Category-specific Conceptual Processing of Color and Form in Left Fronto-temporal Cortex

A meta-analytical account of the functional lateralization of the reading network

The observation that the neural correlates of reading are left-lateralized is ubiquitous in the cognitive neuroscience and neuropsychological literature. Still, reading is served by a constellation of neural units, and the extent to which these units are consistently left-lateralized is unclear. In this regard, the functional lateralization of the fusiform gyrus is of particular interest, by virtue of its hypothesized role as a "visual word form area". A quantitative Activation Likelihood Estimation meta-analysis was conducted on activation foci from 35 experiments investigating silent reading, and both a whole-brain and a bayesian ROI-based approach were used to assess the lateralization of the data submitted to meta-analysis. Perirolandic areas showed the highest level of left-lateralization, the fusiform cortex and the parietal cortex exhibited only a moderate pattern of left-lateralization, while in the occipital, insular cortices and in the cerebellum the lateralization turned out to be the lowest observed. The relatively limited functional lateralization of the fusiform gyrus was further explored in a regression analysis on the lateralization profile of each study. The functional lateralization of the fusiform gyrus during reading was positively associated with the lateralization of the precentral and inferior occipital gyri and negatively associated with the lateralization of the triangular portion of the inferior frontal gyrus and of the temporal pole. Overall, the present data highlight how lateralization patterns differ within the reading network. Furthermore, the present data highlight how the functional lateralization of the fusiform gyrus during reading is related to the degree of functional lateralization of other language brain areas.

The role of visual imagery in story reading: Evidence from aphantasia

Aphantasia is a condition in which people are unable to experience visual imagery. Since visual imagery is thought to be key to language processing, we hypothesized the experience of a story would differ between individuals with aphantasia and controls. Forty-seven individuals with aphantasia were compared to fifty-one matched controls on their experience of reading a short story and their general reading habits. Aphantasics were less likely to be engaged with, interested in, and absorbed in the story, and experienced reduced emotional engagement with and sympathy for the story characters, compared to controls. Yet, aphantasics and controls did not differ in how much they liked or appreciated the story, and in general, the reading habits of the two groups also did not differ. Results have implications for embodied theories of language, suggesting visual imagery may influence how a story is experienced, but it is not the only route to story enjoyment.

Losing the sense of smell does not disrupt processing of odor words

Whether language is grounded in action and perception has been a key question in cognitive science, yet little attention has been given to the sense of smell. We directly test whether smell is necessary for comprehension of odor language, by comparing language processing in a group of participants with no sense of smell (anosmics) to a group of control participants. We found no evidence for a difference in online comprehension of odor and taste language between anosmics and controls using a lexical decision task and a semantic similarity judgment task, suggesting olfaction is not critical to the comprehension of odor language. Contrary to predictions, anosmics were better at remembering odor words, and rated odor and taste words as more positively valenced than control participants. This study finds no detriment to odor language after losing the sense of smell, supporting the proposal that odor language is not grounded in odor perception.

Frontal medial cortex and angular gyrus functional connectivity is related to sex and age differences in odor sensitivity

BACKGROUND AND PURPOSE

Odor preference is one of the key factors for the rehabilitation of the swallowing function. On the other hand, sensitivity to odor differs between sexes and decreases with age. These factors rely on brain neuronal circuits. However, it remains not fully clarified which neuronal circuit determines the sex and age differences in odor sensitivity. In this study, we carried out both the odor sensitivity test and functional MRI (fMRI) to find the key neuronal circuits determining sex and age differences in odor sensitivity.

METHODS

Healthy volunteers (28 males, aged 27-62 years, and 30 females, aged 21-59 years) participated in this study. Some of them (seven males and seven females) underwent fMRI. We prepared five odorous test substances and presented each substance at 1 minute intervals. After 5 minutes of questioning about food intake, the subjects were asked to recall each of the test substances presented from the list. In the fMRI study, all the subjects underwent 15 minutes of the prestimulation, stimulation with peppermint odor, and poststimulation sessions.

RESULTS

The odor test score was significantly higher in females than in males and showed an age-dependent decrease. We found four functional connectivities whose degrees were significantly different between males and females. One of them, the functional connectivity between the frontal medial cortex (MedFC) and the left angular gyrus (AG. l), showed an age-dependent change.

CONCLUSIONS

The functional MedFC-AG.l connectivity is one of the important neuronal circuits that affect the sex- and age-dependent odor sensitivity.

Impact of motor stroke on novel and conventional action metaphor comprehension

Previous studies indicate that damage to motor brain regions impacts comprehension of literal action-related language. However, whether such damage also impacts comprehension of action-metaphors remains unknown. Such a finding would support the notion that metaphors are grounded in sensorimotor representations. Here we tested this hypothesis by comparing comprehension of novel, conventional, and frozen action and non-action metaphors in 14 right-handed adults with right-sided mild to moderate paresis following left hemisphere motor stroke and 23 neurotypical participants. Consistent with our hypothesis, results indicated that only in the stroke group, accuracy for action metaphors was significantly lower than for non-action metaphors. Further, in the stroke group, accuracy was significantly worse in the following pattern: novel < conventional < frozen action metaphors. These results strongly support the notion that motor-related brain regions are important not only for literal action-related language comprehension, but also for action-related metaphor comprehension, especially for less familiar metaphors.

What's "up"? Impaired Spatial Preposition Processing in Posterior Cortical Atrophy

This study seeks to confirm whether lesions in posterior regions of the brain involved in visuo-spatial processing are of functional relevance to the processing of words with spatial meaning. We investigated whether patients with Posterior Cortical Atrophy (PCA), an atypical form of Alzheimer’s Disease which predominantly affects parieto-occipital brain regions, is associated with deficits in working memory for spatial prepositions. Case series of patients with PCA and matched healthy controls performed tests of immediate and delayed serial recall on words from three lexico-semantic word categories: number words (twelve), spatial prepositions (behind) and function words (e.g., shall). The three word categories were closely matched for a number of psycholinguistic and semantic variables including length, bi-/tri-gram frequency, word frequency, valence and arousal. Relative to controls, memory performance of PCA patients on short word lists was significantly impaired on spatial prepositions in the delayed serial recall task. These results suggest that lesions in posterior parieto-occipital regions specifically impair the processing of spatial prepositions. Our findings point to a pertinent role of posterior cortical regions in the semantic processing of words with spatial meaning and provide strong support for modality-specific semantic theories that recognize the necessary contributions of sensorimotor regions to conceptual semantic processing.

Dutch sensory modality norms

Many words are strongly connected to the senses, such as vision, taste, and touch. In order to facilitate research on language and the senses, large sets of linguistic stimuli and their corresponding measures of sensory associations should be available. To aid in such investigations, we present a new set of sensory modality norms for over 24,000 Dutch words. The sensory norms comprise perceptual strength ratings in six perceptual modalities: audition, gustation, haptics, olfaction, vision, and interoception. The new norms improve on existing Dutch sensory norms in three ways: 1) they significantly expand on the number of words rated; 2) they include multiple word classes; 3) they add a new perceptual modality: interoception. We show that the sensory norms are able to predict word processing behavior and outperform existing ratings of sensory experience: concreteness and imageability. The data are available via the Open Science Framework (https://osf.io/ubvy2) and serve as a valuable resource for research into the relationship between language and perception.

Positive effects of grasping virtual objects on memory for novel words in a second language

Theories of embodied cognition describe language processing and representation as inherently connected to the sensorimotor experiences collected during acquisition. While children grasp their world, collect bodily experiences and name them, in second language (L2), students learn bilingual word lists. Experimental evidence shows that embodiment by mean of gestures enhances memory for words in L2. However, no study has been conducted on the effects of grasping in L2. In a virtual scenario, we trained 46 participants on 18 two- and three-syllabic words of Vimmi, an artificial corpus created for experimental purposes. The words were assigned concrete meanings of graspable objects. Six words were learned audio-visually, by reading the words projected on the wall and by hearing them. Another 6 words were trained by observation of virtual objects. Another 6 words were learned by observation and additional grasping the virtual objects. Thereafter participants were subministered free, cued recall, and reaction time tests in order to assess the word retention and the word recognition. After 30 days, the recall tests were repeated remotely to assess the memory in the long term. The results show that grasping of virtual objects can lead to superior memory performance and to lower reaction times during recognition.

Feeling better: Tactile verbs speed up tactile detection

Embodiment of action-related language into the motor system has been extensively documented. Yet the case of sensory words, especially referring to touch, remains overlooked. We investigated the influence of verbs denoting tactile sensations on tactile perception. In Experiment 1, participants detected tactile stimulations on their forearm, preceded by tactile or non-tactile verbs by one of three delays (170, 350, 500 ms) reflecting different word processing stages. Results revealed shorter reaction times to tactile stimulations following tactile than non-tactile verbs, irrespective of delay. To ensure that priming pertained to tactile, and not motor, verb properties, Experiment 2 compared the impact of tactile verbs to both action and non-tactile verbs, while stimulations were delivered on the index finger. No priming emerged following action verbs, therefore not supporting the motor-grounded interpretation. Facilitation by tactile verbs was however not observed, possibly owing to methodological changes. Experiment 3, identical to Experiment 2 except that stimulation was delivered to participants' forearm, replicated the priming effect. Importantly, tactile stimulations were detected faster after tactile than after both non-tactile and action verbs, indicating that verbs' tactile properties engaged resources shared with sensory perception. Our findings suggest that language conveying tactile information can activate somatosensory representations and subsequently promote tactile detection.

Processing of Action and Sound Verbs in Context: An FMRI Study

Recent theories propose a flexible recruitment of sensory and motor brain regions during conceptual processing depending on context and task. The present functional magnetic resonance imaging study investigated the influence of context and task on conceptual processing of action and sound verbs. Participants first performed an explicit semantic context decision task, in which action and sound verbs were presented together with a context noun. The same verbs were repeatedly presented in a subsequent implicit lexical decision task together with new action and sound verbs. Thereafter, motor and acoustic localizer tasks were administered to identify brain regions involved in perception and action. During the explicit task, we found differential activations to action and sound verbs near corresponding sensorimotor brain regions. During the implicit lexical decision task, differences between action and sound verbs were absent. However, feature-specific repetition effects were observed near corresponding sensorimotor brain regions. The present results suggest flexible conceptual representations depending on context and task. Feature-specific effects were observed only near, but not within corresponding sensorimotor brain regions, as defined by the localizer tasks. Our results therefore only provide limited evidence in favor of grounded cognition theories assuming a close link between the conceptual and the sensorimotor systems.

Distinguishing abstract from concrete concepts in supramodal brain regions

Concrete words have been shown to have a processing advantage over abstract words, yet theoretical accounts and neural correlates underlying the distinction between concrete and abstract concepts are still unresolved. In an fMRI study, participants performed a property verification task on abstract and concrete concepts. Property comparisons of concrete concepts were predominantly based on either visual or haptic features. Multivariate pattern analysis successfully distinguished between abstract and concrete stimulus comparisons at the whole brain level. Multivariate searchlight analyses showed that posterior and middle cingulate cortices contained information that distinguished abstract from concrete concepts regardless of feature dominance. These results support the view that supramodal convergence zones play an important role in representation of concrete and abstract concepts.

An Exception to Mental Simulation: No Evidence for Embodied Odor Language

Do we mentally simulate olfactory information? We investigated mental simulation of odors and sounds in two experiments. Participants retained a word while they smelled an odor or heard a sound, then rated odor/sound intensity and recalled the word. Later odor/sound recognition was also tested, and pleasantness and familiarity judgments were collected. Word recall was slower when the sound and sound‐word mismatched (e.g., bee sound with the word typhoon). Sound recognition was higher when sounds were paired with a match or near‐match word (e.g., bee sound with bee or buzzer). This indicates sound‐words are mentally simulated. However, using the same paradigm no memory effects were observed for odor. Instead it appears odor‐words only affect lexical‐semantic representations, demonstrated by higher ratings of odor intensity and pleasantness when an odor was paired with a match or near‐match word (e.g., peach odor with peach or mango). These results suggest fundamental differences in how odor and sound‐words are represented.

Neural reuse of action perception circuits for language, concepts and communication

Neurocognitive and neurolinguistics theories make explicit statements relating specialized cognitive and linguistic processes to specific brain loci. These linking hypotheses are in need of neurobiological justification and explanation. Recent mathematical models of human language mechanisms constrained by fundamental neuroscience principles and established knowledge about comparative neuroanatomy offer explanations for where, when and how language is processed in the human brain. In these models, network structure and connectivity along with action- and perception-induced correlation of neuronal activity co-determine neurocognitive mechanisms. Language learning leads to the formation of action perception circuits (APCs) with specific distributions across cortical areas. Cognitive and linguistic processes such as speech production, comprehension, verbal working memory and prediction are modelled by activity dynamics in these APCs, and combinatorial and communicative-interactive knowledge is organized in the dynamics within, and connections between APCs. The network models and, in particular, the concept of distributionally-specific circuits, can account for some previously not well understood facts about the cortical 'hubs' for semantic processing and the motor system's role in language understanding and speech sound recognition. A review of experimental data evaluates predictions of the APC model and alternative theories, also providing detailed discussion of some seemingly contradictory findings. Throughout, recent disputes about the role of mirror neurons and grounded cognition in language and communication are assessed critically.

The Time-Course of Sentence Meaning Composition. N400 Effects of the Interaction between Context-Induced and Lexically Stored Affordances

Contemporary semantic theories can be classified along two dimensions: (i) the way and time-course in which contextual factors influence sentence truth-conditions; and (ii) whether and to what extent comprehension involves sensory, motor and emotional processes. In order to explore this theoretical space, our ERP study investigates the time-course of the interaction between the lexically specified telic component of a noun (the function of the object to which the noun refers to, e.g., a funnel is generally used to pour liquids into containers) and an ad-hoc affordance contextually induced by the situation described in the discourse. We found that, if preceded by a neutral discourse context, a verb incongruent with the noun's telic component as in “She uses the funnel to hang her coat” elicited an enhanced N400 compared to a congruent verb as in “She uses the funnel to pour water into a container.” However, if the situation introduced in the preceding discourse induced a new function for the object as an ad-hoc affordance (e.g., the funnel is glued to the wall and the agent wants to hang the coat), we observed a crossing-over regarding the direction of the N400 effect: comparing the ad-hoc affordance-inducing context with the neutral context, the N400 for the incongruent verb was significantly reduced, whereas the N400 for the congruent verb was significantly enhanced. We explain these results as a consequence of the incorporation of the contextually triggered ad-hoc affordance into the meaning of the noun. Combining these results with an analysis of semantic similarity values between test sentences and contexts, we argue that one possibility is that the incorporation of an ad-hoc affordance may be explained on the basis of the mental simulation of concurrent motor information.

Semantic word category processing in semantic dementia and posterior cortical atrophy

There is general agreement that perisylvian language cortex plays a major role in lexical and semantic processing; but the contribution of additional, more widespread, brain areas in the processing of different semantic word categories remains controversial. We investigated word processing in two groups of patients whose neurodegenerative diseases preferentially affect specific parts of the brain, to determine whether their performance would vary as a function of semantic categories proposed to recruit those brain regions. Cohorts with (i) Semantic Dementia (SD), who have anterior temporal-lobe atrophy, and (ii) Posterior Cortical Atrophy (PCA), who have predominantly parieto-occipital atrophy, performed a lexical decision test on words from five different lexico-semantic categories: colour (e.g., yellow), form (oval), number (seven), spatial prepositions (under) and function words (also). Sets of pseudo-word foils matched the target words in length and bi-/tri-gram frequency. Word-frequency was matched between the two visual word categories (colour and form) and across the three other categories (number, prepositions, and function words). Age-matched healthy individuals served as controls. Although broad word processing deficits were apparent in both patient groups, the deficit was strongest for colour words in SD and for spatial prepositions in PCA. The patterns of performance on the lexical decision task demonstrate (a) general lexicosemantic processing deficits in both groups, though more prominent in SD than in PCA, and (b) differential involvement of anterior-temporal and posterior-parietal cortex in the processing of specific semantic categories of words.

Population Code Dynamics in Categorical Perception

Categorical perception is a ubiquitous function in sensory information processing, and is reported to have important influences on the recognition of presented and/or memorized stimuli. However, such complex interactions among categorical perception and other aspects of sensory processing have not been explained well in a unified manner. Here, we propose a recurrent neural network model to process categorical information of stimuli, which approximately realizes a hierarchical Bayesian estimation on stimuli. The model accounts for a wide variety of neurophysiological and cognitive phenomena in a consistent framework. In particular, the reported complexity of categorical effects, including (i) task-dependent modulation of neural response, (ii) clustering of neural population representation, (iii) temporal evolution of perceptual color memory, and (iv) a non-uniform discrimination threshold, are explained as different aspects of a single model. Moreover, we directly examine key model behaviors in the monkey visual cortex by analyzing neural population dynamics during categorization and discrimination of color stimuli. We find that the categorical task causes temporally-evolving biases in the neuronal population representations toward the focal colors, which supports the proposed model. These results suggest that categorical perception can be achieved by recurrent neural dynamics that approximates optimal probabilistic inference in the changing environment.

Conceptual grounding of language in action and perception: a neurocomputational model of the emergence of category specificity and semantic hubs

Current neurobiological accounts of language and cognition offer diverging views on the questions of 'where' and 'how' semantic information is stored and processed in the human brain. Neuroimaging data showing consistent activation of different multi-modal areas during word and sentence comprehension suggest that all meanings are processed indistinctively, by a set of general semantic centres or 'hubs'. However, words belonging to specific semantic categories selectively activate modality-preferential areas; for example, action-related words spark activity in dorsal motor cortex, whereas object-related ones activate ventral visual areas. The evidence for category-specific and category-general semantic areas begs for a unifying explanation, able to integrate the emergence of both. Here, a neurobiological model offering such an explanation is described. Using a neural architecture replicating anatomical and neurophysiological features of frontal, occipital and temporal cortices, basic aspects of word learning and semantic grounding in action and perception were simulated. As the network underwent training, distributed lexico-semantic circuits spontaneously emerged. These circuits exhibited different cortical distributions that reached into dorsal-motor or ventral-visual areas, reflecting the correlated category-specific sensorimotor patterns that co-occurred during action- or object-related semantic grounding, respectively. Crucially, substantial numbers of neurons of both types of distributed circuits emerged in areas interfacing between modality-preferential regions, i.e. in multimodal connection hubs, which therefore became loci of general semantic binding. By relating neuroanatomical structure and cellular-level learning mechanisms with system-level cognitive function, this model offers a neurobiological account of category-general and category-specific semantic areas based on the different cortical distributions of the underlying semantic circuits.

Changes in intrinsic connectivity of the brain's reading network following intervention in children with autism

While task-based neuroimaging studies have identified alterations in neural circuitry underlying language processing in children with autism spectrum disorders [ASD], resting state functional magnetic resonance imaging [rsfMRI] is a promising alternative to the constraints posed by task-based fMRI. This study used rsfMRI, in a longitudinal design, to study the impact of a reading intervention on connectivity of the brain regions involved in reading comprehension in children with ASD. Functional connectivity was examined using group independent component analysis (GICA) and seed-based correlation analysis of Broca's and Wernicke's areas, in three groups of participants: an experimental group of ASD children (ASD-EXP), a wait list control group of ASD children (ASD-WLC), and a group of typically developing (TD) control children. Both GICA and seed-based analyses revealed stronger functional connectivity of Broca's and Wernicke's areas in the ASD-EXP group postintervention. Additionally, improvement in reading comprehension in the ASD-EXP group was correlated with greater connectivity in both Broca's and Wernicke's area in the GICA identified reading network component. In addition, increased connectivity between the Broca's area and right postcentral and right STG, and the Wernicke's area and LIFG, were also correlated with greater improvement in reading comprehension. Overall, this study revealed widespread changes in functional connectivity of the brain's reading network as a result of intervention in children with ASD. These novel findings provide valuable insights into the neuroplasticity of brain areas underlying reading and the impact of intensive intervention in modifying them in children with ASD.

Verb gapping: an action-gap compatibility study

This study addresses the processing of verb-gapping sentences, e.g., John closes a juice bottle and Jim [ ] a lemonade bottle. The goal was to explore if there would be an interaction between language comprehension and motor action not only for overt action verbs but also for gapped verbs. Participants read gapping sentences that either described clockwise or counter-clockwise manual rotations (e.g., closes vs. opens a juice bottle). Adopting a paradigm developed by Zwaan and Taylor (2006), sentence presentation was frame-by-frame. Participants proceeded from frame to frame by turning a knob either clockwise or counter clockwise. Analyses of the frame reading-times yielded a significant effect of compatibility between the linguistically conveyed action and the knob turning for the overt-verb (e.g., closes/opens a juice bottle) as well as for the gapped-verb frame (e.g., a lemonade bottle) - with longer reading times in the match condition than in the mismatch condition - but not for any of the other frames (e.g., and Jim). The results are promising in providing novel evidence for the real-time reactivation of gapped verbs and in suggesting that action simulation is not bound to the processing of overt verbs.

How do conceptual representations interact with processing demands: An fMRI study on action- and abstract-related words

This fMRI study investigated the functional mechanisms related to mental simulation of abstract- and action-related words and measured the effect of the type of stimulus (Abstract vs. action verbs) and the type of task (imagery vs. control task) to explore how conceptual representations interact with processing demands. A significant task by stimuli interaction showed that action-related words activated the left sensorimotor cortex during explicit imagery (as compared to the control task), whereas abstract-related verbs did not automatically activate this area. Rather, as we made sure that Abstract verbs were not associated with motor states (as tested in a rating study of our stimulus list), imagery elicited by abstract verb processing (as compared to Action verbs, and controlled for letter detection) differentially activated a right hemisphere neural network including the right supramarginal (SMG) gyrus and the precuneus which might be related to mental imagery of emotion-related scenes and not to the semantics of the stimuli per se. Our results confirmed the view that the activation of the sensorimotor cortex during language processing of abstract- and action-related words is strategy-dependent.

Differentiating Semantic Categories during the Acquisition of Novel Words: Correspondence Analysis Applied to Event-related Potentials

Growing evidence suggests that semantic knowledge is represented in distributed neural networks that include modality-specific structures. Here, we examined the processes underlying the acquisition of words from different semantic categories to determine whether the emergence of visual- and action-based categories could be tracked back to their acquisition. For this, we applied correspondence analysis (CA) to ERPs recorded at various moments during acquisition. CA is a multivariate statistical technique typically used to reveal distance relationships between words of a corpus. Applied to ERPs, it allows isolating factors that best explain variations in the data across time and electrodes. Participants were asked to learn new action and visual words by associating novel pseudowords with the execution of hand movements or the observation of visual images. Words were probed before and after training on two consecutive days. To capture processes that unfold during lexical access, CA was applied on the 100–400 msec post-word onset interval. CA isolated two factors that organized the data as a function of test sessions and word categories. Conventional ERP analyses further revealed a category-specific increase in the negativity of the ERPs to action and visual words at the frontal and occipital electrodes, respectively. The distinct neural processes underlying action and visual words can thus be tracked back to the acquisition of word-referent relationships and may have its origin in association learning. Given current evidence for the flexibility of language-induced sensory-motor activity, we argue that these associative links may serve functions beyond word understanding, that is, the elaboration of situation models.

The role of visual representations during the lexical access of spoken words

Do visual representations contribute to spoken word recognition? We examine, using MEG, the effects of sublexical and lexical variables at superior temporal (ST) areas and the posterior middle temporal gyrus (pMTG) compared with that of word imageability at visual cortices. Embodied accounts predict early modulation of visual areas by imageability--concurrently with or prior to modulation of pMTG by lexical variables. Participants responded to speech stimuli varying continuously in imageability during lexical decision with simultaneous MEG recording. We employed the linguistic variables in a new type of correlational time course analysis to assess trial-by-trial activation in occipital, ST, and pMTG regions of interest (ROIs). The linguistic variables modulated the ROIs during different time windows. Critically, visual regions reflected an imageability effect prior to effects of lexicality on pMTG. This surprising effect supports a view on which sensory aspects of a lexical item are not a consequence of lexical activation.

Nouns, verbs, objects, actions, and abstractions: local fMRI activity indexes semantics, not lexical categories

Noun/verb dissociations in the literature defy interpretation due to the confound between lexical category and semantic meaning; nouns and verbs typically describe concrete objects and actions. Abstract words, pertaining to neither, are a critical test case: dissociations along lexical-grammatical lines would support models purporting lexical category as the principle governing brain organisation, whilst semantic models predict dissociation between concrete words but not abstract items. During fMRI scanning, participants read orthogonalised word categories of nouns and verbs, with or without concrete, sensorimotor meaning. Analysis of inferior frontal/insula, precentral and central areas revealed an interaction between lexical class and semantic factors with clear category differences between concrete nouns and verbs but not abstract ones. Though the brain stores the combinatorial and lexical-grammatical properties of words, our data show that topographical differences in brain activation, especially in the motor system and inferior frontal cortex, are driven by semantics and not by lexical class.

Semantic embodiment, disembodiment or misembodiment? In search of meaning in modules and neuron circuits

"Embodied" proposals claim that the meaning of at least some words, concepts and constructions is grounded in knowledge about actions and objects. An alternative "disembodied" position locates semantics in a symbolic system functionally detached from sensorimotor modules. This latter view is not tenable theoretically and has been empirically falsified by neuroscience research. A minimally-embodied approach now claims that action-perception systems may "color", but not represent, meaning; however, such minimal embodiment (misembodiment?) still fails to explain why action and perception systems exert causal effects on the processing of symbols from specific semantic classes. Action perception theory (APT) offers neurobiological mechanisms for "embodied" referential, affective and action semantics along with "disembodied" mechanisms of semantic abstraction, generalization and symbol combination, which draw upon multimodal brain systems. In this sense, APT suggests integrative-neuromechanistic explanations of why both sensorimotor and multimodal areas of the human brain differentially contribute to specific facets of meaning and concepts.

Insights into the origins of knowledge from the cognitive neuroscience of blindness

Children learn about the world through senses such as touch, smell, vision, and audition, but they conceive of the world in terms of objects, events, agents, and their mental states. A fundamental question in cognitive science is how nature and nurture contribute to the development of such conceptual categories. What innate mechanisms do children bring to the learning problem? How does experience contribute to development? In this article we discuss insights into these longstanding questions from cognitive neuroscience studies of blindness. Despite drastically different sensory experiences, behavioural and neuroscientific work suggests that blind children acquire typical concepts of objects, actions, and mental states. Blind people think and talk about these categories in ways that are similar to sighted people. Neuroimaging reveals that blind people make such judgements relying on the same neural mechanisms as sighted people. One way to interpret these findings is that neurocognitive development is largely hardwired, and so differences in experience have little consequence. Contrary to this interpretation, neuroimaging studies also show that blindness profoundly reorganizes the visual system. Most strikingly, developmental blindness enables "visual" circuits to participate in high-level cognitive functions, including language processing. Thus, blindness qualitatively changes sensory representations, but leaves conceptual representations largely unchanged. The effect of sensory experience on concepts is modest, despite the brain's potential for neuroplasticity.

The Body of Evidence: What Can Neuroscience Tell Us about Embodied Semantics?

Semantic knowledge is based on the way we perceive and interact with the world. However, the jury is still out on the question: to what degree are neuronal systems that subserve acquisition of semantic knowledge, such as sensory-motor networks, involved in its representation and processing? We will begin with a critical evaluation of the main behavioral and neuroimaging methods with respect to their capability to define the functional roles of specific brain areas. Any behavioral or neuroscientific measure is a conflation of representations and processes. Hence, a combination of behavioral and neurophysiological interactions as well as time-course information is required to define the functional roles of brain areas. This will guide our review of the empirical literature. Most research in this area has been done on semantics of concrete words, where clear theoretical frameworks for an involvement of sensory-motor systems in semantics exist. Most of this evidence still stems from correlational studies that are ambiguous with respect to the behavioral relevance of effects. Evidence for causal effects of sensory-motor systems on semantic processes is still scarce but evolving. Relatively few neuroscientific studies so far have investigated the embodiment of abstract semantics for words, numbers, and arithmetic facts. Here, some correlational evidence exists, but data on causality are mostly absent. We conclude that neuroimaging data, just as behavioral data, have so far not disentangled the fundamental link between process and representation. Future studies should therefore put more emphasis on the effects of task and context on semantic processing. Strong conclusions can only be drawn from a combination of methods that provide time-course information, determine the connectivity among poly- or amodal and sensory-motor areas, link behavioral with neuroimaging measures, and allow causal inferences. We will conclude with suggestions on how this could be accomplished in future research.

At the mercy of strategies: the role of motor representations in language understanding

Classical cognitive theories hold that word representations in the brain are abstract and amodal, and are independent of the objects’ sensorimotor properties they refer to. An alternative hypothesis emphasizes the importance of bodily processes in cognition: the representation of a concept appears to be crucially dependent upon perceptual-motor processes that relate to it. Thus, understanding action-related words would rely upon the same motor structures that also support the execution of the same actions. In this context, motor simulation represents a key component. Our approach is to draw parallels between the literature on mental rotation and the literature on action verb/sentence processing. Here we will discuss recent studies on mental imagery, mental rotation, and language that clearly demonstrate how motor simulation is neither automatic nor necessary to language understanding. These studies have shown that motor representations can or cannot be activated depending on the type of strategy the participants adopt to perform tasks involving motor phrases. On the one hand, participants may imagine the movement with the body parts used to carry out the actions described by the verbs (i.e., motor strategy); on the other, individuals may solve the task without simulating the corresponding movements (i.e., visual strategy). While it is not surprising that the motor strategy is at work when participants process action-related verbs, it is however striking that sensorimotor activation has been reported also for imageable concrete words with no motor content, for “non-words” with regular phonology, for pseudo-verb stimuli, and also for negations. Based on the extant literature, we will argue that implicit motor imagery is not uniquely used when a body-related stimulus is encountered, and that it is not the type of stimulus that automatically triggers the motor simulation but the type of strategy. Finally, we will also comment on the view that sensorimotor activations are subjected to a top-down modulation.

Neural correlates of executive functions in healthy G2019S LRRK2 mutation carriers

INTRODUCTION

The G2019S mutation in the leucine rich repeat kinase 2 (LRRK2) gene is prevalent among Ashkenazi Jewish patients with Parkinson's disease (PD). Cognitive deficits are common in early stage PD. We aimed to characterize the effect of the G2019S mutation on neural mechanisms of executive function processing by testing whether healthy mutation carriers who are an "at risk" population for the future development of PD differed from non-carriers on an functional magnetic resonance imaging (fMRI) Stroop interference task.

METHODS

Cognitive performance and task related cerebral activity were measured in 40 healthy first-degree relatives of Ashkenazi PD patients (19 carriers and 21 non-carriers of the G2019S mutation). Both regional differences in neural activity and seed region driven functional connectivity methods were performed using fMRI.

RESULTS

Compared to non-carriers, mutation carriers had greater baseline deactivation and increased task related activity in the right inferior parietal lobe, right precuneus and right fusiform gyrus. Whole brain functional connectivity analysis revealed stronger coupling between these regions and both basal ganglia structures as well as cortical regions in the carrier group. Non-manifesting G2019S mutation carriers and non-carriers performed similarly on the task and on all other assessed measures, so behavioral differences in task performance and baseline cognitive functions cannot explain the observed imaging differences.

CONCLUSIONS

G2019S carriers, at risk for developing PD, had similar behavioral performance as non-carriers during the Stroop task, but increased activity in brain regions that have previously been found to be part of the ventral attention system together with stronger coupling between task related areas and structures that make up the ventral and dorsal attention system as well as the basal ganglia-thalamocortical network. This suggests a neural compensatory mechanism that enables intact cognitive performance in asymptomatic mutation carriers.

Category-specific semantic memory: converging evidence from bold fMRI and Alzheimer's disease

Patients with Alzheimer's disease have category-specific semantic memory difficulty for natural relative to manufactured objects. We assessed the basis for this deficit by asking healthy adults and patients to judge whether pairs of words share a feature (e.g. "banana:lemon-COLOR"). In an fMRI study, healthy adults showed gray matter (GM) activation of temporal-occipital cortex (TOC) where visual-perceptual features may be represented, and prefrontal cortex (PFC) which may contribute to feature selection. Tractography revealed dorsal and ventral stream white matter (WM) projections between PFC and TOC. Patients had greater difficulty with natural than manufactured objects. This was associated with greater overlap between diseased GM areas correlated with natural kinds in patients and fMRI activation in healthy adults for natural kinds. The dorsal WM projection between PFC and TOC in patients correlated only with judgments of natural kinds. Patients thus remained dependent on the same neural network as controls during judgments of natural kinds, despite disease in these areas. For manufactured objects, patients' judgments showed limited correlations with PFC and TOC GM areas activated by controls, and did not correlate with the PFC-TOC dorsal WM tract. Regions outside of the PFC-TOC network thus may help support patients' judgments of manufactured objects. We conclude that a large-scale neural network for semantic memory implicates both feature knowledge representations in modality-specific association cortex and heteromodal regions important for accessing this knowledge, and that patients' relative deficit for natural kinds is due in part to their dependence on this network despite disease in these areas.

Grip force reveals the context sensitivity of language-induced motor activity during "action words" processing: evidence from sentential negation

BACKGROUND

Studies demonstrating the involvement of motor brain structures in language processing typically focus on time windows beyond the latencies of lexical-semantic access. Consequently, such studies remain inconclusive regarding whether motor brain structures are recruited directly in language processing or through post-linguistic conceptual imagery. In the present study, we introduce a grip-force sensor that allows online measurements of language-induced motor activity during sentence listening. We use this tool to investigate whether language-induced motor activity remains constant or is modulated in negative, as opposed to affirmative, linguistic contexts.

METHODOLOGY/PRINCIPAL FINDINGS

Participants listened to spoken action target words in either affirmative or negative sentences while holding a sensor in a precision grip. The participants were asked to count the sentences containing the name of a country to ensure attention. The grip force signal was recorded continuously. The action words elicited an automatic and significant enhancement of the grip force starting at approximately 300 ms after target word onset in affirmative sentences; however, no comparable grip force modulation was observed when these action words occurred in negative contexts.

CONCLUSIONS/SIGNIFICANCE

Our findings demonstrate that this simple experimental paradigm can be used to study the online crosstalk between language and the motor systems in an ecological and economical manner. Our data further confirm that the motor brain structures that can be called upon during action word processing are not mandatorily involved; the crosstalk is asymmetrically governed by the linguistic context and not vice versa.

Reading salt activates gustatory brain regions: fMRI evidence for semantic grounding in a novel sensory modality

Because many words are typically used in the context of their referent objects and actions, distributed cortical circuits for these words may bind information about their form with perceptual and motor aspects of their meaning. Previous work has demonstrated such semantic grounding for sensorimotor, visual, auditory, and olfactory knowledge linked to words, which is manifest in activation of the corresponding areas of the cortex. Here, we explore the brain basis of gustatory semantic links of words whose meaning is primarily related to taste. In a blocked functional magnetic resonance imaging design, Spanish taste words and control words matched for a range of factors (including valence, arousal, image-ability, frequency of use, number of letters and syllables) were presented to 59 right-handed participants in a passive reading task. Whereas all the words activated the left inferior frontal (BA44/45) and the posterior middle and superior temporal gyri (BA21/22), taste-related words produced a significantly stronger activation in these same areas and also in the anterior insula, frontal operculum, lateral orbitofrontal gyrus, and thalamus among others. As these areas comprise primary and secondary gustatory cortices, we conclude that the meaning of taste words is grounded in distributed cortical circuits reaching into areas that process taste sensations.

On-line changing of thinking about words: the effect of cognitive context on neural responses to verb reading

Activity in frontocentral motor regions is routinely reported when individuals process action words and is often interpreted as the implicit simulation of the word content. We hypothesized that these neural responses are not invariant components of action word processing but are modulated by the context in which they are evoked. Using fMRI, we assessed the relative weight of stimulus features (i.e., the intrinsic semantics of words) and contextual factors, in eliciting word-related sensorimotor activity. Participants silently read action-related and state verbs after performing a mental rotation task engaging either a motor strategy (i.e., referring visual stimuli to their own bodily movements) or a visuospatial strategy. The mental rotation tasks were used to induce, respectively, a motor and a nonmotor "cognitive context" into the following silent reading. Irrespective of the verb category, reading in the motor context, compared with reading in the nonmotor context, increased the activity in the left primary motor cortex, the bilateral premotor cortex, and the right somatosensory cortex. Thus, the cognitive context induced by the preceding motor strategy-based mental rotation modulated word-related sensorimotor responses, possibly reflecting the strategy of referring a word meaning to one's own bodily activity. This pattern, common to action and state verbs, suggests that the context in which words are encountered prevails over the intrinsic semantics of the stimuli in mediating the recruitment of sensorimotor regions.

Context-dependent changes in functional connectivity of auditory cortices during the perception of object words

Embodied theories hold that cognitive concepts are grounded in our sensorimotor systems. Specifically, a number of behavioral and neuroimaging studies have buttressed the idea that language concepts are represented in areas involved in perception and action [Pulvermueller, F. Brain mechanisms linking language and action. Nature Reviews Neuroscience, 6, 576-582, 2005; Barsalou, L. W. Perceptual symbol systems. Behavioral and Brain Sciences, 22, 577-660, 1999]. Proponents of a strong embodied account argue that activity in perception/action areas is triggered automatically upon encountering a word and reflect static semantic representations. In contrast to what would be expected if lexical semantic representations are automatically triggered upon encountering a word, a number of studies failed to find motor-related activity for words with a putative action-semantic component [Raposo, A., Moss, H. E., Stamatakis, E. A., & Tyler, L. K. Modulation of motor and premotor cortices by actions, action words and action sentences. Neuropsychologia, 47, 388-396, 2009; Rueschemeyer, S.-A., Brass, M., & Friederici, A. D. Comprehending prehending: Neural correlates of processing verbs with motor stems. Journal of Cognitive Neuroscience, 19, 855-865, 2007]. In a recent fMRI study, Van Dam and colleagues [Van Dam, W. O., Van Dijk, M., Bekkering, H., & Rueschemeyer, S.-A. Flexibility in embodied lexical-semantic representations. Human Brain Mapping, in press] showed that the degree to which a modality-specific region contributes to a representation considerably changes as a function of context. In the current study, we presented words for which both motor and visual properties (e.g., tennis ball, boxing glove) were important in constituting the concept. Our aim was to corroborate on earlier findings of flexible and context-dependent language representations by testing whether functional integration between auditory brain regions and perception/action areas is modulated by context. Functional connectivity was investigated by means of a psychophysiological interaction analysis, in which we found that bilateral superior temporal gyrus was more strongly connected with brain regions relevant for coding action information: (1) for Action Color words vs. Abstract words, and (2) for Action Color words presented in a context that emphasized action vs. a context that emphasized color properties.

Beyond colour perception: auditory-visual synaesthesia induces experiences of geometric objects in specific locations

Our brain constantly integrates signals across different senses. Auditory-visual synaesthesia is an unusual form of cross-modal integration in which sounds evoke involuntary visual experiences. Previous research primarily focuses on synaesthetic colour, but little is known about non-colour synaesthetic visual features. Here we studied a group of synaesthetes for whom sounds elicit consistent visual experiences of coloured 'geometric objects' located at specific spatial location. Changes in auditory pitch alter the brightness, size, and spatial height of synaesthetic experiences in a systematic manner resembling the cross-modal correspondences of non-synaesthetes, implying synaesthesia may recruit cognitive/neural mechanisms for 'normal' cross-modal processes. To objectively assess the impact of synaesthetic objects on behaviour, we devised a multi-feature cross-modal synaesthetic congruency paradigm and asked participants to perform speeded colour or shape discrimination. We found irrelevant sounds influenced performance, as quantified by congruency effects, demonstrating that synaesthetes were not able to suppress their synaesthetic experiences even when these were irrelevant for the task. Furthermore, we found some evidence for task-specific effects consistent with feature-based attention acting on the constituent features of synaesthetic objects: synaesthetic colours appeared to have a stronger impact on performance than synaesthetic shapes when synaesthetes attended to colour, and vice versa when they attended to shape. We provide the first objective evidence that visual synaesthetic experience can involve multiple features forming object-like percepts and suggest that each feature can be selected by attention despite it being internally generated. These findings suggest theories of the brain mechanisms of synaesthesia need to incorporate a broader neural network underpinning multiple visual features, perceptual knowledge, and feature integration, rather than solely focussing on colour-sensitive areas.

Neural representations of unfamiliar objects are modulated by sensorimotor experience

Sensory/functional accounts of semantic memory organization emphasize that object representations in the brain reflect the modalities involved in object knowledge acquisition. The present study aimed to elucidate the impact of different types of object-related sensorimotor experience on the neural representations of novel objects. Sixteen subjects engaged in an object matching task while their brain activity was assessed with functional magnetic resonance imaging (fMRI), before and after they acquired knowledge about previously unfamiliar objects. In three training sessions subjects learned about object function, actively manipulating only one set of objects (manipulation training objects, MTO), and visually exploring a second set (visual training objects, VTO). A third object set served as control condition and was not part of the training (no training objects, NTO). While training-related activation increases were observed in the fronto-parietal cortex for both VTO and MTO, post training activity in the left inferior/middle frontal gyrus and the left posterior inferior parietal lobule was higher for MTO than VTO and NTO. As revealed by Dynamic Causal Modeling of effective connectivity between the regions with enhanced post training activity, these effects were likely caused, respectively, by a down-regulation of a fronto-parietal tool use network in response to VTO, and by an increased connectivity for MTO. This pattern of findings indicates that the modalities involved in sensorimotor experience influence the formation of neural representations of objects in semantic memory, with manipulation experience specifically yielding higher activity in regions of the fronto-parietal cortex.

Inflection in action: Semantic motor system activation to noun- and verb-containing phrases is modulated by the presence of overt grammatical markers

A recent breakthrough in understanding brain-language mechanisms is the discovery of local motor cortex activations that index specific meaning features of words, phrases and sentences. The words "talk" and "walk" activate different parts of the motor cortex, reflecting the body part relationship of actions the linguistic items are typically used to speak about. It has been suggested that such semantic motor mapping can be explained by behaviorist theories, based on conditioning mechanisms also effective in Pavlov's dog when it salivates to bell sounds. In contrast, a neurobiological approach to language predicts modulation of semantic activation by grammatical, including inflectional-morphological, information. Here, we test these competing predictions by putting action words into different phrasal contexts invoking morphosyntactic and morphophonological processes and demonstrate that semantic motor mappings are modulated by grammatical sentence properties, especially the presence of overtly realized inflectional affixes on nouns or verbs embedded in grammatical phrases. Mechanistic neuroscience theories taking into account both meaning and grammar, including morphology and syntax, are required to explain these observations. A direct comparison between phrases containing nouns and verbs revealed a tendency towards greater activation to noun phrases in left-inferior premotor cortex and posterior Broca's region (BA 44), thus questioning previous suggestions that left inferiorfrontal areas might be dedicated to verb processing per se.

Dissociation and association of the embodied representation of tool-use verbs and hand verbs: An fMRI study

Embodied semantic theories suppose that representation of word meaning and actual sensory-motor processing are implemented in overlapping systems. According to this view, association and dissociation of different word meaning should correspond to dissociation and association of the described sensory-motor processing. Previous studies demonstrate that although tool-use actions and hand actions have overlapping neural substrates, tool-use actions show greater activations in frontal-parietal-temporal regions that are responsible for motor control and tool knowledge processing. In the present study, we examined the association and the dissociation of the semantic representation of tool-use verbs and hand action verbs. Chinese verbs describing tool-use or hand actions without tools were included, and a passive reading task was employed. All verb conditions showed common activations in areas of left middle frontal gyrus, left inferior frontal gyrus (BA 44/45) and left inferior parietal lobule relative to rest, and all conditions showed significant effects in premotor areas within the mask of hand motion effects. Contrasts between tool-use verbs and hand verbs demonstrated that tool verbs elicited stronger activity in left superior parietal lobule, left middle frontal gyrus and left posterior middle temporal gyrus. Additionally, psychophysiological interaction analyses demonstrated that tool verbs indicated greater connectivity among these regions. These results suggest that the brain regions involved in tool-use action processing also play more important roles in tool-use verb processing and that similar systems may be responsible for word meaning representation and actual sensory-motor processing.

When do you grasp the idea? MEG evidence for instantaneous idiom understanding

We investigated the time-course of cortical activation during comprehension of literal and idiomatic sentences using MEG and anatomically guided distributed source analysis. Previous fMRI work had shown that the comprehension of sentences including action-related words elicits somatotopic semantic activation along the motor strip, reflecting meaning aspects of constituent words. Furthermore, idioms more strongly activated temporal pole and prefrontal cortex than literal sentences. Here we show that, compared to literal sentences, processing of idioms in a silent reading task modulates anterior fronto-temporal activity very early-on, already 150-250 ms after the sentences' critical disambiguating words ("kick the habit"). In parallel, the meaning of action words embedded in sentences is reflected by somatotopic activation of precentral motor systems. As neural reflections of constituent parts of idiomatic sentences are manifest at the same early latencies as brain indexes of idiomatic vs. literal meaning processing, we suggest that within ¼ of a second, compositional and abstract context-driven semantic processes in parallel contribute to the understanding of idiom meaning.

Flexibility in embodied lexical-semantic representations

According to an embodied view of language comprehension, language concepts are grounded in our perceptual systems. Evidence for the idea that concepts are grounded in areas involved in action and perception comes from both behavioral and neuroimaging studies (Glenberg [1997]: Behav Brain Sci 20:1-55; Barsalou [1999]: Behav Brain Sci 22:577-660; Pulvermueller [1999]: Behav Brain Sci 22:253-336; Barsalou et al. [2003]: Trends Cogn Sci 7:84-91). However, the results from several studies indicate that the activation of information in perception and action areas is not a purely automatic process (Raposo et al. [2009]: Neuropsychologia 47:388-396; Rueschemeyer et al. [2007]: J Cogn Neurosci 19:855-865). These findings suggest that embodied representations are flexible. In these studies, flexibility is characterized by the relative presence or absence of activation in our perceptual systems. However, even if the context in which a word is presented does not undermine a motor interpretation, it is possible that the degree to which a modality-specific region contributes to a representation depends on the context in which conceptual features are retrieved. In the present study, we investigated this issue by presenting word stimuli for which both motor and visual properties (e.g., Tennis ball, Boxing glove) were important in constituting the concept. Conform with the idea that language representations are flexible and context dependent, we demonstrate that the degree to which a modality-specific region contributes to a representation considerably changes as a function of context.

A role for the motor system in binding abstract emotional meaning

Sensorimotor areas activate to action- and object-related words, but their role in abstract meaning processing is still debated. Abstract emotion words denoting body internal states are a critical test case because they lack referential links to objects. If actions expressing emotion are crucial for learning correspondences between word forms and emotions, emotion word–evoked activity should emerge in motor brain systems controlling the face and arms, which typically express emotions. To test this hypothesis, we recruited 18 native speakers and used event-related functional magnetic resonance imaging to compare brain activation evoked by abstract emotion words to that by face- and arm-related action words. In addition to limbic regions, emotion words indeed sparked precentral cortex, including body-part–specific areas activated somatotopically by face words or arm words. Control items, including hash mark strings and animal words, failed to activate precentral areas. We conclude that, similar to their role in action word processing, activation of frontocentral motor systems in the dorsal stream reflects the semantic binding of sign and meaning of abstract words denoting emotions and possibly other body internal states.

Visual Puzzles, Figure Weights, and Cancellation: Some Preliminary Hypotheses on the Functional and Neural Substrates of These Three New WAIS-IV Subtests

In this study, five consecutive patients with focal strokes and/or cortical excisions were examined with the Wechsler Adult Intelligence Scale and Wechsler Memory Scale-Fourth Editions along with a comprehensive battery of other neuropsychological tasks. All five of the lesions were large and typically involved frontal, temporal, and/or parietal lobes and were lateralized to one hemisphere. The clinical case method was used to determine the cognitive neuropsychological correlates of mental rotation (Visual Puzzles), Piagetian balance beam (Figure Weights), and visual search (Cancellation) tasks. The pattern of results on Visual Puzzles and Figure Weights suggested that both subtests involve predominately right frontoparietal networks involved in visual working memory. It appeared that Visual Puzzles could also critically rely on the integrity of the left temporoparietal junction. The left temporoparietal junction could be involved in temporal ordering and integration of local elements into a nonverbal gestalt. In contrast, the Figure Weights task appears to critically involve the right temporoparietal junction involved in numerical magnitude estimation. Cancellation was sensitive to left frontotemporal lesions and not right posterior parietal lesions typical of other visual search tasks. In addition, the Cancellation subtest was sensitive to verbal search strategies and perhaps object-based attention demands, thereby constituting a unique task in comparison with previous visual search tasks.

Differential effects of semantic processing on memory encoding

Deeper semantic processing of words leads to enhanced memory encoding (depth of processing effect). The left inferior prefrontal cortex (LIPC) and the left hippocampus are known to be involved in this effect. We tested the hypothesis that different semantic encoding processes contribute qualitatively differently to memory encoding. In a memory experiment using functional magnetic resonance imaging, we compared three different encoding tasks: a nonsemantic alphabetical, an animacy decision, and a size comparison tasks. Recognition memory was tested subsequently. We hypothesized that the size comparison task would activate brain areas involved in the processing of object features and that this would be associated with successful memory encoding. Results showed that the size comparison task led to significantly better memory encoding than the two other tasks. As with the animacy decision task, it led to stronger activation of the LIPC and left hippocampus than the nonsemantic task. Both regions also had stronger activations for later remembered than for nonremembered words. The size comparison task additionally led to stronger activation in the left anterior fusiform gyrus, which was also associated with successful memory encoding. We conclude that different types of semantic processing affect memory encoding based on distinguishable brain processes.

Cortical brain regions associated with color processing: an FMRI study

To clarify whether the neural pathways concerning color processing are the same for natural objects, for artifacts objects and for non-objects we examined brain responses measured with functional magnetic resonance imaging (FMRI) during a covert naming task including the factors color (color vs. black&white (B&W)) and stimulus type (natural vs. artifacts vs. non-objects). Our results indicate that the superior parietal lobule and precuneus (BA 7) bilaterally, the right hippocampus and the right fusifom gyrus (V4) make part of a network responsible for color processing both for natural objects and artifacts, but not for non-objects. When color objects (both natural and artifacts) were contrasted with color non-objects we observed activations in the right parahippocampal gyrus (BA 35/36), the superior parietal lobule (BA 7) bilaterally, the left inferior middle temporal region (BA 20/21) and the inferior and superior frontal regions (BA 10/11/47). These additional activations suggest that colored objects recruit brain regions that are related to visual semantic information/retrieval and brain regions related to visuo-spatial processing. Overall, the results suggest that color information is an attribute that can improve object recognition (behavioral results) and activate a specific neural network related to visual semantic information that is more extensive than for B&W objects during object recognition.