Co-activation patterns distinguish cortical modules, their connectivity and functional differentiation

The role of the human ventral striatum and the medial orbitofrontal cortex in the representation of reward magnitude - an activation likelihood estimation meta-analysis of neuroimaging studies of passive reward expectancy and outcome processing

Reward maximization is a core motivation of every organism. In humans, several brain regions have been implicated in the representation of reward magnitude. Still, it is unclear whether identical brain regions consistently play a role in reward prediction and its consumption. In this study we used coordinate-based ALE meta-analysis to determine the individual roles of the ventral striatum (vSTR) and the medial orbitofrontal cortex (mOFC/VMPFC) in the representation of reward in general and of reward magnitude in particular. Specifically, we wanted to assess commonalities and differences in regional brain activation during the passive anticipation and consumption of rewards. Two independent meta-analyses of neuroimaging data from the past decade revealed a general role for the vSTR in reward anticipation and consumption. This was the case particularly when the consumed rewards occurred unexpectedly or were uncertain. In contrast, for the mOFC/VMPFC the present meta-analytic data suggested a rather specific function in reward consumption as opposed to passive anticipation. Importantly, when considering only coordinates that compared different reward magnitudes, the same parts of the vSTR and the mOFC/VMPFC showed concordant responses across studies, although areas of coherence were regionally more confined. These meta-analytic data suggest that the vSTR may be involved in both prediction and consumption of salient rewards, and may also be sensitive to different reward magnitudes, while the mOFC/VMPFC may rather process the magnitude during reward receipt. Collectively, our meta-analytic data conform with the notion that these two brain regions may subserve different roles in processing of reward magnitude.

Parsing the neural correlates of moral cognition: ALE meta-analysis on morality, theory of mind, and empathy

Morally judicious behavior forms the fabric of human sociality. Here, we sought to investigate neural activity associated with different facets of moral thought. Previous research suggests that the cognitive and emotional sources of moral decisions might be closely related to theory of mind, an abstract-cognitive skill, and empathy, a rapid-emotional skill. That is, moral decisions are thought to crucially refer to other persons' representation of intentions and behavioral outcomes as well as (vicariously experienced) emotional states. We thus hypothesized that moral decisions might be implemented in brain areas engaged in 'theory of mind' and empathy. This assumption was tested by conducting a large-scale activation likelihood estimation (ALE) meta-analysis of neuroimaging studies, which assessed 2,607 peak coordinates from 247 experiments in 1,790 participants. The brain areas that were consistently involved in moral decisions showed more convergence with the ALE analysis targeting theory of mind versus empathy. More specifically, the neurotopographical overlap between morality and empathy disfavors a role of affective sharing during moral decisions. Ultimately, our results provide evidence that the neural network underlying moral decisions is probably domain-global and might be dissociable into cognitive and affective sub-systems.

Distributed processing; distributed functions?

After more than twenty years busily mapping the human brain, what have we learned from neuroimaging? This review (coda) considers this question from the point of view of structure-function relationships and the two cornerstones of functional neuroimaging; functional segregation and integration. Despite remarkable advances and insights into the brain's functional architecture, the earliest and simplest challenge in human brain mapping remains unresolved: We do not have a principled way to map brain function onto its structure in a way that speaks directly to cognitive neuroscience. Having said this, there are distinct clues about how this might be done: First, there is a growing appreciation of the role of functional integration in the distributed nature of neuronal processing. Second, there is an emerging interest in data-driven cognitive ontologies, i.e., that are internally consistent with functional anatomy. We will focus this review on the growing momentum in the fields of functional connectivity and distributed brain responses and consider this in the light of meta-analyses that use very large data sets to disclose large-scale structure-function mappings in the human brain.

Neural substrates of smoking cue reactivity: a meta-analysis of fMRI studies

Reactivity to smoking-related cues may be an important factor that precipitates relapse in smokers who are trying to quit. The neurobiology of smoking cue reactivity has been investigated in several fMRI studies. We combined the results of these studies using activation likelihood estimation, a meta-analytic technique for fMRI data. Results of the meta-analysis indicated that smoking cues reliably evoke larger fMRI responses than neutral cues in the extended visual system, precuneus, posterior cingulate gyrus, anterior cingulate gyrus, dorsal and medial prefrontal cortex, insula, and dorsal striatum. Subtraction meta-analyses revealed that parts of the extended visual system and dorsal prefrontal cortex are more reliably responsive to smoking cues in deprived smokers than in non-deprived smokers, and that short-duration cues presented in event-related designs produce larger responses in the extended visual system than long-duration cues presented in blocked designs. The areas that were found to be responsive to smoking cues agree with theories of the neurobiology of cue reactivity, with two exceptions. First, there was a reliable cue reactivity effect in the precuneus, which is not typically considered a brain region important to addiction. Second, we found no significant effect in the nucleus accumbens, an area that plays a critical role in addiction, but this effect may have been due to technical difficulties associated with measuring fMRI data in that region. The results of this meta-analysis suggest that the extended visual system should receive more attention in future studies of smoking cue reactivity.

The functional connectivity of the human caudate: an application of meta-analytic connectivity modeling with behavioral filtering

Meta-analysis based techniques are emerging as powerful, robust tools for developing models of connectivity in functional neuroimaging. Here, we apply meta-analytic connectivity modeling to the human caudate to 1) develop a model of functional connectivity, 2) determine if meta-analytic methods are sufficiently sensitive to detect behavioral domain specificity within region-specific functional connectivity networks, and 3) compare meta-analytic driven segmentation to structural connectivity parcellation using diffusion tensor imaging. Results demonstrate strong coherence between meta-analytic and data-driven methods. Specifically, we found that behavioral filtering resulted in cognition and emotion related structures and networks primarily localized to the head of the caudate nucleus, while perceptual and action specific regions localized to the body of the caudate, consistent with early models of nonhuman primate histological studies and postmortem studies in humans. Diffusion tensor imaging (DTI) revealed support for meta-analytic connectivity modeling's (MACM) utility in identifying both direct and indirect connectivity. Our results provide further validation of meta-analytic connectivity modeling, while also highlighting an additional potential, namely the extraction of behavioral domain specific functional connectivity.

Probabilistic fibre tract analysis of cytoarchitectonically defined human inferior parietal lobule areas reveals similarities to macaques

The human inferior parietal lobule (IPL) is a multimodal brain region, subdivided in several cytoarchitectonic areas which are involved in neural networks related to spatial attention, language, and higher motor processing. Tracer studies in macaques revealed differential connectivity patterns of IPL areas as the respective structural basis. Evidence for comparable differential fibre tracts of human IPL is lacking. Here, anatomical connectivity of five cytoarchitectonic human IPL areas to 64 cortical targets was investigated using probabilistic tractography. Connection likelihood was assessed by evaluating the number of traces between seed and target against the distribution of traces from that seed to voxels in the same distance as the target. The main fibre tract pattern shifted gradually from rostral to caudal IPL: Rostral areas were predominantly connected to somatosensory and superior parietal areas while caudal areas more strongly connected with auditory, anterior temporal and higher visual cortices. All IPL areas were strongly connected with inferior frontal, insular and posterior temporal areas. These results showed striking similarities with connectivity patterns in macaques, providing further evidence for possible homologies between these two species. This shift in fibre tract pattern supports a differential functional involvement of rostral (higher motor functions) and caudal IPL (spatial attention), with probable overlapping language involvement. The differential functional involvement of IPL areas was further supported by hemispheric asymmetries of connection patterns which showed left-right differences especially with regard to connections to sensorimotor, inferior frontal and temporal areas.

The BrainMap strategy for standardization, sharing, and meta-analysis of neuroimaging data

BACKGROUND

Neuroimaging researchers have developed rigorous community data and metadata standards that encourage meta-analysis as a method for establishing robust and meaningful convergence of knowledge of human brain structure and function. Capitalizing on these standards, the BrainMap project offers databases, software applications, and other associated tools for supporting and promoting quantitative coordinate-based meta-analysis of the structural and functional neuroimaging literature.

FINDINGS

In this report, we describe recent technical updates to the project and provide an educational description for performing meta-analyses in the BrainMap environment.

CONCLUSIONS

The BrainMap project will continue to evolve in response to the meta-analytic needs of biomedical researchers in the structural and functional neuroimaging communities. Future work on the BrainMap project regarding software and hardware advances are also discussed.