Differential right hemisphere involvement in two reading tasks

[The development of ideas about the organization of the speech system]

This work represents an insight into a problem of studying one of the higher mental functions of humans - speech, its primary role in the development of man as a biosocial being. Various concepts of speech and the problem of the dominance of cerebral hemispheres in language function are analyzed. It touched upon the ontogenesis of hemispheric asymmetry. The problem of 'codominance' of right and left hemispheres depending on the nature of the task solving by the subject and the functional level of information processing is discussed. The authors highlight that the problem has an interdisciplinary nature, it is marked at the junction of neurophysiology, neuropsychology, neurology and defectology.

Patient education about anticoagulant medication: is narrative evidence or statistical evidence more effective?

OBJECTIVE

To determine the relative impact of incorporating narrative evidence, statistical evidence or both into patient education about warfarin, a widely used oral anticoagulant medication.

METHODS

600 patients receiving anticoagulant therapy were randomly assigned to view one of three versions of a video depicting a physician-patient encounter where anticoagulation treatment was discussed, or usual care (no video). The videos differed in whether the physician used narrative evidence (patient anecdotes), statistical evidence, or both to highlight key information. 317 patients completed both the baseline and post-test questionnaires. Questions assessed knowledge, beliefs and adherence to medication and laboratory monitoring regimens.

RESULTS

All three approaches positively effected patients' warfarin-related knowledge, and beliefs in the importance of lab testing; there was also some indication that viewing a video strengthened belief in the benefits of warfarin. There was some indication that narrative evidence had a greater impact than statistical evidence on beliefs about the importance of lab testing and on knowledge. No other evidence of the differential effectiveness of either approach was found. No statistically significant effect was found on intent to adhere, or documented adherence to lab monitoring.

CONCLUSION

Videos depicting a physician-patient dialogue about warfarin were effective in educating patients about anticoagulant medication, and had a positive impact on their beliefs. The use of narrative evidence in the form of patient anecdotes may be more effective than statistical evidence for some patient outcomes.

PRACTICE IMPLICATIONS

Patients on oral anticoagulant therapy may benefit from periodic educational efforts reinforcing key medication safety information, even after initial education and ongoing monitoring. Incorporating patient anecdotes into physician-patient dialogues or educational materials may increase the effectiveness of the message.

The peculiarity of the right-hemisphere function in depression: solving the paradoxes

Depression is characterized by functional insufficiency of the right hemisphere combined with its physiological overactivation. This paradox can be solved in the frame of the general concept of brain laterality. According to the present assumption, the left hemisphere organizes any information in an unambiguous monosemantic context, and this process requires an additional activation of the brain cortex in order to restrict natural relationships between objects and events. On the contrary, the right hemisphere organizes any information in the polysemantic context based on the simultaneous capture of the numerous natural relationships between elements of information. In healthy creative subjects this process does not require additional physiological activation of the cortex. In depression the physiological overactivation of the right hemisphere reflects the unsuccessful effort to overcome its functional insufficiency.

The prisoners of despair: right hemisphere deficiency and suicide

This paper presents an integrative approach to understanding of the inner experience of suicidal persons in terms of hemispheric asymmetry. The right hemisphere is involved in formation of polysemantic context. Polysemantic context is determined by multiple interconnections among its elements, while each concrete element bears the stamp of the whole context. Left hemisphere functioning leads to formation of monosemantic context. It is suggested that due to functional insufficiency of the right hemisphere the suicidal person demonstrates a compensatory shift to left hemisphere functioning. This shift manifests itself in reversed asymmetry of neurotransmitters, tendency to dissociation, alienated and negative perception of the body, lower sensitivity to pain, disintegration of self-representation, cognitive constriction, overly general nature of personal memories, difficulties in affect regulation as well as such personality traits as low openness to experience and personal constriction. This hypothesis raises a number of suggestions for future research.

An integrative psychophysiological approach to brain hemisphere functions in schizophrenia

The present paper proposes a new psychophysiological approach to the genesis of positive and negative schizophrenic symptoms. According to this approach, the initial factor in schizophrenic disorders is a functional insufficiency of the right hemisphere which can be determined by early emotional experience in combination with subtle brain damage. This functional insufficiency causes (a) the inability to grasp and select information before its realization; and (b) the inability to produce a polysemantic context which is crucial for creativity, psychological defense, and the restoration of search activity, all of which determine psychophysiological adaptation to the environment. Right hemisphere insufficiency causes left hemisphere hyperactivity as an ineffective attempt to compensate for this functional deficiency. As a result, normal search activity is replaced by artificial search activity which is represented by "positive" symptoms, and which uses the predisposition of the left hemisphere's catecholamine system for its increased activity. The suggestion is made that cognitive impairment in schizophrenia (the inability to use appropriate previous information in relation to current perceptual input) is related to the competition between information processing which requires left hemisphere activity, and the formation of positive symptoms, also based on left hemisphere activity.

Early and late VEPs for reading stimuli are altered by common binocular misalignments

Effects of mild binocular anomalies on early and late evoked response complexes to word stimuli were examined in visual evoked potentials (VEPs) recorded over occipital cortex, Wernicke's area, and its right side homolog in university students with (fixation disparity group) and without (normal group) fixation disparity. Stimuli were monocularly or binocularly viewed words of a paragraph presented individually for 100 ms, one per second, and a binocular control condition without linguistic content. An early complex (P125-N170) recorded at Oz and a late complex (N170-late P) recorded from the temporoparietal placements were analyzed. The early complex was not influenced by linguistic content. Binocular stimuli generally resulted in larger early and late VEP amplitudes than did monocular stimuli except that the fixation disparity group had no binocular amplitude enhancement at Oz. Left hemisphere amplitude was greater than right for all conditions, more so for words than for nonlinguistic stimuli. For words, the left hemisphere advantage was significant only for the normal group. Relationships between basic visual processing and language processing in relation to early and late complexes are considered from several perspectives.

Individual use of judgmental dimensions and hemispheric specificity

The present study investigated the relationship of hemispheric functional specificity to a subject's use of judgmental dimensions when discriminating temporal and spatial visual stimuli using a multidimensional scaling (MDS) paired-comparison paradigm. The major purposes of the study were: To identify the judgmental dimensions used in discriminating unidimensional (temporal or spatial) and multidimensional (combinations of temporal and spatial parameters) stimuli presented to the two visual hemifields; to study the relationship of the use of judgmental dimensions to the visual hemifields; to investigate whether the use of judgmental dimensions in discriminating unidimensional stimuli can be used to predict their use in discriminating multidimensional stimuli. Subjects used two dimensions in discriminating the spatial and temporal unidimensional stimuli: A dimension whose scaling paralleled the physically interval-scaled stimuli; a dimension, in which the extreme values were located on one end of the scale, while the mid-values are located at the other end of the scale. There is significantly greater use of the spatial dimension when spatial stimuli are presented to the left visual field (LVF) then when presented to the right visual field (RVF). Conversely, there is significantly greater use of the temporal dimension when temporal stimuli are presented to the RVF then when they are presented to the LVF. Three perceptual dimensions were used to judge multidimensional stimuli: Spatial-to-temporal; stimulus quality; apparent movement. Two groups of subjects were identified who differed in their relative use of the temporally and spatially scaled unidimensional stimuli presented to the RVF. These two groups differed with respect to their relative use of a spatial-to-temporal dimension when multidimensional stimuli were presented to the RVF.

The effects of visual feedback on hemispheric alpha asymmetries and reported processing strategies: a single-subject experimental design

A double reversal single-subject experimental design was used to study the effects of visual feedback on the hemispheric alpha asymmetries of a male subject during a linguistic task. Results indicated that the subject demonstrated flexibility in hemispheric alpha and corresponding processing strategies employed when an alpha biofeedback procedure was used. These results provide further support for the notion that right and left hemispheric activation is associated with different, yet compatible, cognitive strategies and that both can be manipulated under conditions of feedback.

Toward a psychophysiology of waking fantasy: EEG studies

EEG investigations into the psychophysiology of waking fantasy have yielded interesting but inconclusive results. The most promising lines of research are reviewed with particular reference to the methodological complexities involved. Studies of alpha blocking, alpha states, theta states, and cerebral asymmetries are described. Comparisons are drawn between these lines of investigation and the methods of experimental dream research.

Lateralized cortical/cognitive processing and bilateral electrodermal activity: effects of sensory mode and sex

Forty-eight subjects were assigned to four equal-size cells defined by sex and familial handedness (presence versus absence of an immediate family member who is left-handed or ambidextrous). Subjects were presented a series of 40 stimuli, each of which was designed to represent the intersection of a sensory mode (visual versus auditory) and hemisphere mode (verbal versus spatial). The dependent measures were the number of stimulus-specific and nonspecific responses with magnitude larger on the lefthand. On the whole, results are supportive of the contralateral inhibitory process hypothesized by LaCroix and Comper (1979). Nonspecific response data appear to be sensitive to hemispheric manipulation as observed previously in this laboratory. Sensory mode appears to be an important determinant of lateralized phasic magnitude differences, with males showing the most striking verbal-spatial distinctions during visual mode presentation.

Differentially Talented Females: Some Critical Methodological Issues for the 1980s

Usually psychometric studies have searched for the personality correlates associated with L (high linguistic and low quantitative ability) and Q (low linguistic and high quantitative ability) patterns. Neuropsychological studies, on the other hand, have searched for the cortical processes associated with L and Q patterns or for the psychological functions (presumably linguistic and visuospatial) associated with left- and right-hemispheric processing, respectively. To further our understanding of the relationship of L and Q patterns to personality correlates and modes of information processing and to clarify conflicting interpretations attributed to sex and sex-role factors, a cohort-sequential methodology and a convergence of psychometry with neuropsychology are recommended; three critical methodological issues are explored.

Asymmetries of the contingent negative variation (CNV) and its after positive wave (APW) related to differential hemispheric involvement in verbal and non-verbal tasks

The CNV and the subsequent positive wave (including both the P300 wave and the slow positivity following it) were recorded at left and right frontal and central electrodes during the performance of tasks in which nine right-handed subjects (male and female) had to determine whether S1 and S2 were the same or different. In one task, works had to be matched for meaning while in a second, faces had to be matched for identity. Words elicited CNVs which were more negative over left than right frontal regions. This effect was reversed when the stimuli were faces. Since the CNV is presumed to reflect processes of anticipation rather than stimulus processing, the asymmetry cannot be explained in terms of the lateralisation of neural mechanisms specialised for the analysis of verbal or visuospatial stimuli. Instead the observation is regarded as evidence for mechanisms of lateral activation of a more general nature than would be necessary for the facultative selection of cognitive mode. The amplitude of the CNV relative to baseline was affected by the amplitude of P300 response to S1. This was larger to faces than words in both hemispheres. A small asymmetry in the positive wave following S2 was observed, the amplitude being greater over the right hemisphere for words and over the left for faces. This is interpreted in terms of the subjective probability of the two types of stimulus for a hemisphere ill-equipped to receive them.

EEG and slow cortical potentials in anticipation of mental tasks with different hemispheric involvement

Mental arithmetic is supposed to be processed by the left hemisphere, while pattern matching has been considered to be processed by the right hemisphere. These different mental tasks were presented to 16 right-handed male subjects. As a variable task difficulty was varied for the two task categories. The task presentations were preceded by 6 sec warning stimuli which indicated the level of difficulty of the task. EEG and slow cortical potentials (SCPs) were recorded from temporal and precentral leads of both hemispheres. The reference was noncephalic. During the anticipation interval beta-activity was enhanced above the hemisphere primarily involved in the particular task. SCPs failed to show a comparable clear pattern. A late negative component showed task-dependent asymmetries prior to easy tasks, but not prior to difficult tasks.

Lateralized differences associated with semantically varied auditory material

EEGs were recorded from 13 subjects while they listened to four tape-recorded passages differing in semantic content. The distribution of alpha band power over the two hemispheres, measured at T3/T4, was found to show significant task-dependent shifts. More reality-oriented passages tended to be processed with greater left-hemisphere involvement, while "pleasurable" material showed significant right-hemisphere involvement. Since the differences in laterality were not related to grammatical measures of linguistic complexity, the apparent shifts were attributed to semantic differences between the tasks. Explanation of the results is made in terms of a theory of the metacontrol of cerebral processing.