scholarly journals Brain Activation During Reading in Deep Dyslexia: An MEG Study

2000 ◽  
Vol 12 (4) ◽  
pp. 622-634 ◽  
Author(s):  
Matti Laine ◽  
Riitta Salmelin ◽  
Päivi Helenius ◽  
Reijo Marttila
Keyword(s):  
Semantic Processing ◽  
Semantic Analysis ◽  
Right Hemisphere ◽  
Word Reading ◽  
Brain Activity ◽  
Temporal Cortex ◽  
Single Word ◽  
Lexical Semantic ◽  
Deep Dyslexia ◽  
Single Word Reading

Magnetoencephalographic (MEG) changes in cortical activity were studied in a chronic Finnish-speaking deep dyslexic patient during single-word and sentence reading. It has been hypothesized that in deep dyslexia, written word recognition and its lexical-semantic analysis are subserved by the intact right hemisphere. However, in our patient, as well as in most nonimpaired readers, lexical-semantic processing as measured by sentence-final semantic-incongruency detection was related to the left superior-temporal cortex activation. Activations around this same cortical area could be identified in single-word reading as well. Another factor relevant to deep dyslexic reading, the morphological complexity of the presented words, was also studied. The effect of morphology was observed only during the preparation for oral output. By performing repeated recordings 1 year apart, we were able to document significant variability in both the spontaneous activity and the evoked responses in the lesioned left hemisphere even though at the behavioural level, the patient's performance was stable. The observed variability emphasizes the importance of estimating consistency of brain activity both within and between measurements in brain-damaged individuals.

Lexical Processing as Revealed by Lateralized Event-Related Brain Potentials

2019 ◽  
Vol 33 (3) ◽  
pp. 148-164 ◽  
Author(s):  
Judith Koppehele-Gossel ◽  
Robert Schnuerch ◽  
Henning Gibbons
Keyword(s):  
Word Processing ◽  
Semantic Processing ◽  
Semantic Analysis ◽  
Lexical Processing ◽  
Word Reading ◽  
Recognition Task ◽  
Time Range ◽  
Processing Negativity ◽  
Written Word ◽  
Single Word Reading

Abstract. Neurocognitive models of written-word processing from low-level perceptual up to semantic analysis include the notion of a strongly left-lateralized posterior-to-anterior stream of activation. Two left-lateralized components in the event-related brain potential (ERP), N170 and temporo-parietal PSA (posterior semantic asymmetry; peak at 300 ms), have been suggested to reflect sublexical analysis and semantic processing, respectively. However, for intermediate processing steps, such as lexical access, no posterior left-lateralized ERP signature has yet been observed under single-word reading conditions. In combination with a recognition task, lexicality and depth of processing were varied. Left-minus-right difference ERPs optimally suited to accentuate left-lateralized language processes revealed an occipito-temporal processing negativity (210–270 ms) for all stimuli except alphanumerical strings. This asymmetry showed greater sensitivity to the combined effects of attention and lexicality than other ERPs in this time range (i.e., N170, P1, and P2). It is therefore introduced as “lexical asymmetry.”

Scanning the stammering brain

2000 ◽  
Vol 17 (4) ◽  
pp. 140-142 ◽  
Author(s):  
Caoimhghín S Breathnach
Keyword(s):  
Public Speaking ◽  
Right Hemisphere ◽  
Word Reading ◽  
Motor Preparation ◽  
Single Word ◽  
Regional Cerebral Blood ◽  
Self Monitoring ◽  
Single Word Reading ◽  
The Right ◽  
Abnormal Motor

AbstractStammering (or stuttering) may be defined as an impairment of continuous utterance. Developmental stammering, regardless of country or language, affects one per cent of adult populations. Exacerbation by the stress of adult conversation or public speaking contrasts sharply with normal flow during singing, acting or conversation with children. Alterations in regional cerebral blood flow suggest that there are underlying differences in sensorimotor function in developmental stammerers whose symptoms commonly appear during the period of intensive language acquisition around the third and fourth year. Emotional tensions may exacerbate the disturbance, but equally psychological growth is adversely affected by the handicap. Abnormal motor control is confirmed by the exaggerated activity in the right hemisphere. The normal sequence of articulatory programming and motor preparation for single word reading is reversed. Absence of activation over the left auditory cortex supports the notion of impaired or diminished auditory feedback in the self-monitoring of speech seen in normal brains. Subcortical abnormalities are a feature of both developmental and acquired stammering.

scholarly journals Cortical Effects of Shifting Letter Position in Letter Strings of Varying Length

2003 ◽  
Vol 15 (5) ◽  
pp. 731-746 ◽  
Author(s):  
Piers Cornelissen ◽  
Antti Tarkiainen ◽  
Päivi Helenius ◽  
Riitta Salmelin
Keyword(s):  
Word Length ◽  
Right Hemisphere ◽  
Word Reading ◽  
Temporal Dynamics ◽  
Temporal Cortex ◽  
Letter Position ◽  
Opposite Pattern ◽  
Spatio Temporal ◽  
Single Word Reading ◽  
The Right

Neuroimaging and lesion studies suggest that occipitotemporal brain areas play a necessary role in recognizing a wide variety of objects, be they faces, letters, numbers, or household items. However, many questions remain regarding the details of exactly what kinds of information are processed by the occipito-temporal cortex. Here, we address this question with respect to reading. Ten healthy adult subjects performed a single word reading task. We used whole-head magnetoencephalography to measure the spatio-temporal dynamics of brain responses, and investigated their sensitivity to: (1) lexicality (defined here as the difference between words and consonant strings), (2) word length, and (3) variation in letter position. Analysis revealed that midline occipital activity around 100 msec, consistent with low-level visual feature analysis, was insensitive to lexicality and variation in letter position, but was slightly affected by string length. Bilateral occipito-temporal activations around 150 msec were insensitive to lexicality and reacted to word length only in the timing (and not strength) of activation. However, vertical shifts in letter position revealed a hemispheric imbalance: The right hemisphere activation increased with the shifts, whereas the opposite pattern was evident in the left hemisphere. The results are discussed in the light of Caramazza and Hillis's (1990) model of early reading.

A Positron Emission Tomography Study of Silent and Oral Single Word Reading in Stuttering and Nonstuttering Adults

2000 ◽  
Vol 43 (4) ◽  
pp. 1038-1053 ◽  
Author(s):  
Luc F. De Nil ◽  
Robert M. Kroll ◽  
Shitij Kapur ◽  
Sylvain Houle
Keyword(s):  
Positron Emission Tomography ◽  
Right Hemisphere ◽  
Word Reading ◽  
Statistical Parametric Mapping ◽  
Anterior Cingulate ◽  
Emission Tomography ◽  
Single Word ◽  
Positron Emission ◽  
Single Word Reading ◽  
Group Comparisons

Over the last decade positron emission tomography (PET) has been used extensively for the study of language and other cognitive and sensorimotor processes in healthy and diseased individuals. In the present study, [ 15 O]H 2 O PET scanning was used to investigate the lateralization and functional distribution of cortical and subcortical activity involved in single word reading in stuttering and non-stuttering individuals. Ten right-handed male stuttering adults and matched nonstuttering individuals were instructed to read individually presented single words either silently or out loud. Subtraction of functional brain images obtained during each of the two reading tasks, and during a non-linguistic baseline task, was used to calculate within-group and between-group differences in regional cerebral blood flow by means of statistical parametric mapping. Increased activation in the left anterior cingulate cortex (ACC) was observed during silent reading in the stuttering speakers but not in the nonstuttering group. Because of the hypothesized role of the ACC in selective attention and covert articulatory practice, it is suggested that the observed increased ACC activation in the stuttering individuals reflects the presence of cognitive anticipatory reactions related to stuttering. During the oral reading task, within-group comparisons showed bilateral cortical and subcortical activation in both the stuttering and the nonstuttering speakers. Between-group comparisons showed a proportionally greater left hemisphere activation in the nonstuttering speakers, and a proportionally greater right hemisphere activation in the stuttering individuals. The results of the present study provide qualified support for the hypothesis that stuttering adults show atypical lateralization of language processes.

Differential components of sentence comprehension: Beyond single word reading and memory

NeuroImage ◽  
2006 ◽  
Vol 29 (2) ◽  
pp. 429-438 ◽  
Author(s):  
L.E. Cutting ◽  
A.M. Clements ◽  
S. Courtney ◽  
S.L. Rimrodt ◽  
J.G.B. Schafer ◽  
...  
Keyword(s):  
Sentence Comprehension ◽  
Word Reading ◽  
Single Word ◽  
Single Word Reading

scholarly journals Localization of Syntactic and Semantic Brain Responses using Magnetoencephalography

2007 ◽  
Vol 19 (7) ◽  
pp. 1193-1205 ◽  
Author(s):  
Elisabet Service ◽  
Päivi Helenius ◽  
Sini Maury ◽  
Riitta Salmelin
Keyword(s):  
Temporal Lobe ◽  
Semantic Processing ◽  
Sentence Comprehension ◽  
Right Hemisphere ◽  
Temporal Cortex ◽  
Word Class ◽  
Sentence Reading ◽  
Word Onset ◽  
Semantic Errors ◽  
The Right

Electrophysiological methods have been used to study the temporal sequence of syntactic and semantic processing during sentence comprehension. Two responses associated with syntactic violations are the left anterior negativity (LAN) and the P600. A response to semantic violation is the N400. Although the sources of the N400 response have been identified in the left (and right) temporal lobe, the neural signatures of the LAN and P600 have not been revealed. The present study used magnetoencephalography to localize sources of syntactic and semantic activation in Finnish sentence reading. Participants were presented with sentences that ended in normally inf lected nouns, nouns in an unacceptable case, verbs instead of nouns, or nouns that were correctly inflected but made no sense in the context. Around 400 msec, semantically anomalous last words evoked strong activation in the left superior temporal lobe with significant activation also for word class errors (N400). Weaker activation was seen for the semantic errors in the right hemisphere. Later, 600-800 msec after word onset, the strongest activation was seen to word class and morphosyntactic errors (P600). Activation was significantly weaker to semantically anomalous and correct words. The P600 syntactic activation was localized to bilateral sources in the temporal lobe, posterior to the N400 sources. The results suggest that the same general region of the superior temporal cortex gives rise to both LAN and N400 with bilateral reactivity to semantic manipulation and a left hemisphere effect to syntactic manipulation. The bilateral P600 response was sensitive to syntactic but not semantic factors.

scholarly journals Task-Dependent Modulation of Regions in the Left Inferior Frontal Cortex during Semantic Processing

2001 ◽  
Vol 13 (6) ◽  
pp. 829-843 ◽  
Author(s):  
A. L. Roskies ◽  
J. A. Fiez ◽  
D. A. Balota ◽  
M. E. Raichle ◽  
S. E. Petersen
Keyword(s):  
Frontal Cortex ◽  
Language Processing ◽  
Semantic Processing ◽  
Semantic Analysis ◽  
Lexical Processing ◽  
Temporal Cortex ◽  
Dependent Manner ◽  
Inferior Frontal Cortex ◽  
Semantic Judgment ◽  
The Right

To distinguish areas involved in the processing of word meaning (semantics) from other regions involved in lexical processing more generally, subjects were scanned with positron emission tomography (PET) while performing lexical tasks, three of which required varying degrees of semantic analysis and one that required phonological analysis. Three closely apposed regions in the left inferior frontal cortex and one in the right cerebellum were significantly active above baseline in the semantic tasks, but not in the nonsemantic task. The activity in two of the frontal regions was modulated by the difficulty of the semantic judgment. Other regions, including some in the left temporal cortex and the cerebellum, were active across all four language tasks. Thus, in addition to a number of regions known to be active during language processing, regions in the left inferior frontal cortex were specifically recruited during semantic processing in a task-dependent manner. A region in the right cerebellum may be functionally related to those in the left inferior frontal cortex. Discussion focuses on the implications of these results for current views regarding neural substrates of semantic processing.

Investigation of the Functional Neuroanatomy of Single Word Reading and Its Development

2018 ◽  
pp. 203-223
Author(s):  
Erica D. Palmer ◽  
Timothy T. Brown ◽  
Steven E. Petersen ◽  
Bradley L Schlaggar
Keyword(s):  
Word Reading ◽  
Functional Neuroanatomy ◽  
Single Word ◽  
Single Word Reading
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