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A corollary discharge maintains
auditory sensitivity during sound
production
Interdisciplinary Program in Brain Science
Eye Movement & Vision Research LAB
Hwang, Jae Won
http://luna.cas.usf.edu/~husband/percept/corolary.htm
Corollary Discharge Theory
The brain may discriminate self-motion (movement of the eye) from object motion
(something moving in the environment) by comparing activity in the eye muscles with
retinal image movement. If a corollary motor signal (C) and a sensory signal (S) reach the
Comparator at the same time, then eye movement is inferred and not object movement.
http://home.dongguk.edu/user/ento/file2/c.figure.htm
Cricket
귀뚜라미의 날개는 앞날개1쌍과 뒷날개1쌍이
있는데 수컷이 소리를 낼 수 있는 것은 앞날개
에 있는 줄과 마찰편 때문입니다. 앞날개는 배
끝까지 덮지는 못하지만 배 옆구리로 날개가
꺾이면서 옆구리까지 덮게 됩니다. 뒷날개는
퇴화하여 작아지거나 반대로 발달하는 것도 있
습니다. 뒷날개의 역할은 귀뚜라미가 나는 데
사용할 수 있다는 것입니다.
귀뚜라미의 귀는 특이하게도 앞다리 종아리 마
디에 있습니다. 사진은 앞다리의 바깥쪽(오른
쪽 사진)과 안쪽(왼쪽 사진)을 보여주고 있는데
사진에서 보이는 하얀 고막이 바로 귀입니다.
http://www.zoo.cam.ac.uk/zoostaff/hedwig/index.html
Release of Singing Behavior
Microinjections of neuroactive
substances like cholinergic
agonists or ACh esterase
blockers into the brain are most
effective in grasshoppers and in
crickets. Stridulation may last
for many minutes and different
song patterns are released.
Calling song stridulation is
released in the cricket Gryllus
bimaculatus by microinjection of
eserine into the protocerebrum.
http://www.a-msystems.com/physiology/products/electrodes/suction.asp
Suction Electrode
The Suction Electrode is used to
record or stimulate a tissue which
remains submerged in saline. It is
a popular choice to overcome the
difficulties associated with air and
oil recordings. With the Suction
Electrode, it is quite easy to record
extracellularly from very small
hearts (insects), intestinal nerves,
eye neurons and to stimulate
muscles by an electrical pulse to
their neurons.
Auditory System of Cricket
synapse
60 Auditory
Afferent Neuron
(along 5th prothoracic nerve)
Ear(right)
Omega 1
Neuron
Prothoracic
Ganglion
60 Auditory
Afferent Neuron
(along 5th prothoracic nerve)
Ear(left)
synapse
Omega 1
Neuron
Two Fundamental Problems
Speaking and singing present the auditory system of the caller with two
fundamental problems :
• Discrimination between self-generated and external auditory signals
• Prevention against desensitization
Sonorous Singing
• Intracellular recordings were
made from the dendritic region
of ON1
• An Inhibitory input influenced
auditory processing.
- Max spike fq. of ON1(176±28Hz) was
much lower than at rest(376 ±50Hz).
-Vertical Scale bar
intracellular : 25mV
extracellular : 10mV
wing : 1mm
- Horizontal Scale bar : 250ms
Silent Singing
• Sound production was prevented by
removing one forewing.
• ON1 received inhibitory postsynaptic
potentials(IPSPs) during the syllables.
- The activity of ON1 during sonorous stridulation is due
to the cricket’s own song.
• ON1 response to external acoustic stimuli
was inhibited during the chirps.
- Only excitatory postsynaptic potentials, and occasionally
a spike, were elicited by the stimuli during silent chirps.
Fictive Singing
• To determine whether the inhibition was
elicited by sensory feedback or by the
network of neurons that generate the motor
pattern.
• Either thoracic or thoracic and abdominal
galglia was isolated from muscles and sense
organs, except for the fifth prothoracic nerve.
• IPSPs were also present in the fictively
singing cricket.
• IPSPs even persisted when the ear were
removed.
Auditory Afferents
• Primary afferent depolarizations
(PADs) were presented with a
similar timing to the IPSPs in ON1.
- Vertical Scale bar
intracellular : 15mV
extracellular : 10mV
wing : (a) 1mm, (b) 0.25mm, (c) 0.5mm
- Horizontal Scale bar : 250ms
Auditory Afferents(cont’d)
• The PADs did not affect spike production in the auditory afferents.
• But in many sensory systems, PADs have an inhibitory function as they reduce
synaptic efficacy at the afferent terminals.
Effectiveness of Inhibition
• At rest and during the chirp interval
each sound pulse evoked a burst of
spike in ON1 with an average maximum
spike frequency of 376±50Hz.
-Vertical Scale bar
intracellular : 25mV
wing : 1mm
- Horizontal Scale bar : 100ms
• During silent chirps ON1 responded
with bursts of only 123±29Hz.
Effect of Inhibition on ON1
• At 80dB SPL each sound pulse elicited
a burst of spikes with 203±24Hz.
• When normal singing was mimicked
with 100dB SPL chirps, the response to
the following 80dB SPL test stimuli was
reduced to 30±1Hz.
-Vertical Scale bar
intracellular : 25mV
current : 20nA
- Horizontal Scale bar : 100ms
Effect of Inhibition on ON1(cont’d)
• Injected hyperpolarizing current prevented ON1 from spiking during the 100dB
SPL chirp. The average maximum response to subsequent 80dB SPL stimuli was a
burst of spikes at 143±32Hz, which was significantly higher than the response
without current injection.
Conclusion
• In the cricket an efferent signal(a ‘corollary discharge’) modulates
auditory information processing at two levels of the auditory system :
PADs in auditory afferent terminals and IPSPs in ON1.
• Inhibition by the corollary discharge reduces the neural response to
self-generated sound and protects the cricket’s auditory pathway
from self-induced desensitization.