Mathematical treatment of context effects in phoneme and word recognition.

Percent recognition of phonemes and whole syllables, measured in both consonant-vowel-consonant (CVC) words and CVC nonsense syllables, is reported for normal young adults listening at four signal-to-noise (S/N) ratios. Similar data are reported for the recognition of words and whole sentences in three types of sentence: high predictability (HP) sentences, with both semantic and syntactic constraints; low predictability (LP) sentences, with primarily syntactic constraints; and zero predictability (ZP) sentences, with neither semantic nor syntactic constraints. The probability of recognition of speech units in context (pc) is shown to be related to the probability of recognition without context (pi) by the equation pc = 1 - (1-pi)k, where k is a constant. The factor k is interpreted as the amount by which the channels of statistically independent information are effectively multiplied when contextual constraints are added. Empirical values of k are approximately 1.3 and 2.7 for word and sentence context, respectively. In a second analysis, the probability of recognition of wholes (pw) is shown to be related to the probability of recognition of the constituent parts (pp) by the equation pw = pjp, where j represents the effective number of statistically independent parts within a whole. The empirically determined mean values of j for nonsense materials are not significantly different from the number of parts in a whole, as predicted by the underlying theory. In CVC words, the value of j is constant at approximately 2.5. In the four-word HP sentences, it falls from approximately 2.5 to approximately 1.6 as the inherent recognition probability for words falls from 100% to 0%, demonstrating an increasing tendency to perceive HP sentences either as wholes, or not at all, as S/N ratio deteriorates.

Individual differences in cerebral organization: influence of sex and familial sinistrality in the language lateralization of strongly right-handed subjects.

Sixty right-handed subjects, divided into four groups of 15 according to sex and familial sinistrality (FS), performed a test of language lateralization. A verbal-manual dual-task paradigm was employed. Results suggest that the pattern of cerebral organization may differ among right-handers in relation to both sex and FS. However, it is not merely the separate influence of these two factors, but rather their interaction which determines the pattern. It is stressed that identification of individual predictors of language laterality may provide some information on prognosis and management of aphasic patients.

An outline of human neuroethology.

Neuroethology is concerned with the analysis of neural substrates and mechanisms that underlie invariant forms of species-typical behavior. The aim of this outline is to delineate in an evolutionary perspective some specific human functional brain states and mechanisms which form the foundation of homo-typical behavior and experience. Dreaming, as one example, is considered to belong to the universals of human experience. Another example is the repertoire of human emotion and mental phenomena evoked by the electrical stimulation of the human limbic system. The expression of emotions by vocal behavior gains momentum in man and is based on certain transformations of the CNS that were fundamental for the emergence of speech. The phonemes in speech are the species-typical articulatory gestures for which a special decoding device is required. This innate mechanism may have features in common with the vocal signal decoding mechanism of subhuman primates.

Topographic analysis of auditory event-related potentials associated with acoustic and semantic processing.

The topography of auditory event-related potentials (ERPs) was examined during 3 kinds of tasks: selection of a specified real word or nonsense syllable from a list; simple detection of each of the same stimuli without discrimination; and classification of a set of words according to a specified semantic category. The potentials that were associated with the additional processing required by the discriminative tasks were disclosed by subtracting the wave forms obtained in the detection condition from those obtained during discriminative performance. Difference wave forms were also derived between the semantic classification and verbal discriminative ERP to delineate the changes associated with the extraction of word meaning. The topography of the ERP associated with stimulus detection was comparable to that found in previous studies of evoked potentials to non-speech stimuli. This distribution was consistent with 2 cortical generators, one within the supratemporal plane and the other on the lateral surface of the superior temporal gyrus. When discriminative performance was required on the basis of acoustic stimulus properties, the topography of the difference wave form that reflected this discriminative processing extended more posteriorly over temporal cortex. Semantic processing elicited a further posterior extension of ERP components by 330 msec after stimulus onset, as well as longer latency potentials that were not present in the verbal selection task. These differences imply that a more extensive portion of language cortex is engaged in semantic classification than in verbal identification.

Localization of cortical function: new information from extraoperative monitoring of patients with epilepsy.

Intraoperative cortical stimulation for evaluation of cortical function has been used extensively to define the extent of cortical excisions for surgical treatment of epilepsy. With chronic implantation of subdural electrodes, extraoperative cortical stimulation becomes possible, and these favorable testing conditions permit more precise mapping of the cortex. This assists the surgeon in planning details of the surgical removal and also provides additional data about the function of the human cortex. Four aspects in which detailed extraoperative studies have provided information complementing the pioneer studies of Foerster, Penfield, and others will be discussed here: (1) Frontal eye field: In the human, this is always an integral part of the motor strip (most probably located in Brodman's area 4 and/or 6) and elicits only conjugate eye movements to the contralateral side with a variable upward component. (2) Negative motor area: Stimulation of the inferior frontal gyrus immediately in front of the face area and of the supplementary motor area of the dominant and nondominant hemisphere produces "inhibition" of voluntary fine movements. (3) The movement related potentials (bereitschaftpotential, negative slope, and motor potential) are strictly localized to the portion of the sensorimotor strip where the movement is represented. Lower amplitude bereitschaftpotentials can also be detected in the homotopic ipsilateral sensorimotor cortex and in the supplementary motor cortex. (4) Three language areas can be distinguished by electrical stimulation: Broca's, Wernicke's, and the basal temporal language area. Electrical stimulation in all these areas produces a similar deficit, but Broca's area tends to overlap with the inferior frontal negative motor area. This may explain the predominant motor deficit of Broca's aphasia.

El lenguaje: es posible pensarlo como aprendizaje o como adquisición en la estructuración del sujeto? / The language: can it be conceived as a learning or as acquisition in the structuring of the subject?

El ser humano está permanentemente en discurso desde adentro y de fuera adentro. Estos elementos convergen para formar la base del lenguaje y tienen también un rol de la estructuración del sujeto como miembro de la familia. En ese sentido el proceso simbólico es primordial. Establece la diferencia entre lenguaje como un juego de códigos, y lenguaje como producción creativa. La autora concluye que desde esta perspectiva el lenguaje va más alla de la neurología, pero no lo suficientemente más alla de la comunicación e información; involucra al ser humano como un todo y esto debe ser entendido por quienes se ocupan de la patología del lenguaje

El lenguaje: es posible pensarlo como aprendizaje o como adquisición en la estructuración del sujeto? / The language: can it be conceived as a learning or as acquisition in the structuring of the subject?

El ser humano está permanentemente en discurso desde adentro y de fuera adentro. Estos elementos convergen para formar la base del lenguaje y tienen también un rol de la estructuración del sujeto como miembro de la familia. En ese sentido el proceso simbólico es primordial. Establece la diferencia entre lenguaje como un juego de códigos, y lenguaje como producción creativa. La autora concluye que desde esta perspectiva el lenguaje va más alla de la neurología, pero no lo suficientemente más alla de la comunicación e información; involucra al ser humano como un todo y esto debe ser entendido por quienes se ocupan de la patología del lenguaje (AU)

Basal temporal language area demonstrated by electrical stimulation.

We report on a 38-year-old patient with intractable complex partial seizures originating in the dominant left medial temporal region. In the work-up for seizure surgery, arrays of subdural electrodes were placed, and electrical stimulation revealed marked language interference in a 2 X 2-cm area in the left basal temporal fusiform gyrus (3.5 to 5.5 cm posterior to the temporal tip). Complete receptive and expressive aphasia, inability to repeat, agraphia, and alexia were elicited, but visual memory was preserved, and no constructional apraxia was noted. Stimulation of the basal temporal gyrus at lower stimulus intensities produced a relatively selective and severe anomia.

And all the daughters of musick shall be brought low. Language function in the elderly.

Language, including articulated speech and also, communication of ideas in writing, is liable to progressive alteration with advancing years. This process may appear early or late and may advance throughout the presenescent-senescent-senility continuum. An attempt is made to discuss these changes objectively, and from the standpoint of linguistics, their possible bearing upon the more fundamental problem as to the nature of the aging process is mentioned.

Dissociation of language and cognition. A psychological profile of two disconnected right hemispheres.

Two split-brain patients who differ in their right hemisphere language capacity were tested on a variety of simple cognitive tasks. Both isolated right hemispheres performed poorly on most tests. The results suggest that the presence of language in the right hemisphere, a brain system that ordinarily does not possess such competence, need not necessarily confer the full complement of cognitive skills associated with the language processing skills of the left hemisphere.

Symmetry and asymmetry in the human posterior thalamus. I. Cytoarchitectonic analysis in normal persons.

We parceled the posterior thalami of nine normal human brains according to cytoarchitectonic criteria, measured relevant nuclear volumes, and sought left-right asymmetries. We found that thalamic zones with multiple projections to the cerebral cortex, using the centromedian-parafascicular nucleus as a prototype, were mostly symmetric. This group includes the medial, lateral, and inferior pulvinar nuclei. Thalamic zones that project discretely to a few, clearly defined cortical receptor fields (using the medial geniculate nucleus [MG] as a prototype) closely reflected the asymmetry of the cortical fields to which they project. Hence, the MG showed a slight right-sided bias, and the lateralis posterior nucleus (related to the grossly asymmetric inferior parietal lobule) showed a significant leftsided bias in eight of the nine brains measured. This asymmetry may partially explain the apparent language specialization of the dominant thalamus.

Language-related potentials specific to human language cortex.

Event-related potentials following silently named object pictures were recorded directly from the exposed left hemisphere of the human cortex at sites whose relation to naming was subsequently established by electrical stimulation mapping. Two simultaneous potential changes are specific to sites where stimulation disrupts naming: slow potentials as premotor sites and focal desynchronization at posterior sites surrounding the Sylvian fissure. These anatomically specific changes are also specific to the task--present with silent naming and absent in a spatial task with the same visual input. Overt speech is also preceded by slow potentials with earliest onset at premotor sites.

Individual variability in cortical localization of language.

Individual variability in the localization of language, as measured by object-naming, was assessed for left lateral peri-Sylvian cortex with a multi-sample technique of stimulation mapping at a constant current. This study was performed during craniotomy under local anesthesia in 10 patients with medically intractable epilepsy and the usual pattern of left brain dominance for language. A high degree of variability in the exact location of naming was present. Only one area, a small portion of the third frontal convolution immediately in front of the motor strip, showed naming changes in all patients in whom it was sampled. This area is considerably smaller than the classical Broca's area. Elsewhere in language cortex, including all parts of the posterior language area, there was considerable individual variability. Because of this, the classical model of language localization is an inaccurate basis for establishing the risk of aphasia in surgical therapy of dominant hemisphere peri-Sylvian lesions in this and related patient populations. Rather, that risk should be assessed from the individual localization of language, established by the multisample technique of stimulation mapping.