Marta Ghio

Semantic domain-specific functional integration for action-related vs. abstract concepts

A central topic in cognitive neuroscience concerns the representation of concepts and the specific neural mechanisms that mediate conceptual knowledge. Recently proposed modal theories assert that concepts are grounded on the integration of multimodal, distributed representations. The aim of the present work is to complement the available neuropsychological and neuroimaging evidence suggesting partially segregated anatomo-functional correlates for concrete vs. abstract concepts, by directly testing the semantic domain-specific patterns of functional integration between language and modal semantic brain regions. We report evidence from a functional magnetic resonance imaging study, in which healthy participants listened to sentences with either an action-related (actions involving physical entities) or an abstract (no physical entities involved) content. We measured functional integration using dynamic causal modeling, and found that the left superior temporal gyrus was more strongly connected: (1) for action-related vs. abstract sentences, with the left-hemispheric action representation system, including sensorimotor areas; (2) for abstract vs. action-related sentences, with left infero-ventral frontal, temporal, and retrosplenial cingulate areas. A selective directionality effect was observed, with causal modulatory effects exerted by perisylvian language regions on peripheral modal areas, and not vice versa. The observed condition-specific modulatory effects are consistent with embodied and situated language processing theories, and indicate that linguistic areas promote a semantic content-specific reactivation of modal simulations by top-down mechanisms.

Decoding the neural representation of fine-grained conceptual categories.

Neuroscientific research on conceptual knowledge based on the grounded cognition framework has shed light on the organization of concrete concepts into semantic categories that rely on different types of experiential information. Abstract concepts have traditionally been investigated as an undifferentiated whole, and have only recently been addressed in a grounded cognition perspective. The present fMRI study investigated the involvement of brain systems coding for experiential information in the conceptual processing of fine-grained semantic categories along the abstract-concrete continuum. These categories consisted of mental state-, emotion-, mathematics-, mouth action-, hand action-, and leg action-related meanings. Thirty-five sentences for each category were used as stimuli in a 1-back task performed by 36 healthy participants. A univariate analysis failed to reveal category-specific activations. Multivariate pattern analyses, in turn, revealed that fMRI data contained sufficient information to disentangle all six fine-grained semantic categories across participants. However, the category-specific activity patterns showed no overlap with the regions coding for experiential information. These findings demonstrate the possibility of detecting specific patterns of neural representation associated with the processing of fine-grained conceptual categories, crucially including abstract ones, though bearing no anatomical correspondence with regions coding for experiential information as predicted by the grounded cognition hypothesis.

Differentiating among pragmatic uses of words through timed sensicality judgments

Pragmatic and cognitive accounts of figurative language posit a difference between metaphor and metonymy in terms of underlying conceptual operations. Recently, other pragmatic uses of words have been accounted for in the Relevance Theory framework, such as approximation, described in terms of conceptual adjustment that varies in degree and direction with respect to the case of metaphor. Despite the theoretical distinctions, there is very poor experimental evidence addressing the metaphor/metonymy distinction, and none concerning approximation. Here we used meticulously built materials to investigate the interpretation mechanisms of these three phenomena through timed sensicality judgments. Results revealed that interpreting metaphors and approximations differs from literal interpretation both in accuracy and reaction times, with higher difficulty and costs for metaphors than for approximations. This suggests similar albeit gradual interpretative costs, in line with the latest account of Relevance Theory. Metonymy, on the contrary, almost equates literal comprehension and calls for a theoretical distinction from metaphor. Overall, this work represents a first attempt to provide an empirical basis for a theory-sound and psychologically-grounded taxonomy of figurative and loose uses of language.

Neural representations of novel objects associated with olfactory experience

Object conceptual knowledge comprises information related to several motor and sensory modalities (e.g. for tools, how they look like, how to manipulate them). Whether and to which extent conceptual object knowledge is represented in the same sensory and motor systems recruited during object-specific learning experience is still a controversial question. A direct approach to assess the experience-dependence of conceptual object representations is based on training with novel objects. The present study extended previous research, which focused mainly on the role of manipulation experience for tool-like stimuli, by considering sensory experience only. Specifically, we examined the impact of experience in the non-dominant olfactory modality on the neural representation of novel objects. Sixteen healthy participants visually explored a set of novel objects during the training phase while for each object an odor (e.g., peppermint) was presented (olfactory-visual training). As control conditions, a second set of objects was only visually explored (visual-only training), and a third set was not part of the training. In a post-training fMRI session, participants performed an old/new task with pictures of objects associated with olfactory-visual and visual-only training (old) and no training objects (new). Although we did not find any evidence of activations in primary olfactory areas, the processing of olfactory-visual versus visual-only training objects elicited greater activation in the right anterior hippocampus, a region included in the extended olfactory network. This finding is discussed in terms of different functional roles of the hippocampus in olfactory processes.

Event-related desynchronization of mu and beta oscillations during the processing of novel tool names

&NA; According to the embodied cognition framework, the formation of conceptual representations integrates the type of experience during learning. In this electroencephalographic study, we applied a linguistic variant of a training paradigm, in which participants learned to associate novel names to novel tools while either manipulating or visually exploring them. The analysis focused on event‐related desynchronization (ERD) of oscillations in the mu and beta frequency range, which reflects activation of sensorimotor brain areas. After three training sessions, processing names of manipulated tools elicited a stronger ERD of the beta (18–25 Hz, 140–260 ms) and the lower mu rhythm (8–10 Hz, 320–440 ms) than processing names of visually explored tools, reflecting a possible reactivation of experiential sensorimotor information. Given the unexpected result that familiarized pseudo‐words elicited an ERD comparable to names of manipulated tools, our findings could reflect a suppression of sensorimotor activity during the processing of objects with exclusively visual features.

Grounding Sentence Processing in the Sensory-Motor System

A decade of evidence in favor of or against the involvement of the primary motor and premotor cortices in conceptual-semantic sentence processing has generated an animated debate among scholars on the necessary versus epiphenomenal nature of such an involvement. As both the strong embodied and the strictly disembodied theoretical positions increasingly lose explanatory power, an open experimental question that becomes highly relevant is how to clarify the flexible sentential linguistic context under which this involvement occurs and whether the grounding in the motor system can be beneficial to language processing. The emerging generalized grounded cognition framework of conceptual-semantic sentence processing emphasizes the functional role of distributed sensory-motor and experiential neurocognitive systems that are differentially involved, depending on the specific semantic features and meanings of the concepts’ referents and depending on the lexical and grammatical sentential format used to express them linguistically.

Sentential negation of abstract and concrete conceptual categories: a brain decoding multivariate pattern analysis study

We rarely use abstract and concrete concepts in isolation but rather embedded within a linguistic context. To examine the modulatory impact of the linguistic context on conceptual processing, we isolated the case of sentential negation polarity, in which an interaction occurs between the syntactic operator not and conceptual information in the negations scope. Previous studies suggested that sentential negation of concrete action-related concepts modulates activation in the fronto-parieto-temporal action representation network. In this functional magnetic resonance imaging study, we examined the influence of negation on a wider spectrum of meanings, by factorially manipulating sentence polarity (affirmative, negative) and fine-grained abstract (mental state, emotion, mathematics) and concrete (related to mouth, hand, leg actions) conceptual categories. We adopted a multivariate pattern analysis approach, and tested the accuracy of a machine learning classifier in discriminating brain activation patterns associated to the factorial manipulation. Searchlight analysis was used to localize the discriminating patterns. Overall, the neural processing of affirmative and negative sentences with either an abstract or concrete content could be accurately predicted by means of multivariate classification. We suggest that sentential negation polarity modulates brain activation in distributed representational semantic networks, through the functional mediation of syntactic and cognitive control systems. This article is part of the theme issue ‘Varieties of abstract concepts: development, use and representation in the brain’.

ERP correlates of processing the auditory consequences of own versus observed actions

Research has so far focused on neural mechanisms that allow us to predict the sensory consequences of our own actions, thus also contributing to ascribing them to ourselves as agents. Less attention has been devoted to processing the sensory consequences of observed actions ascribed to another human agent. Focusing on audition, there is consistent evidence of a reduction of the auditory N1 ERP for self- versus externally generated sounds, while ERP correlates of processing sensory consequences of observed actions are mainly unexplored. In a between-groups ERP study, we compared sounds generated by self-performed (self group) or observed (observation group) button presses with externally generated sounds, which were presented either intermixed with action-generated sounds or in a separate condition. Results revealed an overall reduction of the N1 amplitude for processing action- versus externally generated sounds in both the intermixed and the separate condition, with no difference between the groups. Further analyses, however, suggested that an N1 attenuation effect relative to the intermixed condition at frontal electrode sites might exist only for the self but not for the observation group. For both groups, we found a reduction of the P2 amplitude for processing action- versus all externally generated sounds. We discuss whether the N1 and the P2 reduction can be interpreted in terms of predictive mechanisms for both action execution and observation, and to what extent these components might reflect also the feeling of (self) agency and the judgment of agency (i.e., ascribing agency either to the self or to others).

Effects of feedback delay on learning from positive and negative feedback in patients with Parkinson's disease off medication

ABSTRACT Phasic dopamine (DA) signals conveyed from the substantia nigra to the striatum and the prefrontal cortex crucially affect learning from feedback, with DA bursts facilitating learning from positive feedback and DA dips facilitating learning from negative feedback. Consequently, diminished nigro‐striatal dopamine levels as in unmedicated patients suffering from Parkinsons Disease (PD) have been shown to lead to a negative learning bias. Recent studies suggested a diminished striatal contribution to feedback processing when the outcome of an action is temporally delayed. This study investigated whether the bias towards negative feedback learning induced by a lack of DA in PD patients OFF medication is modulated by feedback delay. To this end, PD patients OFF medication and healthy controls completed a probabilistic selection task, in which feedback was given immediately (after 800 ms) or delayed (after 6800 ms). PD patients were impaired in immediate but not delayed feedback learning. However, differences in the preference for positive/negative learning between patients and controls were seen for both learning from immediate and delayed feedback, with evidence of stronger negative learning in patients than controls. A Bayesian analysis of the data supports the conclusion that feedback timing did not affect the learning bias in the patients. These results hint at reduced, but still relevant nigro‐striatal contribution to feedback learning, when feedback is delayed. HighlightsBias towards better learning from negative feedback in PD patients Off medication.No effect of feedback timing on the negative learning bias in PD patients.Role of dopamine also for learning from delayed feedback.

Cognitive training with action-related verbs induces neural plasticity in the action representation system as assessed by gray matter brain morphometry

ABSTRACT Embodied cognition theories of semantic memory still face the need for multiple sources of converging evidence in support of the involvement of sensory‐motor systems in action‐related knowledge. Previous studies showed that training manual actions improves semantic processing of verbs referring to the trained actions. The present work aimed to provide complementary evidence by measuring the brain plasticity effects of a cognitive training requiring sustained lexical‐semantic processing of action‐related verbs. We included two groups of participants, namely the Proximal Group (PG) and the Distal Group (DG), which underwent a 3‐week training with verbs referring to actions involving the proximal and the distal upper limb musculature, respectively. Before and after training, we measured gray matter voxel brain morphometry based on T1 structural magnetic resonance imaging. By means of this 2 (Group: PG, DG) × 2 (Time: pre‐, post‐training) factorial design, we tested whether sustained cognitive experience with specific action‐related verbs induces congruent brain plasticity modifications in target regions of interest pertaining to the action representation system. We found significant post‐ versus pre‐training gray matter volume increases, specifically for PG in the left dorsal precentral gyrus, and for DG in the right cerebellar lobule VIIa. These preliminary results suggest that a cognitive training can induce structural plasticity modifications in brain regions specifically coding for the distal and proximal motor actions the trained verbs refer to. HIGHLIGHTSTraining motor actions improves processing verb meaning referring to those actions.We sought complementary effects by training verbs and measuring brain plasticity.Gray matter volume increased action‐specifically in premotor and cerebellar areas.Cognitive training steered by embodiment theory noticeably affects the action system.