Holcombe:TactileReceptors

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Alex Holcombe
Sarah McIntyre
Fahed Jbarah
• Shih-Yu Lo
• Patrick Goodbourn
Lizzy Nguyen
Alumni

action precision
Fahed
Tactile Motion
Tactile Receptors
Binding, grouping


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Skin receptors

Receptor depth skin type Fave temp freq$ afferent stimulation it responds to driven by adapts to vibration?
Merkel's disk top skin layers glabrous and hairy[a] ~1 Hz, <5Hz SA-1 pressure, orientation spatial period[1] YES
Meissner's corpuscle glabrous ~10 Hz FA-1 (RA) flutter, some stretch (b/c very sensitive to indentation) spatial frequency and also speed, NOT temporal freq[1] YES
Ruffini corpuscle glabrous and hairy? ~100 Hz SA-2 stretching NO [2]
nail beds nails SA-2[3] fingertip force, fingertip direction[3]
Pacinian corpuscle glabrous? ~400 Hz[b] FA-2 (PC) vibration speed AND tf[1]
free nerve ending deep? sometimes on hair, lowww? C,? pain, ache, heat, cold,

a-At high amplitude, all the mechanoreceptors respond to all freqs b-Preferred frequency may change with indentation amplitude

Check out Darian & Oke 1980, they test RA, SA, Pacinian at wide range of temporal frequencies.

when stimuli move across the receptive fields of tactile afferents, the responses are different depending on the direction of movement (Goodwin and Morley, 1987; LaMotte and Srinivasan 1987; Srinivasan et al., 1990; Edin et al., 1995). Directionality of tactile afferent responses most likely results from different strains produced at the receptor site when forces are applied in different directions. In the case of the fingertip, its geometry and composite material properties may account for widespread complex patterns of strain changes that depend on the direction of the applied force (Maeno et al., 1998). Consequently, the site of stimulation, the location of the receptor in the fingertip per se as well as in relation to the stimulation site, and possible inherent directional preferences of the end-organ attributable to its microanatomy, all could contribute to the directionality of an afferent- I. Birznieks

"Both FA-I and SA-I afferents respond to changes in the magnitude and direction of tangential torque, but differ in the relative importance of specific stimulus features. FA-I fibres discriminate the onset and magnitude of changes in torque more accurately and rapidly than SA-I fibres, but rarely distinguish clockwise from anti- clockwise rotations, or signal steady-state torques. FA-I fibres are silent during static grasp or lift actions when normal forces are constant. In contrast, SA-I fibres distinguish the applied normal force with latencies as brief as 250 ms, and also discriminate torque direction more accurately and faster than FA-I fibres. These findings suggest that FA-I fibres provide early warning signals of rotational as well as translational slips when objects held in the hand are manipulated or perturbed by external forces. The absence of tonic activity in FA-I fibres during static grasp enhances the sudden appearance of spike trains signalling object motion, aiding rapid adjustment of grip force in parallel with the onset of tangential motion over the skin (Kinoshita et al. 1997; Goodwin et al. 1998)" [4]

  1. Goodwin AW and Morley JW. . pmid:3612236. PubMed HubMed [GoodwinMorley87]
  2. Birznieks I, Macefield VG, Westling G, and Johansson RS. . pmid:19625527. PubMed HubMed [BirznieksEtAl09]
  3. Gardner EP. . pmid:20360027. PubMed HubMed [Gardner10]
All Medline abstracts: PubMed HubMed
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