Eric W. Howland

The effects of induced mood on laboratory pain

&NA; Sixty‐five subjects experienced 2 cold pressor immersions. Following the initial immersion, subjects participated in the Velten mood induction procedure by reading either depressive, neutral or elative statements. The sensory discriminative response to pain was measured by ratings of pain, and the affective‐reactive response to pain was measured by pain tolerance. Pain tolerance, but not pain ratings, were affected by mood inductions with subjects in the depression condition shortening their tolerance times more than the subjects in the neutral condition and the subjects in the elative condition increasing their tolerance times.

Tonic changes in alpha power during immersion of the hand in cold water

Phasic event-related desynchronization (ERD) of alpha activity briefly follows many types of stimulation. In order to define EEG changes resulting from longer stimulation. EEG records were made before and during hand immersion into cool and painfully cold water (cold pressor). Five minutes of 13-lead EEG records were obtained from 14 subjects for each condition. EEG frequency analysis was performed on artifact-free epochs from 60 to 240 sec following immersion. Following an initial phasic decrease in alpha power during cold water immersion, there was an augmentation of alpha power (8-12 Hz) in bilateral frontal and posterior electrodes. This augmentation was largely the result of an increase in the low alpha band (8-10 Hz). Alpha power at both central electrodes C3 and C4 changed little during cold water immersion. Cool water immersion produced less alpha power augmentation than cold water immersion. These observed changes were primarily in the high alpha band (10-12 Hz) and were larger in electrodes ipsilateral rather than contralateral to the stimulation. There was also an increase of beta bilaterally in frontal and posterior regions with cold water immersion. Our data demonstrate sustained topographic EEG responses during tonic stimulation from hand immersion in painfully cold water. These changes differ from those produced by stimulation with cool water immersion.

Whole head mapping of magnetic fields following painful electric finger shock

Painful intracutaneous electric finger shock was delivered to the fifth digit of the non-dominant hand of five healthy volunteers. Whole head evoked magnetic field maps were collected and cortical localizations were calculated using local sphere equivalent current dipole fits. MRI scans were used to identify the anatomical structures where magnetic field sources were located. Anatomically, sources were identified bilaterally in the primary somatosensory region and SII-Insula regions. Additionally, frontal operculum sources were observed contralaterally in two subjects. Temporally, an initial contralateral SI activation at 40-60 ms was followed by several SII-Insula responses over the next several hundred milliseconds (ms). These SII-Insula responses were often interspersed with additional activations of the SI region. These later responses were observed in both hemispheres.

Effects of Oral Morphine on Cold Pressor Tolerance Time and Neuropsychological Performance

We investigated the analgesic effects of escalating doses (0.214, 0.286, 0.357, and 0.429 mg/kg) of oral morphine on tolerance to painful cold pressor in a double-blind, active placebo-controlled (diphenhydramine) study in 45 normal volunteers. The highest dose of morphine administered is equivalent to the starting dose recommended by the Agency for Health Care Policy and Research for the management of cancer pain and acute postoperative pain. We assessed analgesia in terms of cold pressor tolerance time and self-reported ratings of pain intensity and unpleasantness. Subjects receiving the highest dose of oral morphine showed significantly higher tolerance time than subjects receiving diphenhydramine. Neither morphine or diphenhydramine significantly reduced ratings of pain intensity and unpleasantness. Neuropsychological testing revealed that the two highest doses of morphine impaired the episodic retrieval of a word list, but the same doses did not affect motor, perceptual, or attentional tasks.

Late pain-related magnetic fields and electric potentials evoked by intracutaneous electric finger stimulation ☆

Surface magnetic and electric recordings were used to localize the sources of late pain-related magnetic fields and electric potentials, evoked by painful intracutaneous electric finger stimulation. We find that the source of the P90m component of the evoked magnetic field lies in the finger area of the primary somatosensory cortex; the sources of the N150m and P250m are found to reside in the frontal operculum. These findings are unexpected from the evoked electric potential data, which suggest a central location for these sources. We also note that the interpretation of the electric data was confounded by the presence of an alpha-like oscillation, which overlapped many components of the evoked potential.

Ocular and stabilization feedback: An evaluation of two EMG biofeedback control procedures

This study evaluated the adequacy of two novel EMG biofeedback control procedures. During a single training session, 36 subjects received either (1) contingent EMG feedback from the frontal region (Veridical), (2) contingent feedback for vertical eye movements (Ocular), or (3) a feedback condition where the signal increased with deviations in any direction from baseline EMG levels (Stabilization). The results supported the use of Ocular but not Stabilization feedback as a control procedure in frontalis EMG biofeedback studies. Ocular feedback did not produce reductions in frontalis EMG but did lead to changes in subjective measures of nonspecific treatment effects that were at least comparable to those obtained with Veridical feedback. Stabilization subjects produced small but significant reductions in EMG, felt the most bored as a result of their feedback training, and were the most likely to rate themselves as having received false feedback. The implications of attribution theory and multiprocess relaxation theory for the evaluation of nonspecific treatment effects are discussed.

Comments on veerasarn and stohler, PAIN, 49 (1992) 349–360 and Chen et al., PAIN, 37 (1989) 129–141

First we want to thank Dr. Procacci for his comment on our paper. He mainly addresses two questions. The first concerns whether cervicogenic headache can be in part due to osteoarthritis in the cervical region. In a previous paper from our centre (Fredriksen, T.A. et al. 1989) radiological findings in the head and neck were studied in patients with cervicogenic headache. There were no signs of any traumatic or inflammato~ changes. This does, of course. in itself not exclude the possibility that osteoarthritis in part can give rise to pain fulfilling the criteria for cervicogenic headache. Nevertheless, we think that most cervicogenic headache patients have no such inflammatory or degenerative disorders. The second question raised by Dr. Procacci concerns the injection site for our greater occipital nerve (GON) blockade. Is the blockade effect due to trigger point injection or is anesthesia of the CON necessary’? We have not addressed this specific problem directly. and we think that such a study should be possible and the conclusion interesting. We have, however, tried to give some treatment to tender points in the neck and shoulder region of our cervicogenic headache patients. lntracutaneous sterile water injections, by others reported effective in whip-lash syndrome (Byrn et al. 19911, were of no avail in our patients (Sand et al.). It is also OUT impwssion that a proper pain-reducing effect of the injection depends on anesthesia in the GON territory. The scientific basis for this impression is, however, at this point sparse.

Neuromagnetic Localization of Late Pain-Related Field Sources

Since the early work of Chatrian et al. (1974), pain-related evoked potentials (PEPs) have been extensively investigated as possible physiological correlates of laboratory pain (see Chapman et al. 1979). The utility of PEPs is largely based upon studies which show that the amplitudes of the late potentials often correlate well with stimulus intensity and subjective report, and exhibit a consistent diminution when analgesic or behavioral pain control methods are introduced. It is also notable that for most types of stimulation, the dominant components of the evoked response occur at latencies near 150 and 250 ms (N150-P250), with largest amplitudes measured at the vertex. Hence, many studies have focussed specifically upon the N150-P250 as a likely correlate of laboratory pain.

Versatility in computer automation for biofeedback: The Behavioral Assessment and Rehabilitative Training System (BARTS)

User versatility in a system for computer-automated biofeedback training is the degree to which the assessment and training parameters may be altered by the users employing English language or other simple code, that is, without altering the systems applications software. The Behavioral Assessment and Rehabilitative Training System (BARTS) includes a design and control program that allows for the specification of assessment and training protocols by persons who are entirely lacking in computer programming skills. This paper describes the logic for data acquisition and training that is incorporated in the BARTS, describes the parameters that must be specified in constituting unique assessment or training protocols, and illustrates the systems application in a research-oriented biofeedback clinic.