Inferior Frontal Sulcus Research Articles

Investigation of topographical anatomy of Broca's area: an anatomic cadaveric study.

The sulci constituting the structure of the pars triangularis and opercularis, considered as 'Broca's area', present wide anatomical and morphological variations between different hemispheres. The boundaries are described differently from one another in various studies. The aim of this study was to explore the topographical anatomy, confirm the morphological asymmetry and highlight anatomical variations in Broca's area. This study was performed with 100 hemispheres to investigate the presence, continuity, patterns and connections of the sulcal structures that constitute the morphological asymmetry of Broca's area. Considerable individual anatomical and morphological variations between the inferior frontal gyrus and related sulcal structures were detected. Rare bilateralism findings supported the morphological asymmetry. The inferior frontal sulcus was identified as a single segment in 54% of the right and two separate segments in 52% of the left hemispheres, which was the most common pattern. The diagonal sulcus was present in 48% of the right and 54% of the left hemispheres. It was most frequently connected to the ascending ramus on both sides. A 'V' shape was observed in 42.5% of the right hemispheres and a 'Y' shape in 38.3% of the left hemispheres, which was the most common shape of the pars triangularis. Moreover, the full results are specified in detail. Knowledge of the anatomical variations in this region is indispensable for understanding the functional structure and performing safe surgery. However, most previously published studies have aimed to determine the anatomical asymmetry of the motor speech area without illuminating the topographical anatomy encountered during surgery.

EP 59. Multi-modal imaging of neural correlates of motor speed performance in the trail making test

The assessment of motor and executive functions following stroke or traumatic brain injury is a key aspect of impairment evaluation and used to guide further therapy. In clinical routine such assessments are largely dominated by pen-and-paper tests. While these provide standardized, reliable and ecologically valid measures of the individual level of functioning, rather little is yet known about their neurobiological underpinnings. Therefore, the aim of this study was to investigate brain regions and their associated networks that are related to upper extremity motor function, as quantified by the Motor Speed subtest of the Trail Making Test (TMT-MS) ( Delis et al., 2001 ). Whole brain voxel-based morphometry ( Ashburner and Friston, 2000 ) and whole brain tract-based spatial statistics ( Smith et al., 2006 ) were used to investigate the association between TMT-MS performance with gray matter volume (GMV) and white matter integrity respectively. While results demonstrated no relationship to local white-matter properties, we found a significant correlation between TMT-MS performance and GMV of the lower bank of the inferior frontal sulcus, a region associated with cognitive processing, as indicated by assessing its functional profile by the BrainMap database ( Laird et al., 2011 ). Using this finding as a seed region, we further examined and compared networks as reflected by resting state connectivity ( Fox and Raichle, 2007 ), meta-analytic-connectivity modeling ( Eickhoff et al., 2011 ), structural covariance ( Albaugh et al., 2013 ) and probabilistic tractography ( Behrens et al., 2003 ). While differences between the different approaches were observed, all approaches converged on a network comprising regions that overlap with the multiple-demand network. Our data therefore indicates that performance may primarily depend on executive function, thus suggesting that motor speed in a more naturalistic setting should be more associated with executive rather than primary motor function. Moreover, results showed that while there were differences between the approaches, a convergence indicated that common networks can be revealed across highly divergent methods.

There is more into ‘doing’ than ‘knowing’: The function of the right inferior frontal sulcus is specific for implementing versus memorising verbal instructions

In the present study we examine the mechanism underlying the human ability to implement newly instructed stimulus-response mappings for their future application. We introduce a novel procedure in which we can investigate the processes underlying such implementation while controlling for more general working-memory demands. The results indicate that a region within the dorso-lateral prefrontal cortex (DLPFC) in the vicinity of the inferior frontal sulcus (IFS) is specifically recruited when new instructions are implemented compared to when new instructions are memorised. In addition, we observed that this area is more strongly activated when task performance is effective. Together, these findings suggest that the DLPFC, and more specific the IFS, plays an important role during the formation of procedural representations in working memory.

Mapping the cortical representation of speech sounds in a syllable repetition task

Speech repetition relies on a series of distributed cortical representations and functional pathways. A speaker must map auditory representations of incoming sounds onto learned speech items, maintain an accurate representation of those items in short-term memory, interface that representation with the motor output system, and fluently articulate the target sequence. A “dorsal stream” consisting of posterior temporal, inferior parietal and premotor regions is thought to mediate auditory-motor representations and transformations, but the nature and activation of these representations for different portions of speech repetition tasks remains unclear. Here we mapped the correlates of phonetic and/or phonological information related to the specific phonemes and syllables that were heard, remembered, and produced using a series of cortical searchlight multi-voxel pattern analyses trained on estimates of BOLD responses from individual trials. Based on responses linked to input events (auditory syllable presentation), predictive vowel-level information was found in the left inferior frontal sulcus, while syllable prediction revealed significant clusters in the left ventral premotor cortex and central sulcus and the left mid superior temporal sulcus. Responses linked to output events (the GO signal cueing overt production) revealed strong clusters of vowel-related information bilaterally in the mid to posterior superior temporal sulcus. For the prediction of onset and coda consonants, input-linked responses yielded distributed clusters in the superior temporal cortices, which were further informative for classifiers trained on output-linked responses. Output-linked responses in the Rolandic cortex made strong predictions for the syllables and consonants produced, but their predictive power was reduced for vowels. The results of this study provide a systematic survey of how cortical response patterns covary with the identity of speech sounds, which will help to constrain and guide theoretical models of speech perception, speech production, and phonological working memory.

Exploring the role of the posterior middle temporal gyrus in semantic cognition: Integration of anterior temporal lobe with executive processes

Making sense of the world around us depends upon selectively retrieving information relevant to our current goal or context. However, it is unclear whether selective semantic retrieval relies exclusively on general control mechanisms recruited in demanding non-semantic tasks, or instead on systems specialised for the control of meaning. One hypothesis is that the left posterior middle temporal gyrus (pMTG) is important in the controlled retrieval of semantic (not non-semantic) information; however this view remains controversial since a parallel literature links this site to event and relational semantics. In a functional neuroimaging study, we demonstrated that an area of pMTG implicated in semantic control by a recent meta-analysis was activated in a conjunction of (i) semantic association over size judgements and (ii) action over colour feature matching. Under these circumstances the same region showed functional coupling with the inferior frontal gyrus — another crucial site for semantic control. Structural and functional connectivity analyses demonstrated that this site is at the nexus of networks recruited in automatic semantic processing (the default mode network) and executively demanding tasks (the multiple-demand network). Moreover, in both task and task-free contexts, pMTG exhibited functional properties that were more similar to ventral parts of inferior frontal cortex, implicated in controlled semantic retrieval, than more dorsal inferior frontal sulcus, implicated in domain-general control. Finally, the pMTG region was functionally correlated at rest with other regions implicated in control-demanding semantic tasks, including inferior frontal gyrus and intraparietal sulcus. We suggest that pMTG may play a crucial role within a large-scale network that allows the integration of automatic retrieval in the default mode network with executively-demanding goal-oriented cognition, and that this could support our ability to understand actions and non-dominant semantic associations, allowing semantic retrieval to be ‘shaped’ to suit a task or context.

Modulation of frontal effective connectivity during speech

Noninvasive neurostimulation methods such as transcranial direct current stimulation (tDCS) can elicit long-lasting, polarity-dependent changes in neocortical excitability. In a previous concurrent tDCS-fMRI study of overt picture naming, we reported significant behavioural and regionally specific neural facilitation effects in left inferior frontal cortex (IFC) with anodal tDCS applied to left frontal cortex (Holland et al., 2011). Although distributed connectivity effects of anodal tDCS have been modelled at rest, the mechanism by which ‘on-line’ tDCS may modulate neuronal connectivity during a task-state remains unclear. Here, we used Dynamic Causal Modelling (DCM) to determine: (i) how neural connectivity within the frontal speech network is modulated during anodal tDCS; and, (ii) how individual variability in behavioural response to anodal tDCS relates to changes in effective connectivity strength. Results showed that compared to sham, anodal tDCS elicited stronger feedback from inferior frontal sulcus (IFS) to ventral premotor (VPM) accompanied by weaker self-connections within VPM, consistent with processes of neuronal adaptation. During anodal tDCS individual variability in the feedforward connection strength from IFS to VPM positively correlated with the degree of facilitation in naming behaviour. These results provide an essential step towards understanding the mechanism of ‘online’ tDCS paired with a cognitive task. They also identify left IFS as a ‘top-down’ hub and driver for speech change.

Multi-Modal Imaging of Neural Correlates of Motor Speed Performance in the Trail Making Test.

The assessment of motor and executive functions following stroke or traumatic brain injury is a key aspect of impairment evaluation and used to guide further therapy. In clinical routine, such assessments are largely dominated by pen-and-paper tests. While these provide standardized, reliable, and ecologically valid measures of the individual level of functioning, rather little is yet known about their neurobiological underpinnings. Therefore, the aim of this study was to investigate brain regions and their associated networks that are related to upper extremity motor function, as quantified by the motor speed subtest of the trail making test (TMT-MS). Whole-brain voxel-based morphometry and whole-brain tract-based spatial statistics were used to investigate the association between TMT-MS performance with gray-matter volume (GMV) and white-matter integrity, respectively. While results demonstrated no relationship to local white-matter properties, we found a significant correlation between TMT-MS performance and GMV of the lower bank of the inferior frontal sulcus, a region associated with cognitive processing, as indicated by assessing its functional profile by the BrainMap database. Using this finding as a seed region, we further examined and compared networks as reflected by resting state connectivity, meta-analytic connectivity modeling, structural covariance, and probabilistic tractography. While differences between the different approaches were observed, all approaches converged on a network comprising regions that overlap with the multiple-demand network. Our data therefore indicate that performance may primarily depend on executive function, thus suggesting that motor speed in a more naturalistic setting should be more associated with executive rather than primary motor function. Moreover, results showed that while there were differences between the approaches, a convergence indicated that common networks can be revealed across highly divergent methods.

Patterns of effective connectivity during memory encoding and retrieval differ between patients with mild cognitive impairment and healthy older adults

Previous research has shown that there is considerable overlap in the neural networks mediating successful memory encoding and retrieval. However, little is known about how the relevant human brain regions interact during these distinct phases of memory or how such interactions are affected by memory deficits that characterize mild cognitive impairment (MCI), a condition that often precedes dementia due to Alzheimer's disease. Here we employed multivariate Granger causality analysis using autoregressive modeling of inferred neuronal time series obtained by deconvolving the hemodynamic response function from measured blood oxygenation level-dependent (BOLD) time series data, in order to examine the effective connectivity between brain regions during successful encoding and/or retrieval of object location associations in MCI patients and comparable healthy older adults. During encoding, healthy older adults demonstrated a left hemisphere dominant pattern where the inferior frontal junction, anterior intraparietal sulcus (likely involving the parietal eye fields), and posterior cingulate cortex drove activation in most left hemisphere regions and virtually every right hemisphere region tested. These regions are part of a frontoparietal network that mediates top-down cognitive control and is implicated in successful memory formation. In contrast, in the MCI patients, the right frontal eye field drove activation in every left hemisphere region examined, suggesting reliance on more basic visual search processes. Retrieval in the healthy older adults was primarily driven by the right hippocampus with lesser contributions of the right anterior thalamic nuclei and right inferior frontal sulcus, consistent with theoretical models holding the hippocampus as critical for the successful retrieval of memories. The pattern differed in MCI patients, in whom the right inferior frontal junction and right anterior thalamus drove successful memory retrieval, reflecting the characteristic hippocampal dysfunction of these patients. These findings demonstrate that neural network interactions differ markedly between MCI patients and healthy older adults. Future efforts will investigate the impact of cognitive rehabilitation of memory on these connectivity patterns.

Patients with idiopathic normal pressure hydrocephalus improved executive dysfunction after shunt operation

Background: Idiopathic normal pressure hydrocephalus (iNPH) is a syndrome characterized by cognitive decline, gait disturbance and impairment in bladder control. We evaluate changes in cognitive function before and after medical treatment for patients with iNPH. Objective: To report the changes of frontal dysfunctions. Patients and methods: We have diagnosed clinical inspection using Japanese NPH Grading Scale-revised to them. First of all, patients took mini-mental state test (MMSE) for memory decline, then took frontal assessment battery (FAB) and Behavioural Assessment of the Dysexecutive Syndrome (BADS). Only the cases that improved by tap tests were performed lumboperioneal (LP) shunt operations. We examined neuropsychological tests once before tap test and same tests in a half year after surgery. Results: Twenty six patients with iNPH were operated. Significant improvement between before and after operation was found in profile scores of FAB (9.6 ± 3.0 to 11.2 ± 2.9) and BADS (7.6 ± 3.8 to 9.6 ± 3.8). At the Conflicting Instructions and Go/No-Go of FAB item showed significant improvement after the operation. And the categorized item of Action Program in BADS was also improved, although no changeable of MMSE score. Conclusion: It was controversial that the executive dysfunction was recovered by LP shunted taking FAB and BADS. The executive dysfunction is related to the prefrontal area. Especially, Go/No-Go and Conflicting Instructions item showed activity in the posterior part of the inferior frontal sulcus. Memory disturbance is not the main affected impairment by iNPH. We think that the obstacle in iNPH is related with frontal lobe functions such as the executive dysfunction.

How prior expectations shape multisensory perception

The brain generates a representation of our environment by integrating signals from a common source, but segregating signals from different sources. This fMRI study investigated how the brain arbitrates between perceptual integration and segregation based on top-down congruency expectations and bottom-up stimulus-bound congruency cues.Participants were presented audiovisual movies of phonologically congruent, incongruent or McGurk syllables that can be integrated into an illusory percept (e.g. “ti” percept for visual «ki» with auditory /pi/). They reported the syllable they perceived. Critically, we manipulated participants' top-down congruency expectations by presenting McGurk stimuli embedded in blocks of congruent or incongruent syllables.Behaviorally, participants were more likely to fuse audiovisual signals into an illusory McGurk percept in congruent than incongruent contexts. At the neural level, the left inferior frontal sulcus (lIFS) showed increased activations for bottom-up incongruent relative to congruent inputs. Moreover, lIFS activations were increased for physically identical McGurk stimuli, when participants segregated the audiovisual signals and reported their auditory percept. Critically, this activation increase for perceptual segregation was amplified when participants expected audiovisually incongruent signals based on prior sensory experience.Collectively, our results demonstrate that the lIFS combines top-down prior (in)congruency expectations with bottom-up (in)congruency cues to arbitrate between multisensory integration and segregation.

Spatial selectivity in the temporoparietal junction, inferior frontal sulcus, and inferior parietal lobule.

Spatial selectivity, as measured by functional magnetic resonance imaging (fMRI) activity patterns that vary consistently with the location of visual stimuli, has been documented in many human brain regions, notably the occipital visual cortex and the frontal and parietal regions that are active during endogenous, goal-directed attention. We hypothesized that spatial selectivity also exists in regions that are active during exogenous, stimulus-driven attention. To test this hypothesis, we acquired fMRI data while subjects maintained passive fixation. At jittered time intervals, a briefly presented wedge-shaped array of rapidly expanding circles appeared at one of three contralateral or one of three ipsilateral locations. Positive fMRI activations were identified in multiple brain regions commonly associated with exogenous attention, including the temporoparietal junction, the inferior parietal lobule, and the inferior frontal sulcus. These activations were not organized as a map across the cortical surface. However, multivoxel pattern analysis of the fMRI activity correctly classified every pair of stimulus locations, demonstrating that patterns of fMRI activity were correlated with spatial location. These observations held for both contralateral and ipsilateral stimulus pairs as well as for stimuli of different textures (radial checkerboard) and shapes (squares and rings). Permutation testing verified that the obtained accuracies were not due to systematic biases and demonstrated that the findings were statistically significant.

Structural brain aging and speech production: a surface-based brain morphometry study.

While there has been a growing number of studies examining the neurofunctional correlates of speech production over the past decade, the neurostructural correlates of this immensely important human behaviour remain less well understood, despite the fact that previous studies have established links between brain structure and behaviour, including speech and language. In the present study, we thus examined, for the first time, the relationship between surface-based cortical thickness (CT) and three different behavioural indexes of sublexical speech production: response duration, reaction times and articulatory accuracy, in healthy young and older adults during the production of simple and complex meaningless sequences of syllables (e.g., /pa-pa-pa/ vs. /pa-ta-ka/). The results show that each behavioural speech measure was sensitive to the complexity of the sequences, as indicated by slower reaction times, longer response durations and decreased articulatory accuracy in both groups for the complex sequences. Older adults produced longer speech responses, particularly during the production of complex sequence. Unique age-independent and age-dependent relationships between brain structure and each of these behavioural measures were found in several cortical and subcortical regions known for their involvement in speech production, including the bilateral anterior insula, the left primary motor area, the rostral supramarginal gyrus, the right inferior frontal sulcus, the bilateral putamen and caudate, and in some region less typically associated with speech production, such as the posterior cingulate cortex.

Structural and functional connectivity of visual and auditory attentional networks: insights from the Human Connectome Project

Abstract Recent work in our laboratory has suggested that human caudal lateral frontal cortex contains four interleaved regions in each hemisphere that exhibit strong sensory-specific biases in attention tasks (Michalka et al, 2014). Two visually-biased attention regions, superior and inferior pre-central sulcus (sPCS, iPCS), anatomically alternate with two auditory-biased attention regions, caudal inferior frontal sulcus (cIFS) and the transverse gyrus intersection the precentral sulcus (tgPCS). These small regions were identified in fMRI studies in a small number of individual subjects. Here, we have investigated these regions and their putative networks by mining the WashU-Minn Human Connectome Project (HCP) dataset. We used data from the 482 HCP participants with both diffusion-weighted imaging and resting-state fMRI. We defined seed regions from our individual subject data in a task that contrasted auditory and visual spatial attention. Probabilistic activation maps were constructed and thresholded to generate ROIs. These ROIs served as seed regions for resting state and tractography analyses of the HCP dataset. Stronger functional connectivity was observed for the sPCS and iPCS than for tgPCS and cIFS with superior parietal lobule visual attention regions, and conversely stronger connectivity was observed for the tgPCS and cIFS than for sPCS and iPCS with superior temporal lobe auditory attention regions. A similar pattern was observed with tractography for all ROIs, except for tgPCS. We next analyzed the whole-brain connectivity patterns of these ROIs using a multivariate approach; we found that the modality of sensory-bias can be predicted well above chance in both hemispheres at a voxelwise scale (L:71%, R:80%), using only the connectivity pattern of an individual voxel. A long-term goal of this analysis is to develop reliable methods for identifying fine-scale brain networks in large population datasets, which could have important clinical applications. Our preliminary results reveal both successes and challenges of these efforts. Meeting abstract presented at VSS 2015.

THE NEURAL BASIS OF GENERAL INTELLIGENCE

Professor John Duncan Educated at the University of Oxford (1970–1976) and spent two years at the University of Oregon working with Michael Posner before taking up a research position with...

Short-Term Memory for Space and Time Flexibly Recruit Complementary Sensory-Biased Frontal Lobe Attention Networks

The frontal lobes control wide-ranging cognitive functions; however, functional subdivisions of human frontal cortex are only coarsely mapped. Here, functional magnetic resonance imaging reveals two distinct visual-biased attention regions in lateral frontal cortex, superior precentral sulcus (sPCS) and inferior precentral sulcus (iPCS), anatomically interdigitated with two auditory-biased attention regions, transverse gyrus intersecting precentral sulcus (tgPCS) and caudal inferior frontal sulcus (cIFS). Intrinsic functional connectivity analysis demonstrates that sPCS and iPCS fall within a broad visual-attention network, while tgPCS and cIFS fall within a broad auditory-attention network. Interestingly, we observe that spatial and temporal short-term memory (STM), respectively, recruit visual and auditory attention networks in the frontal lobe, independent of sensory modality. These findings not only demonstrate that both sensory modality and information domain influence frontal lobe functional organization, they also demonstrate that spatial processing co-localizes with visual processing and that temporal processing co-localizes with auditory processing in lateral frontal cortex.

P111. Brain volume differences between healthy females with high and low emphatic behavior

Introduction Empathizing is the ability to identify the mental states of others, for predicting their behavior and responding with appropriate emotion. Two routes to empathy are discussed: One relatively automatically process, with fast emotional responding and late appraisal. A second way is less automatic with early cognitive appraisal. Brain areas with structural changes related to empathy comprising regions from the mirror neuron system (MNS) and the default mode network (DMN). Positive and negative associations between empathizing and regional gray matter (GM) volume were found in healthy controls in the left inferior frontal gyrus (IFG), insula and superior temporal sulcus. Facing these divergent correlative effects, we compared GM volume of healthy females with low and high empathic behavior. Methods From a sample of 269 female healthy students completing the Empathy Quotient (EQ), 20 individuals with EQ > 45 (mean age 22.8) were compared with 20 age-matched individuals with an EQ p p Results In the region-of-interest-based analysis, none of the regions was showing a significant group difference. The exploratory voxelwise analysis yielded clusters of reduced GM volume in the LE group in right and more prominent in left frontal, bilateral occipital and temporal regions, comprising the left middle and superior frontal gyrus, the right middle and inferior temporal gyrus, the bilateral IFG, fusiform gyrus, lingual gyrus and cerebellum. For the HE group, the most prominent cluster of reduced GM volume comprising the right parahippocampus, temporal inferior gyrus and cerebellum. Another cluster was consisting of voxels from the left insula, superior temporal gyrus, rolandic operculum and superior part of temporal pole and clusters were also found in the right caudate and less pronounced in the left middle occipital lobe and in the right superior medial frontal gyrus. Discussion We did not find any group effects in the region-of-interest-based analysis. Most likely are variations in normal empathic behavior in healthy individuals associated with localized sub-regional brain structure differences. Indeed, the exploratory voxel-wise approach revealed that both groups show different clusters of altered GM volume. The HE group showed increased GM volume in frontal regions, comprising MNS and in lateral occipital and temporal regions associated with social recognition. Regions with increased GM volume were found in regions related to reconstructive empathy (left insula and right parahippocampal gyrus) in the LE group.

A preliminary study of the effects of working memory training on brain function.

Working memory (WM) training improves WM ability in Attention-Deficit/Hyperactivity Disorder (ADHD), but its efficacy for non-cognitive ADHD impairments ADHD has been sharply debated. The purpose of this preliminary study was to characterize WM training-related changes in ADHD brain function and see if they were linked to clinical improvement. We examined 18 adolescents diagnosed with DSM-IV Combined-subtype ADHD before and after 25 sessions of WM training using a frequently employed approach (Cogmed™) using a nonverbal Sternberg WM fMRI task, neuropsychological tests, and participant- and parent-reports of ADHD symptom severity and associated functional impairment. Whole brain SPM8 analyses identified ADHD activation deficits compared to 18 non-ADHD control participants, then tested whether impaired ADHD frontoparietal brain activation would increase following WM training. Post hoc tests examined the relationships between neural changes and neurocognitive or clinical improvements. As predicted, WM training increased WM performance, ADHD clinical functioning, and WM-related ADHD brain activity in several frontal, parietal and temporal lobe regions. Increased left inferior frontal sulcus region activity was seen in all Encoding, Maintenance, and Retrieval Sternberg task phases. ADHD symptom severity improvements were most often positively correlated with activation gains in brain regions known to be engaged for WM-related executive processing; improvement of different symptom types had different neural correlates. The responsiveness of both amodal WM frontoparietal circuits and executive process-specific WM brain regions was altered by WM training. The latter might represent a promising, relatively unexplored treatment target for researchers seeking to optimize clinical response in ongoing ADHD WM training development efforts.

Reading a suspenseful literary text activates brain areas related to social cognition and predictive inference.

Stories can elicit powerful emotions. A key emotional response to narrative plots (e.g., novels, movies, etc.) is suspense. Suspense appears to build on basic aspects of human cognition such as processes of expectation, anticipation, and prediction. However, the neural processes underlying emotional experiences of suspense have not been previously investigated. We acquired functional magnetic resonance imaging (fMRI) data while participants read a suspenseful literary text (E.T.A. Hoffmann's “The Sandman”) subdivided into short text passages. Individual ratings of experienced suspense obtained after each text passage were found to be related to activation in the medial frontal cortex, bilateral frontal regions (along the inferior frontal sulcus), lateral premotor cortex, as well as posterior temporal and temporo-parietal areas. The results indicate that the emotional experience of suspense depends on brain areas associated with social cognition and predictive inference.

Prediction During Natural Language Comprehension.

The notion of prediction is studied in cognitive neuroscience with increasing intensity. We investigated the neural basis of 2 distinct aspects of word prediction, derived from information theory, during story comprehension. We assessed the effect of entropy of next-word probability distributions as well as surprisal A computational model determined entropy and surprisal for each word in 3 literary stories. Twenty-four healthy participants listened to the same 3 stories while their brain activation was measured using fMRI. Reversed speech fragments were presented as a control condition. Brain areas sensitive to entropy were left ventral premotor cortex, left middle frontal gyrus, right inferior frontal gyrus, left inferior parietal lobule, and left supplementary motor area. Areas sensitive to surprisal were left inferior temporal sulcus ("visual word form area"), bilateral superior temporal gyrus, right amygdala, bilateral anterior temporal poles, and right inferior frontal sulcus. We conclude that prediction during language comprehension can occur at several levels of processing, including at the level of word form. Our study exemplifies the power of combining computational linguistics with cognitive neuroscience, and additionally underlines the feasibility of studying continuous spoken language materials with fMRI.

Co-Activation-Based Parcellation of the Lateral Prefrontal Cortex Delineates the Inferior Frontal Junction Area.

The inferior frontal junction (IFJ) area, a small region in the posterior lateral prefrontal cortex (LPFC), has received increasing interest in recent years due to its central involvement in the control of action, attention, and memory. Yet, both its function and anatomy remain controversial. Here, we employed a meta-analytic parcellation of the left LPFC to show that the IFJ can be isolated based on its specific functional connections. A seed region, oriented along the left inferior frontal sulcus (IFS), was subdivided via cluster analyses of voxel-wise whole-brain co-activation patterns. The ensuing clusters were characterized by their unique connections, the functional profiles of associated experiments, and an independent topic mapping approach. A cluster at the posterior end of the IFS matched previous descriptions of the IFJ in location and extent and could be distinguished from a more caudal cluster involved in motor control, a more ventral cluster involved in linguistic processing, and 3 more rostral clusters involved in other aspects of cognitive control. Overall, our findings highlight that the IFJ constitutes a core functional unit within the frontal lobe and delineate its borders. Implications for the IFJ's role in human cognition and the organizational principles of the frontal lobe are discussed.