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PubMed2004

Intensive language training enhances brain plasticity in chronic aphasia.

BACKGROUND: Focal clusters of slow wave activity in the delta frequency range (1-4 Hz), as measured by magnetencephalography (MEG), are usually located in the vicinity of structural damage in the brain. Such oscillations are usually considered pathological and indicative of areas incapable of normal functioning owing to deafferentation from relevant input sources. In the present study we investigated the change in Delta Dipole Density in 28 patients with chronic aphasia (>12 months post onset) following cerebrovascular stroke of the left hemisphere before and after intensive speech and language therapy (3 hours/day over 2 weeks). RESULTS: Neuropsychologically assessed language functions improved significantly after training. Perilesional delta activity decreased after therapy in 16 of the 28 patients, while an increase was evident in 12 patients. The magnitude of change of delta activity in these areas correlated with the amount of change in language functions as measured by standardized language tests. CONCLUSIONS: These results emphasize the significance of perilesional areas in the rehabilitation of aphasia even years after the stroke, and might reflect reorganisation of the language network that provides the basis for improved language functions after intensive training.

Adult↗

PubMed2000

Dysfunction of the auditory cortex persists in infants with certain cleft types.

Language and learning disabilities occur in almost half of individuals with oral clefts. The characteristics of these cognitive dysfunctions vary according to the cleft type, and the mechanisms underlying the relation between cleft type, cognitive dysfunction, and cleft-caused middle-ear disease are unknown. This study investigates preattentive auditory discrimination, which plays a significant role in language acquisition and usage, in infants with different cleft types. A mismatch negativity (MMN) component of brain evoked potentials, which indexes preconscious sound discrimination, and brain responses to rare sine-wave tones were recorded in 12 healthy infants and 32 infants with oral clefts at the ages of 0 and 6 months. Infants with clefts were subdivided into two categories: those with cleft lip and palate (CLP) (n=11 at birth, n=6 at the age of 6 months) and those with cleft palate only (CPO) (n=17 at birth, n=8 at the age of 6 months). At both ages, brain responses to rare sounds tended to be smaller in both cleft subgroups than in healthy peers. However, in the latency range of 300 to 500 ms, the MMN was significantly smaller in infants with CPO. In infants with CLP, the MMN was comparable to that of healthy infants. Differences in auditory discrimination between infants with CLP and CPO, as reflected by MMN, were detectable at birth and persisted into later infancy. This pattern parallels known behavioural differences between children with these cleft types. Brain responses to rare sounds, in contrast, had no differentiative power with respect to the cleft type.

Auditory Cortex↗

PubMed1990

Interleukin-1 receptors in mouse brain: characterization and neuronal localization.

The cytokine interleukin-1 (IL-1) has a variety of effects in brain, including induction of fever, alteration of slow wave sleep, and alteration of neuroendocrine activity. To examine the potential sites of action of IL-1 in brain, we used iodine-125-labeled recombinant human interleukin-1 [( 125I]IL-1) to identify and characterize IL-1 receptors in crude membrane preparations of mouse (C57BL/6) hippocampus and to study the distribution of IL-1-binding sites in brain using autoradiography. In preliminary homogenate binding and autoradiographic studies, [125I]IL-1 alpha showed significantly higher specific binding than [125I]IL-1 beta. Thus, [125I]IL-1 alpha was used in all subsequent assays. The binding of [125I]IL-1 alpha was linear over a broad range of membrane protein concentrations, saturable, reversible, and of high affinity, with an equilibrium dissociation constant value of 114 +/- 35 pM and a maximum number of binding sites of 2.5 +/- 0.4 fmol/mg protein. In competition studies, recombinant human IL-1 alpha, recombinant human IL-1 beta, and a weak IL-1 beta analog. IL-1 beta +, inhibited [125I]IL-1 alpha binding to mouse hippocampus in parallel with their relative bioactivities in the T-cell comitogenesis assay, with inhibitory binding affinity constants of 55 +/- 18, 76 +/- 20, and 2940 +/- 742 pM, respectively; rat/human CRF and human tumor necrosis factor showed no effect on [125I]IL-1 alpha binding. Autoradiographic localization studies revealed very low densities of [125I]IL-1 alpha-binding sites throughout the brain, with highest densities present in the molecular and granular layers of the dentate gyrus of the hippocampus and in the choroid plexus. Quinolinic acid lesion studies demonstrated that the [125I]IL-1 alpha-binding sites in the hippocampus were localized to intrinsic neurons. After hypophysectomy, homogenate binding and autoradiographic studies showed that there was no apparent change in the relative density of IL-1 receptors in the hippocampus. The identification of IL-1 receptors in brain with characteristics similar to IL-1 receptors in immune and neuroendocrine tissues provides further support for a physiological role for IL-1 to regulate central nervous system activity.

Animals↗

PubMed1990

Cochlear potentials and auditory evoked potentials in the caiman (Caiman crocodilus (L.)).

Brain-stem auditory evoked potentials (BAEPs) and round window compound action potentials (CAPs) in response to rarefaction and condensation clicks were recorded from anaesthetized and artificially respired caiman. The recorded wave forms were substantially different from the brain-stem and round window potentials recorded in mammals, including man. In particular, wave latencies were much longer than in mammals. Wave amplitudes increased and latencies decreased significantly and reversibly with increases in stimulus intensity and body temperature. The latencies of the first positive wave (P1) in the BAEP and the first negative wave (N1) in the CAP are correlated and co-vary with stimulus level and body temperature. BAEP P1 thus represents the response of the auditory nerve. The cochlear microphonic (CM) latency in caiman is unaffected by stimulus intensity and by cooling of the animal.

Action Potentials↗

PubMed1995

Suppression of Ottoson waves in the isolated olfactory bulb during sleep in the pontine cat.

In the chronic pontine cat, in which the olfactory bulbs are isolated from the brain stem, the Ottoson and/or Adrian-induced waves are suppressed during paradoxical sleep. This phenomenon cannot be explained by a central centrifugal control. The suppression of olfactory electrical activity was found to correlate with vasodilatation of the nasal mucosa. It is likely, therefore that control of the olfactory bulb activity might be mediated through the vasomotor innervation of the nasal mucosa originating from the medulla.

Animals↗

PubMed2001

Synaptic transmission with the glia.

For decades, scientists thought that all of the missing secrets of brain function resided in neurons. However, a wave of new findings indicates that glial cells, formerly considered mere supporters and subordinate to neurons, participate actively in synaptic integration and processing of information in the brain.

Calcium Signaling↗

PubMed1984

Augmentation of the auditory event related potentials of the brain during diastole.

Previous studies demonstrated that stimuli synchronized with systolic and diastolic phases of the pulse pressure wave enhanced the visual event related potentials (ERPs) of the brain. The present study extended these observations to the auditory ERP in passive and attentional conditions. Pure tones were synchronized with systolic and diastolic phases of the cephalic and palmar arteries. During one condition, subjects were paid a bonus for reporting accurately the number of times they heard a tone (attention condition) and in a second condition they listened passively (non-attend). Stimuli synchronized with the diastolic phase, reliably produced augmentation of the N1 component across all conditions. The N2 component was smaller in the right hemisphere of attentive subjects when stimulation was synchronized with diastole. These results were discussed in the context of the cognitive psychophysiology proposed by Picton and Hillyard (1974).

Adult↗

PubMed1994

[Auditory results after transtemporal removal of acoustic neurinoma].

A retrospective study was conducted to assess results of hearing in patients who underwent resections of acoustic neuromas via the middle fossa approach. A statistical correlation of results with preoperative clinical and audiological data determined if any prognostic indicators could be associated with successful preservation of hearing. Of 93 patients included in the study, useful hearing was preserved in 54 (58%), while hearing was preserved within 10 dB of preoperative levels in 42 patients (45%). The possibility for hearing preservation appeared to be inversely related to the size of the acoustic tumor, with hearing preserved in 39 of 65 patients (60%) with tumors less than or equal to 0.5 cm. Preoperative hearing levels and electronystagmography seemed to have no prognostic value. However, auditory brain stem responses showed that a wave V latency of less than 6.8 msec was associated with an increased chance of hearing preservation. Additionally, the presence of vertigo as a pre-operative complaint appeared to be a good prognostic indicator for successful hearing preservation.

Adult↗

PubMed1999

Patterns of immediate early gene mRNA expression following rodent and human traumatic brain injury.

Cell stimulation which leads to degeneration triggers a prolonged wave of immediate early gene (IEG) transcription that correlates with neuronal demise. In order to determine the relevance of the prolonged IEG response to human traumatic brain injury, we analyzed IEG mRNA levels in brain tissue isolated following a controlled penetrating injury and an injection of the excitotoxin Quinolinic acid (QA), as well as from tissue recovered during routine neurosurgery for trauma. Total RNA was extracted from tissue and subjected to Northern analysis of IEG mRNAs (c-fos and zif/268). Both models produced rapid and prolonged waves of IEG transcription that appeared to correlate with the severity of injury. Increases in zif/268 mRNA were observed within 1 h with levels reaching their peak at 6 h following excitotoxic injury and 3 h following a controlled penetration. In general, human traumatic brain injury resulted in variable increases in IEG mRNA levels following traumatic injury with the largest IEG mRNA increases observed in tissue collected 0-10 h after injury. This post-injury time corresponds to the peak of the prolonged IEG response observed in rodents following excitotoxic injury. Comparisons were made in IEG response between rodent frontal cortex and human cortex, because the majority of the human tissue originated from the cerebral cortex. These results further support the hypothesis that prolonged IEG transcription serves as a marker of traumatic brain injury and may play a role in neurodegeneration and/or glial activation. Moreover, observations of similar IEG patterns of expression reinforces the importance of rodent models of brain injury providing useful information directly applicable to human brain injury.

Animals↗

PubMed1994

Cerebral energy metabolism following ESWL brain injury model and effects of cerebral protective drugs.

The goal of this study was to introduce a new method inducing an experimental brain injury model using ESWL(Extracorporeal Shock Wave Lithotripsy) and to evaluate findings of localized lesions on 1H MR imaging and the response of cerebral energy metabolism using a 31P MR spectroscope to the ESWL brain injury in cats. This study also examined effects of cerebral protective drugs. 1) There were no statistically significant changes in pH at all measurement points. 2) In the trauma group, initial decrease of PCr/Pi was seen at 30 to 60 minutes with return to control levels by 2 hours after injury(P < 0.05), followed by a second decline at 4 hours which lasted until 8 hours after injury. 3) Significant recovery in PCr/Pi(P < 0.05) was observed in both the THAM and dexamethasone treated groups at all measurement points and in the mannitol treated group only temporary recovery at 30 and 60 minutes (P < 0.05). 4) High intensity signals were seen on 1H MR imaging in traumatized animals. This study demonstrated the immediate and persistent recovery of cerebral energy metabolism using THAM or dexamethasone and an immediate but transient effect with mannitol in traumatized animals.

Adenosine Triphosphate↗

PubMed2000

Spreading depression-induced cyclooxygenase-2 expression in the cortex.

Spreading depression (SD) is a wave of sustained depolarization challenging the energy metabolism of the cells without causing irreversible damage. However, brain injury, especially focal ischemic stroke, triggers SD-like waves, which in the vicinity of the original damage site contribute to enlargement of the dying brain tissue. Brain injury induces expression of several genes, which are thought to play a role in neuronal death, and therefore represent potential targets for therapy. One such gene is cyclooxygenase-2 (COX-2), an inducible prostaglandin and superoxide producing enzyme. Here we review our recent studies on the regulation of COX-2 in SD.

Animals↗

PubMed1987

Oscillatory potentials of visually inattentive children.

The oscillatory potentials (OPs) are probably generated in the proximal retina. The OPs of 20 visually inattentive infants and children were recorded. All 20 had evidence of abnormalities of the visual parts of the brain. The a- and b-waves, indices of distal retinal function, were normal in 10 patients, abnormal in the other 10. Among the patients with abnormal, attenuated a- and b-waves, OP amplitudes were more attenuated than among those with normal a- and b-waves. However, the timing of the OP wavelets was not correlated with distal retinal activity. These results suggest that in humans OP amplitude may be determined by inputs from the distal retina, but OP latency and periodicity are governed by processes within the proximal retina.

Adult↗

PubMed1986

[Dynamic thermomapping of the brain of the rat during sensory stimulation and spreading depression].

Dynamics of spatial distribution of temperature over the dorsal surface of white rat cerebral cortex was studied through the skull with the thermovision technics. Visual, somatosensory and acoustic stimulation revealed both diffuse and regionally specific thermoreactions of the brain as well as multiple local termoresponses. After injection of KCl into the cortex temperature waves spreading over the cortex were obtained. Mechanisms of brain patterned thermoreactions dealing with blood flow and neuronal metabolic thermoproduction are discussed.

Animals↗

PubMedDate not supplied

Brain-stem auditory evoked responses as indicators of early brain insult.

The relationship between cranial ultrasonograms (SONOs) and brain-stem auditory evoked responses (BAERs) was evaluated in 2 independent samples of newborn infants at risk for brain injury (n = 113 and 203). Features of the BAER wave forms subjected to stepwise linear discriminant analysis formed the basis of an algorithm used to detect and follow early brain injury. Using this algorithm, information derived from BAERs reliably predicted SONO abnormalities at least 82.3% of the time in the initial study which was replicated with the second sample (77.3%). The wave I component latency (CL) and the wave III-V inter-peak latency interval (IPL) were independent of each other, and both contributed to a prediction of SONO abnormality. Possible mechanisms for these BAER results include compromise to the cochlear membrane or to the auditory nerve itself as well as prolongation of transmission in the brain-stem due to brain-stem hemorrhage, edema, or compression. Normative BAER values and non-linear regression functions for the wave I, III and V CLs, and the I-III, III-V, and I-V IPLs were calculated across age using data from 109 infants who demonstrated normal BAER patterns and had no history of SONO abnormalities. Our analyses indicate BAER techniques, where a single higher intensity is used to produce the BAER wave form, are both valid and efficient for use in the evaluation of early brain injury.

Brain Injuries↗

PubMed1987

Low-level microwave irradiations affect central cholinergic activity in the rat.

Sodium-dependent high-affinity choline uptake was measured in various regions of the brains of rats irradiated for 45 min with either pulsed or continuous-wave low-level microwaves (2,450 MHz; power density, 1 mW/cm2; average whole-body specific absorption rate, 0.6 W/kg). Pulsed microwave irradiation (2-microseconds pulses, 500 pulses/s) decreased choline uptake in the hippocampus and frontal cortex but had no significant effect on the hypothalamus, striatum, and inferior colliculus. Pretreatment with a narcotic antagonist (naloxone or naltrexone; 1 mg/kg i.p.) blocked the effect of pulsed microwaves on hippocampal choline uptake but did not significantly alter the effect on the frontal cortex. Irradiation with continuous-wave microwaves did not significantly affect choline uptake in the hippocampus, striatum, and hypothalamus but decreased the uptake in the frontal cortex. The effect on the frontal cortex was not altered by pretreatment with narcotic antagonist. These data suggest that exposure to low-level pulsed or continuous-wave microwaves leads to changes in cholinergic functions in the brain.

Animals↗

PubMedDate not supplied

[Effect of diazepam and phenazepam on Leao's depression in brain edema].

Experiments on rats with brain edema under water intoxication were made to examine the effect of the benzodiazepine tranquilizers diazepam and phenazepam on the time course of the recovery of brain electrical activity after passing the spreading Leao's depression wave. It was found that the drugs indicated possess antiedematous properties and improve brain function under these conditions. It is assumed that the drug action on the spreading depression is linked with their effect on metabolic processes in the brain and antiedematous properties.

Animals↗

PubMed1988

Central organization of wave localization in the clawed frog, Xenopus laevis. I. Involvement and bilateral organization of the midbrain.

The central nervous organization of water wave localization in the clawed frog Xenopus laevis was investigated by performing behavioral tests on frogs that had various brain ablations. The criterion of localization was the orientation of response turns toward the origin of stimulus waves. After complete midbrain ablation, Xenopus still detected impinging waves but could not localize them. After thalamopretectal ablation, however, Xenopus localized waves with normal accuracy. Thus, wave localization can be accomplished in the brainstem, and the midbrain is necessary for it. After forebrain ablation, the frogs no longer responded to water waves, which shows that higher brain centers modulate localization. Tectal lesions that spared the ventrolateral tectum did not abolish localization. After unilateral extirpation of tectum and torus, all ipsilateral waves were localized, but contralateral waves were not. This indicates a functional chiasm for the determination of wave directions in the midbrain. Total localization failure after unilateral midbrain destruction demonstrates that wave localization also requires the ipsilateral motorial tegmentum. When wave localization was abolished, a residual correlation between stimulus directions and response angles remained.

Animals↗

PubMed1976

Histochemical fluorescence studies of brain monoamines in goldthioglucose-treated rabbits.

Fluorescence histochemical experiment of brain monoamines and chemical analysis of brain 5-hydroxytryptamine (5-HT) in goldthioglucose (GTG)-treated rabbits were performed. The fluorescence of brain catecholamines (CA) and 5-HT were strengthened in intensity until first week after treatment and reduced from second week. Body weight in GTG-treated rabbits showed decreasing tendency in the period when monoamine fluorescence was strengthened and increased when monoamine fluorescence was lowered in intensity. Content of brain 5-HT second day after treatment showed an increasing tendency in the cortex. In comparison with EEG findings by Matsumura, it is speculated that there is correspondence between slow wave in EEG and increased fluorescence of brain monoamines and between spiky and decreased fluorescence.

Animals↗