Independent Representations of Verbs and Actions in Left Lateral Temporal Cortex

Verbs and nouns differ not only on formal linguistic grounds but also in what they typically refer to: Verbs typically refer to actions, whereas nouns typically refer to objects. Prior neuroimaging studies have revealed that regions in the left lateral temporal cortex (LTC), including the left posterior middle temporal gyrus (pMTG), respond selectively to action verbs relative to object nouns. Other studies have implicated the left pMTG in action knowledge, raising the possibility that verb selectivity in LTC may primarily reflect action-specific semantic features. Here, using functional neuroimaging, we test this hypothesis. Participants performed a simple memory task on visually presented verbs and nouns that described either events (e.g., "he eats" and "the conversation") or states (e.g., "he exists" and "the value"). Verb-selective regions in the left pMTG and the left STS were defined in individual participants by an independent localizer contrast between action verbs and object nouns. Both regions showed equally strong selectivity for event and state verbs relative to semantically matched nouns. The left STS responded more to states than events, whereas there was no difference between states and events in the left pMTG. Finally, whole-brain group analysis revealed that action verbs, relative to state verbs, activated a cluster in pMTG that was located posterior to the verb-selective pMTG clusters. Together, these results indicate that verb selectivity in LTC is independent of action representations. We consider other differences between verbs and nouns that may underlie verb selectivity in LTC, including the verb property of predication.Psycholog

Independent representations of verbs and actions in left lateral temporal cortex

Verbs and nouns differ not only on formal linguistic grounds but also in what they typically refer to: verbs typically refer to actions, whereas nouns typically refer to objects. Prior neuroimaging studies have revealed that regions in the left lateral temporal cortex (LTC), including the left posterior middle temporal gyrus (pMTG), respond selectively to action verbs relative to object nouns. Other studies have implicated the left pMTG in action knowledge, raising the possibility that verb selectivity in LTC may primarily reflect action-specific semantic features. Here, using functional neuroimaging, we test this hypothesis. Participants performed a simple memory task on visually presented verbs and nouns that described either events (e.g., “he eats” and “the conversation”) or states (e.g., “he exists” and “the value”). Verb-selective regions in the left pMTG and the left STS were defined in individual participants by an independent localizer contrast between action verbs and object nouns. Both regions showed equally strong selectivity for event and state verbs relative to semantically matched nouns. The left STS responded more to states than events, whereas there was no difference between states and events in the left pMTG. Finally, whole-brain group analysis revealed that action verbs, relative to state verbs, activated a cluster in pMTG that was located posterior to the verb-selective pMTG clusters. Together, these results indicate that verb selectivity in LTC is independent of action representations. We consider other differences between verbs and nouns that may underlie verb selectivity in LTC, including the verb function of predication

The Origin of Word-related Motor Activity

Conceptual processing of verbs consistently recruits the left posterior middle temporal gyrus (lpMTG). The left precentral motor cortex also responds to verbs, with higher activity for action than nonaction verbs. The early timing of this effect has suggested that motor features of words' meaning are accessed directly, bypassing access to conceptual representations in lpMTG. An alternative hypothesis is that the retrieval of conceptual representations in lpMTG is necessary to drive more specific, motor-related representations in the precentral gyrus. To test these hypotheses, we first showed that repetitive transcranial magnetic stimulation (rTMS) applied to the verb-preferring lpMTG site selectively impoverished the semantic processing of verbs. In a second experiment, rTMS perturbation of lpMTG, relative to no stimulation (no-rTMS), eliminated the action–nonaction verb distinction in motor activity, as indexed by motor-evoked potentials induced in peripheral muscles with single-pulse TMS over the left primary motor cortex. rTMS pertubation of an occipital control site, relative to no-rTMS, did not affect the action–nonaction verb distinction in motor activity, but the verb contrast did not differ reliably from the lpMTG effect. The results show that lpMTG carries core semantic information necessary to drive the activation of specific (motor) features in the precentral gyrus

On word class-specification: evidence from linguistics and cognitive neuroscience

The aim of the present paper is to provide a clear answer to critical aspects of the following key questions: 1) is word class-specification necessarily incorporated into lexical items? 2) does the organization of word knowledge in the brain rely on word class-specific information? To do this we combine diachronic evidence and typological observations on word classes with data on the noun/verb processing in aphasia and neuroimaging findings on the representation of verbs, adjectives and nouns and, consequently, show how linguistics and cognitive neuroscience crucially benefit from each other

Exploring the neurocognitive basis of language processing: the case of word classes and the key role of interface semantics

In the present paper, we address the question of the linking mechanisms of the multifactorial and graded conceptual space with the formally discrete language structures by 1) investigating the neurocognitive basis of interface semantics and 2) exploring the representation of word classes in the brain. Data from cognitive neuropsychological and brain imaging studies are discussed, and an answer is provided to certain critical aspects of the relationship between conceptual categorization and linguistic categorization. KEYWORDS: Conceptual categorization, linguistic categorization, interface semantics, word classes, cognitive neuropsychology, fMRIIn the present paper, we address the question of the linking mechanisms of the multifactorial and graded conceptual space with the formally discrete language structures by 1) investigating the neurocognitive basis of interface semantics and 2) exploring the representation of word classes in the brain. Data from cognitiveneuropsychological and brain imaging studies are discussed, and an answer is provided to certain critical aspects of the relationship between conceptual categorization and linguistic categorization. KEYWORDS: Conceptual categorization, linguistic categorization, interface semantics, word classes, cognitive neuropsychology, fMR

Shared neural processes support semantic control and action understanding

Executive-semantic control and action understanding appear to recruit overlapping brain regions but existing evidence from neuroimaging meta-analyses and neuropsychology lacks spatial precision; we therefore manipulated difficulty and feature type (visual vs. action) in a single fMRI study. Harder judgements recruited an executive-semantic network encompassing medial and inferior frontal regions (including LIFG) and posterior temporal cortex (including pMTG). These regions partially overlapped with brain areas involved in action but not visual judgements. In LIFG, the peak responses to action and difficulty were spatially identical across participants, while these responses were overlapping yet spatially distinct in posterior temporal cortex. We propose that the co-activation of LIFG and pMTG allows the flexible retrieval of semantic information, appropriate to the current context; this might be necessary both for semantic control and understanding actions. Feature selection in difficult trials also recruited ventral occipital-temporal areas, not implicated in action understanding

Object-action dissociation : a voxel-based lesion-symptom mapping study on 102 patients after glioma removal

Data concerning the neural basis of noun and verb processing are inconsistent. Some authors assume that action-verb processing is based on frontal areas while nouns processing relies on temporal regions; others argue that the circuits processing verbs and nouns are closely interconnected in a predominantly left-lateralized fronto-temporal-parietal network; yet, other researchers consider that the primary motor cortex plays a crucial role in processing action verbs. In the present study, one hundred and two patients with a tumour either in the right or left hemisphere were submitted to picture naming of objects and actions before and after surgery. To test the effect of specific brain regions in object and action naming, patients' lesions were mapped and voxel-lesion-symptom mapping (VLSM) was computed. Behavioural results showed that left-brain damaged patients were significantly more impaired than right brain-damaged patients. The VLSM showed that these two grammatical classes are segregated in the left hemisphere. In particular, scores in naming of objects correlated with damage to the anterior temporal region, while scores in naming of actions correlated with lesions in the parietal areas and in the posterior temporal cortex. In addition, VLSM analyses carried out on non-linguistic tasks were not significant, confirming that the regions associated with deficits in object and action naming were not generally engaged in all cognitive tasks. Finally, the involvement of subcortical pathways was investigated and the inferior longitudinal fasciculus proved to play a role in object naming, while no specific bundle was identified for actions

The characterization of actions at the superordinate, basic and subordinate level

Objects can be categorized at different levels of abstraction, ranging from the superordinate (e.g., fruit) and the basic (e.g., apple) to the subordinate level (e.g., golden delicious). The basic level is assumed to play a key role in categorization, e.g., in terms of the number of features used to describe these actions and the speed of processing. To which degree do these principles also apply to the categorization of observed actions? To address this question, we first selected a range of actions at the superordinate (e.g., locomotion), basic (e.g., to swim) and subordinate level (e.g., to swim breaststroke), using verbal material (Experiments 1–3). Experiments 4–6 aimed to determine the characteristics of these actions across the three taxonomic levels. Using a feature listing paradigm (Experiment 4), we determined the number of features that were provided by at least six out of twenty participants (common features), separately for the three different levels. In addition, we examined the number of shared (i.e., provided for more than one category) and distinct (i.e., provided for one category only) features. Participants produced the highest number of common features for actions at the basic level. Actions at the subordinate level shared more features with other actions at the same level than those at the superordinate level. Actions at the superordinate and basic level were described with more distinct features compared to those provided at the subordinate level. Using an auditory priming paradigm (Experiment 5), we observed that participants responded faster to action images preceded by a matching auditory cue corresponding to the basic and subordinate level, but not for superordinate level cues, suggesting that the basic level is the most abstract level at which verbal cues facilitate the processing of an upcoming action. Using a category verification task (Experiment 6), we found that participants were faster and more accurate to verify action categories (depicted as images) at the basic and subordinate level in comparison to the superordinate level. Together, in line with the object categorization literature, our results suggest that information about action categories is maximized at the basic level

The Neural Representation Of Duration In Event Concepts

Little is known about the neural basis of temporal concepts. Some have suggested that temporal concepts are grounded in spatial or temporal processes. Here we aimed to examine the representation of duration of event concepts, and compare them with judgments of object size, which may entail spatial processing. A 2x2 block design used event and object nouns as stimuli that were presented during functional imaging. Participants made judgments about event duration, object size, and event and object valence. In addition to whole-brain analyses, we examined activations in areas known to be involved in temporal processing and spatial processing. Knowledge of events compared to objects activated a distributed network with large clusters in bilateral angular gyri, precuneus, middle temporal lobules and prefrontal cortices in whole-brain analyses. The whole-brain analyses of duration minus valence revealed a right hemispheric preference for processing of semantic duration information compared to valence tasks. Peak activation of clusters for duration were located in the right dorsomedial prefrontal cortex, precuneus, lingual gyrus, SMG, left middle MTG/ITG, parahippocampal gyrus and bilateral angular gyri. ROI analyses of angular gyri suggested the processing of semantic information of duration occurred mainly the right AG and left PGp. ROI analyses of temporal perception areas suggested a role of the right SMG in the representation of duration. Additionally, temporal ROIs suggested that the right pSTS and left SMG were involved in event processing relative to objects. IPS ROI revealed that the right middle IPS was activated for event duration minus event valence and object size minus object valance. Additionally, PPA ROI revealed that event duration compared to event valence and object size compared to object valence activated the PPA. Thus, we found that event concepts were supported by bilateral inferior parietal and anterior and middle temporal cortex, as well as precuneus and posterior cingulate. This is consistent with the role of AG in integrating temporal sequences. Conceptual duration processing is grounded in both temporal perception (right SMG) and space (IPS and PPA)