like imageability and word frequency improve cued recall of verbal paired-associates. We asked whether these enhancements follow simply from prior effects on item-memory, or also strengthen associations between items. Participants studied word pairs varying in imageability or frequency: pairs were “pure” (high–high, low–low) or “mixed” (high–low, low–high) where “high” and “low” refer to imageability or frequency values and are probed with forward (A–?) and backward (?–B) cues. Probabilistic model fits to the data suggested that imageability primarily improved retrieval of associations, but frequency primarily improved recall of target items. All pair types exhibited a high correlation between forward and backward probe accuracy, a measure of holistic learning (Kahana, 2002), which extends the boundary conditions of holistic association-memory and challenges Paivio’s (1971) suggestion that holistic learning depends critically on imagery. In sum, item properties can bo..
    • 2012
    • Christopher R. Madan et al
    • Emotional arousal does not enhance association-memory
    • Emotionally arousing information is remembered better than neutral information. This enhancement effect has been shown for memory for items. In contrast, studies of association-memory have found both impairments and enhancements of association-memory by arousal. We aimed to resolve these conflicting results by using a cued-recall paradigm combined with a model-based data analysis method (Madan, Glaholt, & Caplan, 2010) that simultaneously obtains separate estimates of arousal effects on memory for associations and memory for items. Participants studied sequentially presented words in pairs that were pure (NEGATIVE–NEGATIVE or NEUTRAL–NEUTRAL) or mixed (NEGATIVE–NEUTRAL or NEUTRAL–NEGATIVE). Cued recall tests had NEUTRAL or NEGATIVE probes and NEUTRAL or NEGATIVE targets. We found impaired memory for associations involving negative words despite enhanced item-memory (more retrievable targets). A category-list control condition explained away the item-memory enhancement but could not e..