The most cited articles published since 2010, extracted from Scopus
Volume 83, Issue 2, February 2012, Pages 120-131
Alexandra Bendixen | Iria SanMiguel | Erich Schröger
The auditory system essentially deals with sequential type of input and thus requires processing that is particularly suited to extract stimulus relations within a sequence. Evidence from a variety of paradigms converges to show that the auditory system automatically uses stimulus predictability for facilitating its sequential processing. This type of predictive processing does not require attentional processing of the sounds or cognitive control of the predictions, nor does it involve the preparation of motor responses to the auditory stimuli. We will present a taxonomy of paradigms and resulting electrophysiological indicators for such automatic predictive processing in terms of event-related potential components and oscillatory activity. These indicators will include signals of fulfilled predictions (match signals such as N1 attenuation, repetition positivity, and early evoked gamma band response enhancement) as well as signals of violated predictions (mismatch signals such as the mismatch negativity and stimulus omission responses). We will show how recent approaches have revealed particularly early indicators of predictive processing down to the level of the auditory middle-latency responses. We will discuss the strength of the various indicators in terms of a truly predictive account of auditory processing (as opposed to, e.g., a retrospective verification of predictions). Finally, we will discuss the benefits of a predictive system within and beyond auditory processing. In conclusion, we argue in favor of the overwhelming evidence for predictions in audition, flexibly instantiated on different levels and timescales, and we aim to provide guidance along a variety of research paradigms illustrating the existence of these predictions. © 2011 Elsevier B.V.
Volume 83, Issue 2, February 2012, Pages 176-190
Cyma K. Van Petten | Barbara J. Luka
Because context has a robust influence on the processing of subsequent words, the idea that readers and listeners predict upcoming words has attracted research attention, but prediction has fallen in and out of favor as a likely factor in normal comprehension. We note that the common sense of this word includes both benefits for confirmed predictions and costs for disconfirmed predictions. The N400 component of the event-related potential (ERP) reliably indexes the benefits of semantic context. Evidence that the N400 is sensitive to the other half of prediction - a cost for failure - is largely absent from the literature. This raises the possibility that "prediction" is not a good description of what comprehenders do. However, it need not be the case that the benefits and costs of prediction are evident in a single ERP component. Research outside of language processing indicates that late positive components of the ERP are very sensitive to disconfirmed predictions. We review late positive components elicited by words that are potentially more or less predictable from preceding sentence context. This survey suggests that late positive responses to unexpected words are fairly common, but that these consist of two distinct components with different scalp topographies, one associated with semantically incongruent words and one associated with congruent words. We conclude with a discussion of the possible cognitive correlates of these distinct late positivities and their relationships with more thoroughly characterized ERP components, namely the P300, P600 response to syntactic errors, and the "old/new effect" in studies of recognition memory. © 2011 Elsevier B.V.
Volume 77, Issue 3, September 2010, Pages 186-194
Cornelis Jan Stam
A central question in modern neuroscience is how anatomical and functional connections between brain areas are organized to allow optimal information processing. In particular, both segregation and integration of information have to be dealt with in a single architecture of brain networks. There is strong evidence that synchronization of neural activity, both locally and between distant regions is a crucial code for functional interactions. However, a powerful theoretical framework to describe the structural and functional topology of system-wide brain networks has only become available with the discovery of 'small-world' and 'scale-free' networks in 1998 and 1999. There is now strong evidence that brain networks, ranging from simple nets of interconnected neurons up to macroscopic networks of brain areas display the typical features of complex systems: high clustering, short path lengths (both typical of 'small-world' networks), skewed degree distributions, presence of hubs, assortative mixing and the presence of modules. This has been demonstrated for anatomical and functional networks using neuroanatomical techniques, EEG, MEG and structural and functional MRI, in organisms ranging from C. elegans to man. In addition, network topology has been shown to be highly heritable, and very predictive of cognitive functioning. A short path length, which implies that from any area in the brain any other area can be reached in a small number of steps, is strongly correlated with IQ. Computational models are now beginning to reveal how the complex structure of adult brain networks could arise during development. © 2010 Elsevier B.V.
Volume 83, Issue 2, February 2012, Pages 132-143
István Winkler | István Czigler
Predictive coding theories posit that the perceptual system is structured as a hierarchically organized set of generative models with increasingly general models at higher levels. The difference between model predictions and the actual input (prediction error) drives model selection and adaptation processes minimizing the prediction error. Event-related brain potentials elicited by sensory deviance are thought to reflect the processing of prediction error at an intermediate level in the hierarchy. We review evidence from auditory and visual studies of deviance detection suggesting that the memory representations inferred from these studies meet the criteria set for perceptual object representations. Based on this evidence we then argue that these perceptual object representations are closely related to the generative models assumed by predictive coding theories. © 2011 Elsevier B.V.
Volume 79, Issue 1, January 2011, Pages 9-15
Nathan Earl Crone | Anna Korzeniewska | Piotr Julian Franaszczuk
In this paper, a brief, preliminary attempt is made to frame a scientific debate about how functional responses at gamma frequencies in electrophysiological recordings (EEG, MEG, ECoG, and LFP) should be classified and interpreted. In general, are all gamma responses the same, or should they be divided into different classes according to criteria such as their spectral characteristics (frequency range and/or shape), their spatial-temporal patterns of occurrence, and/or their responsiveness under different task conditions? In particular, are the responses observed in intracranial EEG at a broad range of "high gamma" frequencies (~. 60-200. Hz) different from gamma responses observed at lower frequencies (~. 30-80. Hz), typically in narrower bands? And if they are different, how should they be interpreted? Does the broad spectral shape of high gamma responses arise from the summation of many different narrow-band oscillations, or does it reflect something completely different? If we are not sure, should we refer to high gamma activity as oscillations? A variety of theories have posited a mechanistic role for gamma activity in cortical function, often assuming narrow-band oscillations. These theories continue to influence the design of experiments and the interpretation of their results. Do these theories apply to all electrophysiological responses at gamma frequencies? Although no definitive answers to these questions are immediately anticipated, this paper will attempt to review the rationale for why they are worth asking and to point to some of the possible answers that have been proposed. © 2010 Elsevier B.V.
Volume 85, Issue 1, July 2012, Pages 88-92
Sabine Grimm | Carles Escera
The fast detection of novel or deviant stimuli is a striking property of the auditory processing which reflects basic organizational principles of the auditory system and at the same time is of high practical significance. In human electrophysiology, deviance detection has been related to the occurrence of the mismatch negativity (MMN) - a component of the event-related potential (ERP) evoked 100 to 250. ms after the occurrence of a rare irregular sound. Recently, it has been shown in animal studies that a considerable portion of neurons in the auditory pathway exhibits a property called stimulus-specific adaptation enabling them to encode inter-sound relationships and to discharge at higher rates to rare changes in the acoustic stimulation. These neural responses have been linked to the deviant-evoked potential measured at the human scalp, but such responses occur at lower levels anatomically (e.g. the primary auditory cortex as well as the inferior colliculi) and are elicited earlier (20-30. ms after sound onset) in comparison to MMN. Further, they are not considerable enough in size to be interpreted as a direct neural correlate of the MMN. We review here a series of recent findings that provides a first step toward filling this gap between animal and human recordings by showing that comparably early modulations due to a sound's deviancy can be observed in humans, particularly in the middle-latency portion of the ERP within the first 50. ms after sound onset. The existence of those early indices of deviance detection preceding the well-studied MMN component strongly supports the idea that the encoding of regularities and the detection of violations is a basic principle of human auditory processing acting on multiple levels. This sustains the notion of a hierarchically organized novelty and deviance detection system in the human auditory system. © 2011 Elsevier B.V..
Volume 79, Issue 1, January 2011, Pages 55-63
Christoph Mulert | Valerie Kirsch | Roberto D. Pascual-Marqui | Robert, W. McCarley | Kevin M. Spencer
Phase locking in the gamma-band range has been shown to be diminished in patients with schizophrenia. Moreover, there have been reports of positive correlations between phase locking in the gamma-band range and positive symptoms, especially hallucinations. The aim of the present study was to use a new methodological approach in order to investigate gamma-band phase synchronization between the left and right auditory cortex in patients with schizophrenia and its relationship to auditory hallucinations. Subjects were 18 patients with chronic schizophrenia (SZ) and 16 healthy control (HC) subjects. Auditory hallucination symptom scores were obtained using the Scale for the Assessment of Positive Symptoms. Stimuli were 40-Hz binaural click trains. The generators of the 40. Hz-ASSR were localized using eLORETA and based on the computed intracranial signals lagged interhemispheric phase locking between primary and secondary auditory cortices was analyzed. Current source density of the 40 ASSR response was significantly diminished in SZ in comparison to HC in the right superior and middle temporal gyrus (p < 0.05). Interhemispheric phase locking was reduced in SZ in comparison to HC for the primary auditory cortices (p < 0.05) but not in the secondary auditory cortices. A significant positive correlation was found between auditory hallucination symptom scores and phase synchronization between the primary auditory cortices (p < 0.05, corrected for multiple testing) but not for the secondary auditory cortices. These results suggest that long-range synchrony of gamma oscillations is disturbed in schizophrenia and that this deficit is related to clinical symptoms such as auditory hallucinations. © 2010 Elsevier B.V.
Volume 75, Issue 1, January 2010, Pages 25-32
André W. Keizer | Maurice Verschoor | Roland S. Verment | Bernhard Hommel
Neural synchronization in the gamma band has been associated with feature binding and intelligence. Using neurofeedback, we aimed at changing the power of the gamma band and investigated whether these changes would influence behavioral measures of feature binding and intelligence. The results show that people are indeed able to alter the power in the gamma band if provided with neurofeedback. Moreover, the increase of gamma band power was related to a decrease of binding costs and an increase in intelligence, suggesting that the control of feature binding and intelligence share a common underlying mechanism. © 2009 Elsevier B.V. All rights reserved.
Volume 79, Issue 2, February 2011, Pages 118-126
Markus Muehlhan | Ulrike Lueken | Hans Ülrich Wïttchen | Clemens Kirschbaum
Subjects participating in magnetic resonance imaging (MRI) examinations regularly report anxiety and stress related reactions. This may result in impaired data quality and premature termination of scans. Moreover, cognitive functions and neural substrates can be altered by stress. While prior studies investigated pre-post scan differences in stress reactions only, the present study provides an in-depth analysis of mood changes and hormonal fluctuations during the time course of a typical fMRI session. Thirty-nine subjects participated in the study. Subjective mood, salivary alpha-amylase (sAA) and cortisol were assessed at six time points during the lab visit. Associations between hormonal data and neural correlates of a visual detection task were observed using a region of interest approach applied to the thalamic region. Mood and hormonal levels changed significantly during the experiment. Subjects were most nervous immediately after entering the scanner. SAA was significantly elevated after MRI preparation. A subgroup of n= 5 (12.8%) subjects showed pronounced cortisol responses exceeding 2.5. nmol/l. Preliminary fMRI data revealed an association between sAA levels and left thalamic activity during the first half of the experiment that disappeared during the second half. No significant correlation between cortisol and thalamic activity was observed. Results indicate that an fMRI experiment may elicit subjective and neuroendocrine stress reactions that can influence functional activation patterns. © 2010 Elsevier B.V.
Volume 87, Issue 3, March 2013, Pages 217-233
René Jürgen Huster | Stefanie Enriquez-Geppert | Christina F. Lavallee | Michael Falkenstein | Christoph Siegfried Herrmann
Response inhibition paradigms, as for example stop signal and go/no-go tasks, are often used to study cognitive control processes. Because of the apparent demand to stop a motor reaction, the electrophysiological responses evoked by stop and no-go trials have sometimes likewise been interpreted as indicators of inhibitory processes. Recent research, however, suggests a richer conceptual background. Evidence denotes an association of a frontal-midline N200/theta oscillations with premotor cognitive processes such as conflict monitoring or response program updating, and an anterior P300/delta oscillations with response-related, evaluative processing stages, probably the evaluation of motor inhibition. However, the data are still insufficient to unambiguously relate these electroencephalographic measures to specific inhibitory functions. Beta band activity only recently has become a focus of attention in this task context because of its association with the motor system and regions involved in inhibitory control. Its functional role in response inhibition tasks needs further exploration though. Hence, as things stand, any deduction of differences regarding actual inhibitory capabilities or loads between subject groups or conditions based on electroencephalographic measures has to be treated with caution. © 2012 Elsevier B.V.
Volume 83, Issue 2, February 2012, Pages 248-252
Karl J. Friston
The articles in this special issue provide a rich and thoughtful perspective on the brain as an inference machine. They illuminate key aspects of the internal or generative models the brain might use for perception. Furthermore, they explore the implications for a sense of agency and the nature of false inference in neuropsychiatric syndromes. In this review, I try to gather together some of the themes that emerge in this special issue and use them to illustrate how far one can take the notion of predictive coding in understanding behaviour and agency. © 2011 Elsevier B.V.
Volume 75, Issue 2, February 2010, Pages 66-76
Gina R. Kuperberg | Donna A. Kreher | Tali Ditman
Disturbances of thought and language are fundamental to schizophrenia. Cognitive behavioral and electrophysiological research has implicated problems in two different neurocognitive mechanisms: abnormalities in the structure and function of semantic memory, and abnormalities in combining and integrating words together to build up sentence and discourse context. This review discusses recent electrophysiological evidence suggesting that these two deficits are not completely distinct, but rather that language impairment in schizophrenia results from a dysfunctional interaction between these systems in an effort to build up higher-order meaning. Moreover, although language abnormalities are more pronounced in patients with positive thought disorder, they manifest themselves in all patients when increased demands are placed on the comprehension system. Further investigation of language dysfunction may also provide insights into other aspects of psychotic thought. © 2009.
Volume 75, Issue 3, March 2010, Pages 217-226
Janette Louise Smith | Elizabeth A. Smith | Alexander L. Provost | Andrew Heathcote
In two-choice tasks the preceding sequence of stimuli robustly influences both the P3 ERP component and reaction time (RT) to the current stimulus. We examined sequence effects in both two-choice and Go/NoGo tasks to distinguish between inhibition and conflict accounts of the N2 and P3 components. RT results suggested similar subjective expectancies were generated in the Go/NoGo and two-choice task. N2 was increased for all unexpected stimuli, even when no response inhibition was required, consistent with a conflict interpretation. The Go/NoGo P3 results also suggested a conflict explanation, and that this conflict was reduced if the response had been recently performed. These results support a reconsideration of the roles of N2 and P3 in all inhibition and conflict tasks, and the Go/NoGo task in particular. © 2009 Elsevier B.V. All rights reserved.
Volume 87, Issue 1, January 2013, Pages 19-27
Andre Pittig | Joanna J. Arch | Chi W R Lam | Michelle G. Craske
It remains unclear if diminished high frequency heart rate variability (HF-HRV) can be found across anxiety disorders. HF-HRV and heart rate (HR) were examined in panic (PD), generalized anxiety (GAD), social anxiety (SAD), and obsessive-compulsive disorder (OCD) relative to healthy controls at baseline and during anxiety stressors. All disorders evidenced diminished baseline HF-HRV relative to controls. Baseline HRV differences were maintained throughout relaxation. For hyperventilation, PD and GAD demonstrated greater HR than controls. Psychotropic medication did not account for HF-HRV differences except in OCD. Age and sex evidenced multiple main effects. Findings suggest that low baseline HF-HRV represents a common index for inhibitory deficits across PD, GAD, and SAD, which is consistent with the notion of autonomic inflexibility in anxiety disorders. Elevated HR responses to hyperventilation, however, are specific to PD and GAD. © 2012 Elsevier B.V.
Volume 80, Issue 2, May 2011, Pages 103-111
Xinjun Yu | Masaki Fumoto | Yasushi Nakatani | Tamami Sekiyama | Hiromi Kikuchi | Yoshinari Seki | Ikuko Sato-Suzuki | Hideho Arita
To gain insight into the neurophysiological mechanisms involved in Zen meditation, we evaluated the effects of focused attention (FA) on breathing movements in the lower abdomen (Tanden) in novices. We investigated hemodynamic changes in the prefrontal cortex (PFC), an attention-related brain region, using 24-channel near-infrared spectroscopy during a 20-minute session of FA on Tanden breathing in 15 healthy volunteers. We found that the level of oxygenated hemoglobin in the anterior PFC was significantly increased during FA on Tanden breathing, accompanied by a reduction in feelings of negative mood compared to before the meditation session. Electroencephalography (EEG) revealed increased alpha band activity and decreased theta band activity during and after FA on Tanden breathing. EEG changes were correlated with a significant increase in whole blood serotonin (5-HT) levels. These results suggest that activation of the anterior PFC and 5-HT system may be responsible for the improvement of negative mood and EEG signal changes observed during FA on Tanden breathing. © 2011 Elsevier B.V.
Volume 84, Issue 1, April 2012, Pages 86-94
Elisabeth V C Friedrich | Reinhold Scherer | Christa Neuper
Motor imagery is the task most commonly used to induce changes in electroencephalographic (EEG) signals for mental imagery-based brain computer interfacing (BCI). In this study, we investigated EEG patterns that were induced by seven different mental tasks (i.e. mental rotation, word association, auditory imagery, mental subtraction, spatial navigation, imagery of familiar faces and motor imagery) and evaluated the binary classification performance. The aim was to provide a broad range of reliable and user-appropriate tasks to make individual optimization of BCI control strategies possible. Nine users participated in four sessions of multi-channel EEG recordings. Mental tasks resulting most frequently in good binary classification performance include mental subtraction, word association, motor imagery and mental rotation. Our results indicate that a combination of 'brain-teasers' - tasks that require problem specific mental work (e.g. mental subtraction, word association) - and dynamic imagery tasks (e.g. motor imagery) result in highly distinguishable brain patterns that lead to an increased performance. © 2012 Elsevier B.V.
Volume 83, Issue 2, February 2012, Pages 144-155
Since the discovery of an event-related brain potential (ERP) component, auditory mismatch negativity (auditory MMN), there has been a long-lasting debate regarding the existence of its counterparts in other sensory modalities. Over the past few decades, several studies have confirmed the existence of mismatch negativity in the visual modality (visual MMN) and have revealed the various characteristics of visual MMN. In the present review, a full range of visual MMN studies are overviewed from the perspective of the predictive framework of visual MMN recently proposed by Kimura et al. (2011b). In the first half, the nature of visual MMN is reviewed in terms of (1) typical paradigm and morphologies, (2) underlying processes, (3) neural generators, and (4) functional significance. The main message in this part is that visual MMN is closely associated with the unintentional prediction of forthcoming visual sensory events on the basis of abstract sequential rules embedded in the temporal context of visual stimulation (i.e., "unintentional temporal-context-based prediction in vision"). In the second half, the nature of the unintentional prediction is discussed in terms of (1) behavioral indicators, (2) cognitive properties, and (3) neural substrates and mechanisms. As the main message in this part, I put forward a hypothetical model, which suggests that the unintentional prediction might be implemented by a bi-directional cortical network that includes the visual and prefrontal areas. © 2011 Elsevier B.V.
Volume 76, Issue 2, May 2010, Pages 72-79
Andres H. Neuhaus | Carsten Urbanek | Carolin Opgen-Rhein | Eric Hahn | Thi Ta | Simone Koehler | Melanie Gross | Michael Dettling
Selective visual attention is thought to be comprised of distinct neuronal networks that serve different attentional functions. The Attention Network Test (ANT) has been introduced to allow for assessment of alerting, orienting, and response inhibition. Information on associated measures of neural processing during ANT is still scarce. We topographically analyzed top-down ANT effects on visual event-related potential morphology in 44 healthy participants. Significant reaction time effects were obtained for all attention networks. Posterior cue-locked target N1 amplitude was significantly increased during both alerting and orienting. P3 amplitude was significantly modulated at frontal and parietal leads as a function of inhibition. Our data suggests that attentional mechanisms of alerting and orienting are employed simultaneously at early stages of the visual processing stream to amplify perceptual discrimination and load onto the same ERP component. Fronto-parietal modulations of P3 amplitude seem to mirror both response inhibition and visual target detection and may be interesting markers for further studies. © 2010 Elsevier B.V.
Volume 79, Issue 2, February 2011, Pages 266-271
Stéphanie Caharel | Benoît Montalan | Emilie Fromager | Christian Bernard | Robert Lalonde | Rebaï Mohamed
To investigate the mechanisms underlying the other-race effect, in particular at what stage of face processing differences between same-race (SR) and other-race (OR) stimuli occur, electrophysiological and behavioral data were obtained on Caucasian participants viewing photographs of Caucasian, Asian, and African faces in upright and inverted orientations. During a race categorization task, reaction times were faster for African than Asian faces, and both of them faster than Caucasian ones, independent of their orientation. The face-sensitive N170 component was low in amplitude for Caucasian, intermediate for Asian, and maximal for African faces. The face inversion effect was observed for all ethnic groups on N170 amplitudes, but was more evident for Caucasian faces. According to the perceptual expertise hypothesis, our results indicate that SR faces involve more configural/holistic processing OR faces. © 2010 Elsevier B.V.
Volume 85, Issue 2, August 2012, Pages 206-211
Mehran Ahmadlou | Hojjat Adeli | Amir Adeli
EEGs of the frontal brain of patients diagnosed with major depressive disorder (MDD) have been investigated in recent years using linear methods but not based on nonlinear methods. This paper presents an investigation of the frontal brain of MDD patients using the wavelet-chaos methodology and Katz's and Higuchi's fractal dimensions (KFD and HFD) as measures of nonlinearity and complexity. EEGs of the frontal brain of healthy adults and MDD patients are decomposed into 5 EEG sub-bands employing a wavelet filter bank, and the FDs of the band-limited as well as those of their 5 sub-bands are computed. Then, using the ANOVA statistical test, HFDs and KFDs of the left and right frontal lobes in EEG full-band and sub-bands of MDD and healthy groups are compared in order to discover the FDs showing the most meaningful differences between the two groups. Finally, the discovered FDs are used as input to a classifier, enhanced probabilistic neural network (EPNN), to discriminate the MDD from healthy EEGs. The results of HFD show higher complexity of left, right and overall frontal lobes of the brain of MDD compared with non-MDD in beta and gamma sub-bands. Moreover, it is observed that HFD of the beta band is more discriminative than HFD of the gamma band for discriminating MDD and non-MDD participants, while the KFD did not show any meaningful difference. A high accuracy of 91.3% is achieved for classification of MDD and non-MDD EEGs based on HFDs of left, right, and overall frontal brain beta sub-band. The findings of this research, however, should be considered tentative because of limited data available to the authors. © 2012 Elsevier B.V.
Volume 76, Issue 3, June 2010, Pages 186-192
Gert Pfùrtscheller | Günther Bauernfeind | Selina Christin Wriessnegger | Christa Neuper
Near-infrared spectroscopy (NIRS) is a functional brain imaging method able to study hemodynamic changes during cortical activation. We studied the changes of oxy- and deoxyhemoglobin ([oxy-Hb], [deoxy-Hb]) with a 52-channel NIRS system during simple mental arithmetic in ten healthy volunteers over the prefrontal cortex. We found that eight of the ten subjects showed a relative focal bilateral increase of [oxy-Hb] in the dorsolateral prefrontal cortex (DLPFC) in parallel with a decrease in the medial area of the anterior prefrontal cortex (APFC). The [oxy-Hb] response in left DLPFC and APFC was significant, while the [deoxy-Hb] response was clearly smaller and not significant. These observations were discussed within the context of "focal activation/surround deactivation". © 2010 Elsevier B.V.
Volume 78, Issue 3, December 2010, Pages 299-307
Mareike Bayer | Werner Sommer | Annekathrin Kathrin Schacht
Effects of emotional word meaning have been studied exclusively for words in isolation but not in the context of sentences. We addressed this question within the framework of two-dimensional models of affect, conceiving emotion as a function of valence and arousal. Negative and neutral target verbs, embedded within sentences, were presented while event-related brain potentials (ERPs) and the activity of the Corrugator muscle were recorded. Twenty-one participants performed a semantic decision task on the target verbs. In contrast to single word studies no early posterior negativity was present. However, emotion effects in ERPs were evident in a late positive complex (LPC) for negative, high-arousal words in comparison to neutral words. Interestingly, the LPC was unaffected by pure arousal variation when valence was controlled for, indicating the importance of valence for this emotion-related ERP effect. © 2010 Elsevier B.V.
Volume 78, Issue 1, October 2010, Pages 80-88
Craig Barr Taylor
Depression is a risk factor for both onset of cardiovascular disease (CVD) and increased morbidity and mortality for those with CVD. Many, but not all studies, have found that depressed patients have alterations in heart rate (HR) and heart rate variability (HRV). This variability is thought to reflect autonomic dysfunction. HR tends to be higher in depressed patients and HRV lower. Both higher heart rates and lower HRV increase CVD risk. Beta-blockers reduce HR and increase HRV and should be considered for depressed patients with CVD, elevated HR and/or reduced HRV. Exercise has similar, but smaller effects. Few studies have examined the effects of psychological interventions on HRV and the results have either been modest or examined only short term. Future research should focus on well-characterized subgroups of depressed patients at risk for CVD with assessment of other important factors that may affect HRV and CVD risk. Studies of high frequency HRV need to account for the effects of respiration. © 2010 Elsevier B.V.
Volume 77, Issue 2, August 2010, Pages 106-117
Sara Jane Webb | Emily J H Jones | Kristen L. Merkle | Michael Murias | Jessica N. Greenson | Todd L. Richards | Elizabeth Hoppes Aylward | Geraldine I. Dawson
Individuals with autism spectrum disorders (ASD) have pervasive impairments in social functioning, which may include problems with processing and remembering faces. In this study, we examined whether posterior ERP components associated with identity processing (P2, N250 and face-N400) and components associated with early-stage face processing (P1 and N170) are atypical in ASD. We collected ERP responses to a familiar repeated face (Familiar), an unfamiliar repeated face (Other) and novel faces (Novels) in 29 high-functioning adults with ASD and matched controls. For both groups, the P2 and N250 were sensitive to repetition (Other vs. Novels) and personal familiarity (Familiar vs. Other), and the face-N400 was sensitive to repetition. Adults with ASD did not show significantly atypical processing of facial familiarity and repetition in an ERP paradigm, despite showing significantly poorer performance than controls on a behavioral test of face memory. This study found no evidence that early-stage facial identity processing is a primary contributor to the face recognition deficit in high-functioning ASD. © 2010 Elsevier B.V.
Volume 75, Issue 3, March 2010, Pages 349-356
Dominik R. Bach | Guillaume Flandin | Karl J. Friston | Ray J. Dolan
Analytic tools for psychophysiological signals often make implicit assumptions that are unspecified. In developing a mathematical framework for analysis of skin conductance responses [SCRs], we formalise our assumptions by positing that SCRs can be regarded as the output of a linear time-invariant filter. Here, we provide an empirical test of these assumptions. Our findings indicate that a large component of the variance in SCRs can be explained by one response function per individual. We note that baseline variance (i.e. variance in the absence of evoked responses) is higher than variance that could not be explained by a linear time-invariant model of evoked responses. Furthermore, there was no evidence for nonlinear interactions among evoked responses that depended on their temporal overlap. We develop a canonical response function and show that it can be used for signals from different recording sites. We discuss the implications of these observations for model-based analysis of SCRs. © 2010 Elsevier B.V. All rights reserved.