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Biomedical subjects

B Kenton

Publications and source records attributed to B Kenton.

13 recordsLinked to original sources
PubMed1980

Peripheral fiber correlates to noxious thermal stimulation in humans.

Minimal conduction velocities of peripheral nerves contributing to acute thermal pain sensation in human volunteer subjects were calculated. Purely thermal stimulation was administered by a low power laser beam directed at the subjects' fingers, and subjective pain responses correlated with a peak in the event-related brain potential (ERBP). These cerebral responses were found to preclude C fiber peripheral activity from this phenomenon.

Cerebral Cortex↗
PubMed1980

Somatosensory evoked potentials and noxious stimulation in patients with intractable, noncancer pain syndromes.

Investigations of the evoked potentials (EPs) to noxious laser stimulation have indicated consistent strong linear relationships between subjective response (R), stimulus intensity (S), and EP amplitude (A). Thirty patients with chronic intractable benign pain syndromes (CIBPS) were tested to determine whether their patterns differed from previous studies with normal volunteers. Nearly half of the CIBPS patients were found to be relatively insensitive to acute pain stimuli. A large number were also found to show negative relationships between S and A. These differences from control subjects were considered of potential importance in their implications concerning the nature of chronic pain and its differences from the acute pain process.

Adult↗
PubMed1980

Single trial analysis of evoked potentials to noxious thermal stimulation in man.

Thermal (laser) evoked responses were obtained from 13 male volunteers. A single trial analysis technique with a latency adjusting adaptive filter was used to analyze evoked response amplitudes. Significant and substantial within-subject linear correlations were found between the magnitude (A) of the primary waveform (RMS muV of the P200--N300-P400 complex ) and subjective pain response (R) as well as stimulus intensity (S). Since subjective pain response was strongly correlated with stimulus intensity, the partial correlation coefficients were calculated for R vs. A with S controlled, and S vs. A with R controlled, for each subject. The partial correlations revealed a much stronger relationship between subjective response and the evoked response amplitude, suggesting that the primary complex may measure neural events in the pain perception process rather than transduction and transmission of the stimulus event.

Computers↗
PubMed1976

Neurophysiology of pain-peripheral aspects. Speculation concerning the possibility of a unitary peripheral cutaneous input system for pressure, hot, cold and tissue damage.

The gate theory of pain is criticized at three levels: (1) at the dorsal horn "gate", where pre-synaptic inhibition in the primary afferent endings may go beyond mere reduction of synaptic power at the afferent endings and induce antidromic impulses (dorsal root reflexes) that may modulate peripherally by blocking; (2) central to the "gate", where postsynaptic neuronal repetitive (epileptiform) firing is believed to be an important underlying mechanism in clinical chronic pain syndromes; and, (3) in the periphery, where there is more to input coding than a balance between the ratio of large and smaller fiber inputs. Contrary to the belief of many sensory neurophysiologists, the present authors contend that pattern theory is viable; and that specificity, while important and not to be ignored, should be considered as only a partially evolved refinement superimposed on a basic underlying spatial and temporal patterning of input that probably requires central decoding, which begins in the dorsal horn.

Mechanoreceptors↗
PubMed1976

What is a pain center?

The authors present the concept that a multi-disciplinary interdepartmental pain center should include: 1) an initial out-patient pain clinic, 2) an inpatient pain service for diagnosis of pain problems and treatment of patients with intractable pain, including pain from cancer, 3) a psychotherapeutically-oriented chronic benign Pain Unit, 4) facilities for clinical and basic pain research, and 5) affiliations for an adequate teaching program.

California↗
PubMed1976

The role of cutaneous mechanoreceptors in thermal sensation and pain.

The functional behavior of slowly adapting cutaneous mechanoreceptors under combined thermal-mechanical stimulation was investigated by single-unit recordings from the lumbar dorsal roots of the cat. Increased sensitivity to bimodal stimulation was observed in 24 of the 28 units studied, employing stimulus-response functional behavior as the basis for judgment. Low-threshold receptors generally did not exhibit increased spontaneous firing as accompaniment to heightened sensitivity, while such enhanced basal activity was usually observed in moderate-threshold units in addition to increased reactivity. Information theory calculations performed on these stimulus-response data revealed that 15 of the 24 "heat-sensitive" receptors were additionally characterized by an enhanced ability to transmit neural information under bimodal stimulation. These results were interpreted as supporting pattern theories of pain as opposed to the concept of receptor specificity. No contradiction was observed, however, between the present results and those of other investigators. The present conclusions derive from new criteria for thermal reactivity based upon innovative stimulus conditions.

Animals↗
PubMed1971

Two classes of slowly adapting mechanoreceptor fibres in reptile cutaneous nerve.

1. The myelinated fibre spectrum of the plantar nerve of reptile consists of a unimodal distribution corresponding approximately to the delta elevation in mammalian nerve and contains a variety of receptor categories similar to those of mammals except for the obvious absence of structures related to hairs.2. The various receptor types of reptilian skin do not fall into discrete groups on the basis of conduction velocity.3. Only a few thermoreceptor fibres were identified but a large proportion of slowly adapting mechanoreceptors responded to rapid temperature transients.4. Two distinct categories of slowly adapting receptors whose discharge is related to the amplitude of skin displacement have been identified and studied in detail. These two receptors can be distinguished by their patterns of discharge, and display several distinctive features including differences in resting discharge, receptive field size, threshold, response to DC polarization, etc.5. The mathematical functions describing the response to stimuli of varying magnitude for one receptor type is markedly affected by the sequence of stimulus presentation.

Animals↗