@article {3275,
	title = {Chronic exposure of primates to 60-Hz electric and magnetic fields: II. Neurochemical effects.},
	journal = {Bioelectromagnetics},
	volume = {10},
	year = {1989},
	month = {01/1989},
	pages = {289{\textendash}301},
	abstract = {We exposed Macaca nemestrina (pig-tailed macaques) to electric (E) and magnetic (B) fields ranging in intensity from 3 kV/m and 0.1 G to 30 kV/m and 0.9 G for three 21-day (d) periods. Experimental animals were exposed to sham E and B fields for two 21-d periods, one prior to and one following actual exposure to E and B fields, resulting in a total of five 21-d periods. Control animals were exposed to sham E and B fields for the entire 105-d interval. At the end of each 21-d period cerebrospinal fluid (CSF) was obtained by lumbar puncture and analyzed for concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), metabolites of dopamine and serotonin neurotransmitters, respectively, by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Results are based on an examination of six experimental and four control animals. Exposure to E and B fields at all strengths was associated with a significant decline in CSF concentrations of both HVA and 5-HIAA when statistical comparisons were made against values obtained at the end of the preexposure interval. However, HVA returned to preexposure levels during the postexposure period, while 5-HIAA did not. No significant change in the concentrations of HVA or 5-HIAA was noted in the control animals. These results strongly suggest that exposure of the nonhuman primate to E and B fields can significantly affect specific biochemical estimates of nervous system function. These effects may involve alterations either in neuronal activity or in the activity of enzymes that catabolize the neurotransmitters.},
	keywords = {Neurotransmitter Agents},
	issn = {0197-8462},
	doi = {10.1002/bem.2250100307},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2473755},
	author = {Seegal, R. F. and Jonathan Wolpaw and Dowman, R.}
}
@article {3273,
	title = {Chronic exposure of primates to 60-Hz electric and magnetic fields: I. Exposure system and measurements of general health and performance.},
	journal = {Bioelectromagnetics},
	volume = {10},
	year = {1989},
	month = {01/1989},
	pages = {277{\textendash}288},
	abstract = {We exposed pigtailed macaques (Macaca nemestrina) to electric (E) and magnetic (B) fields at strengths of 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G for three 21 day segments. These three exposure segments were preceded and followed by 21 day sham exposure segments. Additional animals received only sham exposure for five 21 day segments. Detailed description of the exposure chamber and field generation apparatus is given. We evaluated measures of animal well-being, including weight, blood chemistry, blood cell counts, and performance on a simple motor task, and performed postmortem examinations. Reliable and consistent results were obtained throughout data collection. None of the measures evaluated was significantly affected by E- and B-field exposures. Data obtained during actual exposure segments were not distinguishable from those obtained during the initial and final sham exposure segments, nor were they different from data obtained from the sham-exposed animals. Thus, field exposure had no apparent effects on general health or performance.},
	keywords = {60-Hz fields, central nervous system, electric field, magnetic field, primate},
	issn = {0197-8462},
	doi = {10.1002/bem.2250100306},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2751702},
	author = {Jonathan Wolpaw and Seegal, R. F. and Dowman, R.}
}
@article {3272,
	title = {Chronic exposure of primates to 60-Hz electric and magnetic fields: III. Neurophysiologic effects.},
	journal = {Bioelectromagnetics},
	volume = {10},
	year = {1989},
	month = {01/1989},
	pages = {303{\textendash}317},
	abstract = {The neurophysiologic effects of combined 60-Hz electric (E) and magnetic (B) fields, of magnitudes comparable to those produced by high-voltage powerlines, were investigated in 10 monkeys (Macaca nemestrina). Six animals (experimental group) were each exposed to three different levels of E and B fields: 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G. Field exposures were preceded and followed by sham exposures, during which factors of field generation were present (e.g., heat, vibration, noise, etc.) without E and B fields. Each of the five segments (i.e., the three exposure segments and the initial and final sham exposure segments) lasted 3 weeks. Animals were exposed for 18 h/day (fields on at 1600 h, off at 1000 h). Four other animals (external control group) were given sham exposure for the entire 15-week period. Auditory, visual, and somatosensory evoked potentials were recorded twice a week, during the daily 6-h field-off period. E- and B-field exposure had no effect on the early or mid-latency evoked potential components, suggesting that exposure at these levels has no effect on peripheral or central sensory afferent pathways. However, there was a statistically significant decrease in the amplitudes of late components of the somatosensory evoked potential during the 10kV/m and 0.3 G, and 30 kV/m and 0.9 G exposure levels. This result is possibly related to the opiate antagonist effect of electromagnetic field exposure reported by others.},
	keywords = {60-Hz electromagnetic radiation, auditory, brainstem auditory, evoked potential, primates, somatosensory, visual},
	issn = {0197-8462},
	doi = {10.1002/bem.2250100308},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2751703},
	author = {Dowman, R. and Jonathan Wolpaw and Seegal, R. F. and Satya-Murti, S.}
}
@article {3276,
	title = {Diurnal rhythms in primate spinal reflexes and accompanying cortical somatosensory evoked potentials.},
	journal = {Electroencephalography and clinical neurophysiology},
	volume = {72},
	year = {1989},
	month = {01/1989},
	pages = {69{\textendash}80},
	abstract = {We recorded spinal reflexes and cortical somatosensory evoked potentials (SEPs), elicited by stretching the biceps or the triceps muscle or by electrically stimulating the posterior tibial nerve, from monkeys throughout the day. Amplitudes of the spinal stretch reflex (SSR) and of its electrically evoked analogue, the H-reflex, varied diurnally: both were greatest midway through the lights-off period and smallest during the lights-on period. Stretch-evoked and electrically evoked SEP amplitudes also varied diurnally, but were out of phase with the spinal reflex rhythms. The H-reflex is elicited by direct stimulation of the nerve and thus, unlike the SSR, bypasses the muscle spindle. The H-reflex diurnal rhythm and the phase difference between the spinal reflex and SEP diurnal rhythms indicate that these rhythms are mediated at least in part by central mechanisms. Furthermore, both the spinal reflex and SEP diurnal rhythms appeared to be entrained by the light-dark cycle, which suggests that they may be coupled to the same oscillator. Besides their theoretical importance, these rhythms have important implications for experimental and clinical studies of spinal reflexes and SEPs. These rhythms are especially pertinent to the interpretation of long-term monitoring studies, as are often carried out in the Intensive Care Unit and during lengthy neurosurgical procedures.},
	keywords = {Spinal Cord},
	issn = {0013-4694},
	doi = {10.1016/0013-4694(89)90032-1},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2464477},
	author = {Dowman, R. and Jonathan Wolpaw}
}
@article {3277,
	title = {Jendrassik maneuver facilitates soleus H-reflex without change in average soleus motoneuron pool membrane potential.},
	journal = {Experimental neurology},
	volume = {101},
	year = {1988},
	month = {08/1988},
	pages = {288{\textendash}302},
	abstract = {Facilitation of spinal reflex amplitude by remote muscle contraction, otherwise known as the Jendrassik maneuver (JM), was first shown over 100 years ago, yet the mechanism by which this facilitation operates remains undetermined. Earlier work has eliminated participation of the muscle spindle in JM-induced spinal reflex facilitation, leaving changes in postsynaptic (e.g., change in average soleus motoneuron membrane potential) and presynaptic (e.g., inhibition of presynaptic inhibition) mechanisms as viable candidates. We recorded background EMG in the soleus muscle during JM-induced soleus H-reflex facilitation in humans. The JM in this experiment consisted of wrist muscle contraction. Soleus background EMG was maintained by the subject at either a zero level (e.g., relaxed) or a specified moderate level prior to and during the JM. The JM increased H-reflex amplitude by comparable amounts in both situations, but had no effect on soleus background EMG. Given the well-known relationship between the average motoneuron pool membrane potential and background EMG, we conclude that JM facilitation of the soleus H-reflex is not caused by an increase in background excitatory input to the soleus motoneuron pool. Remaining candidates for mediation of JM induced H-reflex facilitation include change in stimulus-evoked afferent input at some point proximal to the muscle spindle, such as reduction in presynaptic inhibition, or a change in motoneuron input resistance.},
	keywords = {Reflex, Stretch},
	issn = {0014-4886},
	doi = {10.1016/0014-4886(88)90012-X},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/3396646},
	author = {Dowman, R. and Jonathan Wolpaw}
}
@article {3279,
	title = {Operant conditioning of primate spinal reflexes: effect on cortical SEPs.},
	journal = {Electroencephalography and clinical neurophysiology},
	volume = {69},
	year = {1988},
	month = {04/1988},
	pages = {398{\textendash}401},
	abstract = {Previous studies have demonstrated operant conditioning of the primate spinal stretch reflex (SSR) and of its electrical analog, the H-reflex. We studied the evoked potential recorded over primary somatosensory cortex (SEP) which accompanies the H-reflex to determine whether the initial cortical response changes in the course of conditioned H-reflex change. When H-reflex amplitude changed, SEP amplitude also changed, but only half as much as the H-reflex. The results indicate that, while operant conditioning of the H-reflex has its largest effect on the spinal pathway of the reflex, it also has some effect on supraspinal pathways of the initial cortical response.},
	keywords = {cortical response, H-Reflex, Learning, Memory, operant conditioning, plasticity, somatosensory evoked potential, spinal reflex},
	issn = {0013-4694},
	doi = {10.1016/0013-4694(88)90012-0},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2450739},
	author = {Jonathan Wolpaw and Dowman, R.}
}
@article {3280,
	title = {Spinal stretch reflex and cortical evoked potential amplitudes versus muscle stretch amplitude in the monkey arm.},
	journal = {Electroencephalography and clinical neurophysiology},
	volume = {69},
	year = {1988},
	month = {04/1988},
	pages = {394{\textendash}397},
	abstract = {While investigating operant conditioning of the primate spinal stretch reflex (SSR), we studied SSR amplitude and cortical somatosensory evoked potential (SEP) amplitude as stretch amplitude changed in the monkey arm. Initial muscle length and background EMG activity remained constant. With change in stretch amplitude (and proportional change in stretch velocity and acceleration), changes in SSR and SEP amplitudes were respectively 0.75 and 0.66 as great. The lesser change in SSR amplitude may reflect saturation of Ia afferents, while that in SEP amplitude may also reflect participation of other peripheral receptors.},
	keywords = {muscle stretch, primate, Somatosensory Cortex, somatosensory evoked potential, spinal reflex, stretch reflex},
	issn = {0013-4694},
	doi = {10.1016/0013-4694(88)90011-9},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2450738},
	author = {Jonathan Wolpaw and Dowman, R.}
}
@article {3278,
	title = {T complex hemispheric asymmetries: effects of stimulus intensity.},
	journal = {Hearing research},
	volume = {34},
	year = {1988},
	month = {08/1988},
	pages = {225{\textendash}232},
	abstract = {The T complex component of the human auditory evoked potential (AEP) is thought to be produced in auditory cortex, on the posterior lateral surface of the temporal lobe. Recorded over temporal scalp, it consists of an 80-90 ms positive peak, Ta, and a 120-140 negative peak, Tb. As part of an effort to develop the clinical usefulness of the T complex in assessing auditory cortical function, we studied the effects of change in monaural stimulus intensity (20-80 dB SL) on T complex latency, amplitude, and hemispheric differences in normal adults. Ta and Tb peak latencies decreased as stimulus intensity increased. These latency changes were not dependent on ear or hemisphere. Right hemisphere Ta latency was shorter with contralateral than with ipsilateral stimulation; while left hemisphere Ta latency was not dependent on the ear stimulated. Tb latency was shorter over the left hemisphere, and over the contralateral hemisphere. Ta-b amplitude increased as stimulus intensity increased. This amplitude change was not dependent on ear or hemisphere. Ta-b amplitudes were larger over the right hemisphere and over the contralateral hemisphere. Hemispheric asymmetries were not significantly affected by stimulus intensity.},
	keywords = {Reaction Time},
	issn = {0378-5955},
	doi = {10.1016/0378-5955(88)90002-0},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/3170365},
	author = {Anthony T. Cacace and Dowman, R. and Jonathan Wolpaw}
}
