Storage and Computation in Sentence Processing a Neuroimaging Perspective (original) (raw)
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Encoding and storage in working memory during sentence comprehension
The lexical basis of …, 2002
In this article we will discuss evidence from a number of recent neuroimaging experiments. These experiments suggest that three areas play a role in sentence comprehension: the left inferior frontal gyrus (LIFG), the left posterior superior temporal gyrus (STG), and the anterior temporal lobe (ATL). The left posterior STG appears to be important for sentential processing, since activation in this area increases as a function of the structural complexity of the sentences which must be comprehended. The LIFG, on the other hand, is activated by storage of lexical information as well as by sentential complexity. It is possible to explain a range of experimental results by hypothesizing that this area is responsible for storage of both lexical and phrasal information during comprehension. The ATL does not respond to structural complexity during sentence comprehension, but it is consistently more activated during comprehension of sentences than of word lists. On the basis of evidence which shows that the ATL is important for encoding in short-term verbal memory tasks, we suggest that it is responsible for encoding of information about words for use later in comprehension.
Neural Bases of Sentence Processing: Evidence from Neurolinguistic and Neuroimaging Studies
Sentence processing requires rapid integration of information over a short period of time. Models of language processing suggest that syntactic, semantic, and phonological detail must be accessed and coordinated within milliseconds to successfully produce or understand sentences. Exactly how this is accomplished and what neural mechanisms are engaged in real time to carry out these processes is not completely understood. Research examining the neural mechanisms associated with sentence processing elucidates a left hemisphere network involving both anterior and posterior brain regions, although studies show that the right hemisphere is also engaged to some extent. This chapter discusses what is known about the neural systems involved in sentence production and comprehension. Two bodies of research are discussed: neurolinguistic evidence derived from lesion deficit studies with brain-damaged people, and neuroimaging research examining the neural correlates of sentence processing in he...
Brain Networks Subserving the Extraction of Sentence Information and Its Encoding to Memory
Cerebral Cortex, 2007
Sentences are the primary means by which people communicate information. The information conveyed by a sentence depends on how that sentence relates to what is already known. We conducted an fMRI study to determine how the brain establishes and retains this information. We embedded sentences in contexts that rendered them more or less informative and assessed which functional networks were associated with comprehension of these sentences and with memory for their content. We identified two such networks: A frontotemporal network, previously associated with working memory and language processing, showed greater activity when sentences were informative. Independently, greater activity in this network predicted subsequent memory for sentence content. In a separate network, previously associated with resting-state processes and generation of internal thoughts, greater neural activity predicted subsequent memory for informative sentences but also predicted subsequent forgetting for less-informative sentences. These results indicate that in the brain, establishing the information conveyed by a sentence, that is, its contextually based meaning, involves two dissociable networks, both of which are related to processing of sentence meaning and its encoding to memory.
Neural basis for sentence comprehension: Grammatical and short-term memory components
Human Brain Mapping, 2002
We monitored regional cerebral activity with BOLD fMRI while subjects were presented written sentences differing in their grammatical structure (subject-relative or object-relative center-embedded clauses) and their short-term memory demands (short or long antecedent-gap linkages). A core region of left posterior superior temporal cortex was recruited during all sentence conditions in comparison to a pseudofont baseline, suggesting that this area plays a central role in sustaining comprehension that is common to all sentences. Right posterior superior temporal cortex was recruited during sentences with long compared to short antecedent-gap linkages regardless of grammatical structure, suggesting that this brain region supports passive short-term memory during sentence comprehension. Recruitment of left inferior frontal cortex was most clearly associated with sentences that featured both an object-relative clause and a long antecedent-gap linkage, suggesting that this region supports the cognitive resources required to maintain long-distance syntactic dependencies during the comprehension of grammatically complex sentences. Hum. Brain Mapping 15:80 -94, 2001.
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.
The Neural Bases of Sentence Comprehension: a fMRI Examination of Syntactic and Lexical Processing
Cerebral Cortex, 2001
One of the challenges to functional neuroimaging is to understand how the component processes of reading comprehension emerge from the neural activity in a network of brain regions. In this study, functional magnetic resonance imaging (fMRI) was used to examine lexical and syntactic processing in reading comprehension by independently manipulating the cognitive demand on each of the two processes of
Verbal working memory and sentence comprehension
Behavioral and Brain Sciences, 1999
This target article discusses the verbal working memory system used in sentence comprehension. We review the concept of working memory as a short-duration system in which small amounts of information are simultaneously stored and manipulated in the service of accomplishing a task. We summarize the argument that syntactic processing in sentence comprehension requires such a storage and computational system. We then ask whether the working memory system used in syntactic processing is the same as that used in verbally mediated tasks that involve conscious controlled processing. Evidence is brought to bear from various sources: the relationship between individual differences in working memory and individual differences in the efficiency of syntactic processing; the effect of concurrent verbal memory load on syntactic processing; and syntactic processing in patients with poor short-term memory, patients with poor working memory, and patients with aphasia. Experimental results from these normal subjects and patients with various brain lesions converge on the conclusion that there is a specialization in the verbal working memory system for assigning the syntactic structure of a sentence and using that structure in determining sentence meaning that is separate from the working memory system underlying the use of sentence meaning to accomplish other functions. We present a theory of the divisions of the verbal working memory system and suggestions regarding its neural basis.