Supramodal sentence processing in the human brain: fMRI evidence for the influence of syntactic complexity in more than 200 participants

This study investigated two questions. One is: To what degree is sentence processing beyond single words independent of the input modality (speech vs. reading)? The second question is: Which parts of the network recruited by both modalities is sensitive to syntactic complexity? These questions were investigated by having more than 200 participants read or listen to well-formed sentences or series of unconnected words. A largely left-hemisphere frontotemporoparietal network was found to be supramodal in nature, i.e., independent of input modality. In addition, the left inferior frontal gyrus (LIFG) and the left posterior middle temporal gyrus (LpMTG) were most clearly associated with left-branching complexity. The left anterior temporal lobe (LaTL) showed the greatest sensitivity to sentences that differed in right-branching complexity. Moreover, activity in LIFG and LpMTG increased from sentence onset to end, in parallel with an increase of the left-branching complexity. While LIFG, bilateral anterior temporal lobe, posterior MTG, and left inferior parietal lobe (LIPL) all contribute to the supramodal unification processes, the results suggest that these regions differ in their respective contributions to syntactic complexity related processing. The consequences of these findings for neurobiological models of language processing are discussed

Statistical models of morphology predict eye-tracking measures during visual word recognition

We studied how statistical models of morphology that are built on different kinds of representational units, i.e., models emphasizing either holistic units or decomposition, perform in predicting human word recognition. More specifically, we studied the predictive power of such models at early vs. late stages of word recognition by using eye-tracking during two tasks. The tasks included a standard lexical decision task and a word recognition task that assumedly places less emphasis on postlexical reanalysis and decision processes. The lexical decision results showed good performance of Morfessor models based on the Minimum Description Length optimization principle. Models which segment words at some morpheme boundaries and keep other boundaries unsegmented performed well both at early and late stages of word recognition, supporting dual- or multiple-route cognitive models of morphological processing. Statistical models based on full forms fared better in late than early measures. The results of the second, multi-word recognition task showed that early and late stages of processing often involve accessing morphological constituents, with the exception of short complex words. Late stages of word recognition additionally involve predicting upcoming morphemes on the basis of previous ones in multimorphemic words. The statistical models based fully on whole words did not fare well in this task. Thus, we assume that the good performance of such models in global measures such as gaze durations or reaction times in lexical decision largely stems from postlexical reanalysis or decision processes. This finding highlights the importance of considering task demands in the study of morphological processing.Peer reviewe

Supramodal Sentence Processing in the Human Brain: fMRI Evidence for the Influence of Syntactic Complexity in More Than 200 Participants

This study investigated two questions. One is: To what degree is sentence processing beyond single words independent of the input modality (speech vs. reading)? The second question is: Which parts of the network recruited by both modalities is sensitive to syntactic complexity? These questions were investigated by having more than 200 participants read or listen to well-formed sentences or series of unconnected words. A largely left-hemisphere frontotemporoparietal network was found to be supramodal in nature, i.e., independent of input modality. In addition, the left inferior frontal gyrus (LIFG) and the left posterior middle temporal gyrus (LpMTG) were most clearly associated with left-branching complexity. The left anterior temporal lobe showed the greatest sensitivity to sentences that differed in right-branching complexity. Moreover, activity in LIFG and LpMTG increased from sentence onset to end, in parallel with an increase of the left-branching complexity. While LIFG, bilateral anterior temporal lobe, posterior MTG, and left inferior parietal lobe all contribute to the supramodal unification processes, the results suggest that these regions differ in their respective contributions to syntactic complexity related processing. The consequences of these findings for neurobiological models of language processing are discussed

Neural correlates of language learning in adults

The human language-learning ability persists throughout life, indicating considerable flexibility at the cognitive and neural level. This ability spans from expanding the vocabulary in the mother tongue to acquisition of a new language with its lexicon and grammar. The present thesis consists of five studies that tap both of these aspects of adult language learning by using magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) during language processing and language learning tasks. The thesis shows that learning novel phonological word forms, either in the native tongue or when exposed to a foreign phonology, activates the brain in similar ways. The results also show that novel native words readily become integrated in the mental lexicon. Several studies in the thesis highlight the left temporal cortex as an important brain region in learning and accessing phonological forms. Incidental learning of foreign phonological word forms was reflected in functionally distinct temporal lobe areas that, respectively, reflected short-term memory processes and more stable learning that persisted to the next day. In a study where explicitly trained items were tracked for ten months, it was found that enhanced naming-related temporal and frontal activation one week after learning was predictive of good long-term memory. The results suggest that memory maintenance is an active process that depends on mechanisms of reconsolidation, and that these process vary considerably between individuals. The thesis put special emphasis on studying language learning in the context of language production. The neural foundation of language production has been studied considerably less than that of perceptive language, especially on the sentence level. A well-known paradigm in language production studies is picture naming, also used as a clinical tool in neuropsychology. This thesis shows that accessing the meaning and phonological form of a depicted object are subserved by different neural implementations. Moreover, a comparison between action and object naming from identical images indicated that the grammatical class of the retrieved word (verb, noun) is less important than the visual content of the image. In the present thesis, the picture naming was further modified into a novel paradigm in order to probe sentence-level speech production in a newly learned miniature language. Neural activity related to grammatical processing did not differ between the novel language and the mother tongue, but stronger neural activation for the novel language was observed during the planning of the upcoming output, likely related to more demanding lexical retrieval and short-term memory. In sum, the thesis aimed at examining language learning by combining different linguistic domains, such as phonology, semantics, and grammar, in a dynamic description of language processing in the human brain

Säker och sökande: den flexibla folkbildningens vardag

I skriften Säker och sökande intervjuas sex folkbildare; pedagoger och bibliotekarier. De berättar om utmaningarna som it-tekniken medför i deras vardagspraktik. Arbeta som lärare/bibliotekarie i dag, är det samma sak som att arbeta som lärare/bibliotekarie i morgon

srifm: Role of lexical information for perceptual learning

We sought to assess how adults reinterpret ambiguous sounds depending on the availability of phonotactic only versus phonotactic and lexical cues using a version of the perceptual adaptation paradigm. There was no perceptual adaptation

DNA functionalized soft materials: preparation, biophysical properties and analytical applications.

Bio-nanotechnology is the use of biomolecules to control both the structure and property of nanomaterials. No biomolecule has been employed more often than DNA as exemplified in the numerous demonstrations of DNA-directed assembly of nanomaterials. DNA has been used to covalently functionalize and assemble soft nanoparticles (e.g. liposomes) and hard nanoparticles (e.g. gold and silica nanoparticles) into a variety of hierarchical nanostructures. The majority of previous work however has focused on the latter, i.e., the assembly of “hard” nanoparticles such as gold nanoparticles (AuNPs) as oppose to the assembly of soft materials. The primary focus of this thesis is to add to the growing field of DNA-directed assembly of soft materials owing to the promise of such materials in a variety of analytical and biomedical applications. The first class of soft materials considered are liposomes which interestingly can be deformed by relatively weak intermolecular forces. In addition, DNA anchored to its surface can readily diffuse laterally within the lipid bilayer while DNA attached to inorganic nanoparticles remain fixed in position. We systematically consider the effect of varying the liposome structure, size, charge, and fluidity on liposome assemblies, in chapter 2. In addition, the interesting properties of liposomes are highlighted by a side-by-side comparison to DNA-functionalized gold nanoparticles, offering fundamental insights into DNA-directed assembly. Furthermore, hybrid DNA-directed assemblies composed of both AuNPs and liposomes are described in Chapter 3. In particular, the photothermal effects of such DNA-coupled liposome and AuNP assemblies were modulated by controlling the distance between liposome and AuNP allowing such systems to have potential application in drug-delivery. In chapter 4, the utility of liposomes is demonstrated as we exploit the fluidity of its diffuse bilayer with split aptamer functionalization for the rapid and selective detection of metabolites. The second class of soft material of interest in this thesis are hydrogels, which are cross-linked hydrophilic polymers. Because hydrogels are swollen in water, they can be used to immobilize biomolecules such as DNA for a myriad of applications. In chapter 5, the preparation and characterization of DNA-functionalized polyacrylamide hydrogels are presented. The use of such a DNA-modified hydrogel for the simultaneous detection and removal of mercury from water is subsequently demonstrated

Reconstructing meaning from bits of information

Modern theories of semantics posit that the meaning of words can be decomposed into a unique combination of semantic features (e.g., “dog” would include “barks”). Here, we demonstrate using functional MRI (fMRI) that the brain combines bits of information into meaningful object representations. Participants receive clues of individual objects in form of three isolated semantic features, given as verbal descriptions. We use machine-learning-based neural decoding to learn a mapping between individual semantic features and BOLD activation patterns. The recorded brain patterns are best decoded using a combination of not only the three semantic features that were in fact presented as clues, but a far richer set of semantic features typically linked to the target object. We conclude that our experimental protocol allowed us to demonstrate that fragmented information is combined into a complete semantic representation of an object and to identify brain regions associated with object meaning.Peer reviewe