Inferior Frontal Areas Research Articles

A network approach to response inhibition: dissociating functional connectivity of neural components involved in action restraint and action cancellation

The ability to inhibit action tendencies is vital for adaptive human behaviour. Various paradigms are supposed to assess action inhibition and are often used interchangeably. However, these paradigms are based on different conceptualizations (action restraint vs. action cancellation) and the question arises as to what extent different conceptualizations of inhibitory processing are mirrored in a distinct neural activation pattern. We used functional magnetic resonance imaging to investigate the neural correlates of action restraint vs. action cancellation. Analyses of local activity changes as well as network connectivity measures revealed a strong overlap of activation within a common action inhibition network including inferior frontal, pre-supplementary motor and thalamic brain areas as well as the anterior cingulate cortex. Furthermore, our findings pointed to additional neural networks that are distinct for action restraint (i.e. right superior frontal gyrus, left middle frontal gyrus, and bilateral anterior cingulate cortex) and action cancellation (i.e. right middle frontal gyrus, posterior cingulate cortex, and parietal regions). Our connectivity analyses showed that different inhibitory modalities largely relied on a task-independent global inhibition network within the brain. Furthermore, they suggested that the conceptually distinct inhibitory aspects of action restraint vs. action cancellation also activated additional specific brain regions in a task-dependent manner. This has implications for the choice of tasks in an empirical setting, but is also relevant for various clinical contexts in which inhibition deficits are considered a diagnostic feature.

Visual activity predicts auditory recovery from deafness after adult cochlear implantation

Modern cochlear implantation technologies allow deaf patients to understand auditory speech; however, the implants deliver only a coarse auditory input and patients must use long-term adaptive processes to achieve coherent percepts. In adults with post-lingual deafness, the high progress of speech recovery is observed during the first year after cochlear implantation, but there is a large range of variability in the level of cochlear implant outcomes and the temporal evolution of recovery. It has been proposed that when profoundly deaf subjects receive a cochlear implant, the visual cross-modal reorganization of the brain is deleterious for auditory speech recovery. We tested this hypothesis in post-lingually deaf adults by analysing whether brain activity shortly after implantation correlated with the level of auditory recovery 6 months later. Based on brain activity induced by a speech-processing task, we found strong positive correlations in areas outside the auditory cortex. The highest positive correlations were found in the occipital cortex involved in visual processing, as well as in the posterior-temporal cortex known for audio-visual integration. The other area, which positively correlated with auditory speech recovery, was localized in the left inferior frontal area known for speech processing. Our results demonstrate that the visual modality's functional level is related to the proficiency level of auditory recovery. Based on the positive correlation of visual activity with auditory speech recovery, we suggest that visual modality may facilitate the perception of the word's auditory counterpart in communicative situations. The link demonstrated between visual activity and auditory speech perception indicates that visuoauditory synergy is crucial for cross-modal plasticity and fostering speech-comprehension recovery in adult cochlear-implanted deaf patients.

Orthographic Depth Modulates Reading Route Selection: An Electrical Neuroimaging Study

Introduction The orthographic Depth Hypothesis (Katz and Feldman, 1983) posits that different reading routes are engaged depending on the expertise of the reader but also on the type of grapheme/phoneme correspondence of the language being read. Shallow orthographies (e.g. German and Italian) with consistent grapheme to phoneme correspondences favor encoding via non-lexical pathways, where each phoneme is sequentially mapped to its corresponding grapheme. In contrast, deep orthographies (e.g. French and English), with inconsistent grapheme to phoneme correspondences favor lexical pathways, where phonemes are retrieved from memory structures. Only few studies investigated the impact of orthographic depth on brain response while reading. Moreover, because they used between subject or cross-language designs, the interpretability of previous studies on the effect of orthographic depth is limited. The aim of the present study was to investigate the impact of orthographic depth on reading route selection using an experimental design enabling isolating the effect of orthographic depth. Method We presented the same pseudowords (PWs) to highly proficient bilinguals and manipulated the orthographic depth of PW reading by embedding them among two separated language contexts (German and French), implicating either shallow or deep orthography. High density 128-channel electroencephalography was recorded during the task. Results The topographies of the event-related potential were different between PWs read in deep orthographic context and PWs read in shallow orthographic context at 300-360ms after stimulus onset, indicating distinct brain networks engaged in reading during this time window. The brain source underlying these topographic effects were located within left inferior frontal, left parietal and left cingular areas. Conclusion We propose that in deep orthographic context, reading PWs cannot rely on the routine lexical pathways and thus switching to the non-lexical route is necessary. In controast, reading in a shallow orthographic context favors non-lexical route processing which fits PW reading. The topographic modulation might thus reflect the recruitment of lexical pathways in the deep but not in the shallow context. Analysis of electrical source estimation over the period of topographic modulation supports this hypothesis by showing that inferior frontal areas, a region shown to subserve phonological processing, is differentially engaged between the deep vs shallow conditions. In addition, a difference in the activity of parietal-cingular areas suggests a modulation of attentional demands related to route selection processes. Non-lexical route may be less automatized than lexical route processing. These collective results support a modulation of reading route selection by orthographic depth.

The Role of Interhemisphere Interactions in Children Aged 5–6 Years and Adults in Supporting Verbal-Mnestic Activity Associated with the Formation and Analysis of Verbal Utterances

This report describes studies of the establishment of the neurophysiological mechanisms underlying mental speech activity associated with the synthesis of speech units from sets of more elementary units in children aged 5‐6 years. Comparison of the results with data on analogous activity in adults, as well as in children and adults during verbal activity directed to recognizing phonemes in words and grammatical and semantic errors in sentences, showed that support of the speech production processes underlying the mental formation of words and sentences, as well as verbal activity requiring recognition and a critical approach to speech perception, requires coordinated simultaneous activity of the left and right hemispheres. In children and especially in adults, this is apparent as increases in interhemisphere interactions, mainly in the temporal lobes of the two hemispheres, the inferior frontal areas, and the TPO zone (the zone at which the temporal, parietal, and occipital areas of the cortex overlap). These data indicate that the neurophysiological mechanisms originating verbal constructs in preschool children are more mature than the processes accompanying the analytical approach to the grammatical, semantic, and phonetic characteristics of perceived speech.

A case of bilateral frontal tumors without “frontal syndrome”

We report the longitudinal case study of a right-handed patient harboring two frontal tumors that benefited from bilateral simultaneous surgery. The tumors were WHO Grade II gliomas located in the left inferior frontal area (including the cingulate gyrus) and the right anterior superior frontal gyrus. The double tumor resection was guided by direct electrical stimulation of brain areas while the patient was awake. Neuropsychological assessments were administered before and after the surgery to analyse how the brain functions in the presence of two frontal gliomas that affect both hemispheres and reacts to a bilateral resection, which can brutally compromise the neuronal connectivity, progressively established during the infiltrating process. We showed that both the tumor infiltration and their bilateral resection did not lead to a “frontal syndrome” or a “dysexecutive syndrome” predicted by the localization models. However, a subtle fragility was observed in fine-grain language, memory and emotional skills. This case study reveals the significance of brain plasticity in the reorganization of cognitive networks, even in cases of bilateral tumors. It also confirms the clinical relevance of hodotopical brain models, which considers the brain to be organized in parallel-distributed networks around cortical centers and epicenters.

Working memory‐related brain activity is associated with outcome of lifestyle intervention

Lifestyle interventions including reduction of caloric intake are still the most pursued option to treat obesity. However, their outcome in terms of weight loss strongly differs between participants. In our study, we hypothesized that initial differences in brain activation in a food specific memory task are associated with weight change during a lifestyle intervention. Magnetic brain activity was recorded during a one-back visual memory task with food and nonfood pictures in 33 overweight and obese subjects before they underwent a lifestyle intervention. The intervention lasted 6 months and aimed for a reduction in daily caloric intake by 400 kcal. Body mass index (BMI) was determined before and after the intervention. Differences between outer tertiles representing people who increased their BMI by 1.4% ± 1.1% (non-responders) and who reduced their BMI by -6.9% ± 2.6% (responders) are reported. Neuronal activity was related to BMI change in sensor and source space. Non-responders showed higher activation in right inferior frontal and left occipital visual areas, whereas responders showed increased activation in right temporal areas including hippocampus and fusiform gyrus. Differences in the cerebral response during a food specific memory task indicate an altered cognitive control over food intake. These differences might determine the ability to eat less and successfully lose weight.

Cortical thickness asymmetry from childhood to older adulthood

Age-related thinning of the cortical mantle varies regionally, leading to hemispheric asymmetries in cortical thickness that may emerge at various stages of development and aging. Cortical asymmetry may play a role in modulating the functional maturation (or degradation) of language and cognition in humans, but its evolution over the lifespan is unknown. Here cortical thickness was negatively correlated with age in 274 5–59year old, right-handed healthy participants. Pre-adolescents showed limited regions of cortical asymmetry focused on medial occipital lobe (R>L) and inferior frontal gyrus (R>L), namely vision and language relevant areas. More extensive frontal (lateral R>L, medial L>R) and parietal lobe (lateral L>R, medial R>L) asymmetries emerged after adolescence, and increased during aging. Changes of cortical asymmetry in these regions may be linked to specialization of the brain with maturity.

Lexical abilities after temporal lobe epilepsy surgery

Objective. Picture naming and word fluency depend on the integrity of different neural networks including the inferior-lateral temporal, superior parietal and frontal cortices and the ventral visual pathway or the inferior frontal, dorsolateral prefrontal, medial temporal and parietal areas. Although many studies investigated language after epilepsy surgery, scarce attention was given to the postoperative trajectories of different lexical–semantic abilities. This prospective study evaluated the short- and long-term changes of word finding on visual, letter, and category stimuli in patients operated on for drug-resistant temporal lobe epilepsy (TLE).

Longitudinal changes in brains of patients with fluent primary progressive aphasia

Primary progressive aphasia (PPA) is a rare clinical dementia syndrome with predominant, progressive language impairment. Clinical symptoms, linguistic impairment and the course of the disease may vary considerably between patients. In order to capture these aspects, longitudinal assessments of neurofunctional changes in PPA including their relationship to behaviour and clinical symptoms are mandatory, ideally at intervals shorter than 1year. Here, we report a longitudinal fMRI study investigating the development of lexical processing and their neural basis in PPA patients over 1year. Four logopenic PPA patients and four matched controls were scanned 3 times (T1, T2, T3, at 6months intervals) while performing a visual lexical decision task on German words and pseudowords. Group differences for the lexicality effect (pseudowords>words) were assessed at time point T1 and its longitudinal changes in the BOLD signal associated with the lexicality effect were analysed. Brain atrophy was assessed with a high-resolution MPRAGE sequence and analysed using deformation based morphometry (DBM). From the very beginning of the study, PPA patients showed reduced left-hemispheric and increased right-hemispheric activations compared to controls. During the progression of the disease, activation increased predominantly in left posterior middle temporal gyrus (pMTG) and inferior frontal junction area, whereas the same regions decreased in activity in control brains. Interestingly, DBM data showed that this increase in activation in PPA patients was accompanied by progressing atrophy in the same regions. At a behavioural level, the accuracy in the lexical decision task was comparably high for both groups during the whole period of examination, despite some large variability between patients. To conclude, the dissociation between (i) maintained high performance, (ii) increased activity in regions involved in lexical access such as pMTG, and (iii) progressive atrophy of the very same regions supports the notion of a compensatory mechanism in brains of PPA patients for maintaining language while brain atrophy is progressing. The activity increase within a left-lateralised fronto-temporal network seems vital for high-level performance, whereas initial right-hemispheric recruitment of homologue language regions, which is reminiscent of that in vascular aphasics, has no continuous impact on lexical performance.

Tinnitus and musical hallucinosis: The same but more

While tinnitus can be interpreted as a simple or elementary form of auditory phantom perception, musical hallucinosis is a more complex auditory phantom phenomenon not only limited to sound perception, but also containing semantic and musical content. It most often occurs in association with hearing loss. To elucidate the relation between simple and complex auditory phantom percepts a source localized electroencephalography (EEG) study is performed. The analyses showed in both simple and complex auditory phantoms an increase in theta–gamma activity and coupling within the auditory cortex that could be associated with the thalamocortical dysrhythmia model. Furthermore increased beta activity within the dorsal anterior cingulate cortex and anterior insula is demonstrated, that might be related to auditory awareness, salience and its attribution to an external sound source. The difference between simple and complex auditory phantoms relies on differential alpha band activity within the auditory cortex and on beta activity in the dorsal anterior cingulate cortex and (para)hippocampal area. This could be related to memory based load dependency, while suppression within the primary visual cortex might be due the presence of a continuous auditory cortex activation inducing an inhibitory signal to the visual system. Complex auditory phantoms further activate the right inferior frontal area (right sided Broca homolog) and right superior temporal pole that might be associated with the musical content. In summary, this study showed for the first time that simple and complex auditory phantoms might share a common neural substrate but differ as complex auditory phantoms are associated with activation in brain areas related to music and language processing.

The time course of auditory–visual processing of speech and body actions: Evidence for the simultaneous activation of an extended neural network for semantic processing

An extensive network of cortical areas is involved in multisensory object and action recognition. This network draws on inferior frontal, posterior temporal, and parietal areas; activity is modulated by familiarity and the semantic congruency of auditory and visual component signals even if semantic incongruences are created by combining visual and auditory signals representing very different signal categories, such as speech and whole body actions. Here we present results from a high-density ERP study designed to examine the time-course and source location of responses to semantically congruent and incongruent audiovisual speech and body actions to explore whether the network involved in action recognition consists of a hierarchy of sequentially activated processing modules or a network of simultaneously active processing sites.We report two main results:1)There are no significant early differences in the processing of congruent and incongruent audiovisual action sequences. The earliest difference between congruent and incongruent audiovisual stimuli occurs between 240 and 280ms after stimulus onset in the left temporal region. Between 340 and 420ms, semantic congruence modulates responses in central and right frontal areas. Late differences (after 460ms) occur bilaterally in frontal areas.2)Source localisation (dipole modelling and LORETA) reveals that an extended network encompassing inferior frontal, temporal, parasaggital, and superior parietal sites are simultaneously active between 180 and 420ms to process auditory–visual action sequences. Early activation (before 120ms) can be explained by activity in mainly sensory cortices.The simultaneous activation of an extended network between 180 and 420ms is consistent with models that posit parallel processing of complex action sequences in frontal, temporal and parietal areas rather than models that postulate hierarchical processing in a sequence of brain regions.

Altered fronto–limbic activity in children and adolescents with familial high risk for schizophrenia

Early symptoms of schizophrenia tend to emerge during adolescence, hich is a critical period for development of executive and emotional processing. While individuals with familial high risk (FHR) for schizophrenia may show cognitive and emotional changes, the neural mechanisms underlying the development of these changes remain unclear. The goal of this study was to identify functional differences in fronto–striato–limbic regions in children with FHR. Functional magnetic resonance imaging (MRI) data were collected from 21 children with a first-degree family member with schizophrenia and 21 controls without FHR. Participants performed an emotional oddball task requiring both selective attention and suppression of task-irrelevant emotional information. During selective attention, the group with FHR showed enhanced activation in the inferior frontal gyrus and caudate, with decreases in middle frontal gyrus and insular activation. The FHR group also showed greater age-related recruitment of anterior cingulate, temporal and occipital cortical areas during selective attention. During emotional processing, the FHR group showed decreased anterior cingulate activation, with decreased age-related recruitment of inferior frontal, parietal and occipital areas. The results suggest that FHR for schizophrenia may be associated with abnormal hyperactivation and hypoactivation of the neural circuitry engaged during executive and emotional processing and with age-related changes in neural recruitment during adolescence.

Syllabic discrimination in premature human infants prior to complete formation of cortical layers

The ontogeny of linguistic functions in the human brain remains elusive. Although some auditory capacities are described before term, whether and how such immature cortical circuits might process speech are unknown. Here we used functional optical imaging to evaluate the cerebral responses to syllables at the earliest age at which cortical responses to external stimuli can be recorded in humans (28- to 32-wk gestational age). At this age, the cortical organization in layers is not completed. Many neurons are still located in the subplate and in the process of migrating to their final location. Nevertheless, we observed several points of similarity with the adult linguistic network. First, whereas syllables elicited larger right than left responses, the posterior temporal region escaped this general pattern, showing faster and more sustained responses over the left than over the right hemisphere. Second, discrimination responses to a change of phoneme (ba vs. ga) and a change of human voice (male vs. female) were already present and involved inferior frontal areas, even in the youngest infants (29-wk gestational age). Third, whereas both types of changes elicited responses in the right frontal region, the left frontal region only reacted to a change of phoneme. These results demonstrate a sophisticated organization of perisylvian areas at the very onset of cortical circuitry, 3 mo before term. They emphasize the influence of innate factors on regions involved in linguistic processing and social communication in humans.

Task-modulated activation and functional connectivity of the temporal and frontal areas during speech comprehension

There is general consensus in the literature that a distributed network of temporal and frontal brain areas is involved in speech comprehension. However, how active versus passive tasks modulate the activation and the functional connectivity of the critical brain areas is not clearly understood. In this study, we used functional magnetic resonance imaging (fMRI) to identify intelligibility and task-related effects in speech comprehension. Participants performed a semantic judgment task on normal and time-reversed sentences, or passively listened to the sentences without making an overt response. The subtraction analysis demonstrated that passive sentence comprehension mainly engaged brain areas in the left anterior and posterior superior temporal sulcus and middle temporal gyrus (aSTS/MTG and pSTS/MTG), whereas active sentence comprehension recruited bilateral frontal regions in addition to the aSTS/MTG and pSTS/MTG regions. Functional connectivity analysis revealed that during passive sentence comprehension, the left aSTS/MTG was functionally connected with the left Heschl’s gyrus (HG) and bilateral superior temporal gyrus (STG) but no area was functionally connected with the left pSTS/MTG; during active sentence comprehension, however, both the left aSTS/MTG and pSTS/MTG were functionally connected with bilateral superior temporal and inferior frontal areas. While these results are consistent with the view that the ventral stream of the temporo-frontal network subserves semantic processing, our findings further indicate that both the activation and the functional connectivity of the temporal and frontal areas are modulated by task demands.

Aberrant resting-state connectivity in non-psychotic individuals with auditory hallucinations

Although auditory verbal hallucinations (AVH) are a core symptom of schizophrenia, they also occur in non-psychotic individuals, in the absence of other psychotic, affective, cognitive and negative symptoms. AVH have been hypothesized to result from deviant integration of inferior frontal, parahippocampal and superior temporal brain areas. However, a direct link between dysfunctional connectivity and AVH has not yet been established. To determine whether hallucinations are indeed related to aberrant connectivity, AVH should be studied in isolation, for example in non-psychotic individuals with AVH. Resting-state connectivity was investigated in 25 non-psychotic subjects with AVH and 25 matched control subjects using seed regression analysis with the (1) left and (2) right inferior frontal, (3) left and (4) right superior temporal and (5) left parahippocampal areas as the seed regions. To correct for cardiorespiratory (CR) pulsatility rhythms in the functional magnetic resonance imaging (fMRI) data, heartbeat and respiration were monitored during scanning and the fMRI data were corrected for these rhythms using the image-based method for retrospective correction of physiological motion effects RETROICOR. In comparison with the control group, non-psychotic individuals with AVH showed increased connectivity between the left and the right superior temporal regions and also between the left parahippocampal region and the left inferior frontal gyrus. Moreover, this group did not show a negative correlation between the left superior temporal region and the right inferior frontal region, as was observed in the healthy control group. Aberrant connectivity of frontal, parahippocampal and superior temporal brain areas can be specifically related to the predisposition to hallucinate in the auditory domain.

Bilateral inferior frontal language-related activation correlates with verbal recall in patients with left temporal lobe epilepsy and typical language distribution

Language fMRI has been used in the presurgical evaluation of drug-resistant temporal lobe epilepsy patients. Previous studies have demonstrated that left temporal lobe epilepsy (LTLE) patients with atypical language lateralization are at lower risk of postsurgical verbal memory decline, hypothesizing co-occurrence of verbal memory and language reorganization presurgically. Furthermore, it has been proposed that the recruitment of right frontal language-related areas is associated with the preservation of verbal memory performance in these patients. However, less is known about the correlation between these functions specifically in LTLE patients with left language dominance, although they are more prone to postsurgical verbal memory decline. The aim of the present study was to investigate whether the relationship between verbal memory scores and frontal language activation is also observed in LTLE patients with typical language dominance. Eighteen healthy controls, 12 right temporal lobe epilepsy patients and 12 LTLE patients with typical language distribution as assessed by an fMRI verbal fluency task were selected. Verbal memory scores were obtained from the patients' neuropsychological presurgical evaluation. Our results showed a positive correlation between verbal recall and activation of bilateral inferior frontal areas in LTLE patients. These results support the hypothesis of a link between language representation in inferior frontal areas and hippocampal functioning, and indicate that both hemispheres are related to the preservation of verbal memory in patients with hippocampal damage and typical language dominance.

Functional connectivity profile of the human inferior frontal junction: involvement in a cognitive control network

BackgroundThe human inferior frontal junction area (IFJ) is critically involved in three main component processes of cognitive control (working memory, task switching and inhibitory control). As it overlaps with several areas in established anatomical labeling schemes, it is considered to be underreported as a functionally distinct location in the neuroimaging literature. While recent studies explicitly focused on the IFJ's anatomical organization and functional role as a single brain area, it is usually not explicitly denominated in studies on cognitive networks. However based on few analyses in small datasets constrained by specific a priori assumptions on its functional specialization, the IFJ has been postulated to be part of a cognitive control network. Goal of this meta-analysis was to establish the IFJ’s connectivity profile on a high formal level of evidence by aggregating published implicit knowledge about its co-activations. We applied meta-analytical connectivity modeling (MACM) based on the activation likelihood estimation (ALE) method without specific assumptions regarding functional specialization on 180 (reporting left IFJ activity) and 131 (right IFJ) published functional neuroimaging experiments derived from the BrainMap database. This method is based on coordinates in stereotaxic space, not on anatomical descriptors.ResultsThe IFJ is significantly co-activated with areas in the dorsolateral and ventrolateral prefrontal cortex, anterior insula, medial frontal gyrus / pre-SMA, posterior parietal cortex, occipitotemporal junction / cerebellum, thalamus and putamen as well as language and motor areas. Results are corroborated by an independent resting-state fMRI analysis.ConclusionsThese results support the assumption that the IFJ is part of a previously described cognitive control network. They also highlight the involvement of subcortical structures in this system. A direct line is drawn from works on the functional significance of brain activity located at the IFJ and its anatomical definition to published results related to distributed cognitive brain systems. The IFJ is therefore introduced as a convenient starting point to investigate the cognitive control network in further studies.

Patterns of Spontaneous Brain Activity in Amyotrophic Lateral Sclerosis: A Resting-State fMRI Study

By detecting spontaneous low-frequency fluctuations (LFF) of blood oxygen level–dependent (BOLD) signals, resting-state functional magnetic resonance imaging (rfMRI) measurements are believed to reflect spontaneous cerebral neural activity. Previous fMRI studies were focused on the examination of motor-related areas and little is known about the functional changes in the extra-motor areas in amyotrophic lateral sclerosis (ALS) patients. The aim of this study is to investigate functional cerebral abnormalities in ALS patients on a whole brain scale. Twenty ALS patients and twenty age- and sex-matched healthy volunteers were enrolled. Voxel-based analysis was used to characterize the alteration of amplitude of low frequency fluctuation (ALFF). Compared with the controls, the ALS patients showed significantly decreased ALFF in the visual cortex, fusiform gyri and right postcentral gyrus; and significantly increased ALFF in the left medial frontal gyrus, and in right inferior frontal areas after grey matter (GM) correction. Taking GM volume as covariates, the ALFF results were approximately consistent with those without GM correction. In addition, ALFF value in left medial frontal gyrus was negatively correlated with the rate of disease progression and duration. Decreased functional activity observed in the present study indicates the underlying deficits of the sensory processing system in ALS. Increased functional activity points to a compensatory mechanism. Our findings suggest that ALS is a multisystem disease other than merely motor dysfunction and provide evidence that alterations of ALFF in the frontal areas may be a special marker of ALS.

Inter- and Intrahemispheric Dissociations in Ideomotor Apraxia: A Large-Scale Lesion–Symptom Mapping Study in Subacute Brain-Damaged Patients

Pantomimes of object use require accurate representations of movements and a selection of the most task-relevant gestures. Prominent models of praxis, corroborated by functional neuroimaging studies, predict a critical role for left parietal cortices in pantomime and advance that these areas store representations of tool use. In contrast, lesion data points to the involvement of left inferior frontal areas, suggesting that defective selection of movement features is the cause of pantomime errors. We conducted a large-scale voxel-based lesion-symptom mapping analyses with configural/spatial (CS) and body-part-as-object (BPO) pantomime errors of 150 left and right brain-damaged patients. Our results confirm the left hemisphere dominance in pantomime. Both types of error were associated with damage to left inferior frontal regions in tumor and stroke patients. While CS pantomime errors were associated with left temporoparietal lesions in both stroke and tumor patients, these errors appeared less associated with parietal areas in stroke than in tumor patients and less associated with temporal in tumor than stroke patients. BPO errors were associated with left inferior frontal lesions in both tumor and stroke patients. Collectively, our results reveal a left intrahemispheric dissociation for various aspects of pantomime, but with an unspecific role for inferior frontal regions.

“How to do things with Words”: Role of motor cortex in semantic representation of action words

Language, believed to have originated from actions, not only functions as a medium to access other minds, but it also helps us commit actions and enriches our social life. This fMRI study investigated the semantic and neural representations of actions and mental states. We focused mainly on language semantics (comprehending sentences with action words versus those with mental state words). While in an fMRI scanner, twenty-four healthy, right-handed adult volunteers read a series of sentences with a verb depicting either a mental state (e.g., deceive, persuade) or an action (e.g., punch, kick), and answered a comprehension question that followed. Overall, this task showed brain activation in the left inferior frontal gyrus and in the left posterior superior temporal sulci. While comprehending sentences with mental state terms, participants showed greater activation in left orbitofrontal, and in left precuneus areas. On the other hand, the action sentences recruited more primary motor, left inferior parietal, bilateral occipital, right superior temporal, and right inferior frontal areas. The findings of this study underscore the role of motor and visuospatial involvement in action word representation in the human brain.