Introduction

Dr. LaMotte's laboratory investigates the peripheral and central neural mechanisms of pain, itch and touch.

Experiments on pain examine the functional properties of dorsal root ganglion (DRG) neurons in the rodent. We are currently interested in how electrophysiological and neurochemical changes in these properties, occurring after a chronic compression of the DRG (CCD model), lead to behavioral signs of neuropathic pain. This type of pain might be produced in humans, for example, after injuries and degenerative disorders of the spine.

Experiments on itch use psychophysical methods in humans to measure the pruritic and nociceptive sensations and altered sensory states produced by the application of pruritic substances to the skin. As part of a collaborative effort with two other laboratories, our psychophysical findings will be compared with electrophysiologically recorded responses of peripheral nerve fibers and of spinothalamic neurons to the same pruritic stimuli. The goal is to identify neurons mediating itch and itchy skin and to characterize the neurons that modulate pruritic sensations and sensory states. These modulatory neurons might then be targeted in clinical treatments of chronic pruritus.

Experiments on touch have investigated the peripheral neural coding of object texture, shape and softness. The tactual properties of objects are typically perceived by manual palpation. But correlative electrophysiological studies of tactile sensory neurons require that the same stimulus attribute be repetitively delivered under the same stimulus conditions. Thus, corollary aims were to produce stimulus objects expressing graded properties of an attribute such as curvature or compliance and to develop methods of delivering these objects to the passive hand in a way that elicited the cutaneous mechanical events occurring during active touch.