Cognitive neuropsychology. Resolving enigmas about Wernicke's aphasia and other higher cortical disorders

Affective Prosody and Its Impact on the Neurology of Language, Depression, Memory and Emotions

Based on the seminal publications of Paul Broca and Carl Wernicke who established that aphasic syndromes (disorders of the verbal-linguistic aspects of communication) were predominantly the result of focal left-hemisphere lesions, "language" is traditionally viewed as a lateralized function of the left hemisphere. This, in turn, has diminished and delayed the acceptance that the right hemisphere also has a vital role in language, specifically in modulating affective prosody, which is essential for communication competency and psychosocial well-being. Focal lesions of the right hemisphere may result in disorders of affective prosody (aprosodic syndromes) that are functionally and anatomically analogous to the aphasic syndromes that occur following focal left-hemisphere lesions. This paper will review the deductive research published over the last four decades that has elucidated the neurology of affective prosody which, in turn, has led to a more complete and nuanced understanding of the neurology of language, depression, emotions and memory. In addition, the paper will also present the serendipitous clinical observations (inductive research) and fortuitous inter-disciplinary collaborations that were crucial in guiding and developing the deductive research processes that culminated in the concept that primary emotions and related display behaviors are a lateralized function of the right hemisphere and social emotions, and related display behaviors are a lateralized function of the left hemisphere.

Cerebral localization of functions and the neurology of language: fact versus fiction or is it something else?

Over the last 15 years there has been a burgeoning number of publications using functional brain imaging (>40,000 articles based on an ISI/Web of Science search) to localize behavioral and cognitive processes to specific areas in the human brain that are often not confirmed by traditional, lesion-based studies. Thus, there is a need to reassess what cerebral localization of functions is and is not. Otherwise, there is no rational way to interpret the escalating claims of localization in the functional imaging literature that is taking on the appearance of neurophysiologic "phrenology". This article will present arguments to suggest that functional localization in the brain is a robust but very dynamic, four-dimensional process. It is a learned phenomenon driven over time by large-scale, spatially distributed, neural networks seeking to efficiently maximize the processing, storage, and manipulation of information for cognitive and behavioral operations. Because of historical considerations and space limitations, the main focus will be on localization of language-related functions whose theoretical neurological basis can be generalized for any complex cognitive-behavioral function.

Neurology of affective prosody and its functional-anatomic organization in right hemisphere

Unlike the aphasic syndromes, the organization of affective prosody in brain has remained controversial because affective-prosodic deficits may occur after left or right brain damage. However, different patterns of deficits are observed following left and right brain damage that suggest affective prosody is a dominant and lateralized function of the right hemisphere. Using the Aprosodia Battery, which was developed to differentiate left and right hemisphere patterns of affective-prosodic deficits, functional-anatomic evidence is presented in patients with focal ischemic strokes to support the concepts that (1) affective prosody is a dominant and lateralized function of the right hemisphere, (2) the intrahemispheric organization of affective prosody in the right hemisphere, with the partial exception of Repetition, is analogous to the organization of propositional language in the left hemisphere and (3) the aprosodic syndromes are cortically based as part of evolutionary adaptations underlying human language and communication.

Awareness and knowing: Implications for rehabilitation

It has been known for well over a century that brain-damaged patients are often unaware of the very deficits that impair performance in everyday life. Pathologies of awareness have been described for many neurological, psychiatric and neuropsychological deficits and the construct of "awareness" or "insight" understandably now receives attention from many researchers within the clinical and cognitive neurosciences. This paper does not attempt to explain the nature of consciousness or its impairment but rather considers four aspects of consciousness/awareness that health care professionals interested in understanding, measuring and improving deficits of awareness should consider.

Karl Kleist (1879-1960)- a pioneer of neuropsychiatry

Karl Kleist (1879-1960) was instrumental in pioneering German neuropsychiatry and neuropsychology, including the description of frontal, constructional, limb-kinetic (innervatory) and psychomotor apraxias, frontal akinesia and aspontaneity, as well as object and form blindness. Besides isolating episodic twilight states, involutional paranoia and symptomatic (especially influenza) psychoses, he was particularly involved in applying Wernicke's syndromatic and Kraepelin's prognostic and aetiological principles to classify "neurogenous" psychoses by refuting the assumption of mixed entities whenever possible. Thus, has phasophrenias denoted manic-depressive illness, unipolar affective disorders and marginal, i.e., atypical psychoses. The rather benign cycloid psychoses form the most prominent examples of the latter. Schizophrenias, on the other hand, were limited to poor long-term catamnestic outcomes. Kleist conceptualized the core group of schizophrenic illness as psychic system diseases-hence the origin of the term "systematic schizophrenias" within the Wernicke-Kleist-Leonhard School. Kleist was mainly influenced by Wernicke and his psychic reflex arc, but Ernst Mach's empiriocriticism, Theodor Meynert's cerebral connectionism, and associationism also shaped his outlook. Kleist's localization of cerebral functions by lesion analyses was indeed the best available at the time and continues to reveal insights to the interested reader. From his Frankfurt School, which may have been the last of a completely unified neuropsychiatry, came sound representatives of psychiatry, neurology and neurosurgery. His technical mastery and achievements seem indisputable, but his balancing acts during the Third Reich may today be questioned. Despite joining the National Socialist German Workers' Party (NSDAP) and the local Court of Genealogical Health (Erbgesundheitsgericht), Kleist was, however, one of the few German physicians who continued to treat Jewish patients, to employ Jewish colleagues and to voice evident criticism of the policies of "eugenics" and "euthanasia". This paper attempts to illuminate Kleist's biography and life's work in the relevant historical context.

Runner-up in the young physician's section of the Gowers' prize 2000. Epilepsy and the physical basis of consciousness

The issue of human consciousness, in both its popular and neuroscientific sense, is considered from a clinical perspective. The ictal semiologies of the various epilepsies, together with associated clinical features, are demonstrated to highlight certain neuroanatomical and neurophysiological facets of consciousness. It is suggested that further insights into consciousness, even those bordering on the philosophical, may be led by clinical neurological phenomena and emerging neuroinvestigative techniques.

Motor planning center for speech articulation in the normal human brain

In order to locate the coordination center of speech movements in the dominant hemisphere of the normal human brain, we measured magnetoencephalographic (MEG) signals from the left frontal area of right-handed subjects while they pronounced different words. A broad response appeared during a period of 120-320 ms before the onset of speech sound, and its current dipole sources were localized on the magnetic resonance images in a region around the superior end of the left insula. Further, the onset of the MEG response preceded by about 100 ms the perioral muscle activities that occurred for the articulation in speaking the words. These results suggest that the deep frontal region is involved in the articulatory programming of speech movements.

The Organization of Human Language Cortex: Special Adaptation or Common Cortical Design?

Understanding the neural basis of language is one of the oldest and most difficult pursuits in neuroscience. Despite decades of accumulated data on aphasic subjects with cortical damage, we still know relatively little of how language functions are represented within the neural circuitry of the brain. A major issue of debate is whether language is a species-specific adaptation built into the neocortex, or a by-product of neocortical expansion. Cognitive studies emphasizing the universal nature of language abilities, the consistencies of language structure, and the consistent time course of language development have all indicated that language abilities are innate and must be built into the brain by evolutionary forces. Comparative studies of primates are equivocal since we have little evidence indicating that primate communication is homologous to human language systems. Much of this confusion is related to a lack of information regarding the neural basis of human communication. Recent anatomical data from human brains indicates that left hemisphere regions can have unique types of organization that may be responsible for functional specialization.

Role of the nondominant hemisphere and undamaged area during word repetition in poststroke aphasics. A PET activation study

BACKGROUND AND PURPOSE

Although the resting regional cerebral blood flow (rCBF) in aphasic patients has been thoroughly investigated with positron emission tomography (PET) and single-photon emission CT, and PET studies in normal subjects have elucidated the functional localization of language processing, little is known about the activation pattern of language processing in aphasic patients.

METHODS

We measured the changes in rCBF during a repetition task (hearing a single word and repeating it aloud) and the resting state using the H2(15)O PET activation technique in 6 normal subjects (mean +/- SD age, 58.3 +/- 8.1 years) and 16 aphasic patients: 10 fluent aphasics (age, 60.3 +/- 12.5 years) and 6 nonfluent aphasics (age, 50.5 +/- 8.3 years).

RESULTS

In normal subjects, the posteroinferofrontal area (PIF) including Broca's area, the posterosuperotemporal area (PST) including Wernicke's area, the rolandic areas, and a few other areas were activated with left side dominance by the repetition task. In the resting state, the rCBF in the left PIF and the left posterotemporal area was reduced in both fluent and nonfluent aphasics. In aphasic patients, the magnitude of activation in the right PIF and PST by the repetition task was greater than in normal subjects. The increase in rCBF during the repetition task in the left PIF correlated with the Western Aphasia Battery score of spontaneous speech in the nonfluent aphasics with a left inferofrontal lesion.

CONCLUSIONS

This study shows the importance in aphasic patients of the mirror regions of the left PIF and PST in the nondominant (right) hemisphere for performing the word repetition task. The results also show the importance for nonfluent aphasic patients of the recruitment of the undamaged PIF for spontaneous speech.

Modality Specificity as a Criterion for Diagnosing Central Auditory Processing Disorders

A central "auditory" processing disorder (CAPD) is an auditory perceptual dysfunction that cannot be explained on the basis of peripheral hearing loss. As a concept, CAPD has not been completely validated, and many issues continue to be controversial. A primary issue of concern is whether currently used tests to evaluate CAPD are sensitive to factors that are not of an auditory perceptual nature. In this paper, we consider the case for modality specificity as a criterion for improving the specificity of diagnosing CAPD. Demonstrating the modality-specific nature of sensory processing deficits is one way to rule out nonperceptual factors as explanations for observed dysfunction.

Transcortical alexia with agraphia following a right temporo-occipital hematoma in a right-handed patient

We describe the case of a 51-year-old right-handed man who was affected by a transcortical alexia with agraphia and aphasia. Transcortical alexia produces errors in both reading and writing while copying is preserved. The patient had a severe alexia and was unable to read letters, words or sentences. Language examination showed mild aphasia with reduced fluency, intermittent paraphasia but a good comprehension and a normal repetition. Spontaneously and from dictation, writing was impaired by an agraphic jargon, but copying was excellent even though the patient was unable to read his own written production. There was no visual agnosia nor hemianopia. CT scan and MRI of the brain showed that there was a single right temporo-occipital hemorrhage but no lesion in the left hemisphere. Following surgical evacuation of the hematoma, the patient improved. One month after onset, his language was quite intact and reading was possible. We hypothesize that this particular syndrome was the result of a double disconnection: alexia would result from a disconnection of the right angular gyrus and the occipital associative areas by a subangular lesion; agraphia would result from a disconnection of the right angular gyrus and the semantic store, probably located in the right hemisphere.