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See detailA neural network controller for hydronic heating systems of solar buildings
Argiriou, A.; Bellas-Velidis, I.; Kummert, M. et al

in Neural Networks (2004), 17

An artificial neural network (ANN)-based controller for hydronic heating plants of buildings is presented. The controller has forecasting capabilities: it includes a meteorological module, forecasting the ... [more ▼]

An artificial neural network (ANN)-based controller for hydronic heating plants of buildings is presented. The controller has forecasting capabilities: it includes a meteorological module, forecasting the ambient temperature and solar irradiance, an indoor temperature predictor module, a supply temperature predictor module and an optimizing module for the water supply temperature. All ANN modules are based on the Feed Forward Back Propagation (FFBP) model. The operation of the controller has been tested experimentally, on a real-scale office building during real operating conditions. The operation results were compared to those of a conventional controller. The performance was also assessed via numerical simulation. The detailed thermal simulation tool for solar systems and buildings TRNSYS was used. Both experimental and numerical results showed that the expected percentage of energy savings with respect to a conventional controller is of about 15% under North European weather conditions. [less ▲]

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See detailNeural network involved in self-judgment in young and elderly adults
Feyers, Dorothée ULg

Master of advanced studies dissertation (2008)

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See detailNeural network involved in self-judgment in young and elderly adults
Feyers, Dorothée ULg; Collette, Fabienne ULg; D'Argembeau, Arnaud ULg et al

Poster (2008, May 29)

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring ... [more ▼]

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring judgment about self vs. other in the context of a first (1PP) or third (3PP) perspective-taking (Ruby et al., submitted). Here, we have performed functional connectivity analyses to determine the network of cerebral areas associated to the performance of young and elderly subjects. <br />Results indicate that, in the 1PP condition, activity of the VMPFC is related to the inferior frontal gyrus, parahippocampal gyrus in elderly but to the occipital cortex only in young subjects. In the 3PP condition, functional connectivity exist between the VMPFC and medial frontal gyrus, inferior frontal gyrus and superior temporal areas in elderly, but with occipital and parietal areas only in young subjects. <br />The cerebral areas associated to VMPFC activity in young subjects were previously described as involved both in autobiographical memory retrieval and mentalizing processes. With regard to elderly, the cerebral network evidenced is related to retrieval of semantic and episodic memories (parahippocampal and superior temporal) but also to the attribution of emotional valence to the adjectives (inferior frontal) and perspective taking (medial frontal gyrus). <br />These results indicate (1) that the VMPFC is connected to a larger cerebral network in elderly than in young subjects during self judgements; (2) that young subjects perform the task on the basis of autobiographical information retrieval only, while elderly subjects use supplementary, more reflexive, cognitive processes. [less ▲]

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See detailNeural network involved in young and elderly adults
Feyers, Dorothée ULg; Collette, Fabienne ULg; D'Argembeau, Arnaud ULg et al

in Proceedings of the Cognitive Aging Conference (2008, April 11)

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring ... [more ▼]

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring judgment about self vs. other in the context of a first (1PP) or third (3PP) perspective-taking (Ruby et al., submitted). Here, we have performed functional connectivity analyses to determine the network of cerebral areas associated to the performance of young and elderly subjects. Results indicate that, in the 1PP condition, activity of the VMPFC is related to the medial orbito-frontal, posterior and inferior temporal and parietal areas in elderly, but to the occipital cortex only in young subjects. In the 3PP condition, functional connectivity exist between the VMPFC and posterior temporal and lateral orbito-frontal areas in elderly, but with occipital and parietal areas only in young subjects. The cerebral areas associated to VMPFC activity in young subjects were previously described as involved both in autobiographic memory retrieval and mentalizing processes. With regard to elderly, the cerebral network evidenced is related to autobiographic memory retrieval (parietal and temporal areas) but also to the attribution of emotional valence to the adjectives (medial orbito-frontal) and perspective taking both in 1PP and 3PP conditions (lateral orbito-frontal). These results indicate (1) that the VMPFC is connected to a larger cerebral network in elderly than in young subjects during self judgements; (2) that young subjects perform the task on the basis of autobiographical information retrieval only, while elderly subjects use supplementary, more reflexive, cognitive processes. [less ▲]

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See detailA neural network model of sensitization of evoked cortical responses in migraine
Thomas, E.; Sandor, P. S.; Ambrosini, A. et al

in Cephalalgia : An International Journal of Headache (2002), 22(1), 48-53

Migraine patients show abnormalities of cerebral electrophysiology that manifest themselves mainly during the attack interval. Cortical-evoked potentials of migraineurs fail to habituate to repetitive ... [more ▼]

Migraine patients show abnormalities of cerebral electrophysiology that manifest themselves mainly during the attack interval. Cortical-evoked potentials of migraineurs fail to habituate to repetitive presentations of visual stimuli, and the amplitude of components of their auditory cortical-evoked potentials have a higher dependence on the stimulus intensities than in healthy subjects. A computer model of a neural hetwork has been developed that is able to reproduce both these neurophysiological dysfunctions. It predicts a positive correlation between the magnitudes of both these dysfunctions. The model also offers an explanation of why mutations in the same ion channel gene with opposite consequences on channel function, e.g. P/Q Ca2+ channels in migraine, may lead to similar electrophysiological abnormalities. [less ▲]

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See detailNeural networks for musical chords recognition
Osmalsky, Julien ULg; Embrechts, Jean-Jacques ULg; Van Droogenbroeck, Marc ULg et al

in Journées d'informatique musicale (2012, May)

In this paper, we consider the challenging problem of music recognition and present an effective machine learning based method using a feed-forward neural network for chord recognition. The method uses ... [more ▼]

In this paper, we consider the challenging problem of music recognition and present an effective machine learning based method using a feed-forward neural network for chord recognition. The method uses the known feature vector for automatic chord recognition called the Pitch Class Profile (PCP). Although the PCP vector only provides attributes corresponding to 12 semi-tone values, we show that it is adequate for chord recognition. Part of our work also relates to the design of a database of chords. Our database is primarily designed for chords typical of Western Europe music. In particular, we have built a large dataset filled with recorded guitar chords under different acquisition conditions (instruments, microphones, etc), but also with samples obtained with other instruments. Our experiments establish a twofold result: (1) the PCP is well suited for describing chords in a machine learning context, and (2) the algorithm is also capable to recognize chords played with other instruments, even unknown from the training phase. [less ▲]

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See detailNeural networks for short-term memory for order differentiate high and low proficiency bilinguals
Majerus, Steve ULg; Belayachi, Sanaa ULg; De Smedt, Bert et al

in NeuroImage (2008), 42

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See detailNeural networks involved in self-judgement in young and elderly adults
Feyers, Dorothée ULg; Collette, Fabienne ULg; D'Argembeau, Arnaud ULg et al

in NeuroImage (2010)

Recent studies have shown that both young and elderly subjects activate the ventromedial prefrontal cortex (VMPFC) when they make self-referential judgements. However, the VMPFC might interact with ... [more ▼]

Recent studies have shown that both young and elderly subjects activate the ventromedial prefrontal cortex (VMPFC) when they make self-referential judgements. However, the VMPFC might interact with different brain regions during self-referencing in the two groups. In this study, based on data from Ruby et al (2009), we have explored this issue using psychophysiological interaction analyses. Young and elderly participants had to judge adjectives describing personality traits in reference to the self versus a close friend or relative (the other), taking either a first-person or a third-person perspective. The physiological factor was the VMPFC activity observed in all participants during self judgement, and the psychological factor was the self versus other referential process. The main effect of first-person perspective in both groups revealed that the VMPFC was coactivated with the left parahippocampal gyrus and the precuneus for self versus other judgments. The main effect of age showed a stronger correlation between activity in the VMPFC and the lingual gyrus in young compared to elderly subjects. Finally, in the interaction, the VMPFC was specifically co-activated with the orbitofrontal gyrus and the precentral gyrus when elderly subjects took a first-person perspective for self judgements. No significant result was observed for the interaction in young subjects. These findings show that, although the VMPFC is engaged by both young and older adults when making self-referential judgements, this brain structure interacts differently with other brain regions as a function of age and perspective. These differences might reflect a tendency by older people to engage in more emotional/social processing than younger adults when making self-referential judgements with a first-person perspective [less ▲]

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See detailNeural pathways mediating control of reproductive behavior in male Japanese quail.
Wild, J. Martin; Balthazart, Jacques ULg

in The Journal of comparative neurology (2013), 521(9), 2067-87

The sexually dimorphic medial preoptic nucleus (POM) in Japanese quail has for many years been the focus of intensive investigations into its role in reproductive behavior. The present study delineates a ... [more ▼]

The sexually dimorphic medial preoptic nucleus (POM) in Japanese quail has for many years been the focus of intensive investigations into its role in reproductive behavior. The present study delineates a sequence of descending pathways that finally reach sacral levels of the spinal cord housing motor neurons innervating cloacal muscles involved in reproductive behavior. We first retrogradely labeled the motor neurons innervating the large cloacal sphincter muscle (mSC) that forms part of the foam gland complex (Seiwert and Adkins-Regan [1998] Brain Behav Evol 52:61-80) and then putative premotor nuclei in the brainstem, one of which was nucleus retroambigualis (RAm) in the caudal medulla. Anterograde tracing from RAm defined a bulbospinal pathway, terminations of which overlapped the distribution of mSC motor neurons and their extensive dorsally directed dendrites. Descending input to RAm arose from an extensive dorsomedial nucleus of the intercollicular complex (DM-ICo), electrical stimulation of which drove vocalizations. POM neurons were retrogradely labeled by injections of tracer into DM-ICo, but POM projections largely surrounded DM, rather than penetrated it. Thus, although a POM projection to ICo was shown, a POM projection to DM must be inferred. Nevertheless, the sequence of projections in the male quail from POM to cloacal motor neurons strongly resembles that in rats, cats, and monkeys for the control of reproductive behavior, as largely defined by Holstege et al. ([1997], Neuroscience 80:587-598). [less ▲]

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See detailNeural plasticity lessons from disorders of consciousness
Demertzi, Athina ULg; Schnakers, Caroline ULg; Soddu, Andrea ULg et al

in Frontiers in Psychology [=FPSYG] (2011), 1

Communication and intentional behavior are supported by the brain?s integrity at a structural and a functional level. When widespread loss of cerebral connectivity is brought about as a result of a severe ... [more ▼]

Communication and intentional behavior are supported by the brain?s integrity at a structural and a functional level. When widespread loss of cerebral connectivity is brought about as a result of a severe brain injury, in many cases patients are not capable of conscious interactive behavior and are said to suffer from disorders of consciousness (e.g., coma, vegetative state /unresponsive wakefulness syndrome, minimally conscious states). This lesion paradigm has offered not only clinical insights, as how to improve diagnosis, prognosis and treatment, but also put forward scientific opportunities to study the brain?s plastic abilities. We here review interventional and observational studies performed in severely brain-injured patients with regards to recovery of consciousness. The study of the recovered conscious brain (spontaneous and/or after surgical or pharmacologic interventions), suggests a link between some specific brain areas and the capacity of the brain to sustain conscious experience, challenging at the same time the notion of fixed temporal boundaries in rehabilitative processes. Altered functional connectivity, cerebral structural reorganization as well as behavioral amelioration after invasive treatments will be discussed as the main indices for plasticity in these challenging patients. The study of patients with chronic disorders of consciousness may, thus, provide further insights not only at a clinical level (i.e., medical management and rehabilitation) but also from a scientific-theoretical perspective (i.e., the brain?s plastic abilities and the pursuit of the neural correlate of consciousness). [less ▲]

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See detailNeural precursors of delayed insight
Darsaud, Annabelle ULg; Wagner, Ullrich; Balteau, Evelyne ULg et al

in Journal of Cognitive Neuroscience (2011), 23(8), 1900-1910

The solution of a problem left unresolved in the evening can sometimes pop into mind as a sudden insight after a night of sleep in the following morning. Although favorable effects of sleep on insightful ... [more ▼]

The solution of a problem left unresolved in the evening can sometimes pop into mind as a sudden insight after a night of sleep in the following morning. Although favorable effects of sleep on insightful behavior have been experimentally confirmed, the neural mechanisms determining this delayed insight remain unknown. Here, using functional magnetic resonance imaging (fMRI), we characterize the neural precursors of delayed insight in the number reduction task (NRT), in which a hidden task structure can be learned implicitly, but can also be recognized explicitly in an insightful process, allowing immediate qualitative improvement in task performance. Normal volunteers practiced the NRT during two fMRI sessions (training and retest), taking place 12 hours apart after a night of sleep. After this delay, half of the subjects gained insight into the hidden task structure ("solvers," S), whereas the other half did not ("nonsolvers," NS). Already at training, solvers and nonsolvers differed in their cerebral responses associated with implicit learning. In future solvers, responses were observed in the superior frontal sulcus, posterior parietal cortex, and the insula, three areas mediating controlled processes and supporting early learning and novice performance. In contrast, implicit learning was related to significant responses in the hippocampus in nonsolvers. Moreover, the hippocampus was functionally coupled with the basal ganglia in nonsolvers and with the superior frontal sulcus in solvers, thus potentially biasing participants' strategy towards implicit or controlled processes of memory encoding, respectively. Furthermore, in solvers but not in nonsolvers, response patterns were further transformed overnight, with enhanced responses in ventral medial prefrontal cortex, an area previously implicated in the consolidation of declarative memory. During retest in solvers, before they gain insight into the hidden rule, significant responses were observed in the same medial prefrontal area. After insight, a distributed set of parietal and frontal areas is recruited among which information concerning the hidden rule can be shared in a so-called global workspace. [less ▲]

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See detailThe neural substrate of orientation working memory
Cornette, Luc; Dupont, Patrick; Salmon, Eric ULg et al

in Journal of Cognitive Neuroscience (2001), 13(6), 813-828

We have used positron emission tomography (PET) to identify the neural substrate of two major cognitive components of working memory (WM), maintenance and manipulation of a single elementary visual ... [more ▼]

We have used positron emission tomography (PET) to identify the neural substrate of two major cognitive components of working memory (WM), maintenance and manipulation of a single elementary visual attribute, i.e., the orientation of a grating presented in central vision. This approach allowed us to equate difficulty across tasks and prevented subjects from using verbal strategies or vestibular cues. Maintenance of orientations involved a distributed fronto-parietal network, that is, left and right lateral superior frontal sulcus (SFSl), bilateral ventrolateral prefrontal cortex (VLPFC), bilateral precuneus, and right superior parietal lobe (SPL). A more medial superior frontal sulcus region (SFSm) was identified as being instrumental in the manipulative operation of updating orientations retained in the WM. Functional connectivity analysis revealed that orientation WM relies on a coordinated interaction between frontal and parietal regions. In general, the current findings confirm the distinction between maintenance and manipulative processes, highlight the functional heterogeneity in the prefrontal cortex (PFC), and suggest a more dynamic view of WM as a process requiring the coordinated interaction of anatomically distinct brain areas. [less ▲]

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See detailThe Neural Substrates of Memory Suppression: A fMRI Exploration of Directed Forgetting
Bastin, Christine ULg; Feyers, Dorothée ULg; Majerus, Steve ULg et al

in PLoS ONE (2012), 7(1), 29905

The directed forgetting paradigm is frequently used to determine the ability to voluntarily suppress information. However, little is known about brain areas associated with information to forget. The ... [more ▼]

The directed forgetting paradigm is frequently used to determine the ability to voluntarily suppress information. However, little is known about brain areas associated with information to forget. The present study used functional magnetic resonance imaging to determine brain activity during the encoding and retrieval phases of an item-method directed forgetting recognition task with neutral verbal material in order to apprehend all processing stages that information to forget and to remember undergoes. We hypothesized that regions supporting few selective processes, namely recollection and familiarity memory processes, working memory, inhibitory and selection processes should be differentially activated during the processing of to-be-remembered and to-be-forgotten items. Successful encoding and retrieval of items to remember engaged the entorhinal cortex, the hippocampus, the anterior medial prefrontal cortex, the left inferior parietal cortex, the posterior cingulate cortex and the precuneus; this set of regions is well known to support deep and associative encoding and retrieval processes in episodic memory. For items to forget, encoding was associated with higher activation in the right middle frontal and posterior parietal cortex, regions known to intervene in attentional control. Items to forget but nevertheless correctly recognized at retrieval yielded activation in the dorsomedial thalamus, associated with familiarity-based memory processes and in the posterior intraparietal sulcus and the anterior cingulate cortex, involved in attentional processes. [less ▲]

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See detailNeural substrates of phonological and lexicosemantic representations in Alzheimer's disease.
Peters, Frederic; Majerus, Steve ULg; Collette, Fabienne ULg et al

in Human Brain Mapping (2009), 30(1), 185-99

The language profile of patients suffering from Alzheimer's disease (AD) is characterized not only by lexicosemantic impairments but also by phonological deficits, as shown by an increasing number of ... [more ▼]

The language profile of patients suffering from Alzheimer's disease (AD) is characterized not only by lexicosemantic impairments but also by phonological deficits, as shown by an increasing number of neuropsychological studies. This study explored the functional neural correlates underlying phonological and lexicosemantic processing in AD. Using H(215)O PET functional brain imaging, a group of mild to moderate AD patients and a group of age-matched controls were asked to repeat four types of verbal stimuli: words, wordlike nonwords (WL+), non-wordlike nonwords (WL-) and simple vowels. The comparison between the different conditions allowed us to determine brain activation preferentially associated with lexicosemantic or phonological levels of language representations. When repeating words, AD patients showed decreased activity in the left temporo-parietal and inferior frontal regions relative to controls, consistent with distorted lexicosemantic representations. Brain activity was abnormally increased in the right superior temporal area during word repetition, a region more commonly associated with perceptual-phonological processing. During repetition of WL+ and WL- nonwords, AD patients showed decreased activity in the middle part of the superior temporal gyrus, presumably associated with sublexical phonological information; at the same time, AD patients showed larger activation than controls in the inferior temporal gyrus, typically associated with lexicosemantic levels of representation. Overall, the results suggest that AD patients use altered pathways to process phonological and lexicosemantic information, possibly related to a progressive loss of specialization of phonological and lexicosemantic neural networks. [less ▲]

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See detailNeural substrates of recollection and familiarity in Alzheimer’s disease
Genon, Sarah ULg; Salmon, Eric ULg; Collette, Fabienne ULg et al

in Proceedings of the 16th annual meeting of the Organization for Human Brain Mapping (2010)

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See detailThe neural substrates of the central executive: Exploration of the updating and shifting processes
Collette, Fabienne ULg; Van der Linden, Martial ULg; Delchambre, Marie et al

Conference (2002, September)

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See detailThe neural substrates of the central executive: Exploration of the updating and shifting processes
Collette, Fabienne ULg; Van der Linden, Martial ULg; Delchambre, Marie et al

Conference (2002, December)

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See detailNeurally adjusted ventilatory assist (NAVA) improves patient-ventilator interaction during non-invasive ventilation delivered by face mask
Piquilloud, L; Tassaux, D; Bialais, E et al

in Intensive Care Medicine (2012)

PURPOSE: To determine if, compared to pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces patient-ventilator asynchrony in intensive care patients undergoing noninvasive ventilation ... [more ▼]

PURPOSE: To determine if, compared to pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces patient-ventilator asynchrony in intensive care patients undergoing noninvasive ventilation with an oronasal face mask. METHODS: In this prospective interventional study we compared patient-ventilator synchrony between PS (with ventilator settings determined by the clinician) and NAVA (with the level set so as to obtain the same maximal airway pressure as in PS). Two 20-min recordings of airway pressure, flow and electrical activity of the diaphragm during PS and NAVA were acquired in a randomized order. Trigger delay (T(d)), the patient's neural inspiratory time (T(in)), ventilator pressurization duration (T(iv)), inspiratory time in excess (T(iex)), number of asynchrony events per minute and asynchrony index (AI) were determined. RESULTS: The study included 13 patients, six with COPD, and two with mixed pulmonary disease. T(d) was reduced with NAVA: median 35 ms (IQR 31-53 ms) versus 181 ms (122-208 ms); p = 0.0002. NAVA reduced both premature and delayed cyclings in the majority of patients, but not the median T(iex) value. The total number of asynchrony events tended to be reduced with NAVA: 1.0 events/min (0.5-3.1 events/min) versus 4.4 events/min (0.9-12.1 events/min); p = 0.08. AI was lower with NAVA: 4.9 % (2.5-10.5 %) versus 15.8 % (5.5-49.6 %); p = 0.03. During NAVA, there were no ineffective efforts, or late or premature cyclings. PaO(2) and PaCO(2) were not different between ventilatory modes. CONCLUSION: Compared to PS, NAVA improved patient ventilator synchrony during noninvasive ventilation by reducing T(d) and AI. Moreover, with NAVA, ineffective efforts, and late and premature cyclings were absent. [less ▲]

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See detailNeurally Adjusted Ventilatory Assist (NAVA) improves the matching of diaphragmatic electrical activity and tidal volume in comparison to pressure support (PS)
Piquilloud, L; Chiew, YS; Bialais, E et al

in Intensive Care Medicine (2011), 37 (Suppl 1)

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