Social context and drug cues modulate inhibitory control in cocaine addiction: involvement of the STN evidenced through functional MRI.

Addictions often develop in a social context, although the influence of social factors did not receive much attention in the neuroscience of addiction. Recent animal studies suggest that peer presence can reduce cocaine intake, an influence potentially mediated, among others, by the subthalamic nucleus (STN). However, there is to date no neurobiological study investigating this mediation in humans. This study investigated the impact of social context and drug cues on brain correlates of inhibitory control in individuals with and without cocaine use disorder (CUD) using functional Magnetic Resonance Imaging (fMRI). Seventeen CUD participants and 17 healthy controls (HC) performed a novel fMRI "Social" Stop-Signal Task (SSST) in the presence or absence of an observer while being exposed to cocaine-related (vs. neutral) cues eliciting craving in drug users. The results showed that CUD participants, while slower at stopping with neutral cues, recovered control level stopping abilities with cocaine cues, while HC did not show any difference. During inhibition (Stop Correct vs Stop Incorrect), activity in the right STN, right inferior frontal gyrus (IFG), and bilateral orbitofrontal cortex (OFC) varied according to the type of cue. Notably, the presence of an observer reversed this effect in most areas for CUD participants. These findings highlight the impact of social context and drug cues on inhibitory control in CUD and the mediation of these effects by the right STN and bilateral OFC, emphasizing the importance of considering the social context in addiction research. They also comfort the STN as a potential addiction treatment target.

Planum temporale asymmetry in newborn monkeys predicts the future development of gestural communication's handedness.

The planum temporale (PT), a key language area, is specialized in the left hemisphere in prelinguistic infants and considered as a marker of the pre-wired language-ready brain. However, studies have reported a similar structural PT left-asymmetry not only in various adult non-human primates, but also in newborn baboons. Its shared functional links with language are not fully understood. Here we demonstrate using previously obtained MRI data that early detection of PT left-asymmetry among 27 newborn baboons (Papio anubis, age range of 4 days to 2 months) predicts the future development of right-hand preference for communicative gestures but not for non-communicative actions. Specifically, only newborns with a larger left-than-right PT were more likely to develop a right-handed communication once juvenile, a contralateral brain-gesture link which is maintained in a group of 70 mature baboons. This finding suggests that early PT asymmetry may be a common inherited prewiring of the primate brain for the ontogeny of ancient lateralised properties shared between monkey gesture and human language.

Writing letters in two graphic systems: Behavioral and neural correlates in Latin-Arabic biscripters.

Biscriptuality is the ability to read and write using two scripts. Despite the increasing number of biscripters, this phenomenon remains poorly understood. Here, we focused on investigating graphomotor processing in French-Arabic biscripters. We chose the French and Arabic alphabets because they have comparable visuospatial complexity and linguistic features, but differ dramatically in their graphomotor characteristics. In a first experiment we describe the graphomotor features of the two alphabets and showed that while Arabic and Latin letters are produced with the same velocity and fluency, Arabic letters require more pen lifts, contain more right-to-left strokes and clockwise curves, and take longer to write than Latin letters. These results suggest that Arabic and Latin letters are produced via different motor patterns. In a second experiment we used functional magnetic resonance imaging to ask whether writing the two scripts relies upon partially distinct or fully overlapping neural networks, and whether the elements of the previously described handwriting network are recruited to the same extent by the two scripts. We found that both scripts engaged the so-called "writing network", but that within the network, Arabic letters recruited the left superior parietal lobule (SPL) and the left primary motor cortex (M1) more strongly than Latin letters. Both regions have previously been identified as holding scale-invariant representations of letter trajectories. Arabic and Latin letters also activated distinct regions that do not belong to the writing network. Complementary analyses indicate that the differences observed between scripts at the neural level could be driven by the specific graphomotor features of each script. Overall, our results indicate that particular features of the practiced scripts can lead to different motor organization at both the behavioral and brain levels in biscripters.

Problem-solving training modifies cognitive functioning and related functional connectivity in healthy adults.

Cognitive functioning evolves throughout life. Regular practice of stimulating activities maintains or even strengthens cognitive skills. This study investigated the effects of a cognitive training programme based on complex closed-ended problem solving on innovative thinking. To this end, using partial least squares variance-based structural equation modeling, we first evaluated in 83 healthy adults how inhibition, cognitive flexibility, and reasoning were related to the distinct dimensions of innovative thinking. Second, we assessed how these interactions were modified after cognitive training based on problem solving in a subgroup of 16 subjects compared to leisure activity based on crossword solving in another subgroup of 15 subjects. Third, in a pilot fMRI study, we evaluated changes in brain connectivity at rest as a result of training in the problem solving group. Data on cognitive measures showed that innovative thinking was influenced by reasoning in control subjects, whereas it was influenced by cognitive flexibility following problem-solving training. These findings highlight that a cognitive intervention based on complex closed-ended problem solving promotes innovative thinking by changing the way subjects recruit and use relevant cognitive processes. Modifications in the resting-state connectivity of attention, default mode and visual networks were observed in the problem solving group.

Action Observation Network Activity Related to Object-Directed and Socially-Directed Actions in Adolescents.

The human action observation network (AON) encompasses brain areas consistently engaged when we observe other's actions. Although the core nodes of the AON are present from childhood, it is not known to what extent they are sensitive to different action features during development. Because social cognitive abilities continue to mature during adolescence, the AON response to socially-oriented actions, but not to object-related actions, may differ in adolescents and adults. To test this hypothesis, we scanned with functional magnetic resonance imaging (fMRI) male and female typically-developing teenagers (n = 28; 13 females) and adults (n = 25; 14 females) while they passively watched videos of manual actions varying along two dimensions: sociality (i.e., directed toward another person or not) and transitivity (i.e., involving an object or not). We found that action observation recruited the same fronto-parietal and occipito-temporal regions in adults and adolescents. The modulation of voxel-wise activity according to the social or transitive nature of the action was similar in both groups of participants. Multivariate pattern analysis, however, revealed that decoding accuracies in intraparietal sulcus (IPS)/superior parietal lobe (SPL) for both sociality and transitivity were lower for adolescents compared with adults. In addition, in the lateral occipital temporal cortex (LOTC), generalization of decoding across the orthogonal dimension was lower for sociality only in adolescents. These findings indicate that the representation of the content of others' actions, and in particular their social dimension, in the adolescent AON is still not as robust as in adults.SIGNIFICANCE STATEMENT The activity of the action observation network (AON) in the human brain is modulated according to the purpose of the observed action, in particular the extent to which it involves interaction with an object or with another person. How this conceptual representation of actions is implemented during development is largely unknown. Here, using multivoxel pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data, we discovered that, while the action observation network is in place in adolescence, the fine-grain organization of its posterior regions is less robust than in adults to decode the abstract social dimensions of an action. This finding highlights the late maturation of social processing in the human brain.

Graph theoretical analysis reveals the functional role of the left ventral occipito-temporal cortex in speech processing.

The left ventral occipito-temporal cortex (left-vOT) plays a key role in reading. Interestingly, the area also responds to speech input, suggesting that it may have other functions beyond written word recognition. Here, we adopt graph theoretical analysis to investigate the left-vOT's functional role in the whole-brain network while participants process spoken sentences in different contexts. Overall, different connectivity measures indicate that the left-vOT acts as an interface enabling the communication between distributed brain regions and sub-networks. During simple speech perception, the left-vOT is systematically part of the visual network and contributes to the communication between neighboring areas, remote areas, and sub-networks, by acting as a local bridge, a global bridge, and a connector, respectively. However, when speech comprehension is explicitly required, the specific functional role of the area and the sub-network to which the left-vOT belongs change and vary with the quality of speech signal and task difficulty. These connectivity patterns provide insightful information on the contribution of the left-vOT in various contexts of language processing beyond its role in reading. They advance our general understanding of the neural mechanisms underlying the flexibility of the language network that adjusts itself according to the processing context.

Is there evidence for a noisy computation deficit in developmental dyslexia?

The noisy computation hypothesis of developmental dyslexia (DD) is particularly appealing because it can explain deficits across a variety of domains, such as temporal, auditory, phonological, visual and attentional processes. A key prediction is that noisy computations lead to more variable and less stable word representations. A way to test this hypothesis is through repetition of words, that is, when there is noise in the system, the neural signature of repeated stimuli should be more variable. The hypothesis was tested in an functional magnetic resonance imaging experiment with dyslexic and typical readers by repeating words twelve times. Variability measures were computed both at the behavioral and neural levels. At the behavioral level, we compared the standard deviation of reaction time distributions of repeated words. At the neural level, in addition to standard univariate analyses and measures of intra-item variability, we also used multivariate pattern analyses (representational similarity and classification) to find out whether there was evidence for noisier representations in dyslexic readers compared to typical readers. Results showed that there were no significant differences between the two groups in any of the analyses despite robust results within each group (i.e., high representational similarity between repeated words, good classification of words vs. non-words). In summary, there was no evidence in favor of the idea that dyslexic readers would have noisier neural representations than typical readers.

Broca's cerebral asymmetry reflects gestural communication's lateralisation in monkeys (Papio anubis).

Manual gestures and speech recruit a common neural network, involving Broca's area in the left hemisphere. Such speech-gesture integration gave rise to theories on the critical role of manual gesturing in the origin of language. Within this evolutionary framework, research on gestural communication in our closer primate relatives has received renewed attention for investigating its potential language-like features. Here, using in vivo anatomical MRI in 50 baboons, we found that communicative gesturing is related to Broca homologue's marker in monkeys, namely the ventral portion of the Inferior Arcuate sulcus (IA sulcus). In fact, both direction and degree of gestural communication's handedness - but not handedness for object manipulation are associated and correlated with contralateral depth asymmetry at this exact IA sulcus portion. In other words, baboons that prefer to communicate with their right hand have a deeper left-than-right IA sulcus, than those preferring to communicate with their left hand and vice versa. Interestingly, in contrast to handedness for object manipulation, gestural communication's lateralisation is not associated to the Central sulcus depth asymmetry, suggesting a double dissociation of handedness' types between manipulative action and gestural communication. It is thus not excluded that this specific gestural lateralisation signature within the baboons' frontal cortex might reflect a phylogenetical continuity with language-related Broca lateralisation in humans.

Cerebellar and Cortical Correlates of Internal and External Speech Error Monitoring.

An event-related functional magnetic resonance imaging study examined how speakers inspect their own speech for errors. Concretely, we sought to assess 1) the role of the temporal cortex in monitoring speech errors, linked with comprehension-based monitoring; 2) the involvement of the cerebellum in internal and external monitoring, linked with forward modeling; and 3) the role of the medial frontal cortex for internal monitoring, linked with conflict-based monitoring. In a word production task priming speech errors, we observed enhanced involvement of the right posterior cerebellum for trials that were correct, but on which participants were more likely to make a word as compared with a nonword error (contrast of internal monitoring). Furthermore, comparing errors to correct utterances (contrast of external monitoring), we observed increased activation of the same cerebellar region, of the superior medial cerebellum, and of regions in temporal and medial frontal cortex. The presence of the cerebellum for both internal and external monitoring indicates the use of forward modeling across the planning and articulation of speech. Dissociations across internal and external monitoring in temporal and medial frontal cortex indicate that monitoring of overt errors is more reliant on vocal feedback control.

The Human Basal Ganglia Mediate the Interplay between Reactive and Proactive Control of Response through Both Motor Inhibition and Sensory Modulation.

The basal ganglia (BG) have long been known for contributing to the regulation of motor behaviour by means of a complex interplay between tonic and phasic inhibitory mechanisms. However, after having focused for a long time on phasic reactive mechanisms, it is only recently that psychological research in healthy humans has modelled tonic proactive mechanisms of control. Mutual calibration between anatomo-functional and psychological models is still needed to better understand the unclear role of the BG in the interplay between proactive and reactive mechanisms of control. Here, we implemented an event-related fMRI design allowing proper analysis of both the brain activity preceding the target-stimulus and the brain activity induced by the target-stimulus during a simple go/nogo task, with a particular interest in the ambiguous role of the basal ganglia. Post-stimulus activity was evoked in the left dorsal striatum, the subthalamus nucleus and internal globus pallidus by any stimulus when the situation was unpredictable, pinpointing its involvement in reactive, non-selective inhibitory mechanisms when action restraint is required. Pre-stimulus activity was detected in the ventral, not the dorsal, striatum, when the situation was unpredictable, and was associated with changes in functional connectivity with the early visual, not the motor, cortex. This suggests that the ventral striatum supports modulatory influence over sensory processing during proactive control.

Early Left-Planum Temporale Asymmetry in newborn monkeys (Papio anubis): A longitudinal structural MRI study at two stages of development.

The "language-ready" brain theory suggests that the infant brain is pre-wired for language acquisition prior to language exposure. As a potential brain marker of such a language readiness, a leftward structural brain asymmetry was found in human infants for the Planum Temporale (PT), which overlaps with Wernicke's area. In the present longitudinal in vivo MRI study conducted in 35 newborn monkeys (Papio anubis), we found a similar leftward PT surface asymmetry. Follow-up rescanning sessions on 29 juvenile baboons at 7-10 months showed that such an asymmetry increases across the two ages classes. These original findings in non-linguistic primate infants strongly question the idea that the early PT asymmetry constitutes a human infant-specific marker for language development. Such a shared early perisylvian organization provides additional support that PT asymmetry might be related to a lateralized system inherited from our last common ancestor with Old-World monkeys at least 25-35 million years ago.

The handwriting brain in middle childhood.

While the brain network supporting handwriting has previously been defined in adults, its organization in children has never been investigated. We compared the handwriting network of 23 adults and 42 children (8- to 11-year-old). Participants were instructed to write the alphabet, the days of the week, and to draw loops while being scanned. The handwriting network previously described in adults (five key regions: left dorsal premotor cortex, superior parietal lobule (SPL), fusiform and inferior frontal gyri, and right cerebellum) was also strongly activated in children. The right precentral gyrus and the right anterior cerebellum were more strongly activated in adults than in children, while the left fusiform gyrus (FuG) was more strongly activated in children than in adults. Finally, we found that, contrary to adults, children recruited prefrontal regions to complete the writing task. This constitutes the first comparative investigation of the neural correlates of writing in children and adults. Our results suggest that the network supporting handwriting is already established in middle childhood. They also highlight the major role of prefrontal regions in learning this complex skill and the importance of right precentral regions and cerebellum in the performance of automated handwriting.

The aging brain: A set of functional MRI data acquired at rest and during exposure to tactile or muscle proprioceptive stimulation in healthy young and older volunteers.

There is a growing interest in understanding functional brain decline with aging. The dataset provides raw anatomical and functional images recorded in a group of 20 young volunteers and in another group of 19 older volunteers during a 10-minute period of resting state followed by four consecutive task-related runs. During each task-related run, the participants were exposed to two types of sensory stimulation: a tactile stimulation consisting in a textured-disk rotation under the palm of their right hand or a muscle proprioceptive stimulation consisting in a mechanical vibration applied to the muscle tendon of their wrist abductor. These two stimulations are known to evoke illusory sensations of hand movement, while the hand remains actually still. Therefore, the dataset is meant to be used to assess age-related functional brain changes during the perception of hand movements based on muscle proprioception or touch individually. It also allows to explore any structural changes or functional resting connectivity alteration with aging. The dataset is a supplement to the research findings in the paper 'Functional brain changes in the elderly for the perception of hand movements: a greater impairment occurs in proprioception than touch published in NeuroImage.

Functional brain changes in the elderly for the perception of hand movements: A greater impairment occurs in proprioception than touch.

Unlike age-related brain changes linked to motor activity, neural alterations related to self-motion perception remain unknown. Using fMRI data, we investigated age-related changes in the central processing of somatosensory information by inducing illusions of right-hand rotations with specific proprioceptive and tactile stimulation. Functional connectivity during resting-state (rs-FC) was also compared between younger and older participants. Results showed common sensorimotor activations in younger and older adults during proprioceptive and tactile illusions, but less deactivation in various right frontal regions and the precuneus were found in the elderly. Older participants exhibited a less-lateralized pattern of activity across the primary sensorimotor cortices (SM1) in the proprioceptive condition only. This alteration of the interhemispheric balance correlated with declining individual performance in illusion velocity perception from a proprioceptive, but not a tactile, origin. By combining task-related data, rs-FC and behavioral performance, this study provided consistent results showing that hand movement perception was altered in the elderly, with a more pronounced deterioration of the proprioceptive system, likely due to the breakdown of inhibitory processes with aging. Nevertheless, older people could benefit from an increase in internetwork connectivity to overcome this kinesthetic decline.

Top-down activation of the visuo-orthographic system during spoken sentence processing.

The left ventral occipitotemporal cortex (vOT) is considered the key area of the visuo-orthographic system. However, some studies reported that the area is also involved in speech processing tasks, especially those that require activation of orthographic knowledge. These findings suggest the existence of a top-down activation mechanism allowing such cross-modal activation. Yet, little is known about the involvement of the vOT in more natural speech processing situations like spoken sentence processing. Here, we addressed this issue in a functional Magnetic Resonance Imaging (fMRI) study while manipulating the impacts of two factors, i.e., task demands (semantic vs. low-level perceptual task) and the quality of speech signals (sentences presented against clear vs. noisy background). Analyses were performed at the levels of whole brain and region-of-interest (ROI) focusing on the vOT voxels individually identified through a reading task. Whole brain analysis showed that processing spoken sentences induced activity in a large network including the regions typically involved in phonological, articulatory, semantic and orthographic processing. ROI analysis further specified that a significant part of the vOT voxels that responded to written words also responded to spoken sentences, thus, suggesting that the same area within the left occipitotemporal pathway contributes to both reading and speech processing. Interestingly, both analyses provided converging evidence that vOT responses to speech were sensitive to both task demands and quality of speech signals: Compared to the low-level perceptual task, activity of the area increased when efforts on comprehension were required. The impact of background noise depended on task demands. It led to a decrease of vOT activity in the semantic task but not in the low-level perceptual task. Our results provide new insights into the function of this key area of the reading network, notably by showing that its speech-induced top-down activation also generalizes to ecological speech processing situations.

Handedness in monkeys reflects hemispheric specialization within the central sulcus. An in vivo MRI study in right- and left-handed olive baboons.

Handedness, one of the most prominent expressions of laterality, has been historically considered unique to human. This noteworthy feature relates to contralateral inter-hemispheric asymmetries in the motor hand area following the mid-portion of the central sulcus. However, within an evolutionary approach, it remains debatable whether hand preferences in nonhuman primates are associated with similar patterns of hemispheric specialization. In the present study conducted in Old world monkeys, we investigate anatomical asymmetries of the central sulcus in a sample of 86 olive baboons (Papio anubis) from in vivo T1 anatomical magnetic resonance images (MRI). Out of this sample, 35 individuals were classified as right-handed and 28 as left-handed according to their hand use responses elicited by a bimanual coordinated tube task. Here we report that the direction and degree of hand preference (left or right), as measured by this manual task, relates to and correlates with contralateral hemispheric sulcus depth asymmetry, within a mid-portion of the central sulcus. This neuroanatomical manifestation of handedness in baboons located in a region, which may correspond to the motor hand area, questions the phylogenetic origins of human handedness that may date back to their common ancestor, 25-40 millions years ago.

The impact of spelling regularity on handwriting production: A coupled fMRI and kinematics study.

Current models of writing assume that the orthographic processes involved in spelling retrieval and the motor processes involved in the control of the hand are independent. This view has been challenged by behavioral studies, which showed that the linguistic features of words impact motor execution during handwriting. We designed an experiment coupling functional magnetic resonance imaging and kinematic recordings during a writing to dictation task. Participants wrote orthographically regular and irregular words. The presence of an irregularity impacts both the initiation of the movement and its fine motor execution. At the brain level, the left inferior frontal and fusiform gyri, two regions belonging to the core of the written language system, were found to be sensitive to the presence of an irregularity and to its position in the word during writing execution. Moreover, the left superior parietal lobule, the left superior frontal gyrus and the right cerebellum, three motor-related regions, displayed a stronger response to irregular than regular words. These results constitute direct evidence that orthographic and motor processes occur in a continuous and interactive fashion during writing.

Taste at first (person) sight: Visual perspective modulates brain activity implicitly associated with viewing unhealthy but not healthy foods.

Every day, people are exposed to images of appetizing foods that can lead to high-calorie intake and contribute to overweight and obesity. Research has documented that manipulating the visual perspective from which eating is viewed helps resist temptation by altering the appraisal of unhealthy foods. However, the neural basis of this effect has not yet been examined using neuroimaging methods. Moreover, it is not known whether the benefits of this strategy can be observed when people, especially overweight, are not explicitly asked to imagine themselves eating. Last, it remains to be investigated if visual perspective could be used to promote healthy foods. The present work manipulated camera angles and tested whether visual perspective modulates activity in brain regions associated with taste and reward processing while participants watch videos featuring a hand grasping (unhealthy or healthy) foods from a plate during functional magnetic resonance imagining (fMRI). The plate was filmed from the perspective of the participant (first-person perspective; 1PP), or from a frontal view as if watching someone else eating (third-person perspective; 3PP). Our findings reveal that merely viewing unhealthy food cues from a 1PP (vs. 3PP) increases activity in brain regions that underlie representations of rewarding (appetitive) experiences (amygdala) and food intake (superior parietal gyrus). Additionally, our results show that ventral striatal activity is positively correlated with body mass index (BMI) during exposure to unhealthy foods from a 1PP (vs. 3PP). These findings suggest that unhealthy foods should be promoted through third-person (video) images to weaken the reward associated with their simulated consumption, especially amongst overweight people. It appears however that, as such, manipulating visual perspective fails to enhance the perception of healthy foods. Their promotion thus requires complementary solutions.

Left Brain Asymmetry of the Planum Temporale in a Nonhominid Primate: Redefining the Origin of Brain Specialization for Language.

The planum temporale (PT) is a critical region of the language functional network in the human brain showing a striking size asymmetry toward the left hemisphere. Historically considered as a structural landmark of the left-brain specialization for language, a similar anatomical bias has been described in great apes but never in monkeys-indicating that this brain landmark might be unique to Hominidae evolution. In the present in vivo magnetic resonance imaging study, we show clearly for the first time in a nonhominid primate species, an Old World monkey, a left size predominance of the PT among 96 olive baboons (Papio anubis), using manual delineation of this region in each individual hemisphere. This asymmetric distribution was quasi-identical to that found originally in humans. Such a finding questions the relationship between PT asymmetry and the emergence of language, indicating that the origin of this cerebral specialization could be much older than previously thought, dating back, not to the Hominidae, but rather to the Catarrhini evolution at the common ancestor of humans, great apes and Old World monkeys, 30-40 million years ago.

Gravity Cues Embedded in the Kinematics of Human Motion Are Detected in Form-from-Motion Areas of the Visual System and in Motor-Related Areas.

The present study investigated the cortical areas engaged in the perception of graviceptive information embedded in biological motion (BM). To this end, functional magnetic resonance imaging was used to assess the cortical areas active during the observation of human movements performed under normogravity and microgravity (parabolic flight). Movements were defined by motion cues alone using point-light displays. We found that gravity modulated the activation of a restricted set of regions of the network subtending BM perception, including form-from-motion areas of the visual system (kinetic occipital region, lingual gyrus, cuneus) and motor-related areas (primary motor and somatosensory cortices). These findings suggest that compliance of observed movements with normal gravity was carried out by mapping them onto the observer's motor system and by extracting their overall form from local motion of the moving light points. We propose that judgment on graviceptive information embedded in BM can be established based on motor resonance and visual familiarity mechanisms and not necessarily by accessing the internal model of gravitational motion stored in the vestibular cortex.