Some Biochemical Eactors That Modify the Transcephalic Dc Potential

Abstract

The transcephalic DC potential is that voltage recorded across the midline surface of the head between the frontal and occipital emissary vein distributions. Some psychophysiological correlates of this potential are described, and it is noted that little is known about the neuronal or biochemical modulation of it. Experiments are described using mature male cats, rabbits and rats as subjects. The frontal potential is found to shift progressively more positive as the depth of anesthesia increases. Pain causes a brief negative frontal shift and visceral irritation a positive one. Pinch mimics pain responses in etherized animals, but the DC shift is dampened in barbiturate anesthetized ones. Intracarotid injections of histamine and a histamine releaser produce a negative frontal shift. Heparin, serotonin, and nembutal produce positive frontal shifts. Epinephrine produces either a positive or negative shift, and potentiates the effects of histamine and serotonin. Histamine and serotonin combined produce a negative frontal shift. Many of these compounds are effective in 1/ig or smaller doses. These findings, plus further analyses of the persistence, magnitude, latency, and dosage relatedness of the shifts are presented.

Some Aspects of the Transcephalic Dc Circuit

“…3). Although not intended as a quantitative empirical determination of the TCDC potential effects of the stimuli used, none of the cortical responses to a particular stimulus differed in a statistically significant way from such data previously reported for TCDC scalp potential responses to these stimuli (Cowen and Ross, 1967). Of course, the lag for compounds given subcutaneously was much longer than for the same compounds injected by the intracarotid cannula.…”

“…Cats, rats and rabbits lack eccrine sweat glands on the head (Montagna, 1965) yet generate large, maintained, and functionally significant TCDC potentials (Cowen and McDonald, 1965;Cowen and Ross, 1967). Atropine and epinephrine are reported to block the GSR (Darrow, 1936;Wang, 1957;Wang, 1958) yet the former does not noticeably influence the TCDC potential (Cowen and McDonald, 1965), and the latter actually appears to increase the measurable voltage (Cowen and Ross, 1967). The skin-generated potential correlates with a decreased skin resistance, yet no studies have indicated that the transcephalically measured skin resistance is functionally correlated with psychophysiological events.…”

“…In previous papers the authors have described some of the functional correlates of the transcephalic DC potential (TCDC potential) which is recorded between electrodes placed on the midline cutaneous surface of the head over the frontal and occipital emissary vein distributions respectively (Cowen and jNIcDonald, 1965;Cowen, 1967;Cowen and Ross, 1967). In agreement with others who have reported on similarly recorded potentials (Becker, Bachman, and Friedman, 1962;Walter, Cooper, Aldridge, McCallum, and Winter, 1964;Walter, 1964), we have proposed that these surface recorded voltages reflect activity of the subjacent cortex.…”

“…Each set of electrodes was coupled to an Offner Dynagraph DC at two channels each, one set at 20 mv/cm and the other at .5 to .1 mv/cm. Paper speed was 5 mm/sec (Cowen and Ross, 1967). In two animals the skin was permitted to retract for a short recording time to assess the predicted influence of shearing forces on the emissary vein systems on scalp voltages, but the normal scalp position was rigidly maintained in all subsequent animals tested.…”