Characterstics of operant control of centrally evoked potentials in rats

EEG operant conditioning (biofeedback) and traumatic brain injury

A review is presented of the currently sparse literature about EEG operant conditioning or biofeedback as a treatment to reduce symptomology and patient complaints following a traumatic brain injury. The paper also evaluates the general use of quantitative EEG (QEEG) to assess traumatic brain injury and to facilitate EEG biofeedback treatment. The use of an age matched reference normative QEEG database and QEEG discriminant function are presented as a method to evaluate the nature or neurological basis of a patient's complaints as well as to individualize an efficient and optimal feedback protocol and to help evaluate the efficacy of the biofeedback therapy. Univariate and multivariate statistical issues are discussed, different classes of experimental designs are described and then a "double blind" research study is proposed in an effort to encourage future research in the area of EEG biofeedback for the treatment and rehabilitation of traumatic brain injury.

Effects of operantly conditioning the amplitude of the P200 peak of the SEP on pain sensitivity and the spinal nociceptive withdrawal reflex in humans

This study attempted to replicate and extend earlier work that reported that the amplitude of the P200 peak of the human somatosensory evoked potential (SEP) can be increased and decreased when reward is made contingent upon change and that these changes are accompanied by alterations in pain sensitivity. Twenty-one subjects were able to make the amplitude of the P200 peak evoked by sural nerve stimulation larger during increased training (up-training) than during decreased training (down-training). There were no differences in the sural nerve compound action potential between up-training and down-training. This finding demonstrates that the change in P200 amplitude was not due to a change in stimulus efficacy, but rather to a change within the central nervous system. Subjective pain ratings and a nociceptive spinal reflex were the same in up-training as in down-training. Thus, conditioned changes in P200 amplitude do not alter pain sensitivity.

Operant conditioning of somatosensory evoked potential (SEP) amplitude in rats. I. Specific changes in SEP amplitude and a naloxone-reversible somatotopically specific change in facial nociception

The aim of this experiment was to investigate possible endogenous opioid modulation of innocuous somatosensory activity. Somatosensory activity was measured by recording cortical somatosensory evoked potential (SEP) and reflex movement amplitude evoked by innocuous electrical stimulation of the spinal trigeminal tract in awake rats. Putative endogenous opioid activity was blocked using the opiate antagonist naloxone (1 mg/kg). The amplitude of midlatency SEP components (14-50 ms latency) increased following administration of naloxone and repeated stimulus presentations. The amplitude of these components decreased following administration of the opiate agonist morphine (3 mg/kg). An early cortical component (10 ms latency) habituated following the administration of saline but did not habituate following naloxone. Naloxone also enhanced habituation of the late SEP components (60-120 ms latency) and reflex movement evoked at higher stimulus intensities. Morphine decreased the amplitude of the early cortical component but had no consistent effect on the amplitude of the late SEP components.

Operant conditioning of the short-latency cervical somatosensory evoked potential in quadriplegics

Operant conditioning of short-latency cervical somatosensory evoked potentials (CSEP) was demonstrated in five cervical cord injury subjects. Subjects were conditioned to augment the N14 potential, thought to originate from the dorsal column nucleus. Increased N14 potential was associated with an increase in N19 and P22 potentials, and either a decrease (base) or no change (train) in the brachial plexus potential. The N19 potential was correlated with significant reductions in the sensation-twitch (S/T) ratio during conditioning sessions, indexing improved sensation to low-intensity percutaneous stimulation. Moreover, S/T ratios decreased significantly during conditioning sessions, and were reduced significantly relative to initial baseline values. The results do not appear to be associated with trivial mediating influences.

Operant conditioning of trigeminally-evoked cortical potentials: correlated effects on facial nociception

The effects of operant conditioning somatosensory evoked potential (SEP) amplitude on nociceptive sensitivity were studied in albino rats. SEPs were evoked by stimulation to the descending trigeminal tract. Rewarding medial forebrain bundle stimulation (at intensities predetermined to sustain bar pressing) was made contingent upon the animal making the amplitude of the SEP 0.5 standard deviation (S.D.) large (uptraining) or 0.5 S.D. smaller (downtraining) than the predetermined mean value. Nociceptive sensitivity was measured immediately following the conditioning session by heating the rat's face and noting the latency of a defensive face rubbing response directed at that area of the face. Increasing the amplitude of the SEP (uptraining) was associated with a decrease in noxious sensitivity. Decreasing the amplitude of the SEP (downtraining) was associated with an increase in noxious sensitivity.

Operant conditioning of trigeminal nuclear evoked potentials

The purpose of this study was to demonstrate operant conditioning of potentials in the rat's trigeminal complex evoked by stimulation of the primary descending trigeminal tract. The amplitude of the prominent component of the potential, with a peak at 10 to 22 msec after the stimulus, was conditioned. Reinforcement was electrical stimulation of the medial forebrain bundle. A bidirectional conditioning paradigm was used to control for noncontingent effects of the reinforcer. Eight of the thirteen animals demonstrated control of the evoked potential. Application of the neural conditioning paradigm to the investigation of loci of neuronal plasticity is discussed.