Pain research, accelerated in recent decades through refined morphophysiological studies in experimental animals and through precise psychophysical measurements in man, anticipates significant progress from bridging the animal-human gap through combining microneurography (MNG) and microstimulation (INMS). This method allows to explore, at the unitary level in experiencing human subjects, the neurophysiological basis both for encoding stimuli at the periphery and for decoding sensations cognitively. Using safe intraneural microelectrodes, we record nerve signals from identifiable single sensory units in awake subjects, and map their peripheral receptor site. We selectively impose a choice of nerve signals upon identified sensory channels via intraneural microstimulation. We then question the brain about the cognitive characteristics of the sensation evoked. Fundamental knowledge has thus emerged about subjective attributes of elementary sensations evoked from single low threshold mechanoreceptor units innervating the human hand. For example (1) what determines the subjective sensory quality; (2) how afferent input parameters contribute to the subjective magnitude; and (3) how accurately is sensory localization function resolved. Preliminary data on nociception and pain, also contributed through combined MNG/INMS, guarantees feasibility and relevance at basic and clinical levels for a follow-up project involving high threshold sensory systems in man. The present proposal for continuation pursues expansion of our preliminary MNG/INMS research on (1) laws that normally govern cognition of quality, magnitude and localization of pain and itch; (2) pathological deviations of somatosensory quality whereby mild stimuli cause pain (hyperalgesia, allodynia); and (3) mechanisms of pain, spontaneous or sympathetic-dependent, in patients with neuropathy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
7R01NS024740-01
Application #
3409590
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1986-09-01
Project End
1990-08-31
Budget Start
1986-09-01
Budget End
1987-08-31
Support Year
1
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Good Samaritan Hosp & Medical Center(Prtlnd,OR)
Department
Type
DUNS #
City
Portland
State
OR
Country
United States
Zip Code
97210
Verdugo, R J; Ochoa, J L (1994) 'Sympathetically maintained pain.' I. Phentolamine block questions the concept. Neurology 44:1003-10
Verdugo, R J; Campero, M; Ochoa, J L (1994) Phentolamine sympathetic block in painful polyneuropathies. II. Further questioning of the concept of 'sympathetically maintained pain'. Neurology 44:1010-4
Ochoa, J L; Yarnitsky, D (1994) The triple cold syndrome. Cold hyperalgesia, cold hypoaesthesia and cold skin in peripheral nerve disease. Brain 117 ( Pt 1):185-97
Ochoa, J L; Yarnitsky, D (1993) Mechanical hyperalgesias in neuropathic pain patients: dynamic and static subtypes. Ann Neurol 33:465-72
Verdugo, R; Ochoa, J L (1992) Quantitative somatosensory thermotest. A key method for functional evaluation of small calibre afferent channels. Brain 115 ( Pt 3):893-913
Yarnitsky, D; Ochoa, J L (1991) Differential effect of compression-ischaemia block on warm sensation and heat-induced pain. Brain 114 ( Pt 2):907-13
Simone, D A; Ochoa, J (1991) Early and late effects of prolonged topical capsaicin on cutaneous sensibility and neurogenic vasodilatation in humans. Pain 47:285-94
Yarnitsky, D; Ochoa, J L (1991) The sign of Tinel can be mediated either by myelinated or unmyelinated primary afferents. Muscle Nerve 14:379-80
Yarnitsky, D; Ochoa, J L (1991) Warm and cold specific somatosensory systems. Psychophysical thresholds, reaction times and peripheral conduction velocities. Brain 114 ( Pt 4):1819-26
Bennett, G J; Ochoa, J L (1991) Thermographic observations on rats with experimental neuropathic pain. Pain 45:61-7

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