Cortical organization of language

Ojemann, George A.

doi:10.1523/jneurosci.11-08-02281.1991

Cited by 415 publications

(194 citation statements)

References 55 publications

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“…Language processing involves multiple essential areas of the brain as well as widely dispersed neurons, as has been shown in intraoperative electric stimulations of brain tissue (Ojemann, 1991). Thus, it is to be assumed that the stimuli in the present study activated large multifocal neural systems (Mesulam, 1990) of which at least partially different subsets were engaged for nouns and verbs.…”

Section: Discussionmentioning

confidence: 78%

Microstates in Language-Related Brain Potential Maps Show Noun–Verb Differences

Koenig¹,

Lehmann²

1996

Brain and Language

149

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Brain processing of grammatical word class was studied analyzing event-related potential (ERP) brain fields. Normal subjects observed a randomized sequence of single German nouns and verbs on a computer screen, while 20-channel ERP field map series were recorded separately for both word classes. Spatial microstate analysis was applied, based on the observation that series of ERP maps consist of epochs of quasi-stable map landscapes and based on the rationale that different map landscapes must have been generated by different neural generators and thus suggest different brain functions. Space-oriented segmentation of the mean map series identified nine successive, different functional microstates, i.e., steps of brain information processing characterized by quasi-stable map landscapes. In the microstate from 116 to 172 msec, noun-related maps differed significantly from verb-related maps along the left-right axis. The results indicate that different neural populations represent different grammatical word classes in language processing, in agreement with clinical observations. This word class differentiation as revealed by the spatialtemporal organization of neural activity occurred at a time after word input compatible with speed of reading.

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Section: Discussionmentioning

confidence: 78%

Microstates in Language-Related Brain Potential Maps Show Noun–Verb Differences

Koenig¹,

Lehmann²

1996

Brain and Language

149

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“…In the future, we expect to see much more work in the field of geriatric psycholinguistics, not only to understand normal developmental changes in language processing, but also to understand changes caused by diseases such as dementia of the Alzheimer's type, Parkinson's dementia, and strokes that effect both the traditional and nontraditional language areas (Ojemann, 1991). ERP-based research promises to be on the forefront of such research efforts, especially if the ecological validity of ERP paradigms can be increased by technological advances in the presentation of auditory stimuli, and in the use of saccade-related potential research in reading paradigms (e.g.…”

Section: Discussionmentioning

confidence: 99%

Do the waves begin to waver? ERP studies of language processing in the elderly

King

Kutas

1995

Age Differences in Word and Language Processing

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Until recently, relatively little research had been done on language processing in the elderly except as an adjunct to the study of aphasia. While language processes have usually been thought to be fairly impervious to aging, it is now clear that some changes do occur. Moreover, many of these changes often seem to be directly linked to changes in the efficacy of other cognitive operations affected by aging, particularly the active suppression of irrelevant information and the management of working memory (WM). One way to study these changes is to record event-related brain potentials (ERPs) from the scalp in response to individual words either in isolation or in sentences. In this chapter, we review what is currently known about the electrophysiology of visual language processing in the elderly, and what ERPs may tell us about age-related changes in the neural substrates of reading. ERP STUDIES OF LANGUAGE PROCESSING IN THE ELDERLYMuch more research has been focused on the development of language abilities from infancy through early adulthood than on changes in language processing over the next forty to fifty years. Notable exceptions are the investigations of individuals with gross disturbances in language caused by certain strokes or dementing illnesses and their age-matched controls. But a variety of subtle changes do occur within the normal aging brain that can have noticeable effects on language processing. In this chapter, we review some of our results from studies of language processing in presumably normal, healthy, elderly individuals employing event-related brain potentials (ERPs). ERPs provide us with a brain imaging technique that is well-suited for mapping processes at the psychological and linguistic level onto the relevant neural physiology. They are especially useful for our purposes because they provide a potentially continuous measure of on-going brain activity which is sensitive to many of the same variables that influence language processing. Further, ERPs give us a useful measure that does not require

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“…Specifically, evidence now suggests that the hippocampus (and linked parahippocampal gyrus and entorhinal cortex) is important in gating memory storage and retrieval, with memory storage likely occurring at neocortical sites in response to input arising from hippocampus (Squire and Zola-Morgan 1991), and with STG being important for auditory associative memory (Ojemann 1991;Penfield and Perot 1963). More ventral temporal lobe cortex may be involved in N400 abnormalities (see below).…”

Section: Comment On Anatomical Substrate In Schizophrenia For Disturbmentioning

confidence: 99%

Cognitive dysfunction in schizophrenia: unifying basic research and clinical aspects

McCarley

Niznikiewicz

Salisbury

et al. 1999

European Archives of Psychiatry and Clinical Neurosciences

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Seeking to unite psychological and biological approaches, this paper links cognitive and cellular hypotheses and data about thought and language abnormalities in schizophrenia. The common thread, it is proposed, is a dysregulated suppression of associations (at the behavioral and functional neural systems level), paralleled by abnormalities of inhibition at the cellular and molecular level, and by an abnormal anatomical substrate (reduced MRI gray matter volume) in areas subserving language.At the level of behavioral experiments and connectionist modeling, data suggest an abnormal semantic network connectivity (strength of associations) in schizophrenia, but not an abnormality of network size (number of associates). This connectivity abnormality is likely to be a preferential processing of the dominant (strongest) association, with the neglect of preceding contextual information.At the level of functional neural systems, the N400 event-related potential amplitude is used to index the extent of "search" for a semantic match to a word. In a short stimulus-onset-asynchrony condition, both schizophrenic and schizotypal personality disorder subjects showed, compared with controls, a reduced N400 amplitude to the target words that were related to cues, e.g. cat-dog, a result compatible with behavioral data. Other N400 data strongly and directly suggest that schizophrenics do not efficiently utilize context. At the level of anatomical system substrates, considerable MRI data indicate abnormalities in the temporal lobe structures that subserve language and verbal associations. Gray matter volume is reduced in the posterior portion of the dominant superior temporal gyrus in both chronic and first episode schizophrenics (but not in manic-depressive psychosis), with the magnitude of reduction correlating with the degree of thought disorder.At the level of in vitro cellular and molecular analysis, NMDA receptors on inhibitory neurons are much more sensitive to blockade than are excitatory projections. A resulting failure of recurrent inhibition may account for the psychotomimetic effects of such NMDA receptor blockers as ketamine and phencyclidine, and may also be present in schizophrenia, where an endogenous NMDA receptor blocker, NAAG, is increased, and where other abnormalities of recurrent inhibition may be present. A biophysical simulation of this circuit abnormality in a model of learned pattern recognition produced, because of the reduction in recurrent inhibition, aberrant spread of excitation, resulting in confusion of normally distinguishable patterns. We suggest the neural circuit failure of inhibition and consequent aberrant spread of activation may be the substrate for an inability to use context, with the behavioral and functional consequences just described. Furthermore, there is the possibility that the unbalanced excitation might lead to progressive, neurodegenerative changes in gray matter, marked by progressive volume reduction.

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Cortical organization of language

Cited by 415 publications

References 55 publications

Microstates in Language-Related Brain Potential Maps Show Noun–Verb Differences

Microstates in Language-Related Brain Potential Maps Show Noun–Verb Differences

Do the waves begin to waver? ERP studies of language processing in the elderly

Cognitive dysfunction in schizophrenia: unifying basic research and clinical aspects

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