Evie Malaia

Event segmentation in a visual language: neural bases of processing American Sign Language predicates.

Motion capture studies show that American Sign Language (ASL) signers distinguish end-points in telic verb signs by means of marked hand articulator motion, which rapidly decelerates to a stop at the end of these signs, as compared to atelic signs (Malaia and Wilbur, in press). Non-signers also show sensitivity to velocity in deceleration cues for event segmentation in visual scenes (Zacks et al., 2010; Zacks et al., 2006), introducing the question of whether the neural regions used by ASL signers for sign language verb processing might be similar to those used by non-signers for event segmentation. The present study investigated the neural substrate of predicate perception and linguistic processing in ASL. Observed patterns of activation demonstrate that Deaf signers process telic verb signs as having higher phonological complexity as compared to atelic verb signs. These results, together with previous neuroimaging data on spoken and sign languages (Shetreet et al., 2010; Emmorey et al., 2009), illustrate a route for how a prominent perceptual-kinematic feature used for non-linguistic event segmentation might come to be processed as an abstract linguistic feature due to sign language exposure.

The Effect of Individual Differences in Working Memory Capacity on Sentence Comprehension: An fMRI Study

This study explores the interaction between working memory systems and language processing by examining how differences in working memory capacity (WMC) modulates neural activation levels and functional connectivity during sentence comprehension. The results indicate that two working memory systems may be involved in sentence comprehension, the verbal working memory system and the episodic buffer, but during different phases of the task. A sub-region of the left inferior frontal gyrus (BA 45) was correlated with WMC during the probe and not during sentence reading while the only region to reveal a correlation with WMC during sentence reading was the posterior cingulate/precuneus area, a region linked to event representation. In addition, functional connectivity analysis suggests that there were two distinct networks affected by WMC. The first was a semantic network that included the middle temporal cortex, an anterior region of the inferior frontal gyrus and the inferior parietal region. The second included the posterior cingulate and BA 45 of the inferior frontal gyrus. We propose here that high capacity readers may generate an event representation of the sentence during reading that aids in comprehension and that this event representation involves the processing of the posterior cingulate cortex.

It still isn't over: Event boundaries in language and perception

The interaction between language and perception networks in the brain can hold the key to the biological bases of language evolution. In language, every sentence is built around a verb, which describes an event. During perception, humans constantly and automatically segment reality into individualized event (verb) units. The cognitive connection between the perceptual segmentation of events and their grammatical expression in language is a novel direction for research into the neurobiology of language, but it may be a key example of the emergence of linguistic structure – grammatical category – from individualized meaning. This article summarizes the current state of this research, and is divided into three parts. The initial overview of cross-linguistic typology of events shows that events and their boundaries are of vital importance to linguistic communication. We then summarize what is known about perceiving and identifying event boundaries in the most well-studied domain, that of visual perception. Here, sign languages provide the link between visual perception and linguistic expression, showing a complex mapping from perceptual and cognitive event segmentation to linguistic structures at the phonology–syntax interface. The last section reviews current evidence for neural bases of event processing, showing that identification of an event boundary (linguistic or perceptual) is used for memory updates, and suggesting the possible role of an event-type universal in the syntactic structure of human languages.

Deductive Versus Probabilistic Reasoning in Healthy Adults: An EEG Analysis of Neural Differences

This study examined the electrophysiological signatures of deductive and probabilistic reasoning. Deduction is defined as the case in which a conclusion can be found to be true or false due to validity of argument. In probabilistic reasoning, however, conclusions can be considered to be likely or unlikely, but not with certainty due to the lack of validity in the form of the argument. 16 participants were presented with both types of arguments while response times and ERPs were carried out. Participants had to decide with the presentation of each argument, what type of reasoning was appropriate and which of four responses (certainly yes, probably yes, probably no and certainly no) was the most appropriate. Response times indicated faster processing of deductive arguments. N2 amplitude distinguished between positive and negative responses in the deductive condition, but not in the probabilistic one, suggesting partial differentiation between the cognitive processes required for the two types of reasoning.

Assessment of information content in visual signal: analysis of optical flow fractal complexity

ABSTRACT We make a first attempt at distinguishing an information-carrying visual signal by comparing visual characteristics of American Sign Language to everyday human motion, to identify what clues might be available in one but not in the other. The comparison indicated significantly higher fractal complexity in sign language across tested frequency bands (0.01–15 Hz), as compared to everyday motion. A comparison of our results with other work showing high fractal complexity in the speech signal allows us to suggest the underlying properties of linguistic signals which allow babies to “tune into” a specific channel, or modality, during language acquisition.

Effects of Verbal Event Structure on Online Thematic Role Assignment

Event structure describes the relationships between general semantics (Aktionsart) of the verb and its syntactic properties, separating verbs into two classes: telic verbs, which denote change of state events with an inherent end-point or boundary (catch, rescue), and atelic, which refer to homogenous activities (tease, host). As telic verbs describe events, in which the internal argument (Patient) is affected, we hypothesized that processing of telic verb template would activate syntactic position of the Patient during sentence comprehension. Event-related brain potentials (ERPs) were recorded from 20 English speakers, who read sentences with reduced Object relative clauses, in which the verb was either telic or atelic. ERPs in relative clauses diverged on the definite article preceding the Agent: the atelic condition was characterized by larger amplitude negativity at the N100. Such processing differences are explained by activation of the syntactic position for the Patient by the event structure template of telic verbs.

Functional connectivity in task-negative network of the Deaf: effects of sign language experience

Prior studies investigating cortical processing in Deaf signers suggest that life-long experience with sign language and/or auditory deprivation may alter the brain’s anatomical structure and the function of brain regions typically recruited for auditory processing (Emmorey et al., 2010; Pénicaud et al., 2013 inter alia). We report the first investigation of the task-negative network in Deaf signers and its functional connectivity—the temporal correlations among spatially remote neurophysiological events. We show that Deaf signers manifest increased functional connectivity between posterior cingulate/precuneus and left medial temporal gyrus (MTG), but also inferior parietal lobe and medial temporal gyrus in the right hemisphere- areas that have been found to show functional recruitment specifically during sign language processing. These findings suggest that the organization of the brain at the level of inter-network connectivity is likely affected by experience with processing visual language, although sensory deprivation could be another source of the difference. We hypothesize that connectivity alterations in the task negative network reflect predictive/automatized processing of the visual signal.

Does degree of handedness in a group of right-handed individuals affect language comprehension?

The impact of handedness on language processing has been studied extensively and the results indicate that there is a relationship between the two variables; however, the nature of the relationship is not at all clear. In the current study we explored degree of handedness (DH) opposed to direction in a group of right-handed individuals. fMRI was used to explore the impact of DH on the sentence comprehension network. The results revealed that during sentence comprehension activation in regions linked to semantic memory (e.g., anterior temporal cortex) were modulated by DH. Also, unexpectedly the precuneus/posterior cingulate gyrus which has been linked to episodic memory was also affected by DH. These results extend those reported previously by showing that the neural architecture that supports sentence comprehension is modulated by DH. More specifically, together the results presented here support the hypothesis proposed by Townsend, Carrithers, and Bever (2001) that DH interacts with the language system and impacts the strategy used during sentence comprehension.

Altered brain network dynamics in youths with autism spectrum disorder

Abstract The heterogeneity of behavioral manifestation of autism spectrum disorders (ASDs) requires a model which incorporates understanding of dynamic differences in neural processing between ASD and typically developing (TD) populations. We use network approach to characterization of spatiotemporal dynamics of EEG data in TD and ASD youths. EEG recorded during both wakeful rest (resting state) and a social–visual task was analyzed using cross-correlation analysis of the 32-channel time series to produce weighted, undirected graphs corresponding to functional brain networks. The stability of these networks was assessed by novel use of the L1-norm for matrix entries (edit distance). There were a significantly larger number of stable networks observed in the resting condition compared to the task condition in both populations. In resting state, stable networks persisted for a significantly longer time in children with ASD than in TD children; networks in ASD children also had larger diameter, indicative of long-range connectivity. The resulting analysis combines key features of microstate and network analyses of EEG.

Neural bases of event knowledge and syntax integration in comprehension of complex sentences

Comprehension of complex sentences is necessarily supported by both syntactic and semantic knowledge, but what linguistic factors trigger a readers’ reliance on a specific system? This functional neuroimaging study orthogonally manipulated argument plausibility and verb event type to investigate cortical bases of the semantic effect on argument comprehension during reading. The data suggest that telic verbs facilitate online processing by means of consolidating the event schemas in episodic memory and by easing the computation of syntactico-thematic hierarchies in the left inferior frontal gyrus. The results demonstrate that syntax–semantics integration relies on trade-offs among a distributed network of regions for maximum comprehension efficiency.