Search PubMed⌕ Search

Biomedical subjects

O J Andy

Publications and source records attributed to O J Andy.

At least 19 recordsLinked to original sources
PubMed2000

Language representation in the human brain: evidence from cortical mapping.

The manner in which the human brain processes grammatical-syntactic and lexical-semantic functions has been extensively debated in neurolinguistics. The discreteness and selectivity of the representation of syntactic-morphological properties in the dominant frontal cortex and the representation of the lexical-semantics in the temporo-parietal cortex have been questioned. Three right-handed adult male neurosurgical patients undergoing left craniotomy for intractable seizures were evaluated using various grammatical and semantic tasks during cortical mapping. The sampling of language tasks consisted of trials with stimulation (experimental) and without stimulation (control) from sites in the dominant fronto-temporo-parietal cortex The sampling of language implicated a larger cortical area devoted to language (syntactic-morphological and lexical-semantic) tasks. Further, a large part of the fronto-parieto-temporal cortex was involved with syntactic-morphological functions. However, only the parieto-temporal sites were implicated with the ordering of lexicon in sentence construction. These observations suggest that the representation of language in the human brain may be columnar or multilayered.

Adult↗
PubMed1992

Stuttering acquired from subcortical pathologies and its alleviation from thalamic perturbation.

Acquired stuttering subsequent to subcortical pathology of mesothalamus was observed in four neurosurgical subjects. The patients suffered from chronic pain, seizures, and somatosensory disorders. They also exhibited unpredictable and uncontrollable speech, spasmodic blocks which were devoid of accessory features, and adaptation effect. Therapeutic mesothalamic stimulation, used as a treatment of last resort to relieve the pain and associated symptoms, also had an ameliorating effect on the stuttering. Spontaneously occurring focal abnormal EEG discharges were anatomically delineated and used as a guide for therapeutic stimulation electrode placement. Attentuation of the abnormal discharges was followed by alleviation of symptoms. This investigation examines the clinical characteristics of stuttering in four neurosurgical patients and suggests an electropathologic basis for their mesothalamic-generated speech dysfluencies. The cooccurrence of pain, seizures, somatosensory disorders, and stuttering, and their concurrent amelioration, suggests that both chronic pain and stuttering may be implicated by similar or related reticular electropathologic generators, couched in overlapping reticular networks extending from the brain stem to the thalamus, and that the acquired stuttering may be recruited as one component of a larger syndrome complex.

Adult↗
PubMed1992

Peritoneal neutrophil chemotaxis is impaired in biliary obstruction.

Previous studies have shown impaired reticuloendothelial function in biliary obstruction. The chemotactic response of polymorphonuclear leukocytes from peripheral blood and peritoneal fluid of jaundiced rats (Group 1) was compared to that of sham operated controls (Group 2) and normal rats (Group 3). Male Sprague-Dawley rats underwent bile duct ligation or sham celiotomy. Studies were performed from 1 to 3 weeks after surgery. Mean serum bilirubin was 6.8 mg percent in Group 1 and normal in Groups 2 and 3. Peritoneal neutrophils were induced by intraperitoneal injection of 10 ml of 10 percent peptone broth 16 hours before the study, harvested from peritoneal fluid and peripheral blood, and isolated on Ficoll-Hypaque. F-met-leu-phe (FMLP) chemoattractant (10(-7) M) was used to induce migration of neutrophils across 3 mu filters. The filters were removed, mounted on slides, stained, and counts averaged for five oil immersion fields for each of three wells. Data were expressed as number of neutrophils per oil immersion field. Peritoneal neutrophil chemotaxis was significantly decreased in Group 1 (10.3 +/- 8.1) compared with Groups 2 (17.0 +/- 7.3) and 3 (20.2 +/- 6.4). A similar trend was noted in polymorphonuclear leukocytes from peripheral blood (Group 1: 13.1 +/- 7.8, Group 2: 18.2 +/- 6.7, Group 3: 17.4 +/- 5.9; P = 0.1). This impairment in neutrophil chemotaxis may contribute to the high rate of septic complications observed in the jaundiced host.

Animals↗
PubMed1991

Thalamic-induced stuttering (surgical observations).

Repetitive dysfluencies of speech were elicited by mechanical perturbation of the thalamus in a patient, preparatory to therapeutic lesion placement for chronic pain. Perturbation consisted of a 2 mm advancement of a 1 mm diameter electrode in the posteroventromedial thalamus. A thalamogram revealed electropathologic discharges at the site of perturbation. These findings are of special interest anatomically because in other patients, electrical stimulation at the same site was found to alleviate stuttering (Andy, 1987; Andy, 1989; Andy & Jurko, 1985; Bhatnagar & Andy, 1989). It is suggested that dysfluencies in this patient may have resulted from an electrophysiologic disturbance of the mesothalamic component of a speech-regulating corticomesothalamic feedback circuit.

Adult↗
PubMed1989

The effect of thalamic stimulation in processing of verbal stimuli in dichotic listening tasks: a case study.

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct anatomic connection with the left dominant hemisphere. The role played by extralinguistic factors, such as attention and functional tuning of the associated cortical structures, has not been carefully examined. This investigation was undertaken to evaluate the effects of the left thalamic electric stimulation on the processing (recognition and recall) of dichotically presented CVC verbal stimuli in a patient being treated for chronic pain. We report the positive effects of electric stimulation (confirmed by increased subcortical metabolic activity using SPECT, a brain imaging technique) on the processing of dichotically presented verbal stimuli.

Attention↗
PubMed1989

Alleviation of acquired stuttering with human centremedian thalamic stimulation.

Despite many investigations, the cerebral mechanism for stuttering remains unknown. Recently, increased attention has been paid to acquired stuttering of adult onset in the hope that the events associated with it might provide clues to the biological mechanism underlying stuttering. This attention has focused exclusively on the cortical substrates. We present our observations of acquired dysfluency, presumably of subcortical origin in a neurosurgical subject with intractable pain. The stuttering was relieved by thalamic electric stimulation. The effect of thalamic stimulation on the stuttering suggests that the pathophysiology of transient asynchronisation in the balancing and sequencing of multiple impulses is amenable to a diffusely orchestrated functional tuning of the thalamic and brainstem implicated subcortical structures and pathways.

Brain Stem↗
PubMed1989

Mesothalamic discharge sites.

The underlying electrophysiologic abnormality in patients with chronic pain syndrome is demonstrated in 2 patients whose pain and associated symptoms were incapacitating. Mechanical perturbation evoked discharges most easily at the mesodiencephalic junction. Discharging tissue at that level appears to be oriented in both the transverse and sagittal planes. Since the area of involvement is relatively large and nonspecific, it is believed that the reticular formation is the major substrate for generating and propagating the discharges.

Adult↗
PubMed1989

Post concussion syndrome: brainstem seizures, a case report.

Following head injury and associated unconsciousness, a 19 year old woman developed chronic intractable headaches, absence attacks and a cluster of other symptoms which did not respond to conventional medical therapy. During the course of implanting a brain stimulation electrode for the treatment of chronic and recurring incapacitating headaches, diagnostic electrographic recordings revealed focal abnormal discharges in the mesothalamus. Electrical stimulation attenuated the discharges and alleviated the headaches and associated symptoms. A retrospective analysis of this case suggested that a head injury-induced brain stem gliosis was the source of the brainstem abnormal discharges. It is speculated that various biologic systems represented within the brainstem were implicated by the reticular formation generated discharges. Symptoms making up the chronic pain syndrome were thus thought to emanate from the electric malfunctioning of those biologic systems.

Adult↗
PubMed1987

Thalamic stimulation effects on reactive depression.

Depression was evaluated in 10 patients before and after therapeutic mesothalamic brain stimulation for chronic pain. Minnesota multiphasic personality inventory T scores for depression were high in all patients before stimulation. Scores were decreased in 8 of 10 patients with chronic deep brain stimulation, three of whom returned to normal. Pain relief was good to excellent in 9 of 10 patients. It is concluded that depression is secondary to pain or pain-inducing factors which implicate the catecholamine and serotonergic systems.

Adjustment Disorders↗
PubMed1987

Chronic pain syndromes.

Brainstem-scalp discharge propagation was evaluated in 20 patients with chronic pain, of which 10 were ranked according to the frequency of involved systems making up the chronic pain syndrome. It is concluded that brainstem discharges alone were sufficient to generate the chronic pain syndrome.

Brain Stem↗
PubMed1987

Double vision corrected by thalamic stimulation.

Three patients with chronic headaches also complained of double vision. Additional findings were bilateral eye blinking in 1 patient and ipsilateral eye roll in another which became synchronous with heart rate during perturbation of the mesothalamic area. Mesothalamic stimulation attenuated the discharges and the above signs and symptoms. Mechanisms underlying these ocular disturbances are discussed.

Diplopia↗
PubMed1987

Thalamic functional tuning of the cortex in dichotic listening tasks.

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct access to the linguistically dominant left hemisphere. The roles played by the extralinguistic factors, such as induced attentiveness and functional tuning of the auditory system, have not been carefully examined. The evidence for the facilitating effects of subcortical stimulation on processing dichotic stimuli is presented.

Dichotic Listening Tests↗
PubMed1986

Seizure control by mesothalamic reticular stimulation.

A 53 year old woman with chronic back pain and headaches also was considered to have a reticular formation generated "absence status." Both the chronic pain and the absence status were relieved by electrical stimulation in the mesothalamic reticular formation. The various psychologic and physiologic factors contributing to the patient's illness were analyzed and presented to demonstrate the progression of the illness. The discussion considers electrical "mini-discharges" in the reticular formation as the generator of the absence status and associated chronic pain. Therapeutic reticular stimulation electrically "jams" the reticular "mini-discharge" generator and thereby alleviates the absence attacks and pain.

Electric Stimulation Therapy↗
PubMed1985

Absence attacks controlled by thalamic stimulation.

Thalamic electrical stimulation in 3 patients alleviated chronic pain, absence attacks and spontaneously occurring delta and theta EEG discharges. It is suggested that diencephalic discharges may activate and/or lower the threshold for pain at the level of the diencephalon.

Adult↗
PubMed1985

Seizures and pain.

The findings of this case report do not answer the question of whether or not the slow wave discharge specifically represents a permutation of the K-complex. However, the slow wave discharge and the K-complex may be "bed partners" in part, with both residing in the same reticular activating system. It is therefore concluded that the reticular formation which harbors the arousal system also generates the slow wave discharges in this case. The discharge in turn activates the pain and other subsystems within the same reticular core to produce the associated somato-sensory, visceral and autonomic disturbances.

Adult↗
PubMed1984

Right-hemispheric language evidence from cortical stimulation.

While the left-hemispheric dominance for language in most right-handers is unquestionable, clinical observations suggest that the right, nondominant hemisphere has a considerable capacity for language. Under certain neuroanatomical conditions, the right-hemispheric capacity becomes functional and, thus, measurable. This study focuses on evoked language responses during electrical stimulation of the right hemisphere in three left-dominant patients undergoing temporal lobe resections for medically intractable seizures.

Brain Mapping↗
PubMed1983

Language in the nondominant right hemisphere.

Language function was evaluated in the right nondominant hemisphere in three patients undergoing cortical resection for intractable seizures. Three linguistic tests were given during electrical stimulation of the cortex. They represented three different levels of language complexity from lowest to highest as follows: task 1, object naming; task 2, sentence completion; and task 3, responsive naming. The greatest number of linguistic errors occurred with sentence completion. No linguistic errors were made on the most complex task. Wada's test in the right nondominant hemisphere did not impair function, whereas in the left dominant hemisphere it did. To make these seemingly incompatible observations acceptable, we speculate that there is a right nondominant language system that is anatomically and functionally tied to the left dominant system. Under normal conditions it is passively involved and its integrity is not essential to the function of the left dominant language system.

Adult↗