Altered neural function in pediatric bipolar disorder during reversal learning

Dickstein DP, Finger EC, Skup M, Pine DS, Blair JR, Leibenluft E. Altered neural function in pediatric bipolar disorder during reversal learning.
Bipolar Disord 2010: 12: 707–719. © 2010 The Authors.
Journal compilation © 2010 John Wiley & Sons A/S. Objective: Data documenting the functional impairment associated with the diagnosis of bipolar disorder (BD) in children and adolescents highlight the need for greater understanding of its pathophysiology. Toward that end, we demonstrated previously that BD youth have behavioral deficits on reversal learning tasks. On such tasks, participants must first acquire a stimulus/response relationship through trial‐and‐error learning, and then discern when the stimulus/reward relationship reverses. Here, we use event‐related functional magnetic resonance imaging (fMRI) to elucidate neural correlates of reversal learning deficits in euthymic BD youth compared to typically developing controls. Method: We compared euthymic pediatric BD participants (n = 16) versus age‐, sex‐, and IQ‐matched controls (n = 16). Our main outcome measure was blood oxygen level‐dependent (BOLD) signal measured with fMRI during an event‐related probabilistic reversal task. Results: Pediatric BD participants had significantly greater neural activity than controls in fronto‐parietal regions during the reversal phase, particularly in response to punished reversal errors (p < 0.05 corrected for multiple comparisons). Conclusions: Our current study suggests that during reversal learning, BD youths inefficiently recruit regions associated with processing response conflict and implementing alternative responses, including subdivisions of the frontal cortex and the parietal cortex. Such deficits are present in euthymic BD youth. Further work is necessary to evaluate the specificity of such alterations.     

Anatomical and functional distribution of functional MRI language mapping

ObjectiveThe aim of the present study was to compare localization of the language cortex using electrical cortical stimulation (ECS) and functional magnetic resonance imaging (fMRI) to establish the relevance of fMRI language mapping.MethodsLanguage mapping with fMRI and functional ECS mapping were retrospectively compared in ten patients with refractory epilepsy who underwent fMRI language mapping and functional ECS mapping between June 2012 and April 2019. A shiritori task, a popular Japanese word chain game, was used for fMRI language mapping.ResultsBOLD signal activation was observed in the left inferior frontal gyrus (including the pars opecularis and the pars triangularis), and superior temporal gyrus, which is a language-related area, as well as in the left superior and middle frontal gyri, the intraparietal sulcus, and fusiform gyrus. These results were compared with ECS to elucidate the functional role of the activated areas during fMRI language tasks. These activated areas included language areas, negative motor areas, supplementary motor areas (SMAs), and non-functional areas.ConclusionThe activated areas of fMRI language mapping include language-related areas, the negative motor area, and SMAs. These findings suggest the involvement of language and higher order motor networks in verbal expression.     

Effective connectivity underlying reward‐based executive control

Motivational influences on cognitive control play an important role in shaping human behavior. Cognitive facilitation through motivators such as prospective reward or punishment is thought to depend on regions from the dopaminergic mesocortical network, primarily the ventral tegmental area (VTA), inferior frontal junction (IFJ), and anterior cingulate cortex (ACC). However, how interactions between these regions relate to motivated control remains elusive. In the present functional magnetic resonance imaging study, we used dynamic causal modeling (DCM) to investigate effective connectivity between left IFJ, ACC, and VTA in a task‐switching paradigm comprising three distinct motivational conditions (prospective monetary reward or punishment and a control condition). We found that while prospective punishment significantly facilitated switching between tasks on a behavioral level, interactions between IFJ, ACC, and VTA were characterized by modulations through prospective reward but not punishment. Our DCM results show that IFJ and VTA modulate ACC activity in parallel rather than by interaction to serve task demands in reward‐based cognitive control. Our findings further demonstrate that prospective reward and punishment differentially affect neural control mechanisms to initiate decision‐making.     

Impaired reward learning and intact motivation after serotonin depletion in rats

Aside from the well-known influence of serotonin (5-hydroxytryptamine, 5-HT) on emotional regulation, more recent investigations have revealed the importance of this monoamine in modulating cognition. Parachlorophenylalanine (PCPA) depletes 5-HT by inhibiting tryptophan hydroxylase, the enzyme required for 5-HT synthesis and, if administered at sufficiently high doses, can result in a depletion of at least 90% of the brain's 5-HT levels. The present study assessed the long-lasting effects of widespread 5-HT depletions on two tasks of cognitive flexibility in Long Evans rats: effort discounting and reversal learning. We assessed performance on these tasks after administration of either 250 or 500 mg/kg PCPA or saline (SAL) on two consecutive days. Consistent with a previous report investigating the role of 5-HT on effort discounting, pretreatment with either dose of PCPA resulted in normal effortful choice: All rats continued to climb tall barriers to obtain large rewards and were not work-averse. Additionally, rats receiving the lower dose of PCPA displayed normal reversal learning. However, despite intact motivation to work for food rewards, rats receiving the largest dose of PCPA were unexpectedly impaired relative to SAL rats on the pretraining stages leading up to reversal learning, ultimately failing to approach and respond to the stimuli associated with reward. High performance liquid chromatography (HPLC) with electrochemical detection confirmed 5-HT, and not dopamine, levels in the ventromedial frontal cortex were correlated with this measure of associative reward learning.     

Insights into the nature of fronto-temporal interactions from a biconditional discrimination task in the monkey

Previous work in monkeys has shown that both frontal and inferior temporal cortices are required to solve visual learning tasks. When communication between these cortical areas is prevented within the same hemisphere by crossed lesions of the frontal cortex in one hemisphere and the inferior temporal cortex in the opposite hemisphere, most learning tasks are impaired, but learning of object-reward associations is unimpaired. The current experiment aims to understand further the role of the interaction between the frontal and inferior temporal cortices in learning tasks. We trained monkeys on a biconditional discrimination task, in which different visual cues guided behaviour towards choice objects. One visual cue predicted immediate delivery of reward to a correct response, the other visual cue predicted a delayed delivery of reward to a correct response. Pre-operative behavioural data clearly shows that the monkeys form expectations of the reward outcome for the individual cues and choice objects. Crossed lesions of frontal and inferior temporal cortices, however, produce no impairment on this task. The result suggests (in combination with previous experiments) that task difficulty does not determine the reliance of a task on interactions between the frontal cortex and the inferior temporal cortex within the same hemisphere. Instead, we propose that tasks that can be solved by using expectation of the reward outcome do not require interaction of frontal and inferior temporal cortices within the same hemisphere. The results are discussed in the context of other data on frontal interactions with inferior temporal cortex in learning tasks.     

Impulsivity is associated with behavioral decision-making deficits

Impaired decision-making is a key-feature of many neuropsychiatric disorders. In the present study, we examined task performance in a healthy population consisting of those whose scores indicated high and low impulsivity on several behavioral decision-making tasks reflecting orbitofrontal functioning. The measures included tasks that assess decision-making with and without a learning component and choice flexibility. The results show that subjects high on impulsivity display an overall deficit in their decision-making performance as compared with subjects low on impulsivity. More specifically, subjects with high impulsivity show weaknesses in learning of reward and punishment associations in order to make appropriate decisions (reversal-learning task and Iowa Gambling Task), and impaired adaptation of choice behavior according to changes in stimulus-reward contingencies (reversal-learning task). Simple, non-learning, components of reward- and punishment-based decision-making (Rogers Decision-Making Task) seem to be relatively unaffected. Above all, the results indicate that impulsivity is associated with a decreased ability to alter choice behavior in response to fluctuations in reward contingency. The findings add further evidence to the notion that trait impulsivity is associated with decision-making, a function of the orbitofrontal cortex.     

Frontostriatal response to set switching is moderated by reward sensitivity

The reinforcement sensitivity theory (RST) relates individual differences in reward sensitivity to the activation of the behavioral approach system (BAS). Dopamine-related brain structures have been repeatedly associated with reward processing, but also with cognitive processes such as task switching. In the present study, we examined the association between reward sensitivity and the event-related fMRI BOLD response with set switching in 31 males. As expected, the right inferior frontal cortex (rIFG) and the striatum (i.e. the left putamen) were involved in set-switching activity for the overall sample. Interindividual differences in Gray's reward sensitivity were related to stronger activity in the rIFG and the ventral striatum. Thus, trait reward sensitivity contributed to the modulation of brain responsiveness in set-switching tasks. Having considered previous research, we propose that higher BAS activity is associated with a stronger reward to process a better implementation of goal-directed tasks and the diminished processing of secondary cues.     

Identifying Cognitive Remediation Change Through Computational Modelling—Effects on Reinforcement Learning in Schizophrenia

Objective: Converging research suggests that individuals with schizophrenia show a marked impairment in reinforcement learning, particularly in tasks requiring flexibility and adaptation. The problem has been associated with dopamine reward systems. This study explores, for the first time, the characteristics of this impairment and how it is affected by a behavioral intervention—cognitive remediation. Method: Using computational modelling, 3 reinforcement learning parameters based on the Wisconsin Card Sorting Test (WCST) trial-by-trial performance were estimated: R (reward sensitivity), P (punishment sensitivity), and D (choice consistency). In Study 1 the parameters were compared between a group of individuals with schizophrenia (n = 100) and a healthy control group (n = 50). In Study 2 the effect of cognitive remediation therapy (CRT) on these parameters was assessed in 2 groups of individuals with schizophrenia, one receiving CRT (n = 37) and the other receiving treatment as usual (TAU, n = 34). Results: In Study 1 individuals with schizophrenia showed impairment in the R and P parameters compared with healthy controls. Study 2 demonstrated that sensitivity to negative feedback (P) and reward (R) improved in the CRT group after therapy compared with the TAU group. R and P parameter change correlated with WCST outputs. Improvements in R and P after CRT were associated with working memory gains and reduction of negative symptoms, respectively. Conclusion: Schizophrenia reinforcement learning difficulties negatively influence performance in shift learning tasks. CRT can improve sensitivity to reward and punishment. Identifying parameters that show change may be useful in experimental medicine studies to identify cognitive domains susceptible to improvement.Key words: reward systems, cognitive remediation, therapy, sensitivity, Wisconsin Card Sorting test, reward sensitivity, dopamine     

Deficits on a probabilistic response-reversal task in patients with pediatric bipolar disorder

OBJECTIVE: Patients with bipolar disorder become hyperhedonic when manic and anhedonic when depressed; therefore, it is important to test whether patients with bipolar disorder show deficits on behavioral paradigms exploring reward/punishment mechanisms. METHOD: A probabilistic response-reversal task was administered to 24 bipolar children and 25 comparison subjects. RESULTS: Patients made more errors during probabilistic reversal, took longer to learn the new reward object, and were less likely to meet the learning criterion. CONCLUSIONS: Children with bipolar disorder may have a reversal learning deficit.     

Different forms of childhood maltreatment have different impacts on the neural systems involved in the representation of reinforcement value

BackgroundThe current study aimed to address two gaps in the literature on child maltreatment, reinforcement processing and psychopathology. First, the extent to which compromised reinforcement processing might be particularly associated with either neglect or abuse. Second, the extent to which maltreatment-related compromised reinforcement processing might be associated with particular symptom sets (depression, conduct problems, anxiety) or symptomatology more generally.MethodsA sample of adolescents (N = 142) aged between 14 and 18 years with varying levels of prior maltreatment participated in this fMRI study. They were scanned while performing a passive avoidance learning task, where the participant learns to respond to stimuli that engender reward and avoid responding to stimuli that engender punishment. Maltreatment (abuse and neglect) levels were assessed with the Childhood Trauma Questionnaire (CTQ).ResultsWe found that: (i) level of neglect, but not abuse, was negatively associated with differential BOLD responses to reward-punishment within the striatum and medial frontal cortex; and (ii) differential reward-punishment responses within these neglect-associated regions were particularly negatively associated with level of conduct problems.ConclusionOur findings demonstrate the adverse neurodevelopmental impact of childhood maltreatment, particularly neglect, on reinforcement processing. Moreover, they suggest a neurodevelopmental route by which neglect might increase the risk for conduct problems.     

Impaired reward processing in the human prefrontal cortex distinguishes between persistent and remittent attention deficit hyperactivity disorder

Symptoms of attention deficit hyperactivity disorder (ADHD) in children often persist into adulthood and can lead to severe antisocial behavior. However, to‐date it remains unclear whether neuro‐functional abnormalities cause ADHD, which in turn can then provide a marker of persistent ADHD. Using event‐related functional magnetic resonance imaging (fMRI), we measured blood oxygenation level dependent (BOLD) signal changes in subjects during a reversal learning task in which choice of the correct stimulus led to a probabilistically determined ‘monetary’ reward or punishment. Participants were diagnosed with ADHD during their childhood (N = 32) and were paired with age, gender, and education matched healthy controls (N = 32). Reassessment of the ADHD group as adults resulted in a split between either persistent (persisters, N = 17) or remitted ADHDs (remitters, N = 15). All three groups showed significantly decreased activation in the medial prefrontal cortex (PFC) and the left striatum during punished correct responses, however only remitters and controls presented significant psycho‐physiological interaction between these fronto‐striatal reward and outcome valence networks. Comparing persisters to remitters and controls showed significantly inverted responses to punishment (P < 0.05, family‐wise error corrected) in left PFC region. Interestingly, the decreased activation shown after punishment was located in different areas of the PFC for remitters compared with controls, suggesting that remitters might have learned compensation strategies to overcome their ADHD symptoms. Thus, fMRI helps understanding the neuro‐functional basis of ADHD related behavior differences and differentiates between persistent and remittent ADHD. Hum Brain Mapp 36:4648–4663, 2015. © 2015 Wiley Periodicals, Inc.     

Alteration in brain functional connectivity in patients with post-stroke cognitive impairment during memory task: A fNIRS study

ObjectiveThis study attempted to evaluate the functional connectivity (FC) in relevant cortex areas during three memory tasks using the functional near-infrared spectroscopy (fNIRS) method to expound the neural mechanisms in individuals with post-stroke cognitive impairment (PSCI).MethodsShort-term memory and visuospatial abilities were assessed using the clock drawing test, digit span test, and Corsi Block-tapping tests with simultaneous fNIRS. The oxygenated hemoglobin concentration signals were recorded from the bilateral motor sense cortex (LMS/RMS) and prefrontal lobe (LPFT/PFT/RPFT) of 19 subjects with cognitive impairment (PSCI group), 27 stroke subjects (STR group) and 26 healthy subjects (HC group).ResultsMMSE scores were positively correlated with the clock drawing test and digit span test scores but not with Corsi Block-tapping scores. During each test, functional connectivity between the bilateral MS (LMS/RMS) was highest within each group, but the functional connectivity between motor sense cortex and frontal lobe was lowest. PSCI group showed decreased FC between bilateral motor sense cortex (P < 0.05) and between motor sense cortex and frontal lobe (P > 0.05) during clock drawing test and Corsi Block-tapping test while decreased FC between each region of interest during digit span test with no significant difference. Functional connectivity levels were closely related to MMSE scores.ConclusionsDecreased functional connectivity level may be a marker of impaired cognitive function in post-stroke cognitive impairment. The fNIRS-based functional connectivity provides a non-invasive method to recognize cognitive impairment post-stroke. Functional connectivity changes may help to further understand the neural mechanisms of cognitive impairment post stroke.     

Reward breaks through center‐surround inhibition via anterior insula

Focusing attention on a target creates a center‐surround inhibition such that distractors located close to the target do not capture attention. Recent research showed that a distractor can break through this surround inhibition when associated with reward. However, the brain basis for this reward‐based attention is unclear. In this fMRI study, we presented a distractor associated with high or low reward at different distances from the target. Behaviorally the low‐reward distractor did not capture attention and thus did not cause interference, whereas the high‐reward distractor captured attention only when located near the target. Neural activity in extrastriate cortex mirrored the behavioral pattern. A comparison between the high‐reward and the low‐reward distractors presented near the target (i.e., reward‐based attention) and a comparison between the high‐reward distractors located near and far from the target (i.e., spatial attention) revealed a common frontoparietal network, including inferior frontal gyrus and inferior parietal sulcus as well as the visual cortex. Reward‐based attention specifically activated the anterior insula (AI). Dynamic causal modelling showed that reward modulated the connectivity from AI to the frontoparietal network but not the connectivity from the frontoparietal network to the visual cortex. Across participants, the reward‐based attentional effect could be predicted both by the activity in AI and by the changes of spontaneous functional connectivity between AI and ventral striatum before and after reward association. These results suggest that AI encodes reward‐based salience and projects it to the stimulus‐driven attentional network, which enables the reward‐associated distractor to break through the surround inhibition in the visual cortex. Hum Brain Mapp 36:5233–5251, 2015. © 2015 Wiley Periodicals, Inc.     

Ventral striatal network connectivity reflects reward learning and behavior in patients with Parkinson's disease

A subgroup of Parkinson's disease (PD) patients treated with dopaminergic therapy develop compulsive reward‐driven behaviors, which can result in life‐altering morbidity. The mesocorticolimbic dopamine network guides reward‐motivated behavior; however, its role in this treatment‐related behavioral phenotype is incompletely understood. Here, mesocorticolimbic network function in PD patients who develop impulsive and compulsive behaviors (ICB) in response to dopamine agonists was assessed using BOLD fMRI. The tested hypothesis was that network connectivity between the ventral striatum and the limbic cortex is elevated in patients with ICB and that reward‐learning proficiency reflects the extent of mesocorticolimbic network connectivity. To evaluate this hypothesis, 3.0T BOLD‐fMRI was applied to measure baseline functional connectivity on and off dopamine agonist therapy in age and sex‐matched PD patients with (n = 19) or without (n = 18) ICB. An incentive‐based task was administered to a subset of patients (n = 20) to quantify positively or negatively reinforced learning. Whole‐brain voxelwise analyses and region‐of‐interest‐based mixed linear effects modeling were performed. Elevated ventral striatal connectivity to the anterior cingulate gyrus (P = 0.013), orbitofrontal cortex (P = 0.034), insula (P = 0.044), putamen (P = 0.014), globus pallidus (P < 0.01), and thalamus (P < 0.01) was observed in patients with ICB. A strong trend for elevated amygdala‐to‐midbrain connectivity was found in ICB patients on dopamine agonist. Ventral striatum‐to‐subgenual cingulate connectivity correlated with reward learning (P < 0.01), but not with punishment‐avoidance learning. These data indicate that PD‐ICB patients have elevated network connectivity in the mesocorticolimbic network. Behaviorally, proficient reward‐based learning is related to this enhanced limbic and ventral striatal connectivity. Hum Brain Mapp 39:509–521, 2018. © 2017 Wiley Periodicals, Inc.     

Monitoring anesthesia using simultaneous functional Near Infrared Spectroscopy and Electroencephalography

ObjectiveThis study aims to understand the neural and hemodynamic responses during general anesthesia in order to develop a comprehensive multimodal anesthesia depth monitor using simultaneous functional Near Infrared Spectroscopy (fNIRS) and Electroencephalogram (EEG).Methods37 adults and 17 children were monitored with simultaneous fNIRS and EEG, during the complete general anesthesia process. The coupling of fNIRS signals with neuronal signals (EEG) was calculated. Measures of complexity (sample entropy) and phase difference were also quantified from fNIRS signals to identify unique fNIRS based biomarkers of general anesthesia.ResultsA significant decrease in the complexity and power of fNIRS signals characterize the anesthesia maintenance phase. Furthermore, responses to anesthesia vary between adults and children in terms of neurovascular coupling and frontal EEG alpha power.ConclusionsThis study shows that fNIRS signals could reliably quantify the underlying neuronal activity under general anesthesia and clearly distinguish the different phases throughout the procedure in adults and children (with less accuracy).SignificanceA multimodal approach incorporating the specific differences between age groups, provides a reliable measure of anesthesia depth.     

Classification of autism spectrum disorder based on sample entropy of spontaneous functional near infra-red spectroscopy signal

ObjectivesTo assess the possibility of distinguishing autism spectrum disorder (ASD) based on the characteristic of spontaneous hemodynamic fluctuations and to explore the location of abnormality in the brain.MethodsUsing the sample entropy (SampEn) of functional near-infrared spectroscopy (fNIRS) from bilateral inferior frontal gyrus (IFG) and temporal cortex (TC) on 25 children with ASD and 22 typical development (TD) children, the pattern of mind-wandering was assessed. With the SampEn as feature variables, a machine learning classifier was applied to mark ASD and locate the abnormal area in the brain.ResultsThe SampEn was generally lower for ASD than TD, indicating the fNIRS series from ASD was unstable, had low fluctuation, and high self-similarity. The classification between ASD and TD could reach 97.6% in accuracy.ConclusionsThe SampEn of fNIRS could accurately distinguish ASD. The abnormality in terms of the SampEn occurs more frequently in IFG than TC, and more frequently in the left than in the right hemisphere.SignificanceThe results of this study may help to understand the cortical mechanism of ASD and provide a fNIRS-based diagnosis for ASD.     

Individual differences in sensitivity to reward and punishment and neural activity during reward and avoidance learning

In this functional neuroimaging study, we investigated neural activations during the process of learning to gain monetary rewards and to avoid monetary loss, and how these activations are modulated by individual differences in reward and punishment sensitivity. Healthy young volunteers performed a reinforcement learning task where they chose one of two fractal stimuli associated with monetary gain (reward trials) or avoidance of monetary loss (avoidance trials). Trait sensitivity to reward and punishment was assessed using the behavioral inhibition/activation scales (BIS/BAS). Functional neuroimaging results showed activation of the striatum during the anticipation and reception periods of reward trials. During avoidance trials, activation of the dorsal striatum and prefrontal regions was found. As expected, individual differences in reward sensitivity were positively associated with activation in the left and right ventral striatum during reward reception. Individual differences in sensitivity to punishment were negatively associated with activation in the left dorsal striatum during avoidance anticipation and also with activation in the right lateral orbitofrontal cortex during receiving monetary loss. These results suggest that learning to attain reward and learning to avoid loss are dependent on separable sets of neural regions whose activity is modulated by trait sensitivity to reward or punishment.     

Reward-related reversal learning after surgical excisions in orbito-frontal or dorsolateral prefrontal cortex in humans

Neurophysiological studies in primates and neuroimaging studies in humans suggest that the orbito-frontal cortex is involved in representing the reward value of stimuli and in the rapid learning and relearning of associations between visual stimuli and rewarding or punishing outcomes. In the present study, we tested patients with circumscribed surgical lesions in different regions of the frontal lobe on a new visual discrimination reversal test, which, in an fMRI study (O'Doherty, Kringelbach, Rolls, Hornak, & Andrews, 2001), produced bilateral orbito-frontal cortex activation in normal subjects. In this task, touching one of two simultaneously presented patterns produced reward or loss of imaginary money delivered on a probabilistic basis to minimize the usefulness of verbal strategies. A number of types of feedback were present on the screen. The main result was that the group of patients with bilateral orbito-frontal cortex lesions were severely impaired at the reversal task, in that they accumulated less money. These patients often failed to switch their choice of stimulus after a large loss and often did switch their choice although they had just received a reward. The investigation showed that bilateral lesions were required for this deficit, since patients with unilateral orbito-frontal cortex (or medial prefrontal cortex) lesions were not impaired in the probabilistic reversal task. The task ruled out a simple motor disinhibition as an explanation of the deficit in the bilateral orbito-frontal cortex patients, in that the patients were required to choose one of two stimuli on each trial. A comparison group of patients with dorsolateral prefrontal cortex lesions was in some cases able to do the task, and in other cases, was impaired. Posttest debriefing showed that all the dorsolateral prefrontal patients who were impaired at the task had failed to pay attention to the crucial feedback provided on the screen after each trial about the amount won or lost on each trial. In contrast, all dorsolateral patients who paid attention to this crucial feedback performed normally on the reversal task. Further, it was confirmed that the bilateral orbito-frontal cortex patients had also paid attention to this crucial feedback, but in contrast had still performed poorly at the task. The results thus show that the orbital prefrontal cortex is required bilaterally for monitoring changes in the reward value of stimuli and using this to guide behavior in the task; whereas the dorsolateral prefrontal cortex, if it produces deficits in the task, does so for reasons related to executive functions, such as the control of attention. Thus, the ability to determine which information is relevant when making a choice of pattern can be disrupted by a dorsolateral lesion on either side, whereas the ability to use this information to guide behavior is not disrupted by a unilateral lesion in either the left or the right orbito-frontal cortex, but is severely impaired by a bilateral lesion in this region. Because both abilities are important in many of the tasks and decisions that arise in the course of daily life, the present results are relevant to understanding the difficulties faced by patients after surgical excisions in different frontal brain regions.     

Neural substrates of context‐ and person‐dependent altruistic punishment

Human altruistic behaviors are heterogeneous across both contexts and people, whereas the neural signatures underlying the heterogeneity remain to be elucidated. To address this issue, we examined the neural signatures underlying the context‐ and person‐dependent altruistic punishment, conjoining event‐related fMRI with both task‐based and resting‐state functional connectivity (RSFC). Acting as an impartial third party, participants decided how to punish norm violators either alone or in the presence of putative others. We found that the presence of others decreased altruistic punishment due to diffusion of responsibility. Those behavioral effects paralleled altered neural responses in the dorsal anterior cingulate cortex (dACC) and putamen. Further, we identified modulation of responsibility diffusion on task‐based functional connectivity of dACC with the brain regions implicated in reward processing (i.e., posterior cingulate cortex and amygdala/orbital frontal cortex). Finally, the RSFC results revealed that (i) increased intrinsic connectivity strengths of the putamen with temporoparietal junction and dorsolateral PFC were associated with attenuated responsibility diffusion in altruistic punishment and (ii) increased putamen‐dorsomedial PFC connectivity strengths were associated with reduced responsibility diffusion in self‐reported responsibility. Taken together, our findings elucidate the context‐ and person‐dependent altruistic behaviors as well as associated neural substrates and thus provide a potential neurocognitive mechanism of heterogeneous human altruistic behaviors. Hum Brain Mapp 38:5535–5550, 2017. © 2017 Wiley Periodicals, Inc.     

Differential prefrontal and frontotemporal oxygenation patterns during phonemic and semantic verbal fluency

Movement artifacts are still considered a problematic issue for imaging research on overt language production. This motion-sensitivity can be overcome by functional near-infrared spectroscopy (fNIRS). In the present study, 50 healthy subjects performed a combined phonemic and semantic overt verbal fluency task while frontal and temporal cortex oxygenation was recorded using multi-channel fNIRS. Results showed a partial dissociation for phonemic and semantic word generation with equally increased oxygenation in frontotemporal cortices for both types of tasks whereas anterior and superior prefrontal areas were exclusively activated during phonemic fluency. Also, a general left-lateralization was found being more pronounced during semantic processing. These findings line up with earlier imaging and lesion studies emphasizing a crucial role of the temporal lobe for semantic word production, whereas phonemic processing seems to depend on intact frontal lobe function.