Lake Michigan mottled sculpin, Cottus bairdi, exhibit a naturally occurring and unconditioned orienting response that can be triggered by both live prey and chemically inert vibrating spheres, even in blinded animals. CoCl(2)-induced reductions of the orienting response demonstrate that the lateral line is required for this behavior in the absence of non-mechanosensory cues (such as vision), but shed no light on the relative contributions of superficial and canal neuromasts to this behavior. To determine the relative roles of these two subsystems, we measured the frequency with which mottled sculpin oriented towards a small vibrating sphere before and after two treatments: (i) immersion of fish in a solution of gentamicin, an aminoglycoside antibiotic that damages hair cells in canal, but not superficial, neuromasts; and (ii) scraping the skin of the fish, which damages the superficial, but not the canal, neuromasts. To ensure that both superficial and canal neuromasts were adequately stimulated, we tested at different vibration frequencies (10 and 50 Hz) near or at the best frequency for each type of neuromast. At both test frequencies, response rates before treatment were greater than 70 % and were significantly greater than ‘spontaneous’ response frequencies measured in the absence of sphere vibration. Response rates fell to spontaneous levels after 1 day of gentamicin treatment and did not return to pre-treatment levels for 10–15 days. In contrast, response rates stayed approximately the same after superficial neuromasts had been damaged by skin abrasion. Scanning electron microscopy confirmed hair cell damage (loss of apical cilia) in canal, but not superficial, neuromasts of gentamicin-treated animals after as little as 24 h of treatment. The sensory epithelium of canal neuromasts gradually returned to normal, following a time course similar to behavioral loss and recovery of the orienting response, whereas that of superficial neuromasts appeared normal throughout the entire period. This study shows that the orienting response of the mottled sculpin is mediated by canal neuromasts.

REFERENCES

Abdel-Latif
H.
,
Hassan
E. S.
,
von Campenhausen
C.
(
1990
).
Sensory performance of blind Mexican cave fish after destruction of the canal neuromasts.
Naturwissenschaften
77
,
237
–.
Baker
C. F.
,
Montgomery
J. C.
(
1999
).
Lateral-line mediated rheotaxis in the Antarctic fish Pusothenia borchgrevinki.
Polar Biol
21
,
305
–.
Barber
V. C.
,
Emerson
C. J.
(
1979
).
Cupula—receptor cell relationships with evidence provided by SEM microdissection.
Scanning Electron Microsc
3
,
939
–.
Braun
C. B.
,
Coombs
S.
(
2000
).
The overlapping roles of the inner ear and lateral line: the active space of dipole source detection.
Phil. Trans. R. Soc. Lond
355
,
1115
–.
Conley
R. A.
,
Coombs
S.
(
1998
).
Dipole source localization by mottled sculpin. III. Orientation after site-specific, unilateral blockage of the lateral line system.
J. Comp. Physiol
183
,
335
–.
Coombs
S.
(
1994
).
Nearfield detection of dipole sources by the goldfish, Carassius auratus and mottled sculpin, Cottus bairdi.
J. Exp. Biol
190
,
109
–.
Coombs
S.
(
1999
).
Signal detection theory, lateral line excitation348patterns and prey capture behavior of the mottled sculpin.
Anim. Behav
58
,
421
–.
Coombs
S.
,
Conley
R. A.
(
1997
).
Dipole source localization by mottled sculpin. I. Approach strategies.
J. Comp. Physiol
180
,
387
–.
Coombs
S.
,
Conley
R. A.
(
1997
).
Dipole source localization by mottled sculpin. II. The role of lateral line excitation patterns.
J. Comp. Physiol
180
,
401
–.
Coombs
S.
,
Hastings
M.
,
Finneran
J.
(
1996
).
Measuring and modeling lateral line excitation patterns to changing dipole source locations.
J. Comp. Physiol
178
,
359
–.
Denton
E. J.
,
Gray
J. A. B.
(
1982
).
The rigidity of fish and patterns of lateral line stimulation.
Nature
297
,
679
–.
Hoekstra
D.
,
Janssen
J.
(
1986
).
Lateral line receptivity in the mottled sculpin (Cottus bairdi).
Copeia
1986
,
91
–.
Janssen
J.
,
Coombs
S.
,
Hoekstra
D.
,
Platt
C.
(
1987
).
Postembryonic growth and anatomy of the lateral line system in the mottled sculpin, Cottus bairdi (Scorpaeniformes: Cottidae).
Brain Behav. Evol
30
,
210
–.
Jones
W. R.
,
Janssen
J.
(
1992
).
Lateral line development and feeding behavior in the mottled sculpin, Cottus bairdi (Scorpaeniformes: Cottidae).
Copeia
1992
,
485
–.
Kroese
A. B. A.
,
Schellart
N.
(
1992
).
Velocity-and acceleration-sensitive units in the trunk lateral line of the trout.
J. Neurophysiol
68
,
2212
–.
Kroese
A. B. A.
,
van der Zalm
J. M.
,
van den Bercken
J.
(
1978
).
Frequency response of the lateral-line organ of Xenopus laevis.
Pflugers Arch
375
,
167
–.
Lekander
B.
(
1949
).
The sensory line system and the canal bones in the head of some Ostariophysi.
Acta. Zool
30
,
1
–.
Montgomery
J. C.
,
Baker
C. F.
,
Carton
A. G.
(
1997
).
The lateral line can mediate rheotaxis in fish.
Nature
389
,
960
–.
Montgomery
J. C.
,
Carton
G.
,
Voight
R.
,
Baker
C.
,
Diebel
C.
(
2000
).
Sensory processing of water currents by fish.
Phil. Trans. R. Soc. Lond. B
355
,
1325
–.
Montgomery
J.
,
Coombs
S.
,
Janssen
J.
(
1994
).
Form and function relationships in the lateral line system: Comparative data from six species of Antarctic notothenioid fish.
BrainBehav. Evol
44
,
299
–.
Mukai
Y.
,
Yoshikawa
H.
,
Kobayashi
H.
(
1994
).
The relationship between the length of the cupulae of free neuromasts and feeding ability in larvae of the willow shiner Gnathopogon elongatus caerulescens (Teleostei, Cyprinidae).
J. Exp. Biol
197
,
399
–.
Song
J.
,
Hong
Y. Y.
,
Popper
A. N.
(
1995
).
Damage and recovery of hair cells in fish canal (but not superficial) neuromasts after gentamycin exposure.
Hearing Res
91
,
63
–.
Strivastava
C. B. L.
,
Strivastava
M. D. L.
(
1968
).
Lateral line organs in some teleosts: Cirrhina mrigala Ham. Buch (Cyrpinidae), Ophicephalus (Channa) punctatus Bloch (Channidae) and Gobius striatus Day (Gobiidae).
J. Comp. Neurol
134
,
339
–.
Webb
J. F.
,
Northcutt
R. G.
(
1997
).
Morphology and distribution of pit organs and canal neuromasts in non-teleost bony fishes.
Brain Behav. Evol
50
,
139
–.
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