Jean-Claude Roy

Cortical and Hypothalamo-Limbic Control of Electrodermal Responses

Hughlings (1869) was among the first authors to report cortical influences upon the autonomic nervous system. Following Jackson’s studies, cardiovascular changes were elicited by stimulation of the frontal cortex (Danilewsky, 1875; Bochefontaine, 1876). At the beginning of this century, some authors (Bechterew, 1905; Karplus and Kreidl, 1909) also obtained an increase of sweating in the foot-pads of the cat, evoked by stimulating the sensorimotor cortex. During the next decades, other reports approached the role of cortical areas in the regulation of autonomic responses (see reviews of Kaada, 1951; Delgado, 1960; Hoff et al., 1963).

Asymmetry of electrodermal activity: a review

Before the seventies, with a few exceptions, electrodermal activity had been studied only unilaterally, presuming symmetry. Only in the seventies do a growing number of authors take an interest in electrodermal asymmetry, due in part to the enthusiasm evoked by theories of hemispheric specialization. The purpose of this paper is to clarify and summarize the data - often contradictory - collected on this subject and to point out some remaining problems.

Sensorimotor cortex projections to the ventrolateral and the dorsomedial medulla oblongata in the rat

After small pressure injections of Fluorogold (FG), and Dextran-tetramethylrodamine (DR) into the dorsal motor nucleus of the vagus/nucleus of the solitary tract (DMV/NTS) and the rostral ventrolateral medulla (RVLM), respectively, retrograde FG-labelled cells were found mainly in the sensorimotor cortex; retrograde DR-labelled cells were located in the same cortical areas and in the prefrontal cortex. Double-labelled cells were also found in the sensorimotor cortical areas. These results provide evidence of direct projections from the sensorimotor cortex to the DMV/NTS and RVLM and suggest that somatic cortical areas directly control cardiovascular output during sensory and somatic processes.

Neural Control of Electrodermal Activity: Spinal and Reticular Mechanisms

The existence of an electrical current related to sweating on the paws, and evoked by peripheral nerve stimulation, was first discovered in cats by (1878), a discovery which preceded by approximately ten years Fere’s (1888) well-known description of electrodermal activity (EDA) in humans (see Neuman and Blanton, 1970, and Bloch, this volume, for an historical account). (1890) accurately linked skin potential variations in humans with the functioning of the sweat glands. But (1927) was really the first to clearly demonstrate in humans the close relationship between the activity of the sweat glands and electrodermal activity.

Methodological problems in bilateral electrodermal research

Since the beginning of the 1970s, bilaterally recorded electrodermal activity (EDA) has generated a significant amount of research. It has been used in studies of hemispheric asymmetry, as well as in psychiatry as an indicator of left and right hemisphere activity. However an examination of the various studies which have utilized this technique does not show an overall consensus, and the results, as well as their interpretations, are often contradictory. These difficulties can partially be explained in terms of problems of methodology and interpretation. The aim of this paper is to review the methodological considerations, which have been grouped into 3 categories: stimulus specificity; the selection of subjects; and the measurement and interpretation of EDA.

Influence of skin temperature on latency and amplitude of skin potential responses in the cat.

The effect of skin temperature changes on skin potential response (SPR) amplitude and latency was examined in the cat. SPRs were elicited either by stimulating the reticular formation or the distal end of the median nerve. At room temperature, the latency due to the neuroglandular transmission and to the peripheral effector accounts for about half of the total latency of SPR evoked by reticular stimulation. This latency increases to several seconds at low skin temperatures (approximately 10 degrees C), decreases with temperature, and is minimal (300 msec) at high temperatures (over 40 degrees C). SPR amplitude increases with skin temperature, reaches a maximal value (usually around 30 degrees C) and then decreases at higher temperatures. The decrease of latency at higher temperatures confirms results previously obtained in humans. However, the mechanisms of amplitude decrease for high temperatures remain unclear.

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.

Reliability of spontaneous electrodermal activity in the cat as a function of waking and sleep stages

This study was designed to examine the reliability of spontaneous electrodermal activity (EDA) as a function of the stages of sleep and waking in freely moving cats. Five adult cats were observed during waking--sleep sessions. The results show that: (a) for all stages, the reliability of EDA is slightly higher for amplitude of SSPRs than for frequency; (b) during drowsiness, a maximum of reliability is observed, as is a slight decrease during slow wave sleep; during paradoxical sleep, reliability decreases greatly to below that of the waking level; (c) the reliability of spontaneous EDA appears to be higher in waking cats than that quoted for human subjects. These results are discussed with reference to individual characteristics and state variables.

OPIOID PEPTIDE INVOLVEMENT IN THE BULBAR INHIBITION OF ELECTRODERMAL ACTIVITY IN THE CAT

By analogy with supraspinal and spinal inhibitory controls of pain, it was hypothesized that an opioid mechanism could be involved in the bulbar inhibitory control of the electrodermal activity. This activity was evoked as skin potential responses on the footpads of 13 cats by the central tegmental field stimulation (control responses) and inhibited by the simultaneous stimulation of bulbar reticular formation (experimental responses). Then, naloxone, an opioid peptide antagonist, was injected intravenously or intrathecally and its effects were analyzed on both control and experimental responses. Intravenous injections of naloxone increased significantly the amplitude of experimental responses from 6 to 12 min after the injection and had no effect on the amplitude of control responses. Intrathecal injections of naloxone induced significant increases of amplitude of experimental responses from 6 to 42 min after the injection. These results showed that a spinal opioid peptide link could be involved in bulbar inhibition mechanisms of electrodermal activity.