Wernicke Model Research Articles

Neural integration of language production and comprehension.

Two key assumptions underpin the cognitive neuroscience of language. First, there is a clear-cut split between the processes involved in understanding an utterance (recognizing a word, resolving ambiguity) and the processes involved in crafting that utterance (translating an idea into sound or writing). For example, the “classic” Lichtheim–Broca–Wernicke model proposes distinct anatomical pathways associated with production and comprehension, primarily on the basis of deficit–lesion correlations in aphasia (1). Second, researchers assume that the linguistic mechanisms are lateralized, with production processes (e.g., lexical selection, articulation) and, to some extent, comprehension processes primarily occurring in the left hemisphere. Silbert et al. (2) report a neuroimaging study based on the production and comprehension of naturalistic narrative that challenges these two assumptions.

The final rifting evolution at deep magma-poor passive margins from Iberia-Newfoundland: a new point of view

In classical rift models, deformation is either uniformly distributed leading to symmetric fault bounded basins overlying stretched ductile lower crust (e.g. pure shear McKenzie model) or asymmetric and controlled by large scale detachment faulting (simple shear Wernicke model). In both cases rifting is considered as a mono-phase process and breakup is instantaneous resulting in the juxtaposition of continental and oceanic crust. The contact between these two types of crusts is often assumed to be sharp and marked by a first magnetic anomaly; and breakup is considered to be recorded as a major, basin wide unconformity, also referred to as breakup unconformity. These classical models, are currently challenged by new data from deep rifted margins that ask for a revision of these concepts. In this paper, we review the pertinent observations made along the Iberia-Newfoundland conjugate margins, which bear the most complete data set available from deep magma-poor margins. We reevaluate and discuss the polyphase nature of continental rifting, discuss the nature and significance of the different margin domains and show how they document extreme crustal thinning, retardation of subsidence and a complex transition into seafloor spreading. Although our study is limited to the Iberia-Newfoundland margins, comparisons with other margins suggest that the described evolution is probably more common and applicable for a large number of rifted margins. These new results have major implications for plate kinematic reconstructions and invite to rethink the terminology, the processes, and the concepts that have been used to describe continental rifting and breakup of the lithosphere.

Structure and genetic mechanisms of the Precambrian rifts of the East-European Platform in Russia by integrated study of seismic, gravity, and magnetic data

Integrated models of the deep structure and origin of rifts located within the Russian portion of the East-European Platform have been developed from recent DSS results, new gravity and magnetic modelling, and geological and older geophysical data acquired over the last 50 years. The Mezen rift province, the Middle-Russian rift, the Valday rift, the Pachelma rift, and the rifts within the Pre-Caspian depression were studied. All of these rifts were affected by extension and filled with syn-rift sediments at different times through the Riphean (1650–650 Ma). Post-rift sedimentary basins developed from the end of the Neoproterozoic until the Cenozoic. The models indicate that the crustal structure and genesis of the individual rifts are different. The Mezen rift province was formed under a condition of limited extension of the continental crust. The McKenzie pure strain mechanism is acceptable for lithosphere extension in the Middle-Russian rift. The Wernicke model best expresses the Valday and Pachelma rifts. The rift process in the Pre-Caspian area is explained in terms of large-scale sliding apart of lithospheric plates, and approached the stage of development of oceanic crust.

The Legacy of the Wernicke‐Lichtheim Model*

Wernicke established an integrated model of the relation between higher cognitive functions and neurophysiological structure of the human brain in 1874. The previous Bouillaud/Broca view envisaged a mosaic map of centres for specific functions, each of which had no clear inter‐relation with other centres or with input/output pathways, and with no theoretical explanation of how each centre operated in relation to more basic neural elements. Wernicke's model overcame these objections, and, with Lichtheim's systematization in 1885, the “Wernicke‐Lichtheim model”; became the standard neuropsychological theory. In this model, each normal higher function is explained in terms of an underlying neural pathway that includes the input/output systems, related functions employ portions of the pathways used for other functions, pathological syndromes are explained by reference to where in the pathway damage occurred, and previously unobserved pathological syndromes can be predicted. Development of the model at the hands of Lissauer, Dejerine, Liepmann, Geschwind, Heilman, and Ellis and Young is traced.

Observing tilts in midcrustal rocks by paleomagnetism: Examples from southeast British Columbia

Metamorphic core complexes that originated in the middle crust have been exposed by uplift and extension. Indicators of paleohorizontal planes are few or absent, thus it is difficult to determine the degree of tilting that might have accompanied this process. However, if aberrant paleomagnetic directions (paleodirections) are observed in core complexes or their associated intrusive rocks, and if large‐scale rotation and translation can be excluded, then these paleodirections can be used to calculate the sense and magnitude of tilting. We describe paleodirections from mid‐crustal rocks in southeastern British Columbia, where uplift and extension occurred in Eocene time about a central culmination aligned north‐south. Several large extensional faults dip both to the west and to the east of this central culmination. The Eocene Granby pluton (49.3°N, 118.5°W), situated to the west of the main culmination, has a mean direction of magnetization (D°, I°) 309°, 41° (α63° = 7° the standard error) and paleopole at 44°N, 138°E (A63° = 7°). To the east of the main culmination, a 20 km long section of altered Eocene Syringa dikes and associated metadiorite (49.3°N, 117.7°W) has a mean direction of 56°, 47° (α63° = 3°) and paleopole at 56°N, 319°E (A63° = 3°). The paleopoles are very different from one another, and from those calculated from contemporaneous (53 to 49 Ma) rocks of the North American craton to the east. They also differ from those observed from coeval bedded volcanic rocks to the west of the sampling area. Hence, these large aberrancies cannot be caused by translations. We suggest that they are caused by tilting which occurred during the extension process. The tilts are in opposite senses on either side of the central culmination. They are estimated to be down 38°±8° at 99°E for the Granby Pluton, and down 41°±4° at 270°W for the dikes and metadiorite. These tilts are consistent with the Wernicke model for simple extensional shear.

Thermal evolution of a rift basin: The Tyrrhenian Sea

Existing geological and geophysical data support the view that the opening of the Tyrrhenian Sea was by rifting of a formerly continuous continental lithosphere, which began in upper Miocene on the upper Sardinian margin and migrated southeastward to the Calabria margin. Heat flow across the Tyrrhenian Sea shows a pronounced asymmetry, from about 50–70 mW m−2 over the Sardinian margin, to more than 150 mW m−2 over its southeastern margin off southern Italy and Calabria. In this study we use the newly acquired data from Ocean Drilling Program Leg 107, heat flow, seismic velocity, and bathymetric data to constrain a group of models that supposes the Tyrrhenian Sea opened by detachment of a formerly continuous lithosphere along a southeastern facing, low‐angle normal fault. Specific models tested include (1) the Wernicke model, in which thinning and extension of the continental lithosphere are supposed to be accomplished by “simple shear” along a large‐scale, gently dipping detachment fault zone which cut through the entire lithosphere, and (2) the delamination model, in which the low‐angle detachment fault is supposed to cut only the upper and middle crust but to merge subhorizontally into the lower crust, below which concurrent pure shear may occur. A versatile, two‐dimensional finite element procedure is used to evaluate the tectonic and thermal evolution of these models, and the results are compared with observations to test the validity of the models. Delamination models with large pure shear components in the lower lithosphere and the Wernicke model predict heat flow within ±1σ of the measurements. The Wernicke model, however, predicts a basin configuration much too deep in comparison with bathymetry and a subbasinal lithospheric thickness substantially different from Rayleigh wave dispersion results. The delamination model with a large component of pure shear in the subbasinal lower lithosphere, on the other hand, predicts satisfactorily both the bathymetry and the lithospheric thickness beneath the basin.

Low-angle detachment origin for the Red Sea Rift System?

The tectonic and magmatic history of the Jizan coastal plain (Tihama Asir, southwest Arabia) suggests a two-stage evolution. A first stage of extension began during the Oligocene and ended with uplift of the Arabian graben shoulder which began about 14 Ma ago. It was followed by a period of approximately 10 Ma characterized by magmatic and tectonic quiescence. A second stage of extension began roughly contemporaneously with the onset of seafloor spreading in the southern Red Sea some 4–5 Ma ago and is still active today. The geometry of faulting in the Jizan area supports a Wernicke model of simple shear for the development of the southern Red Sea. Regional asymmetries of the Red Sea area, such as the distribution of volcanism, the marginal topography and asymmetries in the geophysical signatures are consistent with such a model. Available seismic profiles allow a rough estimate for β-values of the Arabian Red Sea margin and were used to simulate subsidence history and heat flow of the Red Sea for “classical” two-layer stretching models. Neither finite uniform nor finite non-uniform stretching models can account for observed subsidence and heat flow data. Thus, two model scenarios of whole-lithosphere normal simple-shear are presented for the geological history of the southwestern Arabian margin of the Red Sea. These models are limited because of the Serravallian rearrangement in the kinematics of the Red Sea.

Tonkonogy, Joseph. Vascular Aphasia

Researchers interested in cognition are likely to have at least some passing acquaintance with the issues in aphasia. At some point in their education they may have learned about the Wernicke theory of language and the brain, in which the motor representations for words are presumed to be localized in Broca’s area and the auditory sensory representations for words are presumed to be localized in Wernicke’s area. Those whose interests focus on language may also be familiar with recent approaches to aphasia that attempt to establish deficits in more central cognitive aspects of language such as syntax, semantics, or phonology rather than restricting attention to articulation and perception. In many respects, the book Vascular Aphasia by Joseph Tonkonogy (1986) is in the tradition of the Wernicke approach rather than the more recent cognitive approach. However, the information he presents points out the many inadequacies of the simplistic Wernicke theory. The Wernicke theory holds that Broca’s aphasics have a deficit in speech production due to the disruption of motor speech representations, but preserved comprehension because of the sparing of sensory speech representations. The reverse is assumed to be true for Wernicke’s aphasics, that is, comprehension is impaired, but production is spared. Tonkonogy presents the clinical syndromes in sufficient detail to make it clear that patients classed as either Broca’s or Wernicke’s aphasics have both production and comprehension deficits, but that the character of these deficits may differ for the two groups. Several other syndromes are also discussed and the departure of these syndromes from the predictions of the Wernicke model either in terms of the pattern of symptoms or the brain areas affected is made obvious. To support the claims about localization of function, a wealth of data obtained from postmortem examinations as well as from CAT scans is presented. The most interesting discussion in the book deals with redundancy of representation in the nervous system and the protection that this provides against small lesions. Tonkonogy presents a compromise between the strict localizationist and holistic or equipotential theories of brain function. He argues for what he terms multipotentiality, meaning that different areas are specialized for different functions, but within a given region there are many redundant, parallel channels that carry out the same function. Under this system, destruction of a part of the region does not lead to total failure of the system. He suggests that another means of protecting against system failure might derive from different regions carrying out a function in different ways by responding to different “alphabets” or units of the input. He

Tectonic Denudation of Upper Mantle Along Passive Margins: A Model Based on Drilling (ODP Leg 103) and Diving (Galinaute Cruise) Results, Western Galicia Margin, Spain: ABSTRACT

During ODP Leg 103 (April-June 1985) and the Galinaute cruise (June-July 1986), serpentinized peridotite (clinopyroxene-spinel harzburgite) was recovered within the basement approximately at the boundary between the North Atlantic ocean crust to the west and the thinned continental crust of the Galicia passive margin (Spain) to the east. The exposure of mantle-derived peridotite on the sea floor occurred at the end of the period of rifting, roughly 110 Ma. Ductile shear zones observed in the peridotite are consistent with movements along a deep, low-angle normal fault rooted within the upper mantle and dipping eastward beneath the Galicia margin. To explain the tectonic denudation of the mantle at the ocean-continent boundary, they use a nonuniform stretching model for the lithosphere, set up from Wernicke's model.

Tectonic denudation of the upper mantle along passive margins: a model based on drilling results (ODP leg 103, western Galicia margin, Spain)

During ODP Leg 103, serpentinized peridotite (clinopyroxene-spinel harzburgite) was cored within the basement approximatively at the boundary between the North Atlantic oceanic curst to the west, and the thinned continental crust of the Galicia passive margin (Spain) to the east. The exposure of mantle derived peridotite on the seafloor occurred at the end of the period of rifting, roughly 110 Ma ago. Ductile shear zones observed in the cored peridotite are consistent with movements along a deep low-angle, normal fault rooted within the upper mantle and dipping eastward, beneath the Galicia margin. To explain the tectonic denudation of the mantle at the ocean-continent boundary, we use a non-uniform stretching model for the lithosphere, set up from the Wernicke's model (1985).