Duane Denney

Pharmacological characterization of tardive dyskinesia

Tardive dyskinesia (TD) may be a clinical manifestation of a relative imbalance between the inversely related dopaminergic (DA) and acetylcholinergic (ACh) influences in the central nervous system (CNS). Six patients were evaluated with single challenge doses of a DA agonist, levodopa, and antagonist, droperidol, as well as with an ACh agonist, physostigmine, an antagonist, benztropine, and a placebo. A single blind trial with deanol and placebo followed. Responses, measured by an electrophysiological technique, formed two subgroups. The patients who improved with a DA antagonist or an ACh agonist improved while taking deanol. Another group of patients were made worse with a DA antagonist or ACh agonist and were worsened or had no response while taking deanol. While the results add support to the concept of counterbalancing DA-ACh influences in TD, further investigation of TD subtypes and predictors of drug response is warranted.

Orientation specificity of visual cortical neurons after head tilt

SummaryThe orientation specificity of the receptive fields of single neurons in primary visual cortex of the cat varied as a function of sustained head tilt in a sample of 33 cells. The types of variation suggested analogies to certain psychophysical phenomena. Orientation specificity of visual cortical cells may in part be determined by information from non-visual afferent systems.

Interactions between early life experience and biological factors in schizophrenia

THIS research is based on the life histories of 97 persons who through accident of birth and rearing were eligible for inclusions in a natural experiment bearing on the etiology of schizophrenia. Of these persons, 47 were born to schizophrenic mothers while the remaining 50 were born to mothers with no known history of psychiatric disorder. All mother-child pairs were permanently separated during the first two post-partum weeks. A comparison between these groups allowed assessment of the genetic contribution to schizophrenia where the effects of an environment distorted by the ambivalence and thinking disorder of a schizophrenic parent were separated from the effects of genes from such a parent. The separation of the children from their mothers entailed special rearing for the children. About one-half were partially reared in foundling homes and most of these subjects were eventually adopted. The remaining half were mostly reared in foster families, usually composed of relatives. This made possible assessment of the effects of several environmental variables.

The effects of applied polarization on evoked electro-cortical waves in the cat☆

Abstract 1. 1. Observations on the responsiveness, wave-form, pattern of pyramidal relayed activity, and thalamic threshold stimulus intensity were made during polarization of the cortex giving rise to recruiting and augmenting waves. 2. 2. Augmenting waves were more sensitive to alteration by polarization than were recruiting waves. 3. 3. The latency of the peaks was unchanged by polarization with the exception of the augmenting negativity during surface positive polarization. In this case, the initial responses in the train had a decreased latency which disappeared with the growth of augmenting positivity in the later responses. 4. 4. The net effect of surface positive polarization was an increase in the amount of negativity recorded in each response. Surface negative polarization produced the opposite effect. These changes were explainable on the basis of increases and decreases respectively in the negative component common to both responses. The qualitatively similar reaction to polarization in both phenomena was considered evidence for the idea that the negative components represent similar forms of activity. 5. 5. Polarization produced no change in thalamic stimulus threshold, or the pattern of relayed pyramidal activity. 6. 6. The results were discussed in detail. It was concluded that the effects of polarization were best explained on the basis of alterations produced in the resting membrane potentials of graded-response structures located in the superficial layers of the cortex.

An objective method for measuring dyskinetic movements in tardive dyskinesia

Abstract A simple technique for producing an objective electrophysiological record of abnormal mouth and finger movements in patients suffering from tardive dyskinesia is described. The method is non-invasive, simple, and acceptable for use in psychiatric patients.

Cortical projections of ascending nonspecific systems.

Abstract Areal distributions on cerebral cortex of several types of non specific activity were compared in cat. Spontaneous spindle bursts in pentobarbital and cerveau isole preparations, nonspecific cortical association responses evoked by peripheral stimuli in the chloralosed animal, and short latency cortical responses evoked by single shock stimulation of the midbrain reticular formation were all found to have essentially identical cortical distributions. These occurred in four major foci, two on the middle suprasylvian gyrus, one on the anterior lateral gyrus, and one on pericruciate cortex surrounding the cruciate sulcus.

The relationship between association responses and activity in the pyramidal tract

Abstract 1. 1. Correlation coefficients derived from comparison of the amplitude of association responses and the amplitude of the relayed pyramidal volley following auditory, visual and tactile stimuli were all highly significant. There was no correlation between primary auditory and visual responses and the pyramidal volley. Primary somatosensory responses evoked by contralateral tactile stimulation correlated with the pyramidal volley, but not as highly as with cortical responses elicited by ipsilateral stimuli. 2. 2. The responsiveness of the pericruciate cortex to a cortical stimulus was enhanced for 18–80 msec, then diminished for varying periods up to 500 msec following a peripheral stimulus in any of the three modalities. 3. 3. The results indicate that the association cortex of the pericruciate and other cortical association areas and efferent cortico-spinal fibers respond in a unitary fashion to a peripheral stimulus. The possible functional significance of these efferents is discussed.

Cortical control of specific and nonspecific sensory projections to the cerebral cortex

Activation of the frontal association response field of the cerebral cortex of cat by a brief train of electric shocks is shown to induce a subsequent marked depression of nonspecific evoked cortical association responses and an enhancement of the later components of evoked primary sensory responses. Both effects have been reported to accompany behavioral attending. The two effects of cortical stimulation can be differentiated by drug actions: strychnine abolishes the depression of association responses and picrotoxin abolishes the enhancement of primary responses. It is suggested that the frontal association response field may play a crucial role in the control of specific and nonspecific sensory projections to the cerebral cortex.

Inter-areal differences in the direct cortical response of the middle suprasylvian gyrus of the cat

Abstract 1. 1. A technique for comparing direct cortical responses (DCRs) evoked under comparable stimulating and recording conditions from various points in the middle suprasylvian gyrus was described. The method appeared to be reliable. 2. 2. Increasing stimulus intensity and varying anesthesia conditions both appeared to affect the amplitude of DCRs in ways which differed from one cortical locus to another. 3. 3. Inter-areal differences in amplitude of the response to a standard stimulus could be demonstrated which were independent of the differences due to other factors.