Two-point discrimination

The ability to discern two separate points of contact on the skin

Diagram illustrating two-point discrimination

Comparison of two-point orientation discrimination and traditional two-point discrimination

Two-point discrimination is a measure of the ability to discern that two nearby objects touching the skin are truly two distinct points, not one. This ability varies across different areas of the body and is an important aspect of somatosensory perception.

Physiology

Two-point discrimination is primarily a function of the nervous system, particularly the somatosensory cortex in the brain. The density of nerve endings in the skin, such as Meissner's corpuscles and Merkel cells, influences the ability to distinguish between two points. Areas with higher nerve density, like the fingertips and lips, have a finer two-point discrimination threshold compared to areas with lower nerve density, such as the back.

Measurement

The two-point discrimination test is a common method used to assess the sensory function of the skin. During the test, two points are applied to the skin with a specific distance apart, and the subject is asked whether they feel one or two points. The smallest distance at which the subject can distinguish two points is recorded as the two-point discrimination threshold.

Clinical significance

Two-point discrimination is used in neurology to assess the integrity of the peripheral nervous system and the central nervous system. It can help diagnose conditions that affect sensory perception, such as peripheral neuropathy or spinal cord injury.

Factors affecting two-point discrimination

Several factors can influence two-point discrimination, including age, skin condition, and neurological disorders. For instance, aging can lead to a decline in sensory perception, increasing the two-point discrimination threshold.

Related pages

• Somatosensory system
• Nerve ending
• Sensory receptor

References

• Kandel, E. R., Schwartz, J. H., & Jessell, T. M. (2000). Principles of Neural Science. McGraw-Hill.
• Mountcastle, V. B. (2005). The Sensory Hand: Neural Mechanisms of Somatic Sensation. Harvard University Press.

Two-point_discrimination

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  Two-point discrimination
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  Two-point orientation discrimination compared to traditional two-point discrimination