John Hanley

Non-Gaussian behavior of the EEG in Down's syndrome suggests decreased neuronal connections.

Computer analyses of the electroencephalograms of normal children, and children with Downs syndrome who were mentally retarded, revealed differences in the distribution of amplitude between the two groups. Normal children, in the early postnatal period, generate EEGs which have a non‐Gaussian distribution of amplitude that becomes increasingly Gaussian before one year of age and remains so throughout subsequent development. Conversely, the EEGs of children with Downs syndrome exhibit highly non‐Gaussian properties at all ages studied. The EEGs of two mentally retarded autistic children did not show this property, so it is not merely a concomitant of mental retardation. The first‐order Gaussian distribution may reflect the degree of inteneuronal coupling; since an increased number of connections on any neuron implies decreased functional dependence of that neuron on any other particular single neuron, the present evidence, which indicates stronger interneuronal coupling in mongoloids, suggests that Downs syndrome may be associated with incomplete postnatal development of interconnections between cortical neurons.

The Design and Use of an FM / AM Radiotelemetry System for Multichannel Recording of Biological Data

A multichannel telemetry system for EEG recording has been constructed for study of animal or human behavior correlates under natural, unrestrained conditions. To be useful in research of this kind, the transmitted radio signal must be independent of the environment, so that changes in antenna loading and in signal level cause no artifact. Standard IRIG proportional-bandwidth FM subcarrier channels are used. These subcarriers are generated by twin-T oscillators, modulated in turn by the amplified data signals. The FM subcarriers are then linearly summed and impressed upon a crystal-controlled AM transmitter. The system is also relatively insensitive to major shifts in supply voltage. Wherever possible, fabrication was by means of integrated circuits, thus reducing the bulk of the modules.

Combined telephone and radiotelemetry of the EEG

Abstract Multichannel local radiotelemetry of the EEG has been combined with onward transmission of the EEG data by telephone as frequency modulated audio subcarriers from the radio receiver located in the subjects house. Records are presented from a normal 10-year-old child, and are free from major artifacts. On-line spectral analysis was performed, together with acquisition of paper and analog magnetic tape records.

EEG findings in heroin addicts during induction and maintenance on methadone

This study investigated changes in the EEG of addicts initially on heroin as they progressed through the induction and maintenance phases of a methadone program. Spectral analysis of bipolar recordings revealed significant consistent differences only in the eyes-closed resting state. Patients under the influence of heroin showed large sharp peaks at 9-10 c/sec, particularly in the parieto-occipital recording. Methadone induction led either to marked reduction of this peak and widening of alpha band activity or to an increase in frequency of the alpha peak to 12 c/sec. After several months of methadone the alpha peak was still absent unless heroin abuse was present, a theta peak was present in three of four patients, and the alpha bandwidth remained broad. Changes in the theta band were more difficult to interpret.

EEG electrode-amplifier harness

Abstract An electrode-amplifier harness consisting essentially of a bathing-cap type helmet with snap-in sponge Ag/AgCl electrodes has been described. The system provides signal outputs at millivolt levels at low impedance and requires minimal preparation. It is compatible with cable and radiotelemetry systems and allows acquisition of physiologic data in active subjects on a non-interference basis.

A New Approach to Prosthetic Control: EEG Motor Signal Tracking With an Adaptively Designed Phase-Locked Loop

The feasibility of using brain waves to control an externally powered prosthetic device for amputees was investigated. Two subjects were studied; one normal and one with a right hand disarticulation. Each subject, otherwise at rest, performed the protocol of voluntarily, repetitively opening and closing his hand. The normal accomplished this, while the amputee attempted to use her missing limb as if it were present. The time between opening and the next closing, and between closing and the next opening, was approximately 2 s. Simultaneously with this procedure, electroencephglograms (EEGs) were recorded from scalp electrodes presumably overlying the motor cortex on the left side, and an electromyogram (EMG) was taken from right forearm surface electrodes. The EEG and EMG were recorded on a polygraph and on magnetic tape. The latter recording was later sampled at 128 samples/s and quantized to 2 10 levels.

Cryoablation of the Pituitary in the Treatment of Progressive Diabetic Retinopathy

Sixteen diabetic patients with sight-threatening progressive diabetic retinopathy who were carefully screened ophthalmologically, endocrinologically and medically, underwent stereotaxic transphenoidal pituitary cryoablation and were followed for an average of 26.2 months postoperatively. Hypophysectomy was complete or borderline in fifteen of the sixteen patients with no serious complications except chronic diabetes insipidus in one patient. Two patients died of nonsurgically-related conditions four and one-half and twentyfive months respectively after operation. Endocrine management was uncomplicated except for reversible cholestatic jaundice due to oral methyltestosterone in one patient. Insulin requirements were reduced in most instances following pituitary cryoablation. Ocular improvement occurred in ten of the sixteen patients with two patients stable, indicating a 75 per cent success rate. It is concluded that cryoablation offers a safe, reproducible, simple and effective method of pituitary ablation in well-selected patients with progressive diabetic retinopathy and threatening blindness.

Tracking the dominant frequency of the EEG by phase-locked loop demodulation

Abstract A method is described for tracking changes in the dominant frequency of the EEG on-line. It is based on the principle of phase-locked loop demodulation and uses a monolithic integrated circuit. The low cost (a few dollars), the small size and low power consumption of this device make it useful for long-term monitoring of the EEG.

Electroencephalographic Correlates of Verbally Induced Stress in Man

This article is a review of some of the sparse investigation of EEG concomitants of verbally induced stress. The difficulties encountered in good experimental design in this formidable area, which may account for the paucity of work, are discussed. A recent experiment in which spectral analysis of EEG played a prominent role, with spectral estimators selected as correlated with stressful questions, is presented in some detail. Autonomic measurements provided the stress indicators. The value of animal experiments for psychiatry in the investigation of stress is briefly examined.