A baroreflex mechanism may explain hypertensive hypoalgesia. At rest, arterial baroreceptors are stimulated during the systolic upstroke of the pressure pulse wave. This study examined the effects of naturally occurring variations in baroreceptor activity during the cardiac cycle on an objective measure of pain, the nociceptive flexion reflex (NFR). Two interleaved up–down staircase procedures determined separate NFR thresholds during systole and diastole in 36 healthy, normotensive young adults. On odd-numbered trials, the sural nerve was stimulated electrocutaneously at R + 300 ms whereas on even-numbered trials, stimulation was delivered at R + 600 ms. The NFR threshold was higher at R + 300 ms than R + 600 ms. In contrast, stimulus intensity ratings did not differ between R + 300 ms and R + 600 ms. Stimulation of baroreceptors by natural increases in blood pressure during the systolic phase of the cardiac cycle was associated with dampened nociception.

Cardiac cycle

Systole

Hypoalgesia

Stimulus (psychology)

10.1017/s0048577202011770

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Citations (12)

Effects of essential hypertension on short latency human somatosensory-evoked potentials

Psychophysiology (2009)

Louisa Edwards Christopher Ring David McIntyre Una Martin J. Winer

Reduced perception of somatosensory stimulation in patients with essential hypertension may be due to deficits in the ascending somatosensory pathway. Function in the ascending somatosensory pathway was assessed by measuring N9, N13, and N20 somatosensory-evoked potentials in 14 unmedicated essential hypertensives and 22 normotensives. N9 amplitudes were smaller and N13 amplitudes marginally smaller in hypertensives than normotensives. N9 amplitudes were inversely associated with blood pressure. N20 amplitudes and N9, N13, and N20 latencies did not differ between groups. In addition, plexus-to-cord, cord-to-cortex, and plexus-to-cortex conduction times were not different between groups. These data suggest that hypertension affects the peripheral nervous system by reducing the number of active sensory nerve fibers without affecting myelination. However, hypertension does not seem to affect the afferent somatosensory pathway within the brain.

Somatosensory evoked potential

Essential hypertension

10.1111/j.1469-8986.2009.00939.x

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Citations (7)

Investigating the efficacy of neurofeedback training for expediting expertise and excellence in sport

Psychology of sport and exercise (2014)

Christopher Ring Andrew Cooke Maria Kavussanu David McIntyre Rich S.W. Masters

This experiment examined whether electroencephalographic (EEG)-based neurofeedback could be used to train recreational golfers to regulate their brain activity, expedite skill acquisition, and promote robust performance under pressure. We adopted a mixed-multifactorial design, with group (neurofeedback, control) as a between-subjects factor, and pressure (low, high), session (pre-test, acquisition 1, acquisition 2, acquisition 3, post-test), block (putts within each training session), and epoch (cortical activity in the seconds around movement initiation) as within-subject factors. Recreational golfers received three hours of either true (to reduce frontal EEG high-alpha power, N = 12) or false (control, N = 12) neurofeedback training sandwiched between pre-test and post-test sessions during which we collected measures of cortical activity (EEG) and putting performance under both low and high pressure conditions. Individuals in the neurofeedback group learned to reduce their frontal high-alpha power before striking putts. Despite causing this more “expert-like” pattern of cortical activity, neurofeedback training failed to selectively enhance performance, as both groups improved their putting performance similarly from the pre-test to the post-test. Finally, both groups performed robustly under pressure. Performers can learn to regulate their brain activity using neurofeedback training. However, research identifying the cortical correlates of expertise is required to refine neurofeedback interventions if this training method is to expedite learning. Suggestions for future neurofeedback interventions are discussed.

Sensorimotor rhythm

Biofeedback

10.1016/j.psychsport.2014.08.005

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Citations (78)

Cooperative mapping and exploration using counter-rotational potential fields

David McIntyre Wasif Naeem Cheng Zhang

This paper presents a novel technique for mapping and exploration using cooperating autonomous underwater vehicles. Rather than using the typical lawnmower sweep pattern to search an entire area, the proposed navigational plan involves guiding the formation directly towards each object of interest in turn, before arriving at a final goal position. This is achieved by the use of traditional artificial potential fields alongside counter-rotational potential fields. These clockwise and counter-clockwise fields are employed simultaneously by vehicles to ensure that the entire object is scanned rather than simply avoided as is the case with traditional collision avoidance techniques. The proposed methodology allows a formation to have fluid-like motion whilst a separation distance between cooperating agents (free of angular constraints) is maintained with a greater degree of flexibility than traditional formation control approaches. Owing to its nature, this technique is suited for applications such as exploration, mapping and underwater inspection to name a few. Simulation results demonstrate the efficacy of the proposed approach.

Position (finance)

Potential field

10.1109/issc.2016.7528455

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Citations (1)

A model for phosphocreatine resynthesis

Journal of Applied Physiology (1997)

Alan Nevill David A. Jones David McIntyre Gregory C. Bogdanis Mary E. Nevill

A model for phosphocreatine (PCr) resynthesis is proposed based on a simple electric circuit, where the PCr store in muscle is likened to the stored charge on the capacitor. The solution to the second-order differential equation that describes the potential around the circuit suggests the model for PCr resynthesis is given by PCr(t) = R - [d1.exp(-k1.t) +/- d2.exp(-k2.t)], where R is PCr concentration at rest, d1, d2, k1, and k2 are constants, and t is time. By using nonlinear least squares regression, this double-exponential model was shown to fit the PCr recovery data taken from two studies involving maximal exercise accurately. In study 1, when the muscle was electrically stimulated while occluded, PCr concentrations rose during the recovery phase to a level above that observed at rest. In study 2, after intensive dynamic exercise, PCr recovered monotonically to resting concentrations. The second exponential term in the double-exponential model was found to make a significant additional contribution to the quality of fit in both study 1(P < 0.05) and study 2(P < 0.01).

10.1152/jappl.1997.82.1.329

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Citations (37)

Effects of Opioid Blockade with Naltrexone and Distraction on Cold and Ischemic Pain in Hypertension

Journal of Behavioral Medicine (2007)

Christopher Ring Christopher France Mustafa Al’Absi Louise Beesley Louisa Edwards

Hypoalgesia

Cold pressor test

Endogenous opioid

10.1007/s10865-006-9084-1

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Citations (18)

Effects of baroreceptor stimulation on performance of the Sternberg short-term memory task: A cardiac cycle time study

Biological Psychology (2014)

Amadeu Quelhas Martins David McIntyre Christopher Ring

Cardiac cycle

10.1016/j.biopsycho.2014.10.001

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Citations (16)

Influence of age on respiratory modulation of muscle sympathetic nerve activity and blood pressure in humans

The FASEB Journal (2013)

Alena Shantsila David McIntyre Gregory Y.H. Lip Julian F. R. Paton Paul J. Fadel

We sought to determine the influence of age on respiratory related bursting of muscle sympathetic nerve activity (MSNA) and the coupling of MSNA to the rhythmic fluctuations in blood pressure (BP) which occur with the respiratory cycle (Traube‐Hering Waves; THW). Recordings of MSNA (microneurography), BP (Finometer) and respiration (pneumobelt) were obtained in 10 young (22±1 yr, mean±SE) and 10 older (58±2 yr) healthy men with a similar BMI (~25 kg/m 2 ), while supine and breathing normally. Following correction for nerve conduction delays, respiratory cycle triggered averaging of MSNA and BP was performed. MSNA burst incidence was higher in older individuals (P<0.05, ANOVA), but similarly reduced in the inspiratory to post‐inspiratory period in young and older subjects (18±3 and 37±5 bursts•100 heart beats −1 ) compared to mid‐to‐late expiration (26±4 and 47±5 bursts•100 heart beats −1 in young and older). A significant positive correlation between MSNA and THW magnitude was observed in 90% of young but only 40% of older subjects. Thus, while the cyclic inhibition of MSNA during respiration is preserved in older individuals, the association between MSNA and THW is less robust. Supported by BHF.

Microneurography

Supine position

Expiration

10.1096/fasebj.27.1_supplement.1118.23

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Citations (0)

Psychomotor speed in hypertension: Effects of reaction time components, stimulus modality, and phase of the cardiac cycle

Psychophysiology (2007)

Louisa Edwards Christopher Ring David McIntyre Douglas Carroll Una Martin

Abstract Hypertension is characterized by cognitive deficits. As evidence for impaired psychomotor speed, including slower reaction times, is mixed, we aimed to provide a detailed investigation of simple reaction time in hypertension. Pre‐motor and motor reaction times were measured across the cardiac cycle in 30 hypertensives and 29 normotensives to determine the effects of phasic and tonic blood pressure on performance. Auditory, visual, and tactile simple reaction time tasks were completed with stimuli presented 0, 300, and 600 ms after the R‐wave of the electrocardiogram. Reaction times did not differ between hypertensives and normotensives. Although pre‐motor reaction times were faster during the late phase than the early phase of the cardiac cycle whereas motor reaction times were unchanged, this effect was similar for hypertensives and normotensives. No sensory‐motor deficits were evident in these hypertensives regardless of baroreceptor activity.

Stimulus (psychology)

Stimulus modality

10.1111/j.1469-8986.2007.00521.x

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Citations (71)