First published online December 26, 2008
Journal of Experimental Biology 212, 313-324 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.022459
The cardiac response of the crab Chasmagnathus granulatus as an index of sensory perception
Ana Burnovicz,
Damian Oliva and
Gabriela Hermitte*
Laboratorio de Neurobiología de la Memoria, Departamento de
Fisiología, Biología Molecular y Celular, Facultad de Ciencias
Exactas y Naturales, Universidad de Buenos Aires, IFIBYNE-CONICET, Buenos
Aires 1428, Argentina
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Fig. 1. A drawing of the placement of the recording leads for monitoring the heart
of Chasmagnathus. On the dorsal carapace, two leads spanned the
rostral-caudal axis of the heart to monitor heart rate. The free ends of both
wires were soldered to the pins of a jack cemented to the dorsal carapace in a
more anterior position.
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Fig. 2. (Ai) Representation of the set up used for recording the heart rate and
locomotor activity during the presentation of the different stimuli. The crab
is lodged in the actometer (a bowl-shaped opaque container, c) and connected
to the impedance detector (UFI, model 2991) by means of a jack (J). The
impedance output is sent to a computer to allow HR to be monitored. The crab's
escape response is recorded by means of four microphones (M) cemented to the
bottom of the container. This set up was used for the presentation of three
different stimuli: a light pulse generated by a white light-emitting-diode
(LED) placed 7 cm above the animal, an air puff presented in direction to the
animal's cephalotorax carapace 1 cm from above, and an opaque rectangular
screen (the VDS) placed 6 cm above the crab. (Aii) The VDS is a motor-operated
screen (an opaque rectangular strip of 25.0 cmx7.5 cm) moved
horizontally over the animal from left to right and vice versa. (B)
Representation of the set up used for the recording of the HR and locomotor
activity during the presentation of different virtual looming stimuli. A
single PC using commercial software is used to generate visual expansion
stimuli projecting on a flat screen monitor located at 20 cm in front of the
animal that is lodged in a transparent box and connected to the impedance
detector (UFI, model 2991) by means of a jack. The impedance output is sent to
a computer to allow HR to be monitored. The crab's escape response is recorded
by means of four microphones cemented to the bottom of the box. (C) The
looming stimulus consisted in a simulated projection of an approaching object
from the monitor screen. The simulation corresponded to a black square object
of 5 cm that approached from a distance of 70 cm at different constant
velocities (see methods). (D) Representative recording of cardiac activity.
The duration of the cardiac event or period (p) is measured and used to
calculate the instant heart rate (IHR) as the inverse of the period
(IHR=1/p). The dashed line stands for a stimulus. IHRM,
IHR, R1 and R2 are also defined in the
text.
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Fig. 3. Representative recording of heart rate prior to and during the presentation
of stimuli regarded as innocuous: (A) light pulse, (B) air puff; and
threatening: (C) visual danger stimulus (VDS), (D) looming stimuli. Upper
trace: first presentation; lower trace: second presentation. The solid lines
indicate the stimulus presentation.
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Fig. 4. Representative heart rate (upper trace) and locomotor activity (lower
trace) recordings of two different animals (crab 1 and crab 2) without and
during sensory stimulation. (Ai) no stimulation present, (Aii) during the
presentation of an air puff to the same animal; (Bi) no stimulation present,
(Bii) during the presentation of a VDS to the same animal. The solid lines
indicate the stimulus presentation.
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Fig. 5. Representative recordings of the normalized IHR of three crabs prior to and
during the presentation of a 5 s air puff. The black line is the mean of the
total number of animals. The bar graph in each panel shows, for all animals,
the mean IHR of one event prior to and during stimulation
(R1 and R2, respectively) revealing
significant differences between them (P<0.01). (A) Unrestrained
condition. (B) Restrained condition. The solid line indicates the stimulus
presentation.
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Fig. 6. Representative recordings of the normalized IHR of three crabs prior to and
during the presentation of a light pulse. The black line is the mean of the
total number of animals. The bar graph in each panel shows, for all animals,
the mean instant heart rate (IHR) of one event prior to and after stimulation
(R1 and R2, respectively) revealing
significant differences between them (P<0.01). (A) Unrestrained
condition. (B) Restrained condition. The solid lines indicates the stimulus
presentation.
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Fig. 7. Representative recordings of the normalized instant heart rate (IHR) of
three crabs prior to and during the presentation of the looming stimulus of 20
cm s–1. The black line is the mean of the total number of
animals. The bar graph in each panel shows, for all animals, the mean IHR of
one event prior and after stimulation (R1 and
R2, respectively) revealing significant differences
between them (P<0.01). (A) In the unrestrained condition the
looming stimuli were initiated after a 0.9 s delay relative to the heart rate
recording (vertical dashed line). The mean escape response of freely moving
animals is shown in the black lower trace. (B) In the restrained condition
looming stimuli were initiated simultaneously with the heart rate recording.
The dotted line represents the expansion of the virtual approaching stimulus
plotted against time.
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Fig. 8. Representative recordings of the normalized HR of three crabs prior to and
during the presentation of the looming stimulus of 5 cm s–1.
The black line is the mean of the total number of animals. The bar graph in
each panel shows, for all animals, the mean IHR of one event prior and after
stimulation (R1 and R2, respectively)
revealing significant differences between them (P<0.01). (A) In
the unrestrained condition the looming stimuli were initiated after a 0.9 s
delay relative to the heart rate recording (vertical dashed line). The mean
escape response of freely moving animals is shown in the black lower trace.
(B) In the restrained condition looming stimuli were initiated simultaneously
with the heart rate recording. The dotted line represents the expansion of the
virtual approaching stimulus plotted against time.
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Fig. 9. Representative recordings of the normalized IHR of three restrained crabs
prior and during the presentation of the visual danger stimulus (VDS). The
thick line is the mean of the total number of animals. The bar graph in each
panel shows, for all animals, the mean IHR of one event prior and after
stimulation (R1 and R2, respectively)
revealing significant differences between (P<0.01). The solid line
indicates the stimulus presentation.
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Fig. 10. (A) Probability of response to three stimuli (looming stimulus, air puff,
light pulse). (i) Restrained condition. (ii) Unrestrained condition. (B)
Cardiac response latency to the presentation of different looming expansions.
(i) Restrained condition. (ii) Unrestrained condition.
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Fig. 11. (A) Comparison between the escape response and the cardiac response
latencies to the presentation of different looming stimuli (40 cm
s–1; 20 cm s–1; 10 cm s–1;
5 cm s–1). (B) Linear correlation between cardiac and escape
responses.
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© The Company of Biologists Ltd 2009
