SOMATOSENSORY PHYSIOLOGY (Tactile Discrimination and Proprioception)

Anterolateral and Dorsal Column Systems From Kandel,Schwartz, and Jessell, 2000, 22-14

SOMATOSENSORY SYSTEMS ANTEROLATERAL SYSTEM Light touch sensation (light touch and crude localization) Temperature Nociception (pain, tickle, itch) DORSAL COLUMN SYSTEM Tactile discrimination (point localization, stereognosis) Proprioception (limb position and movement)

Mechanoreceptors From Costanzo, 2006, Fig. 3-8

Berne and Levy, 1998, Fig. 8-2 Berne and Levy, 1998, Fig. 8-2

Receptor Types and Somatosensory Sensations

Point Localization From Kandel,Schwartz, and Jessell, 2000, 21-11

Two Point Discrimination From Kandel,Schwartz, and Jessell, 2000, 23-11

From Schmidt, 1985, Fig 2-4

From Kandel,Schwartz, and Jessell, 2000, 18-6

Receptive Fields From Kandel and Schwartz, 1991, 25-9

From Berne and Levy, 1998, Fig. 9-6

Feature-Dectection Neurons From Kandel,Schwartz, and Jessell, 2000, 23-13, (Adapted from Costanzo and Gardner, J. Neurophysiol. 1980)

Gardner and Costanzo, J. Neurophysiol. 43:1435, 1980)

Receptors Mediating Proprioception

From Berne and Levy, 1998, Fig. 9-8

From Berne and Levy, 1998, Fig. 9-8

From Costanzo and Gardner, Brain Research, 214:327,1981

From Costanzo and Gardner, Brain Research, 214:329,1981

From Gilman & Newman, 1996

Injury To The Dorsal Columns CLINICAL SIGNS Loss of two-point discrimination Loss of vibration sense Inability to recognize limb position without visual information Inability to recognize letters or numbers drawn on the skin (agraphesthesia) Loss of ability to recognize objects by palpation and handling (astereognosis) Inability to maintain posture (balance) when feet are close together and eyes closed (Positive Romberg sign)