Stephan G Boehm
Publications
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1.93Impact points
Emotional faces and the default mode network.
Neuroscience letters. 11/2011; 506(2):229-34.
The default-mode network (DMN) of the human brain has become a central topic of cognitive neuroscience research. Although alterations in its resting state activity and in its recruitment during tasks have been reported for several mental and neurodegenerative disorders, its role in emotion processin... [more] The default-mode network (DMN) of the human brain has become a central topic of cognitive neuroscience research. Although alterations in its resting state activity and in its recruitment during tasks have been reported for several mental and neurodegenerative disorders, its role in emotion processing has received relatively little attention. We investigated brain responses to different categories of emotional faces with functional magnetic resonance imaging (fMRI) and found deactivation in ventromedial prefrontal cortex (VMPFC), posterior cingulate gyrus (PC) and cuneus. This deactivation was modulated by emotional category and was less prominent for happy than for sad faces. These deactivated areas along the midline conformed to areas of the DMN. We also observed emotion-dependent deactivation of the left middle frontal gyrus, which is not a classical component of the DMN. Conversely, several areas in a fronto-parietal network commonly linked with attention were differentially activated by emotion categories. Functional connectivity patterns, as obtained by correlation of activation levels, also varied between emotions. VMPFC, PC or cuneus served as hubs between the DMN-type areas and the fronto-parietal network. These data support recent suggestions that the DMN is not a unitary system but differentiates according to task and even type of stimulus. The emotion-specific differential pattern of DMN deactivation may be explored further in patients with mood disorder, where the quest for biological markers of emotional biases is still ongoing.
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4.35Impact points
Category-sensitivity in the N170 range: a question of topography and inversion, not one of amplitude.
Neuropsychologia. 06/2011; 49(7):2082-9.
Event-related potential studies have identified the N170 as the key neurophysiological marker of human face processing. This functional association relies on the observation of a larger N170 amplitude to faces than items from all other visual object categories. However, N170 amplitude is modulated b... [more] Event-related potential studies have identified the N170 as the key neurophysiological marker of human face processing. This functional association relies on the observation of a larger N170 amplitude to faces than items from all other visual object categories. However, N170 amplitude is modulated by stimulus variations like viewpoint, size and symmetry, and studies comparing similarly sized and symmetric full-front faces and other objects have failed to find amplitude differences. Here we tested whether the effect of inversion - an increase in N170 amplitude seen for faces presented upside down - is similarly observed for full-front views of cars. Participants discriminated pictures of faces and cars, which were presented upright and inverted, and either in full-front view or varying in size, orientation and viewpoint. For upright stimuli, the N170 was stronger for faces than cars at some electrode sites, but of comparable amplitude at others, as shown by topographical differences. The N170 for inverted faces and cars was delayed, with a stronger delay for faces than cars. Inversion increased N170 amplitude for faces, while modulations for full-front view cars were non-significant or N170 amplitude was reduced. These results further limit the widely acknowledged principle of an association between N170 and visual object categorization. Potential face-sensitivity in the N170 range may therefore rely on topographic differences and effects of inversion, rather than amplitude differences.
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4.05Impact points
Upregulation of emotion areas through neurofeedback with a focus on positive mood.
Cognitive, affective & behavioral neuroscience. 11/2010; 11(1):44-51.
Real-time functional magnetic resonance imaging can be used to feed back signal changes from the brain to participants such that they can train to modulate activation levels in specific brain areas. Here we present the first study combining up-regulation of brain areas for positive emotions with psy... [more] Real-time functional magnetic resonance imaging can be used to feed back signal changes from the brain to participants such that they can train to modulate activation levels in specific brain areas. Here we present the first study combining up-regulation of brain areas for positive emotions with psychometric measures to assess the effect of successful self-regulation on subsequent mood. We localized brain areas associated with positive emotions through presentation of standardized pictures with positive valence. Participants up-regulated activation levels in their target area during specific periods, alternating with rest. Participants attained reliable self-control of the target area by the last of three seven-minute runs. This training effect was supported by an extensive network outside the targeted brain region, including higher sensory areas, paralimbic and orbitofrontal cortex. Self-control of emotion areas was not accompanied by clear changes in self-reported emotions; trend-level improvements on depression scores were counteracted by increases on measures of fatigue, resulting in no overall mood improvement. It is possible that benefits of self-control of emotion networks may only appear in people who display abnormal emotional homeostasis. The use of only a single, short, training session, overlap between positive and negative emotion networks and aversive reactions to the scanning environment may have prevented the detection of subtle changes in mood.
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5.74Impact points
Neurofeedback: A promising tool for the self-regulation of emotion networks.
NeuroImage. 08/2009;
Real-time functional magnetic resonance imaging (fMRI) affords the opportunity to explore the feasibility of self-regulation of functional brain networks through neurofeedback. We localised emotion networks individually in thirteen participants using fMRI and trained them to upregulate target areas,... [more] Real-time functional magnetic resonance imaging (fMRI) affords the opportunity to explore the feasibility of self-regulation of functional brain networks through neurofeedback. We localised emotion networks individually in thirteen participants using fMRI and trained them to upregulate target areas, including the insula and amygdala. Participants achieved a high degree of control of these networks after a brief training period. We observed activation increases during periods of upregulation of emotion networks in the precuneus and medial prefrontal cortex and, with increasing training success, in the ventral striatum. These findings demonstrate the feasibility of fMRI-based neurofeedback of emotion networks and suggest a possible development into a therapeutic tool.
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5.38Impact points
Working memory load for faces modulates P300, N170, and N250r.
Journal of cognitive neuroscience. 07/2008; 20(6):989-1002.
We used event-related potential (ERP) methodology to examine neural activity associated with visual working memory (WM) for faces. There were two main goals. First, to extend previous findings of P300 load modulation to WM for faces. Second, to examine whether N170 and N250r are also influenced by W... [more] We used event-related potential (ERP) methodology to examine neural activity associated with visual working memory (WM) for faces. There were two main goals. First, to extend previous findings of P300 load modulation to WM for faces. Second, to examine whether N170 and N250r are also influenced by WM load. Between one and four unfamiliar faces were simultaneously presented for memory encoding. After a 1-sec delay, a target face appeared, and participants had to judge whether this face was part of the previous face array. P300 amplitude decreased as WM load increased, and this P300 suppression was observed at both encoding and retrieval. WM load was also found to modulate other ERPs. The amplitude of the N170 elicited by the target face decreased with load, and this N170 decrease leveled off at load 2, reflecting the behavioral WM capacity of around two faces. In addition, the N250r, observed as an ERP difference for target faces that were present in the encoding array relative to target faces that were absent, was also reduced for higher WM loads. These findings extend previous work by showing that P300 modulation by WM load also occurs for faces. Furthermore, we show, for the first time, that WM load affects the N250r and the early visual N170 component. This suggests that higher visual areas play an important role in WM for faces.
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5.38Impact points
Neural and behavioral evidence for affective priming from unconsciously perceived emotional facial expressions and the influence of trait anxiety.
Journal of cognitive neuroscience. 02/2008; 20(1):95-107.
Abstract Affective judgments can often be influenced by emotional information people unconsciously perceive, but the neural mechanisms responsible for these effects and how they are modulated by individual differences in sensitivity to threat are unclear. Here we studied subliminal affective priming... [more] Abstract Affective judgments can often be influenced by emotional information people unconsciously perceive, but the neural mechanisms responsible for these effects and how they are modulated by individual differences in sensitivity to threat are unclear. Here we studied subliminal affective priming by recording brain potentials to surprise faces preceded by 30-msec happy or fearful prime faces. Participants showed valence-consistent changes in affective ratings of surprise faces, although they reported no knowledge of prime-face expressions, nor could they discriminate between prime-face expressions in a forced-choice test. In conjunction with the priming effect on affective evaluation, larger occipital P1 potentials at 145-175 msec were found with fearful than with happy primes, and source analyses implicated the bilateral extrastriate cortex in this effect. Later brain potentials at 300-400 msec were enhanced with happy versus fearful primes, which may reflect differential attentional orienting. Personality testing for sensitivity to threat, especially social threat, was also used to evaluate individual differences potentially relevant to subliminal affective priming. Indeed, participants with high trait anxiety demonstrated stronger affective priming and greater P1 differences than did those with low trait anxiety, and these effects were driven by fearful primes. Results thus suggest that unconsciously perceived affective information influences social judgments by altering very early perceptual analyses, and that this influence is accentuated to the extent that people are oversensitive to threat. In this way, perception may be subject to a variety of influences that govern social preferences in the absence of concomitant awareness of such influences.
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11.66Impact points
Validating neural correlates of familiarity.
Trends in cognitive sciences. 07/2007; 11(6):243-50.
Familiarity is a pervasive memory phenomenon that occurs in its most basic form when someone recognizes a repeated stimulus without recollecting other aspects of the requisite prior learning episode. Theoretical controversy currently abounds with respect to both the cognitive and neural characterist... [more] Familiarity is a pervasive memory phenomenon that occurs in its most basic form when someone recognizes a repeated stimulus without recollecting other aspects of the requisite prior learning episode. Theoretical controversy currently abounds with respect to both the cognitive and neural characteristics of familiarity. Here, we show that the extant data, particularly brain-potential data, are insufficient for validating putative neural correlates of familiarity, and we outline strategies for making progress on this problem. Conceptual priming is an implicit-memory phenomenon that often occurs together with familiarity; experiments that conflate the two phenomena can be misleading. Avoiding this conflation is required to understand familiarity and to determine the extent to which the neurocognitive processes that support priming also drive familiarity.
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1.12Impact points
Do I know you? Insights into memory for faces from brain potentials.
Clinical EEG and neuroscience : official journal of the EEG and Clinical Neuroscience Society (ENCS). 11/2006; 37(4):322-9.
The recognition of faces is central to human social interaction. Recordings of event-related potentials (ERPs) from the brain can shed light on the various processes that occur when a face is recognized and when knowledge related to a specific person is retrieved. ERP contrasts between processing fa... [more] The recognition of faces is central to human social interaction. Recordings of event-related potentials (ERPs) from the brain can shed light on the various processes that occur when a face is recognized and when knowledge related to a specific person is retrieved. ERP contrasts between processing familiar and processing novel faces offer a gateway into investigations of semantic memory for familiar persons. In particular, activity of face recognition units and semantic information units--memory representations of faces and person-related knowledge, respectively--can be indexed by specific ERPs. These potentials thus provide valuable tools for studying the cognitive and neurobiological architecture of person recognition. ERPs have also been found useful for investigating other types of memory for faces. Specifically, important insights have been derived from the study of a category of memory phenomena known as priming. Priming can be revealed in special tests when face recognition is facilitated based on prior experience. Describing the neural processes associated with memory for faces is an exciting focus of research, and future results from this line of inquiry promise to provide further knowledge about face recognition and the various types of memory that can be provoked by a human face.
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5.74Impact points
Neural correlates of perceptual contributions to nondeclarative memory for faces.
NeuroImage. 05/2006; 30(3):1021-9.
Face priming is a nondeclarative memory phenomenon that can be observed when recognition is facilitated for a recently encountered face. This data-driven form of priming is distinct from conceptually driven priming. Moreover, it includes two dissociable components, the facilitated access to pre-exis... [more] Face priming is a nondeclarative memory phenomenon that can be observed when recognition is facilitated for a recently encountered face. This data-driven form of priming is distinct from conceptually driven priming. Moreover, it includes two dissociable components, the facilitated access to pre-existing representations and facilitation in perceptual processing of faces. In the present study, we measured neural correlates of perceptual contributions to face priming with event-related brain potentials. Faces appeared two times (separated by 7-17 s), while participants discriminated familiar from unfamiliar faces. Half of the initial face stimuli were inverted, thereby disrupting perceptual face processing and making possible an assessment of perceptual contributions to face priming. Whereas none of the brain waves previously linked to perceptual processing of faces showed indications of priming, such effects were observed between 200 and 600 ms at left occipito-parieto-temporal recording sites. This electrical activity was present for both unfamiliar and familiar faces. The scalp topography of this effect was consistent with sources within the temporal and occipital cortices of the left hemisphere (based on a LORETA source localization). These findings suggest that priming of perceptual face processing is subserved by prolonged neural activity from 200 to 600 ms primarily in the left hemisphere. We propose that this priming reflects facilitated selection based on second-order relations among facial features.
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2.14Impact points
Dissociating perceptual and representation-based contributions to priming of face recognition.
Consciousness and cognition. 04/2006; 15(1):163-74.
Repetition priming of object identification refers to the phenomenon whereby experience with an object induces systematic changes in subsequent processing of that same object. This data-driven form of priming is distinct from conceptually-driven priming. To date, considerable controversy exists abou... [more] Repetition priming of object identification refers to the phenomenon whereby experience with an object induces systematic changes in subsequent processing of that same object. This data-driven form of priming is distinct from conceptually-driven priming. To date, considerable controversy exists about whether data-driven priming reflects facilitation in perceptual processing or mediation by preexisting object representations. The present study concerned priming of recognizing familiar and unfamiliar faces and how this priming is influenced by face inversion, which interferes with perceptual face processing. Perceptual and representation-based loci conjointly contributed to priming; the perceptual locus was operative similarly for familiar and unfamiliar faces, whereas the representation-based locus was only invoked for familiar faces and resulted in a response-time reduction triple the magnitude of that from the perceptual locus. The results constrain theoretical accounts of data-driven priming by indicating that improved identification can result from the combination of perceptual and representation-based facilitation.
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3.77Impact points
Neural correlates of intentional and incidental recognition of famous faces.
Brain research. Cognitive brain research. 06/2005; 23(2-3):153-63.
Event-related potentials (ERPs) were used to study the relationship between intentional and incidental recognition of famous faces. Intentional and incidental recognition were operationally defined as repeated presentations of targets and nontargets within a modified Sternberg task. These repetition... [more] Event-related potentials (ERPs) were used to study the relationship between intentional and incidental recognition of famous faces. Intentional and incidental recognition were operationally defined as repeated presentations of targets and nontargets within a modified Sternberg task. These repetitions elicited temporally and topographically distinct ERP modulations. A repetition effect around 300 ms (ERE/N250r) and a preceding modulation did not differ between intentional and incidental recognition, whereas a following repetition effect (LRE/N400) around 500 ms showed differences between incidental and intentional recognition. These results show that during the first few hundred milliseconds intentional and incidental face recognition relate to similar processing, indicating that familiar faces are recognized even when their identification is not required.
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3.05Impact points
Correlates of implicit memory for words and faces in event-related brain potentials.
International journal of psychophysiology : official journal of the International Organization of Psychophysiology. 02/2005; 55(1):95-112.
Prior research has suggested an ERP correlate of implicit memory for words consisting of a centro-parietal positivity around 400 ms. We attempted (1) to replicate this ERP modulation in a different task, involving only trials with correct responses, and (2) to compare the findings to the domain of f... [more] Prior research has suggested an ERP correlate of implicit memory for words consisting of a centro-parietal positivity around 400 ms. We attempted (1) to replicate this ERP modulation in a different task, involving only trials with correct responses, and (2) to compare the findings to the domain of faces. Two experiments were conducted with a modified Sternberg task, in which both targets and nontargets were presented repeatedly. In Experiment 1, positive ERP differences between repeated and new nontargets were observed, which were domain-specific in topography and, for words, replicated the previously reported findings. In Experiment 2, the amplitude of the modulation for words, but not for faces, was unaffected by a variation of the level of processing during encoding, supporting the implicitness of the processes underlying the ERP modulation to nontarget words.
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3.93Impact points
Looking for faces: Attention modulates early occipitotemporal object processing.
Psychophysiology. 06/2004; 41(3):350-60.
Looking for somebody's face in a crowd is one of the most important examples of visual search. For this goal, attention has to be directed to a well-defined perceptual category. When this categorically selective process starts is, however, still unknown. To this end, we used magnetoencephalograp... [more] Looking for somebody's face in a crowd is one of the most important examples of visual search. For this goal, attention has to be directed to a well-defined perceptual category. When this categorically selective process starts is, however, still unknown. To this end, we used magnetoencephalography (MEG) recorded over right human occipitotemporal cortex to investigate the time course of attentional modulation of perceptual processes elicited by faces and by houses. The first face-distinctive MEG response was observed at 160-170 ms (M170). Nevertheless, attention did not start to modulate face processing before 190 ms. The first house-distinctive MEG activity was also found around 160-170 ms. However, house processing was not modulated by attention before 280 ms (90 ms later than face processing). Further analysis revealed that the attentional modulation of face processing is not due to later, for example, back-propagated activation of the M170 generator. Rather, subsequent stages of occipitotemporal object processing were modulated in a category-specific manner and with preferential access to face processing.
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Neuron, Vol. 38, 507-516, May 8, 2003, Copyright 2003 by Cell Press
07/2003;
Introduction Neuropsychological studies of memory have shown that recollection, the subjective experience of remembering, often accompanies the recall and recognition of facts and events (also known as declarative memory), whereas other forms of memory are commonly observed in the absence of conscio... [more] Introduction Neuropsychological studies of memory have shown that recollection, the subjective experience of remembering, often accompanies the recall and recognition of facts and events (also known as declarative memory), whereas other forms of memory are commonly observed in the absence of conscious remembering (Gabrieli, 1998; Mayes and Downes, 1997; Schacter et al., 1993; Squire and Schacter, 2002). People typically exhibit conscious memory when they recognize that a specific stimulus had been presented earlier, and perceptualpriming when processing of that stimulus is otherwise altered in certain ways due to its prior presentation, sometimes with no recollection of that prior episode. Patients with amnesia may be poor at recollecting faces, but like people without a memory disorder, they respond faster during an implicit memory test to recently viewed faces than to new faces (Paller et al., 1992). This pattern of performance is known as preserved priming in amnesia (Schacter and
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13.26Impact points
Neural manifestations of memory with and without awareness.
Neuron. 06/2003; 38(3):507-16.
Neurophysiological events responsible for different types of human memory tend to occur concurrently and are therefore difficult to measure independently. To surmount this problem, we produced perceptual priming (indicated by speeded responses) in the absence of conscious remembering. At encoding, f... [more] Neurophysiological events responsible for different types of human memory tend to occur concurrently and are therefore difficult to measure independently. To surmount this problem, we produced perceptual priming (indicated by speeded responses) in the absence of conscious remembering. At encoding, faces appeared briefly while subjects' attention was diverted to other stimuli. Faces appeared again in either an implicit or explicit memory test. Neural correlates of priming were identified as brain potentials beginning 270 ms after face onset with more negative amplitudes for repeated than for new faces. Remembered faces, in contrast, activated a different configuration of intracranial sources producing positive potentials maximal at 600-700 ms. We thus disentangled and characterized distinct neural events associated with memory with and without awareness.
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Correlates of implicit memory for words and faces in event-related brain potentials
International Journal of Psychophysiology.
Prior research has suggested an ERP correlate of implicit memory for words consisting of a centro-parietal positivity around 400 ms. We attempted (1) to replicate this ERP modulation in a different task, involving only trials with correct responses, and (2) to compare the findings to the domain of f... [more] Prior research has suggested an ERP correlate of implicit memory for words consisting of a centro-parietal positivity around 400 ms. We attempted (1) to replicate this ERP modulation in a different task, involving only trials with correct responses, and (2) to compare the findings to the domain of faces. Two experiments were conducted with a modified Sternberg task, in which both targets and nontargets were presented repeatedly. In Experiment 1, positive ERP differences between repeated and new nontargets were observed, which were domain-specific in topography and, for words, replicated the previously reported findings. In Experiment 2, the amplitude of the modulation for words, but not for faces, was unaffected by a variation of the level of processing during encoding, supporting the implicitness of the processes underlying the ERP modulation to nontarget words.
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Neurofeedback: A promising tool for the self-regulation of emotion networks
NeuroImage.
Real-time functional magnetic resonance imaging (fMRI) affords the opportunity to explore the feasibility of self-regulation of functional brain networks through neurofeedback. We localised emotion networks individually in thirteen participants using fMRI and trained them to upregulate target areas,... [more] Real-time functional magnetic resonance imaging (fMRI) affords the opportunity to explore the feasibility of self-regulation of functional brain networks through neurofeedback. We localised emotion networks individually in thirteen participants using fMRI and trained them to upregulate target areas, including the insula and amygdala. Participants achieved a high degree of control of these networks after a brief training period. We observed activation increases during periods of upregulation of emotion networks in the precuneus and medial prefrontal cortex and, with increasing training success, in the ventral striatum. These findings demonstrate the feasibility of fMRI-based neurofeedback of emotion networks and suggest a possible development into a therapeutic tool.
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Dissociating perceptual and representation-based contributions to priming of face recognition
Consciousness and Cognition. 15:163-174.
Repetition priming of object identification refers to the phenomenon whereby experience with an object induces systematic changes in subsequent processing of that same object. This data-driven form of priming is distinct from conceptually-driven priming. To date, considerable controversy exists abou... [more] Repetition priming of object identification refers to the phenomenon whereby experience with an object induces systematic changes in subsequent processing of that same object. This data-driven form of priming is distinct from conceptually-driven priming. To date, considerable controversy exists about whether data-driven priming reflects facilitation in perceptual processing or mediation by preexisting object representations. The present study concerned priming of recognizing familiar and unfamiliar faces and how this priming is influenced by face inversion, which interferes with perceptual face processing. Perceptual and representation-based loci conjointly contributed to priming; the perceptual locus was operative similarly for familiar and unfamiliar faces, whereas the representation-based locus was only invoked for familiar faces and resulted in a response-time reduction triple the magnitude of that from the perceptual locus. The results constrain theoretical accounts of data-driven priming by indicating that improved identification can result from the combination of perceptual and representation-based facilitation.
Following (7)
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Guido Nolte
Fraunhofer -
Richard E Zinbarg
Northwestern University Chicago -
Stephen Johnston
Brunel University -
David Linden
Cardiff University -
Guillaume Thierry
Bangor University
