Wouter De Baene
Research interests
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InterestsCognitive Control, Task Switching, Cognitive Neuroscience, fMRI
Publications
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4.05Impact points
Cue-switch effects do not rely on the same neural systems as task-switch effects.
Cognitive, affective & behavioral neuroscience. 08/2011; 11(4):600-7.
The cued task-switching paradigm is often used to study cognitive control. In this paradigm, people are generally slower and make more errors when switching tasks as compared with repeating the same task. When two cues are mapped to each task, these switch costs could result from a mixture of cue-sw... [more] The cued task-switching paradigm is often used to study cognitive control. In this paradigm, people are generally slower and make more errors when switching tasks as compared with repeating the same task. When two cues are mapped to each task, these switch costs could result from a mixture of cue-switch effects (which are thought to reflect cue encoding) and task-switch effects (which are thought to reflect task set preparation). In the behavioral literature, there has been a lively debate on the degree to which cue-switch effects and task-switch effects indeed reflect different phenomena. In the present study, we used fMRI to examine whether and to what extent the neural network underlying task-switch effects is also involved in cue-switch effects. We found task-switch but no cue-switch effects in the frequently observed preparation-related activation in fronto-parietal areas. These results suggest that the fronto-parietal areas displaying preparatory activity in task-switching paradigms are engaged in task preparation but not in cue encoding and that task preparation and cue encoding rely on completely different processes.
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3.07Impact points
Subjectively interpreted shape dimensions as privileged and orthogonal axes in mental shape space.
Journal of experimental psychology. Human perception and performance. 04/2011; 37(2):422-41.
The shape of an object is fundamental in object recognition but it is still an open issue to what extent shape differences are perceived analytically (i.e., by the dimensional structure of the shapes) or holistically (i.e., by the overall similarity of the shapes). The dimensional structure of a sti... [more] The shape of an object is fundamental in object recognition but it is still an open issue to what extent shape differences are perceived analytically (i.e., by the dimensional structure of the shapes) or holistically (i.e., by the overall similarity of the shapes). The dimensional structure of a stimulus is available in a primary stage of processing for separable dimensions, although it can also be derived cognitively from a perceived stimulus consisting of integral dimensions. Contrary to most experimental paradigms, the present study asked participants explicitly to analyze shapes according to two dimensions. The dimensions of interest were aspect ratio and medial axis curvature, and a new procedure was used to measure the participants' interpretation of both dimensions (Part I, Experiment 1). The subjectively interpreted shape dimensions showed specific characteristics supporting the conclusion that they also constitute perceptual dimensions with objective behavioral characteristics (Part II): (1) the dimensions did not correlate in overall similarity measures (Experiment 2), (2) they were more separable in a speeded categorization task (Experiment 3), and (3) they were invariant across different complex 2-D shapes (Experiment 4). The implications of these findings for shape-based object processing are discussed.
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6.26Impact points
Challenging a decade of brain research on task switching: Brain activation in the task-switching paradigm reflects adaptation rather than reconfiguration of task sets.
Human brain mapping. 03/2011; 33(3):639-51.
In daily life, we permanently need to adapt our behavior to new task situations, requiring cognitive control. Such adaptive processes are commonly investigated with the task-switching paradigm. Many fMRI studies have interpreted stronger activation for switch than repeat trials in fronto-parietal br... [more] In daily life, we permanently need to adapt our behavior to new task situations, requiring cognitive control. Such adaptive processes are commonly investigated with the task-switching paradigm. Many fMRI studies have interpreted stronger activation for switch than repeat trials in fronto-parietal brain areas as reflecting an active reconfiguration process in switch trials, tuning the cognitive system for proper task execution. From the single cell literature, however, one could deduce the alternative interpretation that switch-specific activity reflects reduced brain activity in repeat trials due to adaptation. These alternative explanations cannot be distinguished by simply comparing brain activity in switch and repeat trials. Therefore, we used a parametric approach to examine which interpretation is more powerful to account for the data. In all areas of the fronto-parietal network, adaptation explained the data better than reconfiguration. Therefore, our results call the classical reconfiguration interpretation into question and provide first evidence for adaptation of abstract task representations. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
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4.36Impact points
Cognitive vs. affective listening modes and judgments of music--an ERP study.
Biological psychology. 12/2010; 85(3):393-409.
The neural correlates of processing deviations from Western music rules are relatively well known. Less is known of the neural dynamics of top-down listening modes and affective liking judgments in relation with judgments of tonal correctness. In this study, subjects determined if tonal chord sequen... [more] The neural correlates of processing deviations from Western music rules are relatively well known. Less is known of the neural dynamics of top-down listening modes and affective liking judgments in relation with judgments of tonal correctness. In this study, subjects determined if tonal chord sequences sounded correct or incorrect, or if they liked them or not, while their electroencephalogram (EEG) was measured. The last chord of the sequences could be congruous with the previous context, ambiguous (unusual but still enjoyable) or harmonically inappropriate. The cognitive vs. affective listening modes were differentiated in the event-related potential (ERP) responses already before the ending chord, indicating different preparation for the judgment tasks. Furthermore, three neural events tagged the decision process preceding the behavioral responses. First, an early negativity, peaking at about 280ms, was elicited by chord incorrectness and by disliking judgments only over the right hemisphere. Second, at about 500ms from the end of the sequence a positive brain response was elicited by the negative answers of both tasks. Third, at about 1200ms, a late positive potential (LPP) was elicited by the liking judgment task whereas a large negative brain response was elicited by the correctness judgment task, indexing that only at that late latency preceding the button press subjects decided how to judge the cadences. This is the first study to reveal the dissociation between neural processes occurring during affective vs. cognitive listening modes and judgments of music.
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6.98Impact points
Effects of adaptation on the stimulus selectivity of macaque inferior temporal spiking activity and local field potentials.
Cerebral cortex (New York, N.Y. : 1991). 09/2010; 20(9):2145-65.
Stimulus repetition reduces neural response in cortical areas. Such adaptation is used in functional magnetic resonance imaging to infer the selectivity of neuronal populations; however, the mechanisms of adaptation remain elusive, especially in higher areas. We measured adaptation of spiking activi... [more] Stimulus repetition reduces neural response in cortical areas. Such adaptation is used in functional magnetic resonance imaging to infer the selectivity of neuronal populations; however, the mechanisms of adaptation remain elusive, especially in higher areas. We measured adaptation of spiking activity and local field potentials (LFPs) in macaque inferior temporal (IT) cortex for parameterized shapes by comparing tuning for test stimuli following a brief adaptation with predictions derived from different models of adaptation. Adaptation was similar during passive fixation or an attention-demanding task. We found consistent adaptation of spiking activity and LFP power in high- (gamma) but not low-frequency bands when repeating shapes. Contrary to sharpening models, repetition did not affect shape selectivity. The degree of similarity between adapter and test shapes was a stronger determinant of adaptation than was the response to the adapter. Adaptation still occurred when adapter and test stimuli did not spatially overlap, but adaptation was stronger for same, compared with different, adapters and test stimulus positions. These adaptation effects were similar for spiking and for gamma activity. In conclusion, adaptation of IT spiking activity and LFPs in IT is strongly dependent on feature similarities in the adapter and test stimuli, in agreement with input, but not firing-rate fatigue models.
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3.42Impact points
Top-down modulation of auditory processing: effects of sound context, musical expertise and attentional focus.
The European journal of neuroscience. 10/2009;
Abstract By recording auditory electrical brain potentials, we investigated whether the basic sound parameters (frequency, duration and intensity) are differentially encoded among speech vs. music sounds by musicians and non-musicians during different attentional demands. To this end, a pseudoword a... [more] Abstract By recording auditory electrical brain potentials, we investigated whether the basic sound parameters (frequency, duration and intensity) are differentially encoded among speech vs. music sounds by musicians and non-musicians during different attentional demands. To this end, a pseudoword and an instrumental sound of comparable frequency and duration were presented. The accuracy of neural discrimination was tested by manipulations of frequency, duration and intensity. Additionally, the subjects' attentional focus was manipulated by instructions to ignore the sounds while watching a silent movie or to attentively discriminate the different sounds. In both musicians and non-musicians, the pre-attentively evoked mismatch negativity (MMN) component was larger to slight changes in music than in speech sounds. The MMN was also larger to intensity changes in music sounds and to duration changes in speech sounds. During attentional listening, all subjects more readily discriminated changes among speech sounds than among music sounds as indexed by the N2b response strength. Furthermore, during attentional listening, musicians displayed larger MMN and N2b than non-musicians for both music and speech sounds. Taken together, the data indicate that the discriminative abilities in human audition differ between music and speech sounds as a function of the sound-change context and the subjective familiarity of the sound parameters. These findings provide clear evidence for top-down modulatory effects in audition. In other words, the processing of sounds is realized by a dynamically adapting network considering type of sound, expertise and attentional demands, rather than by a strictly modularly organized stimulus-driven system.
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1.93Impact points
Stimulus ambiguity elicits response conflict.
Neuroscience letters. 05/2008; 435(2):158-62.
Conflict monitoring theory [M.M. Botvinick, T. Braver, D. Barch, C. Carter, J.D. Cohen, Conflict monitoring and cognitive control, Psychol. Rev. 108 (2001) 625-652] assumes that perceptual ambiguity among choice stimuli elicits response conflict in choice reaction. It hence predicts that response co... [more] Conflict monitoring theory [M.M. Botvinick, T. Braver, D. Barch, C. Carter, J.D. Cohen, Conflict monitoring and cognitive control, Psychol. Rev. 108 (2001) 625-652] assumes that perceptual ambiguity among choice stimuli elicits response conflict in choice reaction. It hence predicts that response conflict is also involved in elementary variants of choice reaction time (RT) tasks, i.e., those variants that, by contrast with the Stroop task or the Go/No-Go task for instance, are rarely associated with cognitive control. In order to test this prediction, an experiment was designed in which participants performed a simple RT task and a regular between-hand 2-choice RT task under three different levels of stimulus ambiguity. The data show that response conflict, as measured by the N2 component of the event-related brain potential (ERP), was elicited in the 2-choice RT task but not in the simple RT task and that the degree of response conflict in the 2-choice RT task was a function of stimulus ambiguity. These results show that response conflict is also present in a regular choice RT task which is traditionally not considered to be a measure of cognitive conflict.
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4.08Impact points
Effects of category learning on the stimulus selectivity of macaque inferior temporal neurons.
Learning & memory (Cold Spring Harbor, N.Y.). 02/2008; 15(9):717-27.
Primates can learn to categorize complex shapes, but as yet it is unclear how this categorization learning affects the representation of shape in visual cortex. Previous studies that have examined the effect of categorization learning on shape representation in the macaque inferior temporal (IT) cor... [more] Primates can learn to categorize complex shapes, but as yet it is unclear how this categorization learning affects the representation of shape in visual cortex. Previous studies that have examined the effect of categorization learning on shape representation in the macaque inferior temporal (IT) cortex have produced diverse and conflicting results that are difficult to interpret owing to inadequacies in design. The present study overcomes these issues by recording IT responses before and after categorization learning. We used parameterized shapes that varied along two shape dimensions. Monkeys were extensively trained to categorize the shapes along one of the two dimensions. Unlike previous studies, our paradigm counterbalanced the relevant categorization dimension across animals. We found that categorization learning increased selectivity specifically for the category-relevant stimulus dimension (i.e., an expanded representation of the trained dimension), and that the ratio of within-category response similarities to between-category response similarities increased for the relevant dimension (i.e., category tuning). These small effects were only evident when the learned category-related effects were disentangled from the prelearned stimulus selectivity. These results suggest that shape-categorization learning can induce minor category-related changes in the shape tuning of IT neurons in adults, suggesting that learned, category-related changes in neuronal response mainly occur downstream from IT.
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3.48Impact points
Properties of shape tuning of macaque inferior temporal neurons examined using rapid serial visual presentation.
Journal of neurophysiology. 05/2007; 97(4):2900-16.
We used rapid serial visual presentation (RSVP) to examine the tuning of macaque inferior temporal cortical (IT) neurons to five sets of 25 shapes each that varied systematically along predefined shape dimensions. A comparison of the RSVP technique using 100-ms presentations with that using a longer... [more] We used rapid serial visual presentation (RSVP) to examine the tuning of macaque inferior temporal cortical (IT) neurons to five sets of 25 shapes each that varied systematically along predefined shape dimensions. A comparison of the RSVP technique using 100-ms presentations with that using a longer duration showed that shape preference can be determined with RSVP. Using relatively complex shapes that vary along relatively simple shape dimensions, we found that the large majority of neurons preferred extremes of the shape configuration, extending the results of a previous study using simpler shapes and a standard testing paradigm. A population analysis of the neuronal responses demonstrated that, in general, IT neurons can represent the similarities among the shapes at an ordinal level, extending a previous study that used a smaller number of shapes and a categorization task. However, the same analysis showed that IT neurons do not faithfully represent the physical similarities among the shapes. The responses to the two-part shapes could be predicted, virtually perfectly, from the average of the responses to the respective two parts presented in isolation. We also showed that IT neurons adapt to the stimulus distribution statistics. The neural shape discrimination improved when a shape set with a narrower stimulus range was presented, suggesting that the tuning of IT neurons is not static but adapts to the stimulus distribution statistics, at least when stimulated at a high rate with a restricted set of stimuli.
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7.18Impact points
From air oscillations to music and speech: functional magnetic resonance imaging evidence for fine-tuned neural networks in audition.
The Journal of neuroscience : the official journal of the Society for Neuroscience. 09/2006; 26(34):8647-52.
In the auditory modality, music and speech have high informational and emotional value for human beings. However, the degree of the functional specialization of the cortical and subcortical areas in encoding music and speech sounds is not yet known. We investigated the functional specialization of t... [more] In the auditory modality, music and speech have high informational and emotional value for human beings. However, the degree of the functional specialization of the cortical and subcortical areas in encoding music and speech sounds is not yet known. We investigated the functional specialization of the human auditory system in processing music and speech by functional magnetic resonance imaging recordings. During recordings, the subjects were presented with saxophone sounds and pseudowords /ba:ba/ with comparable acoustical content. Our data show that areas encoding music and speech sounds differ in the temporal and frontal lobes. Moreover, slight variations in sound pitch and duration activated thalamic structures differentially. However, this was the case with speech sounds only while no such effect was evidenced with music sounds. Thus, our data reveal the existence of a functional specialization of the human brain in accurately representing sound information at both cortical and subcortical areas. They indicate that not only the sound category (speech/music) but also the sound parameter (pitch/duration) can be selectively encoded.
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1.69Impact points
Further evidence that the SNARC effect is processed along a dual-route architecture: Evidence from the lateralized readiness potential.
Experimental psychology. 01/2006; 53(1):58-68.
In a binary response setting, it has been frequently observed that small numbers are reacted to faster with the left hand and large numbers with the right hand (i. e., the SNARC-effect) which reflects the spatial left-right orientation of the mental number line (Dehaene, Bossini, & Giraux, 1993)... [more] In a binary response setting, it has been frequently observed that small numbers are reacted to faster with the left hand and large numbers with the right hand (i. e., the SNARC-effect) which reflects the spatial left-right orientation of the mental number line (Dehaene, Bossini, & Giraux, 1993). In line with the work of Keus and Schwarz (in press), we investigated the locus of the conflict in the SNARC effect in a parity judgment task with the Arabic numerals 1, 2, 8, or 9. Differences between compatible (left-hand response to 1 or 2 and right-hand response to 8 and 9) and incompatible SNARC conditions (left-hand response to 8 or 9 and right-hand response to 1 or 2) were observed in the lateralized readiness potential (LRP) but not in the peak latency of the P300. In accordance with Keus and colleagues (Keus, Jenks, & Schwarz, 2005), we argue that the locus of the conflict is situated at intermediate response-related stages. However, instead of adopting a single-route processing architecture, a dual route account is proposed as the underlying processing architecture explaining the SNARC effect.
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4.36Impact points
Roughness perception in sounds: behavioral and ERP evidence.
Biological psychology. 12/2004; 67(3):319-30.
The mismatch negativity (MMN) correlates of the perception of roughness, the unpleasant character of sounds caused by the perception of amplitude fluctuation in the range of 20-200 Hz, were studied on the basis of a variation in the degree of modulation (=modulation index m), which is a main paramet... [more] The mismatch negativity (MMN) correlates of the perception of roughness, the unpleasant character of sounds caused by the perception of amplitude fluctuation in the range of 20-200 Hz, were studied on the basis of a variation in the degree of modulation (=modulation index m), which is a main parameter influencing roughness. A psychophysical study showed that perceived roughness of tones increased with modulation index for m-values from 0 up to 1.2. For larger values of m, roughness perception remained stable. In a subsequent ERP-study, infrequent amplitude modulated (AM) tones with varying modulation index were presented in the context of a series of pure tones in an ignore condition. The amplitude of the mismatch negativity correlated highly with the roughness ratings (r = -0.93) and did not increase monotonously with increasing modulation index. We conclude that perceived roughness rather than its physical correlate in sounds is reflected by the MMN and that roughness is thus preattentively encoded.
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6.54Impact points
Journal impact factors and self-citations: implications for psychology journals.
The American psychologist. 02/2004; 59(1):49-51.
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2.67Impact points
Electrical brain responses to descriptive versus evaluative judgments of music.
Annals of the New York Academy of Sciences. 12/2003; 999:155-7.
The present study was aimed at finding neural correlates of aesthetic versus descriptive listening of the same musical cadences. Results showed that aesthetic listening generated greater right frontocentral negativities than did descriptive listening, indicating distinct cortical mechanisms for aest... [more] The present study was aimed at finding neural correlates of aesthetic versus descriptive listening of the same musical cadences. Results showed that aesthetic listening generated greater right frontocentral negativities than did descriptive listening, indicating distinct cortical mechanisms for aesthetic versus descriptive processing of music.
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2.67Impact points
Exploration of roughness by means of the mismatch negativity paradigm.
Annals of the New York Academy of Sciences. 12/2003; 999:170-2.
A mismatch negativity study was set up to find the neural correlates of roughness perception. The results suggest that when the sounds are not attended to, roughness is reflected by the mismatch positivity as evidenced at the mastoid electrodes.... [more] A mismatch negativity study was set up to find the neural correlates of roughness perception. The results suggest that when the sounds are not attended to, roughness is reflected by the mismatch positivity as evidenced at the mastoid electrodes.
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Experience-related effects on the response selectivity of macaque inferior temporal neurons
De laatste decennia hebben verschillende studies de tradionele visie op corticale veranderingen in de volwassen cortex ten gevolge van visuele ervaringen, die erg gelimiteerd zijn na de ‘kritische periode’, ondergraven. In verschillende corticale gebieden werden namelijk ervaringsgerelateerde verand... [more] De laatste decennia hebben verschillende studies de tradionele visie op corticale veranderingen in de volwassen cortex ten gevolge van visuele ervaringen, die erg gelimiteerd zijn na de ‘kritische periode’, ondergraven. In verschillende corticale gebieden werden namelijk ervaringsgerelateerde veranderingen in de functionele organisatie en in de eigenschappen van neuronale responsen gevonden. In dit proefschrift onderzochten we veranderingen in stimulusselectiviteit van neuronen in the inferio-temporale (IT) cortex bij rhesusapen ten gevolge van veranderingen in de stimulus statistieken, categorizatie-leren en adaptatie. Om na te gaan hoe de stimulusselectiviteit van IT neuronen, die gevoelig zijn voor objecteigenschappen als vorm, kleur of textuur, zich aanpast aan veranderingen in de stimulusdistributie statistieken, werd het stimulusbereik op een bepaalde dimensie gemoduleerd, resulterend in twee vormsets die in twee opeenvolgende blokken werden gepresenteerd. De stimuli werden gepresenteerd in een Rapid Serial Visual Presentation (RSVP) paradigma waarvan de validiteit in het bestuderen van vorm-selectiviteit van IT neuronen binnen parametrische vormsets eerst werd aangetoond. De neuronale vormdiscriminatie verbeterde wanneer een vormset met een smaller stimulusbereik (wat onlosmakelijk verbonden was met minder variantie, grotere densiteit en meer inter-stimulus similariteit op pixel-niveau) werd aangeboden. Dit suggereert dat de selectiviteit van IT neuronen zich aanpast aan de stimulusdistributie statistieken bij het snel aanbieden van een beperkte set van stimuli. In een tweede deel onderzochten we de effecten van categorizatie-leren op de neuronale representatie van complexe vormen in IT cortex. Door registraties voor en na het categorizatie-leren en contrabalancering van de relevante dimensie over apen konden we de categorie-gerelateerde effecten onderscheiden van de stimulus-gerelateerde selectiviteitseffecten. We vonden een expansie van de relevante dimensie en een iets gelijkaardiger neuronaal antwoordpatroon voor exemplaren van dezelfde categorie in vergelijking met een verschillende categorie als gevolg van de categorizatie-training. Deze resultaten suggereren dat vorm categorizatie-leren enkel kleine categorie-gerelateerde veranderingen kan induceren in de vormselectiviteit van IT neuronen in volwassen apen. In het laatste deel onderzochten we, zowel met extracellulair gemeten aktiepotentialen van enkelvoudige neuronen als met lokale veld potentialen (LFPs), de effecten van adaptatie op de stimulusselectiviteit van IT neuronen. Voor zowel de aktiepotentialen als de LFP gamma power (61-100Hz) verlaagden de neuronale responses met stimulusrepetitie, zonder dat de tuningbreedte veranderde. De mate van adaptatie was niet enkel afhankelijk van de antwoordsterkte maar werd ook beïnvloed door de relatie tussen adapter en test stimulus, zowel voor veranderingen in vormeigenschappen als positieveranderingen: er was meer adaptatie wanneer de adapter en test stimulus identieke vormeigenschappen hadden en beiden op dezelfde positie gepresenteerd werden in vergelijking met wanneer deze stimuli verschilden in vorm of positie. We vonden ook een dalend adaptatieniveau met dalende adapter-test stimulus similariteit. Deze resultaten suggereren dat adaptatie plaatsvindt voor of op het niveau van de synapse. In the last few decennia, experience-related changes in the functional organization and in the neuronal response properties were observed over a wide range of time scales in different cortical areas in adults, undermining the traditional view that cortical changes dependent on visual experience were limited after the critical period . In this dissertation, we studied changes in stimulus selectivity of neurons in the macaque inferior temporal (IT) cortex as an effect of changes in the stimulus statistics, categorization learning and adaptation. To examine how the stimulus selectivity of IT neurons, which are strongly selective for object attributes as shape, color or texture, adapts to changes in the stimulus distribution statistics, we constructed two shape sets which were presented in two subsequent blocks by modulating the stimulus range on a particular dimension. The shapes were presented in a Rapid Serial Visual Presentation (RSVP) paradigm, of which the validity to study the shape selectivity of IT neurons within parametric shape sets was ascertained first. When a shape set with a narrower stimulus range (which was inextricably bound up with less variance, less (pixel-based) dissimilarity and higher density) was presented, the neural shape discrimination improved, suggesting that the tuning of IT neurons adapts to the stimulus distribution statistics when a restricted set of shapes is presented at a high rate. In a second part, we examined the effects of categorization learning on the neuronal representation of complex shapes in IT cortex. By comparing the IT responses in two monkeys before and after categorization learning, while counterbalancing the relevant categorization dimension across animals, we could disentangle the learned category-related effects from the pre-learned stimulus selectivity effects. We found that categorization learning resulted in an expansion of the representation of the trained dimension and that the responses of the neurons were somewhat more similar for exemplars that belong to the same, compared to different, categories. These results suggest that learning to categorize shapes can only induce minor category-related changes in the shape selectivity of IT neurons in adult monkeys. In the last part, we examined the effects of adaptation on the stimulus selectivity of IT neurons, both with single-cell spiking activity and local field potentials (LFPs). Both for the spiking activity and the LFP gamma (61-100Hz) power, stimulus repetition scaled down the neuronal responses without changing the tuning width. The degree of adaptation was not only response strength dependent but was affected by the relationship between adapter and test stimulus for both shape feature and position changes: more adaptation was found when adapter and test stimulus had identical shape features and were presented at the same position than when these stimuli differed in shape or position. We also found that the degree of adaptation decreased with decreasing similarity between adapter and test stimulus. Our results suggest that adaptation occurs at or before the level of the synapses onto the neuron. Afdeling Neurofysiologie Departement Neurowetenschappen Faculteit Psychologie en Pedagogische Wetenschappen Doctoral thesis Doctoraatsthesis
Following (23)
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Frederick Verbruggen
University of Exeter -
Jelle Demanet
University of Ghent -
Jelle Demanet
University of Ghent -
Marcel Brass
University of Ghent -
dr.ir. Elisabeth Monard
Research Foundation Flanders
