A unique feature and a significant strength of the microneurography method is that subjects are fully awake and able to cooperate in tests requiring mental attention, while impulses in a representative nerve fibre or set of nerve fibres are recorded, e.g. when cutaneous sense organs are stimulated or subjects perform voluntary precision movements.

Working at the Department of Clinical Neurophysiology, Academic Hospital, Uppsala, they collected data resulting in the first papers representing three areas to become major fields of microneurography, i.e. afference from intra-muscular sense organs during voluntary contractions, response of cutaneous sense organs related to touch stimuli, and efferent sympathetic activity controlling the constriction of human blood vessels.

In microneurography recordings, A- and C-fiber impulses differ in shape and polarity of the main upstroke of the action potential.

Once the electrode tip is in the nerve, small adjustments are required, first, to penetrate the sheath of an individual fascicle and, second, to take the tip close to the nerve fibers of the kind you are interested to explore, be it multi-unit sympathetic activity or single unit activity of either a myelinated afferent or a small unmyelinated fibres.

This technique is based on a unique property of many kinds of C-fibres, i.e. a decrease of conduction velocity in the wake of preceding impulses.

However, it generates only semi-quantitative information about unitary activity, whereas recordings of impulse trains allow more comprehensive description of functional properties of sense organs.

Once the functional properties of an afferent have been defined, e.g. with regard to sensitivity, receptive field structure, and adaptation, the electrode may be reconnected to a stimulator to give trains of electrical pulses of controlled strength, rate, and duration.

Although this approach to bridge the gap between biophysical events in a single afferent and mental phenomena within the mind is simple and straight forward in principle it is demanding in practice for a number of reasons.

[citation needed] Microneurography recordings have elucidated the organization as well as normal and pathological function of a fair number of neural systems in human.

Three main groups of neural systems have been explored, i.e. proprioception, cutaneous sensibility, and sympathetic efferent activity.

In contrast, more independent fusimotor activity has been reported in animal experiments, mainly cat hind limb, where larger movements are allowed.

However, it seems likely that detailed information on large as well as small mechanical events in the muscles is essential for neural systems in the brain to produce appropriate commands for dexterous movements.

Microneurography has demonstrated that our brains make use of detailed proprioceptive information not only by deep sense organs but by cutaneous mechanoreceptors as well.

This system allows us to extract detailed information on spatial and temporal features of any skin deformation as well as properties of physical objects such as size, shape, and surface structure.

Micro-stimulation has shown that input from one single Meissner, Merkel, or Pacini unit may produce a distinct and differential percept in the mind of the subject indicating an absolute specificity within the tactile system.

Tactile C-afferents (CT) were described long ago in non-human species but did not attract much interest until it was shown that they are numerous in human hairy skin.

Moreover, any tendency to slipping is monitored by tactile afferents and gives rise to swift reflexes resulting in subconscious adjustments of motor output.

It has been shown that tactile sense organs in the glabrous skin are involved in timely linking the separated phases to a purposeful motor act.

The mechano-insensitive C nociceptors, also known as silent nociceptors, differ from polymodal afferents in other respects as well, e.g. they do not respond to heat or they have very high heat thresholds, receptive fields on the skin are larger, conduction velocity is slower, and activity-dependent slowing of conduction velocity of the axon is more pronounced.

The mechano-insensitive nociceptors may be sensitized particularly by inflammatory mediators to render them mechano-responsive, a process that may account for the tenderness we experience following a physical injury.

Moreover, electrical activation of C-mechano-insensitive fibers demonstrates that they have a role in neurogenic vasodilation which has not been found with polymodal nociceptors.

[15][16][17] Instantaneous sympathetic activity in muscle nerves (MSA / MSNA) is heavily controlled by baroreflex mechanisms, resulting in a characteristic cardiac rhythmicity as well as a close and inverse relation to the small variations of blood pressure that normally occur continuously in phase with respiration.

In contrast, the sympathetic activity in skin nerves (SSA/SSNA) lacks a tight relation to cardiac and respiratory events.

These and other findings demonstrate that sympathetic efferent activity is highly differentiated, as individual effectors are governed by their own control systems and specific reflexes.

Counter-intuitively, there seems to be only a weak and barely significant correlation between sympathetic efferent activity and hypertension as found in group studies.

[18] In 1998, microneurography recordings were performed for the first time on a spaceflight aboard the Space Shuttle Columbia with the purpose to explore the effect of microgravity on the human sympathetic nerve system.

[19] The microneurography technique allows the recording of impulse activity of individual nerve fibers with absolute resolution in attending human subjects.

Hence the subject is able to cooperate in various kinds of tests while the exact and complete information carried by the individual nerve fiber is monitored and offered for analysis of correlations between neural activity and physical or mental events.

On the other hand, the particular physical conditions involving a microelectrode freely floating in the tissue preclude brisk and large movements because the exact electrode position is easily jeopardized.

Microneurography strength is in its unique power for exploration of normal neural mechanisms as well as pathophysiological conditions of various neurological disorders.