Hemodynamic responses in neural circuitries for detection of visual target and novelty: An event-related fMRI study

Toward precision brain health: accurate prediction of a cognitive index trajectory using neuroimaging metrics

The goal of precision brain health is to accurately predict individuals' longitudinal patterns of brain change. We trained a machine learning model to predict changes in a cognitive index of brain health from neurophysiologic metrics. A total of 48 participants (ages 21-65) completed a sensorimotor task during 2 functional magnetic resonance imaging sessions 6 mo apart. Hemodynamic response functions (HRFs) were parameterized using traditional (amplitude, dispersion, latency) and novel (curvature, canonicality) metrics, serving as inputs to a neural network model that predicted gain on indices of brain health (cognitive factor scores) for each participant. The optimal neural network model successfully predicted substantial gain on the cognitive index of brain health with 90% accuracy (determined by 5-fold cross-validation) from 3 HRF parameters: amplitude change, dispersion change, and similarity to a canonical HRF shape at baseline. For individuals with canonical baseline HRFs, substantial gain in the index is overwhelmingly predicted by decreases in HRF amplitude. For individuals with non-canonical baseline HRFs, substantial gain in the index is predicted by congruent changes in both HRF amplitude and dispersion. Our results illustrate that neuroimaging measures can track cognitive indices in healthy states, and that machine learning approaches using novel metrics take important steps toward precision brain health.

Functional lateralization of the medial temporal lobe in novel associative processing during creativity evaluation

Although hemispheric lateralization of creativity has been a longstanding topic of debate, the underlying neurocognitive mechanism remains poorly understood. Here we designed 2 types of novel stimuli-"novel useful and novel useless," adapted from "familiar useful" designs taken from daily life-to demonstrate how the left and right medial temporal lobe (MTL) respond to novel designs of different usefulness. Taking the "familiar useful" design as a baseline, we found that the right MTL showed increased activation in response to "novel useful" designs, followed by "novel useless" ones, while the left MTL only showed increased activation in response to "novel useful" designs. Calculating an asymmetry index suggests that usefulness processing is predominant in the left MTL, whereas the right MTL is predominantly involved in novelty processing. Moreover, the left parahippocampal gyrus (PHG) showed stronger functional connectivity with the anterior cingulate cortex when responding to "novel useless" designs. In contrast, the right PHG showed stronger connectivity with the amygdala, midbrain, and hippocampus. Critically, multivoxel representational similarity analyses revealed that the left MTL was more effective than the right MTL at distinguishing the usefulness differences in novel stimuli, while representational patterns in the left PHG positively predicted the post-behavior evaluation of "truly creative" products. These findings suggest an apparent dissociation of the left and right MTL in integrating the novelty and usefulness information and novel associative processing during creativity evaluation, respectively. Our results provide novel insights into a longstanding and controversial question in creativity research by demonstrating functional lateralization of the MTL in processing novel associations.

mGluR5 binding changes during a mismatch negativity task in a multimodal protocol with [11C]ABP688 PET/MR-EEG

Currently, the metabotropic glutamate receptor 5 (mGluR5) is the subject of several lines of research in the context of neurology and is of high interest as a target for positron-emission tomography (PET). Here, we assessed the feasibility of using [¹¹C]ABP688, a specific antagonist radiotracer for an allosteric site on the mGluR5, to evaluate changes in glutamatergic neurotransmission through a mismatch-negativity (MMN) task as a part of a simultaneous and synchronized multimodal PET/MR-EEG study. We analyzed the effect of MMN by comparing the changes in nondisplaceable binding potential (BP_ND) prior to (baseline) and during the task in 17 healthy subjects by applying a bolus/infusion protocol. Anatomical and functional regions were analyzed. A small change in BP_ND was observed in anatomical regions (posterior cingulate cortex and thalamus) and in a functional network (precuneus) after the start of the task. The effect size was quantified using Kendall's W value and was 0.3. The motor cortex was used as a control region for the task and did not show any significant BP_ND changes. There was a significant ΔBP_ND between acquisition conditions. On average, the reductions in binding across the regions were - 8.6 ± 3.2% in anatomical and - 6.4 ± 0.5% in the functional network (p ≤ 0.001). Correlations between ΔBP_ND and EEG latency for both anatomical (p = 0.008) and functional (p = 0.022) regions were found. Exploratory analyses suggest that the MMN task played a role in the glutamatergic neurotransmission, and mGluR5 may be indirectly modulated by these changes.

Dynamics of task-induced modulation of spontaneous brain activity and functional connectivity in the triple resting-state networks assessed using the visual oddball paradigm

The default mode network (DMN), the salience network (SN), and the central executive network (CEN) are considered as the core resting-state brain networks (RSN) due to their involvement in a wide range of cognitive tasks. Despite the large body of knowledge related to their regional spontaneous activity (RSA) and functional connectivity (FC) of these networks, less is known about the dynamics of the task-associated modulation on these parameters and the task-induced interaction between these three networks. We have investigated the effects of the visual-oddball paradigm on three fMRI measures (amplitude of low-frequency fluctuations for RSA, regional homogeneity for local FC, and degree centrality for global FC) in these three core RSN. A rest-task-rest paradigm was used and the RSNs were identified using independent component analysis (ICA) on the resting-state data. The observed patterns of change differed noticeably between the networks and were tightly associated with the task-related brain activity and the distinct involvement of the networks in the performance of the single subtasks. Furthermore, the inter-network analysis showed an increased synchronization of CEN with the DMN and the SN immediately after the task, but not between the DMN and SN. Higher pre-task inter-network synchronization between the DMN and the CEN was associated with shorter reaction times and thus better performance. Our results provide some additional insights into the dynamics within and between the triple RSN. Further investigations are required in order to understand better their functional importance and interplay.

Changes in Resting-State Spontaneous Brain Activity in Patients With Allergic Rhinitis: A Pilot Neuroimaging Study

BACKGROUND

Allergic rhinitis (AR) is an inflammatory disorder of the nose caused by immunoglobulin E (IgE)-mediated immune response to allergens. Apart from the typical symptoms of sneezing, itching, rhinorrhea, and nasal congestion, behavioral complications were also reported to be associated with the progression of AR, such as cognitive deficits, mood changes, memory decline, attention deficiency, poor school performance, anxiety, and depression. Recent human studies have suggested that alterations in brain function caused by allergen exposure may precipitate high levels of anxiety and emotional reactivity in asthma patients. But until now, there is no direct evidence of the relationship between brain activity and allergic rhinitis.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) was used to excavate whether there remain functional changes of brain activity in AR patients. We measured the amplitude of low-frequency fluctuation (ALFF) and the z conversion of ALFF (zALFF) in 20 patients with AR and 20 age- and sex-matched healthy controls (HCs) using the rs-fMRI data.

RESULTS

Compared with healthy controls, AR patients exhibited lower ALFF values in the precuneus (PCUN) and higher ALFF values in the anterior cingulate cortex (ACC). The ALFF values of these features were significantly correlated with the visual analog scale (VAS) scores, the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) scores, the subscales of RQLQ, and specific IgE, partly.

CONCLUSION

We found changes in resting-state spontaneous brain activity in AR patients with hypoactivity in the PCUN and hyperactivity of the ACC. The brain-related symptoms of AR might be another potential clinical intervention target for improving the life quality of AR patients. Further attention to brain activity is essential for a deeper understanding of AR.

Stress effects on the oddball P300 and N2 in males and females

We examined the effect of psychosocial stress on electrophysiological markers of novelty and deviance processing, the N2 and P300, as well as sex differences therein. Participants underwent the Trier Social Stress Test (TSST) or a control procedure, followed by an oddball paradigm. A physiological stress response was induced in both sexes in the TSST condition. Furthermore, a reduced target P300 amplitude was elicited in the TSST condition in fronto-central electrodes, an effect that did not differ in magnitude between both sexes. By contrast, stressor effects on N2 amplitude differed by sex: In females, N2 amplitude was decreased in the TSST condition, while in males, no stress effects were observed. Exploratory correlational analyses suggested that a stress-induced P300 amplitude reduction, at least in males, could be due to a modulation of adrenergic activity. These results are consistent with sex differences in the manner in which stress affects lower-level, stimulus-driven vs. higher-level, more controlled processing stages.

An fMRI Study Using a Combined Task of Interval Discrimination and Oddball Could Reveal Common Brain Circuits of Cognitive Change

Recent functional neuroimaging studies suggest that the brain networks responsible for time processing are involved during other cognitive processes, leading to a hypothesis that time-related processing is needed to perform a range of tasks across various cognitive functions. To examine this hypothesis, we analyze whether, in healthy subjects, the brain structures activated or deactivated during performance of timing and oddball-detection type tasks coincide. To this end, we conducted two independent signed differential mapping (SDM) meta-analyses of functional magnetic resonance imaging (fMRI) studies assessing the cerebral generators of the responses elicited by tasks based on timing and oddball-detection paradigms. Finally, we undertook a multimodal meta-analysis to detect brain regions common to the findings of the two previous meta-analyses. We found that healthy subjects showed significant activation in cortical areas related to timing and salience networks. The patterns of activation and deactivation corresponding to each task type partially coincided. We hypothesize that there exists a time and change-detection network that serves as a common underlying resource used in a broad range of cognitive processes.

Principles of Neurorehabilitation After Stroke Based on Motor Learning and Brain Plasticity Mechanisms

What are the principles underlying effective neurorehabilitation? The aim of neurorehabilitation is to exploit interventions based on human and animal studies about learning and adaptation, as well as to show that the activation of experience-dependent neuronal plasticity augments functional recovery after stroke. Instead of teaching compensatory strategies that do not reduce impairment but allow the patient to return home as soon as possible, functional recovery might be more sustainable as it ensures a long-term reduction in impairment and an improvement in quality of life. At the same time, neurorehabilitation permits the scientific community to collect valuable data, which allows inferring about the principles of brain organization. Hence neuroscience sheds light on the mechanisms of learning new functions or relearning lost ones. However, current rehabilitation methods lack the exact operationalization of evidence gained from skill learning literature, leading to an urgent need to bridge motor learning theory and present clinical work in order to identify a set of ingredients and practical applications that could guide future interventions. This work aims to unify the neuroscientific literature relevant to the recovery process and rehabilitation practice in order to provide a synthesis of the principles that constitute an effective neurorehabilitation approach. Previous attempts to achieve this goal either focused on a subset of principles or did not link clinical application to the principles of motor learning and recovery. We identified 15 principles of motor learning based on existing literature: massed practice, spaced practice, dosage, task-specific practice, goal-oriented practice, variable practice, increasing difficulty, multisensory stimulation, rhythmic cueing, explicit feedback/knowledge of results, implicit feedback/knowledge of performance, modulate effector selection, action observation/embodied practice, motor imagery, and social interaction. We comment on trials that successfully implemented these principles and report evidence from experiments with healthy individuals as well as clinical work.

Segregated precuneus network and default mode network in naturalistic imaging

A resting-state network centered at the precuneus has been recently proposed as a precuneus network (PCUN) or "parietal memory network". Due to its spatial adjacency and overlapping with the default mode network (DMN), it is still not consensus to consider PCUN and DMN separately. Whether considering PCUN and DMN as different networks is a critical question that influences our understanding of brain functions and impairments. Previous resting-state studies using multiple methodologies have demonstrated a robust separation of the two networks. However, since there is no gold standard in justifying the functional difference between the networks in resting-state, we still lack of biological evidence to directly support the separation of the two networks. This study compared the responses and functional couplings of PCUN and DMN when participants were watching a movie and examined how the continuity of the movie context modulated the response of the networks. We identified PCUN and DMN in resting-state fMRI of 48 healthy subjects. The networks' response to a context-rich video and its context-shuffled version was characterized using the variance of temporal fluctuations and functional connectivity metrics. The results showed that (1) scrambling the contextual information altered the fluctuation level of DMN and PCUN in reversed ways; (2) compared to DMN, the FC within PCUN showed significantly higher sensitivity to the contextual continuity; (3) PCUN exhibited a significantly stronger functional network connectivity with the primary visual regions than DMN. These findings provide evidence for the distinct functional roles of PCUN and DMN in processing context-rich information and call for separately considering the functions and impairments of these networks in resting-state studies.

The signature of undetected change: an exploratory electrotomographic investigation of gradual change blindness

Neuroimaging-based investigations of change blindness, a phenomenon in which seemingly obvious changes in visual scenes fail to be detected, have significantly advanced our understanding of visual awareness. The vast majority of prior investigations, however, utilize paradigms involving visual disruptions (e.g., intervening blank screens, saccadic movements, "mudsplashes"), making it difficult to isolate neural responses toward visual changes cleanly. To address this issue in this present study, high-density EEG data (256 channel) were collected from 25 participants using a paradigm in which visual changes were progressively introduced into detailed real-world scenes without the use of visual disruption. Oscillatory activity associated with undetected changes was contrasted with activity linked to their absence using standardized low-resolution brain electromagnetic tomography (sLORETA). Although an insufficient number of detections were present to allow for analysis of actual change detection, increased beta-2 activity in the right inferior parietal lobule (rIPL), a region repeatedly associated with change blindness in disruption paradigms, followed by increased theta activity in the right superior temporal gyrus (rSTG) was noted in undetected visual change responses relative to the absence of change. We propose the rIPL beta-2 activity to be associated with orienting attention toward visual changes, with the subsequent rise in rSTG theta activity being potentially linked with updating preconscious perceptual memory representations. NEW & NOTEWORTHY This study represents the first neuroimaging-based investigation of gradual change blindness, a visual phenomenon that has significant potential to shed light on the processes underlying visual detection and conscious perception. The use of gradual change materials is reflective of real-world visual phenomena and allows for cleaner isolation of signals associated with the neural registration of change relative to the use of abrupt change transients.

Functional connectivity when detecting rare visual targets in schizophrenia

Individuals with schizophrenia demonstrate difficulties in attending to important stimuli (e.g., targets) and ignoring distractors (e.g., non-targets). We used a visual oddball task during fMRI to examine functional connectivity within and between the ventral and dorsal attention networks to determine the relative contribution of each network to detection of rare visual targets in schizophrenia. The sample comprised 25 schizophrenia patients and 27 healthy controls. Psychophysiological interaction analysis was used to examine whole-brain functional connectivity in response to targets. We used the right temporo parietal junction (TPJ) as the seed region for the ventral network and the right medial intraparietal sulcus (IPS) as the seed region for the dorsal network. We found that connectivity between right IPS and right anterior insula (AI; a component of the ventral network) was significantly greater in controls than patients. Expected patterns of within- and between-network connectivity for right TPJ were observed in controls, and not significantly different in patients. These findings indicate functional connectivity deficits between the dorsal and ventral attention networks in schizophrenia that may create problems in processing relevant versus irrelevant stimuli. Understanding the nature of network disruptions underlying cognitive deficits of schizophrenia may help shed light on the pathophysiology of this disorder.

Decreasing predictability of visual motion enhances feed-forward processing in visual cortex when stimuli are behaviorally relevant

Recent views of information processing in the (human) brain emphasize the hierarchical structure of the central nervous system, which is assumed to form the basis of a functional hierarchy. Hierarchical predictive processing refers to the notion that higher levels try to predict activity in lower areas, while lower levels transmit a prediction error up the hierarchy whenever the predictions fail. The present study aims at testing hypothetical modulatory effects of unpredictable visual motion on forward connectivities within the visual cortex. Functional magnetic resonance imaging was acquired from 35 healthy volunteers while viewing a moving ball under three different levels of predictability. In two different runs subjects were asked to attend to direction changes in the ball's motion, where a button-press was required in one of these runs only. Dynamic causal modeling was applied to a network comprising V1, V5 and posterior parietal cortex in the right hemisphere. The winning model of a Bayesian model selection indicated an enhanced strength in the forward connection from V1 to V5 with decreasing predictability for the run requiring motor response. These results support the notion of hierarchical predictive processing in the sense of an augmented bottom-up transmission of prediction error with increasing uncertainty about motion direction. This finding may be of importance for promoting our understanding of trait characteristics in psychiatric disorders, as an increased forward propagation of prediction error is assumed to underlie schizophrenia and may be observable at early stages of the disease.

The White Matter Microintegrity Alterations of Neocortical and Limbic Association Fibers in Major Depressive Disorder and Panic Disorder: The Comparison

The studies regarding to the comparisons between major depressive disorder (MDD) and panic disorder (PD) in the microintegrity of white matter (WM) are uncommon. Therefore, we tried to a way to classify the MDD and PD. Fifty-three patients with 1st-episode medication-naive PD, 54 healthy controls, and 53 patients with 1st-episode medication-naive MDD were enrolled in this study. The controls and patients were matched for age, gender, education, and handedness. The diffusion tensor imaging scanning was also performed. The WM microintegrity was analyzed and compared between 3 groups of participants (ANOVA analysis) with age and gender as covariates. The MDD group had lower WM microintegrity than the PD group in the left anterior thalamic radiation, left uncinate fasciculus, left inferior fronto-occipital fasciculus, and bilateral corpus callosum. The MDD group had reductions in the microintegrity when compared to controls in the bilateral superior longitudinal fasciculi, inferior longitudinal fasciculi, inferior fronto-occipital fasciculi, and corpus callosum. The PD group had lower microintegrity in bilateral superior longitudinal fasciculi and left inferior fronto-occipital fasciculus when compared to controls. The widespread pattern of microintegrity alterations in fronto-limbic WM circuit for MDD was different from restrictive pattern of alterations for PD.

Emotion-Dependent Functional Connectivity of the Default Mode Network in Adolescent Depression

BACKGROUND

Functional magnetic resonance imaging research suggests that major depressive disorder (MDD) in both adults and adolescents is marked by aberrant connectivity of the default mode network (DMN) during resting state. However, emotional dysregulation is also a key feature of MDD. No studies to date have examined emotion-related DMN pathology in adolescent depression. Comprehensively understanding the dynamics of DMN connectivity across brain states in individuals with depression with short disease histories could provide insight into the etiology of MDD.

METHODS

We collected functional magnetic resonance imaging data during an emotion identification task and during resting state from 26 medication-free adolescents (13-17 years old) with MDD and 37 well-matched healthy control subjects. We examined between-group differences in blood oxygenation level-dependent task responses and emotion-dependent and resting-state functional connectivity of the two primary nodes of the DMN: medial prefrontal cortex and posterior cingulate cortex (PCC). Additionally, we examined between-group differences in DMN functional connectivity and its relationship to depression severity and onset.

RESULTS

Relative to healthy control subjects, unmedicated adolescents with MDD demonstrated reduced medial prefrontal cortex and PCC emotion-related deactivation and greater medial prefrontal cortex and PCC emotion-dependent functional connectivity with precuneus, cingulate gyrus, and striatum/subcallosal cingulate gyrus. The PCC-subcallosal cingulate connectivity remained inflexibly elevated in the subjects with MDD versus healthy control subjects during resting state. Stronger PCC emotion-dependent functional connectivity was associated with greater depression severity and an earlier age of depression onset.

CONCLUSIONS

Adolescent depression is associated with inflexibly elevated DMN connections. Given more recent evidence of DMN maturation throughout adolescence, our findings suggest that early-onset depression adversely affects normal development of functional brain networks.

Functional connectivity associated with hand shape generation: Imitating novel hand postures and pantomiming tool grips challenge different nodes of a shared neural network

Clinical research suggests that imitating meaningless hand postures and pantomiming tool-related hand shapes rely on different neuroanatomical substrates. We investigated the BOLD responses to different tasks of hand posture generation in 14 right handed volunteers. Conjunction and contrast analyses were applied to select regions that were either common or sensitive to imitation and/or pantomime tasks. The selection included bilateral areas of medial and lateral extrastriate cortex, superior and inferior regions of the lateral and medial parietal lobe, primary motor and somatosensory cortex, and left dorsolateral prefrontal, and ventral and dorsal premotor cortices. Functional connectivity analysis revealed that during hand shape generation the BOLD-response of every region correlated significantly with every other area regardless of the hand posture task performed, although some regions were more involved in some hand postures tasks than others. Based on between-task differences in functional connectivity we predict that imitation of novel hand postures would suffer most from left superior parietal disruption and that pantomiming hand postures for tools would be impaired following left frontal damage, whereas both tasks would be sensitive to inferior parietal dysfunction. We also unveiled that posterior temporal cortex is committed to pantomiming tool grips, but that the involvement of this region to the execution of hand postures in general appears limited. We conclude that the generation of hand postures is subserved by a highly interconnected task-general neural network. Depending on task requirements some nodes/connections will be more engaged than others and these task-sensitive findings are in general agreement with recent lesion studies.

Neurophysiological features of Internet gaming disorder and alcohol use disorder: a resting-state EEG study

Despite that Internet gaming disorder (IGD) shares clinical, neuropsychological and personality characteristics with alcohol use disorder (AUD), little is known about the resting-state quantitative electroencephalography (QEEG) patterns associated with IGD and AUD. Therefore, this study compared the QEEG patterns in patients with IGD with those in patients with AUD to identify unique neurophysiological characteristics that can be used as biomarkers of IGD. A total of 76 subjects (34 with IGD, 17 with AUD and 25 healthy controls) participated in this study. Resting-state, eyes-closed QEEGs were recorded, and the absolute and relative power of brains were analyzed. The generalized estimating equation showed that the IGD group had lower absolute beta power than AUD (estimate = 5.319, P < 0.01) and the healthy control group (estimate = 2.612, P = 0.01). The AUD group showed higher absolute delta power than IGD (estimate = 7.516, P < 0.01) and the healthy control group (estimate = 7.179, P < 0.01). We found no significant correlations between the severity of IGD and QEEG activities in patients with IGD. The current findings suggest that lower absolute beta power can be used as a potential trait marker of IGD. Higher absolute power in the delta band may be a susceptibility marker for AUD. This study clarifies the unique characteristics of IGD as a behavioral addiction, which is distinct from AUD, by providing neurophysiological evidence.

A Trio of Concerns

This essay assesses the two most significant changes in psychology over the past century: the attempt to localize psychological phenomena in restricted brain sites and the search for genetic contributions to behavior and psychopathology. Although there are advantages to these new developments, they are accompanied by some questionable assumptions. Because the investigators in these domains often relate variation in their biological measures to variation in personality traits evaluated with questionnaires, an analysis of the unique properties of the verbalreport questionnaires is presented. It is suggested that future research on human personality should try to combine semantic reports with behaviors and biological data in order to arrive at more fruitful constructs.

More than just two sexes: the neural correlates of voice gender perception in gender dysphoria

Gender dysphoria (also known as “transsexualism”) is characterized as a discrepancy between anatomical sex and gender identity. Research points towards neurobiological influences. Due to the sexually dimorphic characteristics of the human voice, voice gender perception provides a biologically relevant function, e.g. in the context of mating selection. There is evidence for a better recognition of voices of the opposite sex and a differentiation of the sexes in its underlying functional cerebral correlates, namely the prefrontal and middle temporal areas. This fMRI study investigated the neural correlates of voice gender perception in 32 male-to-female gender dysphoric individuals (MtFs) compared to 20 non-gender dysphoric men and 19 non-gender dysphoric women. Participants indicated the sex of 240 voice stimuli modified in semitone steps in the direction to the other gender. Compared to men and women, MtFs showed differences in a neural network including the medial prefrontal gyrus, the insula, and the precuneus when responding to male vs. female voices. With increased voice morphing men recruited more prefrontal areas compared to women and MtFs, while MtFs revealed a pattern more similar to women. On a behavioral and neuronal level, our results support the feeling of MtFs reporting they cannot identify with their assigned sex.

Comparison of auditory and visual oddball fMRI in schizophrenia

Individuals with schizophrenia often suffer from attentional deficits, both in focusing on task-relevant targets and in inhibiting responses to distractors. Schizophrenia also has a differential impact on attention depending on modality: auditory or visual. However, it remains unclear how abnormal activation of attentional circuitry differs between auditory and visual modalities, as these two modalities have not been directly compared in the same individuals with schizophrenia. We utilized event-related functional magnetic resonance imaging (fMRI) to compare patterns of brain activation during an auditory and visual oddball task in order to identify modality-specific attentional impairment. Healthy controls (n=22) and patients with schizophrenia (n=20) completed auditory and visual oddball tasks in separate sessions. For responses to targets, the auditory modality yielded greater activation than the visual modality (A-V) in auditory cortex, insula, and parietal operculum, but visual activation was greater than auditory (V-A) in visual cortex. For responses to novels, A-V differences were found in auditory cortex, insula, and supramarginal gyrus; and V-A differences in the visual cortex, inferior temporal gyrus, and superior parietal lobule. Group differences in modality-specific activation were found only for novel stimuli; controls showed larger A-V differences than patients in prefrontal cortex and the putamen. Furthermore, for patients, greater severity of negative symptoms was associated with greater divergence of A-V novel activation in the visual cortex. Our results demonstrate that patients have more pronounced activation abnormalities in auditory compared to visual attention, and link modality specific abnormalities to negative symptom severity.

Spontaneous brain activity in adult patients with moyamoya disease: a resting-state fMRI study

Adult patients with moyamoya disease (MMD) are reported to suffer from vascular cognitive impairment (VCI), including considerable impairment of executive function/attention. The spatial pattern of functional brain activity in adult MMD patients with VCI has not been studied before and can be measured by examining the amplitude of low-frequency fluctuations (ALFF) of blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) during rest. Twenty-three adult patients with MMD were recruited to participate in this study, including 11 with VCI and 12 without VCI (NonVCI), as well as 22 healthy young adults (normal control, NC). Widespread differences in ALFF were observed between the VCI/NonVCI and NC groups in such regions as the frontal, parietal and temporal gyri, with parts of the frontal gyrus, such as the anterior cingulate cortex (ACC) and the right supplemental motor area (SMA), showing significant differences in ALFF. It is worth to note that regions such as the parietal gyrus, the right superior frontal gyrus (SFG), the right superior temporal gyrus (STG) and the left caudate nucleus (CN) exhibited significant changes in ALFF during the progressive cognitive decline of MMD. Taken together, our results demonstrate that MMD exhibits a specific intrinsic pattern of ALFF and that this pattern changes with the progression of cognitive decline, providing insight into the pathophysiological nature of this disease.

Sex differences in the persistence of the amygdala response to negative material

Previous studies have indicated that men and women have different amygdala responses to novel (vs familiar) and valenced (positive vs negative) material. It is not known, however, whether these affective sex differences are related. In this study, we tested whether women have more persistent amygdala responses to familiar, negative material than men do. During fMRI, male and female participants viewed evocative images that varied in novelty and valence. Women and men showed equivalent responses to novel negative material, but women showed a sustained amygdala response to familiar negative material relative to men, indicating that women's amygdala responses were more persistent over multiple repetitions of negative material. Individuals with more persistent amygdala responses also reported greater levels of negative effect. These findings have implications for sex differences in the incidence of affective disorders.

Aberrant functional connectivity of resting state networks in transient ischemic attack

Background

Transient ischemic attack (TIA) is usually defined as a neurologic ischemic disorder without permanent cerebral infarction. Studies have showed that patients with TIA can have lasting cognitive functional impairment. Inherent brain activity in the resting state is spatially organized in a set of specific coherent patterns named resting state networks (RSNs), which epitomize the functional architecture of memory, language, attention, visual, auditory and somato-motor networks. Here, we aimed to detect differences in RSNs between TIA patients and healthy controls (HCs).

Methods

Twenty one TIA patients suffered an ischemic event and 21 matched HCs were enrolled in the study. All subjects were investigated using cognitive tests, psychiatric tests and functional magnetic resonance imaging (fMRI). Independent component analysis (ICA) was adopted to acquire the eight brain RSNs. Then one-sample t-tests were calculated in each group to gather the spatial maps of each RSNs, followed by second level analysis to investigate statistical differences on RSNs between twenty one TIA patients and 21 controls. Furthermore, a correlation analysis was performed to explore the relationship between functional connectivity (FC) and cognitive and psychiatric scales in TIA group.

Results

Compared with the controls, TIA patients exhibited both decreased and increased functional connectivity in default mode network (DMN) and self-referential network (SRN), and decreased functional connectivity in dorsal attention network (DAN), central-executive network (CEN), core network (CN), somato-motor network (SMN), visual network (VN) and auditory network (AN). There was no correlation between neuropsychological scores and functional connectivity in regions of RSNs.

Conclusions

We observed selective impairments of RSN intrinsic FC in TIA patients, whose all eight RSNs had aberrant functional connectivity. These changes indicate that TIA is a disease with widely abnormal brain networks. Our results might put forward a novel way to look into neuro-pathophysiological mechanisms in TIA patients.

Involvement of the dorsal and ventral attention networks in oddball stimulus processing: a meta-analysis

The aim of this study was to provide the first, comprehensive meta-analysis of the neuroimaging literature regarding greater neural responses to a deviant stimulus in a stream of repeated, standard stimuli, termed here oddball effects. The meta-analysis of 75 independent studies included a comparison of auditory and visual oddball effects and task-relevant and task-irrelevant oddball effects. The results were interpreted with reference to the model in which a large-scale dorsal frontoparietal network embodies a mechanism for orienting attention to the environment, whereas a large-scale ventral frontoparietal network supports the detection of salient, environmental changes. The meta-analysis yielded three main sets of findings. First, ventral network regions were strongly associated with oddball effects and largely common to auditory and visual modalities, indicating a supramodal "alerting" system. Most ventral network components were more strongly associated with task-relevant than task-irrelevant oddball effects, indicating a dynamic interplay of stimulus saliency and internal goals in stimulus-driven engagement of the network. Second, the bilateral inferior frontal junction, an anterior core of the dorsal network, was strongly associated with oddball effects, suggesting a central role in top-down attentional control. However, other dorsal network regions showed no or only modest association with oddball effects, likely reflecting active engagement during both oddball and standard stimulus processing. Finally, prominent oddball effects outside the two networks included the sensory cortex regions, likely reflecting attentive and preattentive modulation of early sensory activity, and subcortical regions involving the putamen, thalamus, and other areas, likely reflecting subcortical involvement in alerting responses.

Effects of age and gender on neural networks of motor response inhibition: from adolescence to mid-adulthood

Functional inhibitory neural networks mature progressively with age. However, nothing is known about the impact of gender on their development. This study employed functional magnetic resonance imaging (fMRI) to investigate the effects of age, sex, and sex by age interactions on the brain activation of 63 healthy males and females, between 13 and 38 years, performing a Stop task. Increasing age was associated with progressively increased activation in typical response inhibition areas of right inferior and dorsolateral prefrontal and temporo-parietal regions. Females showed significantly enhanced activation in left inferior and superior frontal and striatal regions relative to males, while males showed increased activation relative to females in right inferior and superior parietal areas. Importantly, left frontal and striatal areas that showed increased activation in females, also showed significantly increased functional maturation in females relative to males, while the right inferior parietal activation that was increased in males showed significantly increased functional maturation relative to females. The findings demonstrate for the first time that sex-dimorphic activation patterns of enhanced left fronto-striatal activation in females and enhanced right parietal activation in males during motor inhibition appear to be the result of underlying gender differences in the functional maturation of these brain regions.

Neural correlates of the perception for novel objects

Perception of novel objects is of enormous importance in our lives. People have to perceive or understand novel objects when seeing an original painting, admiring an unconventional construction, and using an inventive device. However, very little is known about neural mechanisms underlying the perception for novel objects. Perception of novel objects relies on the integration of unusual features of novel objects in order to identify what such objects are. In the present study, functional Magnetic Resonance Imaging (MRI) was employed to investigate neural correlates of perception of novel objects. The neuroimaging data on participants engaged in novel object viewing versus ordinary object viewing revealed that perception of novel objects involves significant activation in the left precuneus (Brodmann area 7) and the right visual cortex. The results suggest that the left precuneus is associated with the integration of unusual features of novel objects, while the right visual cortex is sensitive to the detection of such features. Our findings highlight the left precuneus as a crucial component of the neural circuitry underlying perception of novel objects.

Do EEG paradigms work in fMRI? Varying task demands in the visual oddball paradigm: Implications for task design and results interpretation

We investigate the effects of variations in response requirements on BOLD activation in a visual oddball task and consider implications for fMRI task designs. Sixteen healthy subjects completed 3 runs of a visual oddball task: passive, count and respond. Besides expected activation patterns during passive viewing, we identified joint activations, but more importantly crucial differences between the count and respond versions of the task. Middle frontal gyrus activation was seen in the respond but not the count condition suggesting that this region is associated with action execution rather than the decision-making aspect of the task. In addition, activation observed in the central opercular cortex and parietal operculum in the respond (but not count) condition is likely to reflect integration of the sensory, decision and response processes. We also observed activation in the supplementary motor area (SMA) during count as well as respond. Since the count condition requires no motor planning or response our data provide evidence for an SMA involvement in decision-making. Our study clearly shows that the count and respond versions of the visual oddball task result in different patterns of BOLD activation that could both be attributed to 'target detection' if information on the respective other condition was not available. We also show that considering the elements of a complex task is crucial when transferring it from one imaging modality to another and that a motor response is not always necessary in fMRI studies when the task has been set up appropriately.

A modified oddball paradigm for investigation of neural correlates of attention: a simultaneous ERP-fMRI study

Introduction

The objective of the presented study was to develop and evaluate a P300 experimental protocol for simultaneous registration of event-related potentials (ERPs) and functional MRI (fMRI) data with continuous imaging. It may be useful for investigating attention and working memory processes in specific populations, such as children and neuropsychiatric patients.

Materials and methods

Eleven children were investigated with simultaneous ERP–fMRI. To fulfill requirements of both BOLD and electroencephalographic signal registration, a modified oddball task was used. To verify the ERP–fMRI protocol we also performed a study outside the scanner using a typical two-stimuli oddball paradigm.

Results

Localization of the P300 component of ERPs partially corresponded with fMRI results in the frontal and parietal brain regions. FMRI activations were found in: middle frontal gyrus, insula, SMA, parietal lobule, thalamus, and cerebellum. Our modified oddball task provided ERP–fMRI results with high level of significance (EEG SNR = 35, fMRI p < 0.05–Bonf.). ERPs obtained in the scanner were comparable with those registered outside the scanner, although some differences in the amplitude were noticed, mainly in the N100 component.

Conclusion

In our opinion the presented paradigm may be successfully applied for simultaneous ERP–fMRI registration of neural correlates of attention in vulnerable populations.

Brain correlates of automatic visual change detection

A number of studies support the presence of visual automatic detection of change, but little is known about the brain generators involved in such processing and about the modulation of brain activity according to the salience of the stimulus. The study presented here was designed to locate the brain activity elicited by unattended visual deviant and novel stimuli using fMRI. Seventeen adult participants were presented with a passive visual oddball sequence while performing a concurrent visual task. Variations in BOLD signal were observed in the modality-specific sensory cortex, but also in non-specific areas involved in preattentional processing of changing events. A degree-of-deviance effect was observed, since novel stimuli elicited more activity in the sensory occipital regions and at the medial frontal site than small changes. These findings could be compared to those obtained in the auditory modality and might suggest a "general" change detection process operating in several sensory modalities.

Meta-analytic evidence for a superordinate cognitive control network subserving diverse executive functions

Classic cognitive theory conceptualizes executive functions as involving multiple specific domains, including initiation, inhibition, working memory, flexibility, planning, and vigilance. Lesion and neuroimaging experiments over the past two decades have suggested that both common and unique processes contribute to executive functions during higher cognition. It has been suggested that a superordinate fronto-cingulo-parietal network supporting cognitive control may also underlie a range of distinct executive functions. To test this hypothesis in the largest sample to date, we used quantitative meta-analytic methods to analyze 193 functional neuroimaging studies of 2,832 healthy individuals, ages 18-60, in which performance on executive function measures was contrasted with an active control condition. A common pattern of activation was observed in the prefrontal, dorsal anterior cingulate, and parietal cortices across executive function domains, supporting the idea that executive functions are supported by a superordinate cognitive control network. However, domain-specific analyses showed some variation in the recruitment of anterior prefrontal cortex, anterior and midcingulate regions, and unique subcortical regions such as the basal ganglia and cerebellum. These results are consistent with the existence of a superordinate cognitive control network in the brain, involving dorsolateral prefrontal, anterior cingulate, and parietal cortices, that supports a broad range of executive functions.

The centre of the brain: topographical model of motor, cognitive, affective, and somatosensory functions of the basal ganglia

The basal ganglia have traditionally been viewed as motor processing nuclei; however, functional neuroimaging evidence has implicated these structures in more complex cognitive and affective processes that are fundamental for a range of human activities. Using quantitative meta-analysis methods we assessed the functional subdivisions of basal ganglia nuclei in relation to motor (body and eye movements), cognitive (working-memory and executive), affective (emotion and reward) and somatosensory functions in healthy participants. We document affective processes in the anterior parts of the caudate head with the most overlap within the left hemisphere. Cognitive processes showed the most widespread response, whereas motor processes occupied more central structures. On the basis of these demonstrated functional roles of the basal ganglia, we provide a new comprehensive topographical model of these nuclei and insight into how they are linked to a wide range of behaviors.

Nicotine effects on brain function during a visual oddball task: a comparison between conventional and EEG-informed fMRI analysis

In a previous oddball task study, it was shown that the inclusion of electrophysiology (EEG), that is, single-trial P3 ERP parameters, in the analysis of fMRI responses can detect activation that is not apparent with conventional fMRI data modeling strategies [Warbrick, T., Mobascher, A., Brinkmeyer, J., Musso, F., Richter, N., Stoecker, T., et al. Single-trial P3 amplitude and latency informed event-related fMRI models yield different BOLD response patterns to a target detection task. Neuroimage, 47, 1532-1544, 2009]. Given that P3 is modulated by nicotine, including P3 parameters in the fMRI analysis might provide additional information about nicotine effects on brain function. A 1-mg nasal nicotine spray (0.5 mg each nostril) or placebo (pepper) spray was administered in a double-blind, placebo-controlled, within-subject, randomized, cross-over design. Simultaneous EEG-fMRI and behavioral data were recorded from 19 current smokers in response to an oddball-type visual choice RT task. Conventional general linear model analysis and single-trial P3 amplitude informed general linear model analysis of the fMRI data were performed. Comparing the nicotine with the placebo condition, reduced RTs in the nicotine condition were related to decreased BOLD responses in the conventional analysis encompassing the superior parietal lobule, the precuneus, and the lateral occipital cortex. On the other hand, reduced RTs were related to increased BOLD responses in the precentral and postcentral gyri, and ACC in the EEG-informed fMRI analysis. Our results show how integrated analyses of simultaneous EEG-fMRI data can be used to detect nicotine effects that would not have been revealed through conventional analysis of either measure in isolation. This emphasizes the significance of applying multimodal imaging methods to pharmacoimaging.

Age group and sex differences in performance on a computerized neurocognitive battery in children age 8-21

OBJECTIVE

Examine age group effects and sex differences by applying a comprehensive computerized battery of identical behavioral measures linked to brain systems in youths that were already genotyped. Such information is needed to incorporate behavioral data as neuropsychological "biomarkers" in large-scale genomic studies.

METHOD

We developed and applied a brief computerized neurocognitive battery that provides measures of performance accuracy and response time for executive-control, episodic memory, complex cognition, social cognition, and sensorimotor speed domains. We tested a population-based sample of 3,500 genotyped youths ages 8-21 years.

RESULTS

Substantial improvement with age occurred for both accuracy and speed, but the rates varied by domain. The most pronounced improvement was noted in executive control functions, specifically attention, and in motor speed, with some effect sizes exceeding 1.8 standard deviation units. The least pronounced age group effect was in memory, where only face memory showed a large effect size on improved accuracy. Sex differences had much smaller effect sizes but were evident, with females outperforming males on attention, word and face memory, reasoning speed, and all social cognition tests and males outperforming females in spatial processing and sensorimotor and motor speed. These sex differences in most domains were seen already at the youngest age groups, and age group × sex interactions indicated divergence at the oldest groups with females becoming faster but less accurate than males.

CONCLUSIONS

The results indicate that cognitive performance improves substantially in this age span, with large effect sizes that differ by domain. The more pronounced improvement for executive and reasoning domains than for memory suggests that memory capacities have reached their apex before age 8. Performance was sexually modulated and most sex differences were apparent by early adolescence.

Functional connectivity mapping of the human precuneus by resting state fMRI

Precuneus responds to a wide range of cognitive processes. Here, we examined how the patterns of resting state connectivity may define functional subregions in the precuneus. Using a K-means algorithm to cluster the whole-brain "correlograms" of the precuneus in 225 adult individuals, we corroborated the dorsal-anterior, dorsal-posterior, and ventral subregions, each involved in spatially guided behaviors, mental imagery, and episodic memory as well as self-related processing, with the ventral precuneus being part of the default mode network, as described extensively in earlier work. Furthermore, we showed that the lateral/medial volumes of dorsal anterior and dorsal posterior precuneus are each connected with areas of motor execution/attention and motor/visual imagery, respectively. Compared to the ventral precuneus, the dorsal precuneus showed greater connectivity with occipital and posterior parietal cortices, but less connectivity with the medial superior frontal and orbitofrontal gyri, anterior cingulate cortex as well as the parahippocampus. Compared to dorsal-posterior and ventral precuneus, the dorsal-anterior precuneus showed greater connectivity with the somatomotor cortex, as well as the insula, supramarginal, Heschl's, and superior temporal gyri, but less connectivity with the angular gyrus. Compared to ventral and dorsal-anterior precuneus, dorsal-posterior precuneus showed greater connectivity with the middle frontal gyrus. Notably, the precuneus as a whole has negative connectivity with the amygdala and the lateral and inferior orbital frontal gyri. Finally, men and women differed in the connectivity of precuneus. Men and women each showed greater connectivity with the dorsal precuneus in the cuneus and medial thalamus, respectively. Women also showed greater connectivity with ventral precuneus in the hippocampus/parahippocampus, middle/anterior cingulate gyrus, and middle occipital gyrus, compared to men. Taken together, these new findings may provide a useful platform upon which to further investigate sex-specific functional neuroanatomy of the precuneus and to elucidate the pathology of many neurological illnesses.

Functional development of fronto-striato-parietal networks associated with time perception

Compared to our understanding of the functional maturation of executive functions, little is known about the neurofunctional development of perceptive functions. Time perception develops during late adolescence, underpinning many functions including motor and verbal processing, as well as late maturing higher order cognitive skills such as forward planning and future-related decision making. Nothing, however, is known about the neurofunctional changes associated with time perception from childhood to adulthood. Using functional magnetic resonance imaging we explored the effects of age on the brain activation and functional connectivity of 32 male participants from 10 to 53 years of age during a time discrimination task that required the discrimination of temporal intervals of seconds differing by several hundred milliseconds. Increasing development was associated with progressive activation increases within left lateralized dorsolateral and inferior fronto-parieto-striato-thalamic brain regions. Furthermore, despite comparable task performance, adults showed increased functional connectivity between inferior/dorsolateral interhemispheric fronto-frontal activation as well as between inferior fronto-parietal regions compared with adolescents. Activation in caudate, specifically, was associated with both increasing age and better temporal discrimination. Progressive decreases in activation with age were observed in ventromedial prefrontal cortex, limbic regions, and cerebellum. The findings demonstrate age-dependent developmentally dissociated neural networks for time discrimination. With increasing age there is progressive recruitment of later maturing left hemispheric and lateralized fronto-parieto-striato-thalamic networks, known to mediate time discrimination in adults, while earlier developing brain regions such as ventromedial prefrontal cortex, limbic and paralimbic areas, and cerebellum subserve fine-temporal processing functions in children and adolescents.

Different types of target probability have different prefrontal consequences

One of the factors known to affect target detection is target probability. It is clear, though, that target probability can be manipulated in different ways. Here, in order to more accurately characterize the effects of target probability on frontal engagement, we examined the effects of two commonly-used but different target probability manipulations on neural activity. We found that manipulations that affected global stimulus class probability had a pronounced effect on ventrolateral prefrontal cortex and the insula, an effect which was absent with manipulations that only affected the likelihood of specific target stimuli occurring. This latter manipulation only modulated activity in dorsolateral prefrontal cortex and the precentral sulcus. Our data suggest two key points. First, different types of target probability have different neural consequences, and may therefore be very different in nature. Second, the data indicate that ventral and dorsal portions of prefrontal cortex respond to different types of task-relevant information.

Cognitive control and right ventrolateral prefrontal cortex: reflexive reorienting, motor inhibition, and action updating

Delineating the functional organization of the prefrontal cortex is central to advancing models of goal-directed cognition. Considerable evidence indicates that specific forms of cognitive control are associated with distinct subregions of the left ventrolateral prefrontal cortex (VLPFC), but less is known about functional specialization within the right VLPFC. We report a functional MRI meta-analysis of two prominent theories of right VLPFC function: stopping of motor responses and reflexive orienting to abrupt perceptual onsets. Along with a broader review of right VLPFC function, extant data indicate that stopping and reflexive orienting similarly recruit the inferior frontal junction (IFJ), suggesting that IFJ supports the detection of behaviorally relevant stimuli. By contrast, other right VLPFC subregions are consistently active during motor inhibition, but not reflexive reorienting tasks, with posterior-VLPFC being active during the updating of action plans and mid-VLPFC responding to decision uncertainty. These results highlight the rich functional heterogeneity that exists within right VLPFC.

Direction and magnitude of nicotine effects on the fMRI BOLD response are related to nicotine effects on behavioral performance

Considerable variability across individuals has been reported in both the behavioral and fMRI blood oxygen level-dependent (BOLD) response to nicotine. We aimed to investigate (1) whether there is a heterogeneous effect of nicotine on behavioral and BOLD responses across participants and (2) if heterogeneous BOLD responses are associated with behavioral performance measures. In this double-blind, placebo-controlled, cross-over study, 41 healthy participants (19 smokers)--drawn from a larger population-based sample--performed a visual oddball task after acute challenge with 1 mg nasal nicotine. fMRI data and reaction time were recorded during performance of the task. Across the entire group of subjects, we found increased activation in the anterior cingulate cortex, middle frontal gyrus, superior temporal gyrus, post-central gyrus, planum temporal and frontal pole in the nicotine condition compared with the placebo condition. However, follow-up analyses of this difference in activation between the placebo and nicotine conditions revealed that some participants showed an increase in activation while others showed a decrease in BOLD activation from the placebo to the nicotine condition. A reduction of BOLD activation from placebo to nicotine was associated with a decrease in reaction time and reaction time variability and vice versa, suggesting that it is the direction of BOLD response to nicotine which is related to task performance. We conclude that the BOLD response to nicotine is heterogeneous and that the direction of response to nicotine should be taken into account in future pharmaco-fMRI research on the central action of nicotine.

Cognitive control and right ventrolateral prefrontal cortex: reflexive reorienting, motor inhibition, and action updating

Delineating the functional organization of the prefrontal cortex is central to advancing models of goal-directed cognition. Considerable evidence indicates that specific forms of cognitive control are associated with distinct subregions of the left ventrolateral prefrontal cortex (VLPFC), but less is known about functional specialization within the right VLPFC. We report a functional MRI meta-analysis of two prominent theories of right VLPFC function: stopping of motor responses and reflexive orienting to abrupt perceptual onsets. Along with a broader review of right VLPFC function, extant data indicate that stopping and reflexive orienting similarly recruit the inferior frontal junction (IFJ), suggesting that IFJ supports the detection of behaviorally relevant stimuli. By contrast, other right VLPFC subregions are consistently active during motor inhibition, but not reflexive reorienting tasks, with posterior-VLPFC being active during the updating of action plans and mid-VLPFC responding to decision uncertainty. These results highlight the rich functional heterogeneity that exists within right VLPFC.

Developmental effects of reward on sustained attention networks

Adolescence is typified by significant maturation in higher-level attention functions coupled with less developed control over motivation, and enhanced sensitivity to novelty and reward. This study used event-related functional magnetic resonance imaging (fMRI) in seventy male and female participants aged between 10 and 43 years to identify age-related linear changes in cognitive sustained attention systems and the impact of reward on these systems, using a sustained attention task with and without a rewarded condition. For the non-rewarded sustained attention contrast, increasing age was associated with activation increases in typical regions of sustained attention including right inferior frontal, superior temporo-parietal and cerebellar cortices. Age-related activation decreases were observed within more posterior regions including posterior cingulate, insula and posterior cerebellar cortices, presumably mediating visual-spatial saliency detection. The effect of reward on sustained attention networks was associated with increased activation with age in regions associated with both executive attention control and reward processing, including dorsolateral, inferior and ventromedial prefrontal cortices (PFC), striatum, and temporo-parietal regions, suggestive of greater integration and executive control of motivation and cognition with maturity. Activation in paralimbic posterior cingulate and inferior temporal brain regions of visual-spatial saliency processing was progressively reduced in activation with increasing development. Thus, with increasing development between adolescence and adulthood, reward appears to enhance maturing cognitive sustained attention and executive reward-processing networks, whilst reducing paralimbic regions of saliency detection. These findings may be the neural underpinnings for the progressive maturation of motivational control over risk taking behaviours between adolescence and adulthood.

Musical training induces functional plasticity in human hippocampus

Training can change the functional and structural organization of the brain, and animal models demonstrate that the hippocampus formation is particularly susceptible to training-related neuroplasticity. In humans, however, direct evidence for functional plasticity of the adult hippocampus induced by training is still missing. Here, we used musicians' brains as a model to test for plastic capabilities of the adult human hippocampus. By using functional magnetic resonance imaging optimized for the investigation of auditory processing, we examined brain responses induced by temporal novelty in otherwise isochronous sound patterns in musicians and musical laypersons, since the hippocampus has been suggested previously to be crucially involved in various forms of novelty detection. In the first cross-sectional experiment, we identified enhanced neural responses to temporal novelty in the anterior left hippocampus of professional musicians, pointing to expertise-related differences in hippocampal processing. In the second experiment, we evaluated neural responses to acoustic temporal novelty in a longitudinal approach to disentangle training-related changes from predispositional factors. For this purpose, we examined an independent sample of music academy students before and after two semesters of intensive aural skills training. After this training period, hippocampal responses to temporal novelty in sounds were enhanced in musical students, and statistical interaction analysis of brain activity changes over time suggests training rather than predisposition effects. Thus, our results provide direct evidence for functional changes of the adult hippocampus in humans related to musical training.

Multifocal intraparietal activation during discrimination of action intention in observed tool grasping

The way we grasp an object varies depending on how we want to use that object, and this knowledge can be used to predict the object-related behavior of others. In this study, we assessed the neural correlates that determine the action intention of another person based on observed prehensile movements. Fourteen right-handed volunteers watched video clips of a person performing right-handed transitive grasping gestures that were either aimed at displacing or using a tool-object. Clips showing the grasping and displacement of neutral shapes served as a control condition. By discrimination of the actor's intention, three roughly symmetrical foci were activated in the anterior, middle, and caudal segments of the intraparietal sulci, and in the fusiform gyri and parts of the lateral occipital complex. Anterior intraparietal activation has been associated with the representation of object goals (object specific), and the present findings extend its involvement to functional goals (use-specific). Activation in the middle intraparietal region during intention discrimination was very similar to the activation elicited in a saccadic localizer task, suggesting a relation with spatial attention and eye movements. The caudal intraparietal region has been related with visuospatial guidance of reaching, and its activation during action intention discrimination indicates that the visuospatial properties of the observed reaching movement contribute to understanding of actions. As these parietal regions are strongly linked with motor behavior, our results appear to support the motor simulation hypothesis for action understanding with the preferential recruitment of the mirror-neuron system. This could at least be the case when no contextual information other than the visual properties of the movement is provided to discriminate the intention of an observed hand action.