Remembering a past event involves reactivation of content-specific patterns of neural activity in high-level perceptual regions (e.g., ventral temporal cortex, VTC). In contrast, the subjective ...experience of vivid remembering is typically associated with increased activity in lateral parietal cortex (LPC)--"retrieval success effects" that are thought to generalize across content types. However, the functional significance of LPC activation during memory retrieval remains a subject of active debate. In particular, theories are divided with respect to whether LPC actively represents retrieved content or if LPC activity only scales with content reactivation elsewhere (e.g., VTC). Here, we report a human fMRI study of visual memory recall (faces vs scenes) in which complementary forms of multivoxel pattern analysis were used to test for and compare content reactivation within LPC and VTC. During recall of visual images, we observed robust reactivation of broad category information (face vs scene) in both VTC and LPC. Moreover, recall-related activity patterns in LPC, but not VTC, differentiated between individual events. Importantly, these content effects were particularly evident in areas of LPC (namely, angular gyrus) in which activity scaled with subjective reports of recall vividness. These findings provide striking evidence that LPC not only signals that memories have been successfully recalled, but actively represents what is being remembered.
Wind energy is one of the most important renewable energy sources and many countries are predicted to increase wind energy portion of their whole national energy supply to about twenty percent in the ...next decade. One potential obstacle in the use of wind turbines to harvest wind energy is the maintenance of the wind turbine blades. The blades are a crucial and costly part of a wind turbine and over their service life can suffer from factors such as material degradation and fatigue, which can limit their effectiveness and safety. Thus, the ability to detect damage in wind turbine blades is of great significance for planning maintenance and continued operation of the wind turbine. This paper presents a review of recent research and development in the field of damage detection for wind turbine blades. Specifically, this paper reviews frequently employed sensors including fiber optic and piezoelectric sensors, and four promising damage detection methods, namely, transmittance function, wave propagation, impedance and vibration based methods. As a note towards the future development trend for wind turbine sensing systems, the necessity for wireless sensing and energy harvesting is briefly presented. Finally, existing problems and promising research efforts for online damage detection of turbine blades are discussed.
Functional magnetic resonance imaging (fMRI) studies typically collapse data from many subjects, but brain functional organization varies between individuals. Here we establish that this individual ...variability is both robust and reliable, using data from the Human Connectome Project to demonstrate that functional connectivity profiles act as a 'fingerprint' that can accurately identify subjects from a large group. Identification was successful across scan sessions and even between task and rest conditions, indicating that an individual's connectivity profile is intrinsic, and can be used to distinguish that individual regardless of how the brain is engaged during imaging. Characteristic connectivity patterns were distributed throughout the brain, but the frontoparietal network emerged as most distinctive. Furthermore, we show that connectivity profiles predict levels of fluid intelligence: the same networks that were most discriminating of individuals were also most predictive of cognitive behavior. Results indicate the potential to draw inferences about single subjects on the basis of functional connectivity fMRI.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, UILJ, UKNU, UL, UM, UPUK
Reinforcements and punishments facilitate adaptive behavior in diverse domains ranging from perception to social interactions. A conventional approach to understanding the corresponding neural ...substrates focuses on the basal ganglia and its dopaminergic projections. Here, we show that reinforcement and punishment signals are surprisingly ubiquitous in the gray matter of nearly every subdivision of the human brain. Humans played either matching-pennies or rock-paper-scissors games against computerized opponents while being scanned using fMRI. Multivoxel pattern analysis was used to decode previous choices and their outcomes, and to predict upcoming choices. Whereas choices were decodable from a confined set of brain structures, their outcomes were decodable from nearly all cortical and subcortical structures. In addition, signals related to both reinforcements and punishments were recovered reliably in many areas and displayed patterns not consistent with salience-based explanations. Thus, reinforcement and punishment might play global modulatory roles in the entire brain.
► Reinforcement and punishment signals are broadly distributed in the entire brain ► Ubiquitous reward signals are revealed by multi-voxel pattern analysis on fMRI data ► Sensory and choice signals are more narrowly distributed in the brain ► Ubiquitous reinforcement signals cannot be explained by strategy or salience
Attention and memory are typically studied as separate topics, but they are highly intertwined. Here we discuss the relation between memory and two fundamental types of attention: perceptual and ...reflective. Memory is the persisting consequence of cognitive activities initiated by and/or focused on external information from the environment (perceptual attention) and initiated by and/or focused on internal mental representations (reflective attention). We consider three key questions for advancing a cognitive neuroscience of attention and memory: To what extent do perception and reflection share representational areas? To what extent are the control processes that select, maintain, and manipulate perceptual and reflective information subserved by common areas and networks? During perception and reflection, to what extent are common areas responsible for binding features together to create complex, episodic memories and for reviving them later? Considering similarities and differences in perceptual and reflective attention helps integrate a broad range of findings and raises important unresolved issues.
Neuroimaging is a fast-developing research area in which anatomical and functional images of human brains are collected using techniques such as functional magnetic resonance imaging (fMRI), ...diffusion tensor imaging (DTI), and electroencephalography (EEG). Technical advances and large-scale data sets have allowed for the development of models capable of predicting individual differences in traits and behavior using brain connectivity measures derived from neuroimaging data. Here, we present connectome-based predictive modeling (CPM), a data-driven protocol for developing predictive models of brain-behavior relationships from connectivity data using cross-validation. This protocol includes the following steps: (i) feature selection, (ii) feature summarization, (iii) model building, and (iv) assessment of prediction significance. We also include suggestions for visualizing the most predictive features (i.e., brain connections). The final result should be a generalizable model that takes brain connectivity data as input and generates predictions of behavioral measures in novel subjects, accounting for a considerable amount of the variance in these measures. It has been demonstrated that the CPM protocol performs as well as or better than many of the existing approaches in brain-behavior prediction. As CPM focuses on linear modeling and a purely data-driven approach, neuroscientists with limited or no experience in machine learning or optimization will find it easy to implement these protocols. Depending on the volume of data to be processed, the protocol can take 10-100 min for model building, 1-48 h for permutation testing, and 10-20 min for visualization of results.
Although attention plays a ubiquitous role in perception and cognition, researchers lack a simple way to measure a person's overall attentional abilities. Because behavioral measures are diverse and ...difficult to standardize, we pursued a neuromarker of an important aspect of attention, sustained attention, using functional magnetic resonance imaging. To this end, we identified functional brain networks whose strength during a sustained attention task predicted individual differences in performance. Models based on these networks generalized to previously unseen individuals, even predicting performance from resting-state connectivity alone. Furthermore, these same models predicted a clinical measure of attention--symptoms of attention deficit hyperactivity disorder--from resting-state connectivity in an independent sample of children and adolescents. These results demonstrate that whole-brain functional network strength provides a broadly applicable neuromarker of sustained attention.
Using visual information to guide behaviour requires storage in a temporary buffer, known as visual short-term memory (VSTM), that sustains attended information across saccades and other visual ...interruptions. There is growing debate on whether VSTM capacity is limited to a fixed number of objects or whether it is variable. Here we report four experiments using functional magnetic resonance imaging that resolve this controversy by dissociating the representation capacities of the parietal and occipital cortices. Whereas representations in the inferior intra-parietal sulcus (IPS) are fixed to about four objects at different spatial locations regardless of object complexity, those in the superior IPS and the lateral occipital complex are variable, tracking the number of objects held in VSTM, and representing fewer than four objects as their complexity increases. These neural response patterns were observed during both VSTM encoding and maintenance. Thus, multiple systems act together to support VSTM: whereas the inferior IPS maintains spatial attention over a fixed number of objects at different spatial locations, the superior IPS and the lateral occipital complex encode and maintain a variable subset of the attended objects, depending on their complexity. VSTM capacity is therefore determined both by a fixed number of objects and by object complexity.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Double-strand breaks activate the ataxia telangiectasia mutated (ATM) kinase, which promotes the accumulation of DNA damage factors in the chromatin surrounding the break. The functional significance ...of the resulting DNA damage foci is poorly understood. Here we show that 53BP1 (also known as TRP53BP1), a component of DNA damage foci, changes the dynamic behaviour of chromatin to promote DNA repair. We used conditional deletion of the shelterin component TRF2 (also known as TERF2) from mouse cells (TRF2fl/-) to deprotect telomeres, which, like double-strand breaks, activate the ATM kinase, accumulate 53BP1 and are processed by non-homologous end joining (NHEJ). Deletion of TRF2 from 53BP1-deficient cells established that NHEJ of dysfunctional telomeres is strongly dependent on the binding of 53BP1 to damaged chromosome ends. To address the mechanism by which 53BP1 promotes NHEJ, we used time-lapse microscopy to measure telomere dynamics before and after their deprotection. Imaging showed that deprotected telomeres are more mobile and sample larger territories within the nucleus. This change in chromatin dynamics was dependent on 53BP1 and ATM but did not require a functional NHEJ pathway. We propose that the binding of 53BP1 near DNA breaks changes the dynamic behaviour of the local chromatin, thereby facilitating NHEJ repair reactions that involve distant sites, including joining of dysfunctional telomeres and AID (also known as AICDA)-induced breaks in immunoglobulin class-switch recombination.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Based on my role as Editor in Chief of the journal Language Learning ＆ Technology since 2000 and on my experiences as a technology-enhanced language learning (TELL) researcher, developer and teacher, ...I will provide an overview of recent cutting-edge research on the uses of technologies for second language teaching and learning. I suggest that the ＂L＂ in TELL should represent ＂languaculture＂ rather than just ＂language,＂ as the field of second language education is increasingly placing greater emphasis on the inextricable link between language and culture. I will also look to the future and suggest promising trajectories for TELL development and research.
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Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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