Research Group "Neuronal Pathways of Pain and Itch in Humans"
Led by Adjunct Professor Dr. med. Barbara Namer
Our mission is to address clinically relevant questions in human pain and itch research. Through experimental paradigms and computational modeling, we investigate the function and dysfunction of small-diameter sensory fibers—so-called nociceptors and pruriceptors—in mediating pain and itch sensation in humans. We bridge basic science and clinical care, linking peripheral nerve fiber behavior in tissues to central signal processing and the subjective experience of pain and itch.
Research Focus Areas
Sensory Encoding of Pain and Itch
Slowly conducting C-fibers innervate the skin, deeper structures (e.g., muscle), and internal organs, transmitting signals evoked by thermal, mechanical, or chemical stimuli to the spinal cord and onward to brain centers. Depending on their responsiveness, these fibers function either as nociceptors (pain receptors) or pruriceptors (itch receptors). We use microneurography in awake volunteers to record action potentials from single C-fibers in vivo, correlating distinct firing patterns with participants’ reports of pain or itch.
Functional Roles of C-Fiber Subclasses
Two subclasses of C-fibers contribute differentially to acute pain and itch:
- Mechano-sensitive fibers rapidly encode spatial and temporal features of noxious stimuli, alerting the organism to external threats before ceasing firing.
- Mechano-insensitive fibers (often called CMi or “sleeping nociceptors”) appear to act as a longer-lasting warning system that becomes increasingly responsive in the presence of endogenous or exogenous chemical mediators. We dissect the distinct properties of these fiber classes to illuminate their roles in chronic itch and pain, informing diagnostic and therapeutic strategies.
Dysfunction in Neuropathic Pain
Neuropathic pain arises from damage to the somatosensory system, as seen in diabetic polyneuropathy or small-fiber neuropathy (SFN). SFN is characterized by degeneration and dysfunction of peripheral Aδ- and C-fibers. Using microneurography in patients with SFN, diabetic neuropathy, or genetic neuropathies, we identify fiber hyper- and hypo-function, linking aberrant firing patterns to spontaneous pain and sensory loss. These insights aim to reveal novel treatment targets for persistent neuropathic pain.
Peripheral Fiber Dysfunction in Chronic Itch
Chronic itch markedly impairs quality of life, yet remains understudied and stigmatized. Approximately 13% of German adults suffer from chronic pruritus, for which effective therapies are lacking. We record peripheral C-fiber activity in patients with chronic itch to uncover common pathomechanisms and guide the development of targeted interventions.
Core Methodology: Microneurography
Our hallmark technique is microneurography, the in vivo recording of single-fiber action potentials in awake humans. A microelectrode is inserted into a peripheral sensory nerve (e.g., the superficial peroneal nerve), allowing isolation of C-fiber signals while simultaneously capturing real-time psychophysical reports of sensation. This demanding approach, available in only a few laboratories worldwide (and in Germany solely at Würzburg and Erlangen), uniquely links single-fiber activity to perceptual phenomena in pain and itch patients.
Complementary Techniques
We augment microneurography with detailed psychophysical protocols, laser-Doppler and laser-speckle imaging, and computational models of axonal conduction. In vitro studies in human and animal tissues—using compound action potential recordings, grease-gap membrane potential measurements, and single-fiber recordings in skin–nerve preparations—further elucidate fundamental properties of sensory C-fibers.
Research Group Team
PhD student
Alina Troglio, Computer science
Cand. med.
Sofie Kanno
Pauline Koniarczyk
Andreas Zapf
Cand. dent. med.
Arianne Steder