Pasquale Anthony Della Rosa

Bilingualism Tunes the Anterior Cingulate Cortex for Conflict Monitoring

Monitoring and controlling 2 language systems is fundamental to language use in bilinguals. Here, we reveal in a combined functional (event-related functional magnetic resonance imaging) and structural neuroimaging (voxel-based morphometry) study that dorsal anterior cingulate cortex (ACC), a structure tightly bound to domain-general executive control functions, is a common locus for language control and resolving nonverbal conflict. We also show an experience-dependent effect in the same region: Bilinguals use this structure more efficiently than monolinguals to monitor nonlinguistic cognitive conflicts. They adapted better to conflicting situations showing less ACC activity while outperforming monolinguals. Importantly, for bilinguals, brain activity in the ACC, as well as behavioral measures, also correlated positively with local gray matter volume. These results suggest that early learning and lifelong practice of 2 languages exert a strong impact upon human neocortical development. The bilingual brain adapts better to resolve cognitive conflicts in domain-general cognitive tasks.

The Neural Representation of Abstract Words: The Role of Emotion

It is generally assumed that abstract concepts are linguistically coded, in line with imaging evidence of greater engagement of the left perisylvian language network for abstract than concrete words (Binder JR, Desai RH, Graves WW, Conant LL. 2009. Where is the semantic system? A critical review and meta-analysis of 120 functional neuroimaging studies. Cerebral Cortex. 19:2767-2796; Wang J, Conder JA, Blitzer DN, Shinkareva SV. 2010. Neural representation of abstract and concrete concepts: A meta-analysis of neuroimaging studies. Hum Brain Map. 31:1459-1468). Recent behavioral work, which used tighter matching of items than previous studies, however, suggests that abstract concepts also entail affective processing to a greater extent than concrete concepts (Kousta S-T, Vigliocco G, Vinson DP, Andrews M, Del Campo E. The representation of abstract words: Why emotion matters. J Exp Psychol Gen. 140:14-34). Here we report a functional magnetic resonance imaging experiment that shows greater engagement of the rostral anterior cingulate cortex, an area associated with emotion processing (e.g., Etkin A, Egner T, Peraza DM, Kandel ER, Hirsch J. 2006. Resolving emotional conflict: A role for the rostral anterior cingulate cortex in modulating activity in the amygdala. Neuron. 52:871), in abstract processing. For abstract words, activation in this area was modulated by the hedonic valence (degree of positive or negative affective association) of our items. A correlation analysis of more than 1,400 English words further showed that abstract words, in general, receive higher ratings for affective associations (both valence and arousal) than concrete words, supporting the view that engagement of emotional processing is generally required for processing abstract words. We argue that these results support embodiment views of semantic representation, according to which, whereas concrete concepts are grounded in our sensory-motor experience, affective experience is crucial in the grounding of abstract concepts.

The impact of semantic reference on word class: an fMRI study of action and object naming.

There is a considerable body of neuropsychological and neuroimaging evidence supporting the distinction between the brain correlates of noun and verb processing. It is however still not clear whether the observed differences are imputable to grammatical or semantic factors. Beyond the basic difference that verbs typically refer to actions and nouns typically refer to objects, other semantic distinctions might play a role as organizing principles within and across word classes. One possible candidate is the notion of manipulation and manipulability, which may modulate the word class dissociation. We used functional magnetic resonance imaging (fMRI) to study the impact of semantic reference and word class on brain activity during a picture naming task. Participants named pictures of objects and actions that did or did not involve manipulation. We observed extensive differences in activation associated with the manipulation dimension. In the case of manipulable items, for both nouns and verbs, there were significant activations within a fronto-parietal system subserving hand action representation. However, we found no significant effect of word class when all verbs were compared to all nouns. These results highlight the impact of the biologically crucial sensorimotor dimension of manipulability on the pattern of brain activity associated to picture naming.

Negation in the brain: Modulating action representations

Sentential negation is a universal syntactic feature of human languages that reverses the truth value expressed by a sentence. An intriguing question concerns what brain mechanisms underlie our ability to represent and understand the meaning of negative sentences. We approach this issue by investigating action-related language processing and the associated neural representations. Using functional magnetic resonance imaging we measured brain activity in 18 healthy subjects during passive listening of sentences characterized by a factorial combination of polarity (affirmative vs. negative) and concreteness (action-related vs. abstract). Negation deactivated cortical areas and the left pallidum. Compared to abstract sentences, action-related sentences activated the left-hemispheric action-representation system. Crucially, the polarity by concreteness interactions showed that the activity within the action-representation system was specifically reduced for negative action-related vs. affirmative action-related sentences (compared to abstract sentences). Accordingly, functional integration within this system as measured by Dynamic Causal Modeling was specifically weaker for negative action-related than for affirmative action-related sentences. This modulation of action representations indicates that sentential negation transiently reduces the access to mental representations of the negated information.

Bilingual aphasia and language control: A follow-up fMRI and intrinsic connectivity study

In a world that is becoming more multilingual, bilingual aphasia is a clinical problem with a major clinical impact. However, at present we lack causal explanations of the many features of recovery patterns and there is no consensus about the language in which the patient should receive speech therapy. Further advance requires an understanding of the dynamics of recovery. In a novel longitudinal, single-case study, we combine fMRI and dynamic causal modeling to examine the effects of specific language treatment for picture naming on the representation and control of language areas during the course of recovery. Improved performance in the treated language was associated with increased activation in language areas. Consistent with theoretical expectations, causal modeling indicated increased connectedness of the control and language networks for the treated language. This functional approach holds great promise for investigating recovery patterns and the effects of specific language treatment in bilingual aphasic patients.

Language proficiency modulates the engagement of cognitive control areas in multilinguals

Language proficiency should modulate the regions involved in language control in predictable ways during language switching. However, prior studies reveal inconsistent effects on the regions involved in language monitoring [pre-Supplementary Motor Area/Anterior Cingulate Cortex (pre-SMA/ACC)] and language selection (left caudate) conceivably because variations in relative proficiency are confounded with other between-group differences. We circumvented this problem in an fMRI (functional Magnetic Resonance Imaging) study of overt picture naming in trilingual participants. In this case, the difference between a high-proficient and a low-proficient further language can be assessed within subjects with no between-group confound. We also used a monolingual group to assess the neural correlates of switching between two categories of response within the same language. We report a novel result: relative language proficiency dissociates response of the pre-SMA/ACC and left caudate during language switching. Switching between languages increased pre-SMA/ACC response regardless of proficiency differences. By contrast, left caudate response did vary with proficiency differences. Switching from the most to the least proficient language increased the response. Within-language switching, as contrasted with between-language switching, elicited a comparable increase in pre-SMA/ACC response but a decrease in left caudate response. Taken together, our data support a wider role of pre-SMA/ACC in task monitoring and establish the critical role of the left caudate in the selection of the less proficient language in language switching.

The role of the left putamen in multilingual language production

Subcortical structures are a key component of bilingual language processing. For instance, there is now evidence that the head of the left caudate is involved in controlling languages in bilingual individuals. On the other hand, the left putamen is hypothesized to be involved in articulatory processes but little is known on its engagement in bilingual language processing. Here, our hypothesis was that the left putamen of multilinguals is engaged when producing words in the less proficient language. We investigated this issue with event-related functional Magnetic Resonance (er-fMRI) in a group of multilinguals (n = 14) and in monolinguals (n = 14) during a picture-naming task. Further, we hypothesized increased grey matter density in the left putamen as an effect of experience since multilinguals constantly face a major articulatory load (i.e., speaking multiple languages) during life. To test these hypotheses we measured structural differences between multilinguals and monolinguals using voxel-based morphometry (VBM). Our results indicate that multilinguals have increased activation in the left putamen for a non-native language, but only if they are not highly proficient in that language. In addition, we found increased grey matter density in the left putamen of multilinguals compared to monolinguals. These findings highlight that the multilingual brain handles a complex articulatory repertoire (i.e., dealing with multiple languages) by inducing structural plasticity in the left putamen.

A Standardized [18F]-FDG-PET Template for Spatial Normalization in Statistical Parametric Mapping of Dementia

Abstract[18F]-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) is a widely used diagnostic tool that can detect and quantify pathophysiology, as assessed through changes in cerebral glucose metabolism. [18F]-FDG PET scans can be analyzed using voxel-based statistical methods such as Statistical Parametric Mapping (SPM) that provide statistical maps of brain abnormalities in single patients. In order to perform SPM, a “spatial normalization” of an individual’s PET scan is required to match a reference PET template. The PET template currently used for SPM normalization is based on [15O]-H2O images and does not resemble either the specific metabolic features of [18F]-FDG brain scans or the specific morphological characteristics of individual brains affected by neurodegeneration. Thus, our aim was to create a new [18F]-FDG PET aging and dementia-specific template for spatial normalization, based on images derived from both age-matched controls and patients. We hypothesized that this template would increase spatial normalization accuracy and thereby preserve crucial information for research and diagnostic purposes. We investigated the statistical sensitivity and registration accuracy of normalization procedures based on the standard and new template—at the single-subject and group level—independently for subjects with Mild Cognitive Impairment (MCI), probable Alzheimer’s Disease (AD), Frontotemporal lobar degeneration (FTLD) and dementia with Lewy bodies (DLB). We found a significant statistical effect of the population-specific FDG template-based normalisation in key anatomical regions for each dementia subtype, suggesting that spatial normalization with the new template provides more accurate estimates of metabolic abnormalities for single-subject and group analysis, and therefore, a more effective diagnostic measure.

Computerized Neuropsychological Assessment in Aging: Testing Efficacy and Clinical Ecology of Different Interfaces

Digital technologies have opened new opportunities for psychological testing, allowing new computerized testing tools to be developed and/or paper and pencil testing tools to be translated to new computerized devices. The question that rises is whether these implementations may introduce some technology-specific effects to be considered in neuropsychological evaluations. Two core aspects have been investigated in this work: the efficacy of tests and the clinical ecology of their administration (the ability to measure real-world test performance), specifically (1) the testing efficacy of a computerized test when response to stimuli is measured using a touch-screen compared to a conventional mouse-control response device; (2) the testing efficacy of a computerized test with respect to different input modalities (visual versus verbal); and (3) the ecology of two computerized assessment modalities (touch-screen and mouse-control), including preference measurements of participants. Our results suggest that (1) touch-screen devices are suitable for administering experimental tasks requiring precise timings for detection, (2) intrinsic nature of neuropsychological tests should always be respected in terms of stimuli presentation when translated to new digitalized environment, and (3) touch-screen devices result in ecological instruments being proposed for the computerized administration of neuropsychological tests with a high level of preference from elderly people.

Bilingualism protects anterior temporal lobe integrity in aging.

Cerebral gray-matter volume (GMV) decreases in normal aging but the extent of the decrease may be experience-dependent. Bilingualism may be one protective factor and in this article we examine its potential protective effect on GMV in a region that shows strong age-related decreases-the left anterior temporal pole. This region is held to function as a conceptual hub and might be expected to be a target of plastic changes in bilingual speakers because of the requirement for these speakers to store and differentiate lexical concepts in 2 languages to guide speech production and comprehension processes. In a whole brain comparison of bilingual speakers (n = 23) and monolingual speakers (n = 23), regressing out confounding factors, we find more extensive age-related decreases in GMV in the monolingual brain and significantly increased GMV in left temporal pole for bilingual speakers. Consistent with a specific neuroprotective effect of bilingualism, region of interest analyses showed a significant positive correlation between naming performance in the second language and GMV in this region. The effect appears to be bilateral though because there was a nonsignificantly different effect of naming performance on GMV in the right temporal pole. Our data emphasize the vulnerability of the temporal pole to normal aging and the value of bilingualism as both a general and specific protective factor to GMV decreases in healthy aging.