Hemisphere Stimulation Research Articles

Bilingual effects of unilingual neuropsychological treatment of dyslexic adolescents: A pilot study

Fourteen young adolescents with specific reading disabilities received short term neuropsychological treatment--specifically left hemisphere (LH) or right hemisphere (RH) stimulation--in a clinical pilot project. The effects on single-word and passage reading were evaluated when the language of treatment was either Dutch (mother tongue) or English (foreign language). Transfer effects across the two languages were also studied. In general, the results indicate that these short term interventions may prove successful for the treated language and with the additional transfer to a second (not treated) language.

Enhanced hypnotizability by cerebrally applied magnetic fields depends upon the order of hemispheric presentation: an anistropic effect.

A significant alteration in the hypnotizability of normal subjects after brief (15 min) exposures to weak (1 microT) pulsed magnetic fields over the temporal lobes was determined by the serial order of hemispheric stimulation. Only subjects who received the right hemispheric stimulation first displayed significantly elevated hypnosis induction profile scores (effect size equivalent to a correlation of 0.41). Implications for a technology that can: a) modify hypnotizability, b) encourage the consolidation of quasiexperiences that are reconstructed as autobiographical memory, and c) change the sense of self, are discussed.

A functional vagotomy induced by unilateral forced right nostril breathing decreases intraocular pressure in open and closed angle glaucoma.

There is evidence of the central regulation of intraocular pressure, and it has been suggested that vagal tone might be increased in glaucoma simplex. The nasal cycle, the simultaneous congestion-decongestion response in the nasal cavities, reflects the dynamic lateralisation of the autonomic nervous system. Since this lateralisation presents with sympathetic activity induced by left brain hemisphere stimulation and parasympathetic activity induced by right hemisphere stimulation, it was subsequently demonstrated that forced unilateral nostril breathing induces selective contralateral hemispheric stimulation as measured by relative increases in the electroencephalographic amplitude in the contralateral hemisphere as well as alternating lateralisation of plasma catecholamines. Using this functional vagotomy, we report that left hemispheric stimulation by 20 minutes of forced unilateral right nostril breathing led to a significant bilateral decrease of 4.6 mmHg (25%) in intraocular pressure in 46 patients with open and closed angle glaucoma. However, it significantly increased the IOP in three patients with neovascular, one with juvenile onset, and one with closed angle glaucoma.

Effect of forced unilateral nostril breathing on blink rates: relevance to hemispheric lateralization of dopamine.

The involuntary blink rate is a clinical monitor of dopaminergic activity. Since there is disagreement in the literature on the relative neurochemical hemispheric asymmetry or laterality of dopamine, we studied the effects of differential forced unilateral nostril breathing on blink rate. This technique has been demonstrated to induce selective contralateral hemispheric stimulation as measured by relative increases in the EEG amplitude as well as alternating lateralization of plasma catecholamines. We used the artifact of the two-channel electro-oculogram to measure the endogenous eyeblink in an N = 1 design with 11 reversals of left vs. right hemisphere activation. There was a significant increase in blink rate (p less than .01) with right hemisphere activation, and this suggests that dopamine may be lateralized to the right cerebral hemisphere.

Sex differences in latencies of bilateral electrodermal responses

The present study examined sex differences in the latencies of bilateral electrodermal responses to stimuli presented in monocular vision. The stimuli were spatial-emotional, verbal-emotional, spatial-neutral and verbal-neutral slides, presented for either 35 ms or 1 s. Subjects were 15 males and 15 females. Bilateral latencies were not influenced by type of stimulus or by right/left hemisphere stimulation, which is in keeping with the most recent findings of bilateral electrodermal activity studies. However, females gave a faster right hand than left hand response and appeared to be more lateralized than males. Males showed shorter latencies on the left hand than on the right. These results confirm the importance of gender in experiments using the bilateral recordings of electrodermal activity

Unified response to bilateral hemispheric stimulation by a split-brain patient.

Surgical sectioning of the corpus callosum in epileptic patients has provided a unique opportunity to study separately the competence and processing capacities of the two cerebral hemispheres, each of which is able to perceive, think, memorize and learn independently and essentially outside the realm of awareness of the other. While research has focused on this 'disconnection syndrome', split-brain patients nonetheless behave as unified individuals in their normal environment, and the present study investigated this aspect of their behaviour in an experimental setting. The two hemispheres of a callosotomized patient were simultaneously presented with information associated with conflicting responses, and the subject was requested to produce a single response. In all combinations of hemisphere stimulation and hand responding, the subject was capable of perfect accuracy, suggesting that he could integrate and resolve the conflicting information before the production of his response, and that his two disconnected hemispheres were simultaneously aiming at the same goal.

Children's Books for Right Hemisphere Stimulation

Children's Books for Right Hemisphere Stimulation

Visual evoked response correlates of cerebral specialization after human commissurotomy

Visual evoked responses (VERs) were recorded from commissurotomy patients and normal subjects in order to investigate the electrophysiological correlates of cerebral lateralization and independent hemispheric processing. A verbal task consisted of detecting rhyming words and a spatial task consisted of comparing matching shapes. Stimuli were delivered, by means of a computer graphic display, into the right visual field, the left visual field, or both visual fields. Behavioral results and evoked response waveforms showed lateralization for verbal processing in the left hemisphere for the patient group. Analysis of variance of product moment correlation coefficients between VER waveforms indicated significant differences between unilateral and bilateral stimulation for both patients and normals. Commissurotomy and normal VERs showed similar patterns of correlation when verbal stimuli were delivered to the left hemisphere, but differed during right hemisphere stimulation. The results are discussed in terms of VER correlates of visual-verbal processing.

CORTICAL MOTOR FUNCTION AND THE ANTIDROMIC CORTICAL RESPONSE TO STIMULATION OF THE MEDULLARY PYRAMIDAL TRACT IN THE RAT

1. Adult rats (Wistar King A) were used, thirty-seven animals for recording antidromic cortical responses, five for observation of the motor effect of cortical stimulation and three for histological sections of the cerebral cortex.2. Electrical stimuli were applied to the medullary pyramidal tract in slightly anesthetized rats and the potential changes were recorded at the cortical surface and from various depths of the cortex.3. The resultant responses of the cortex consisted of an initial sharp positive wave (P I) followed by a secondary small positive wave (P II) and a slow negative wave (N). The P I had the lowest threshold to medullary pyramid stimulation and most faithfully followed the increase in frequency of stimulation up to a frequency of 300/sec.4. The distribution of the potential changes at various points of the cortical surface evoked with submaximal stimulation to the medullary pyramidal tract was measured. The maximal potential was recorded at a point 6.0 mm anterior from the line connecting the both ears and 3.0 mm lateral from the midline. The amplitude of the waves gradually decreased in the frontal direction from the maximal responsive point, and in the occipital direction it rapidly decreased to an immeasurably small level. The potential at the frontal pole was about one sixth of the maximum. In a lateral direction, the amplitude at a point 2.0 mm lateral from the midline was slightly small than at 3.0 mm and the amplitude both at 1.0 and 4.0 mm was about a half of that at 3.0 mm.5. The distribution of the antidromic cortical response coincided fairly well with the histological distribution of the pyramidal cell in the cerebral cortex of the rat.6. Recording from the depths of the cortex, the P I changed its polarity into a negative deflection at about 2.0 mm below the pial surface and the P II changed into a negative potential at a depth of about 1.5 mm. The N decreased to zero and sometimes seemed to reverse into a very small positive wave at about 1.5 mm below the surface.7. The above results suggest that the P I corresponds to antidromic impulses which invaded the large pyramidal cells in the deeper cortical layers with axons of faster conduction velocity and that the P II is composed of the antidromic impulses of the pyramidal neurons in the more superficial layers with axons of slower conduction velocity. It is considered that the N might represent the potentials of the apical dendrites of pyramidal cells conducting toward. the pial surface.8. The studies of cortical hemisphere stimulation reveal that the functional motor area occupies a part a little anterior to a location of the antidromic cortical response and the pyramidal cells.9. The functional significance of the pyramidal tract in the rat was discussed.