264
be an integrative response between these two acoustic modalities. Unless the role of
each system can be explicitly identifi ed, we would recommend that future wholebrain physiological work be identifi ed as acousticolateralis evoked potentials rather
than the current ABR/AEP terminology.
8 “Hearing” as a Behavioural Response
In a more behavioural setup, there is also good evidence that lateral line afferents
can also drive “hearing” responses, although the effect seems to vary with species.
The Mauthner-mediated (M-cell) escape response is a reliable behavioural measure
of reaction to aversive stimuli in fi sh that is driven by M-cell innervation of trunk
musculature (Eaton et al. 1977 ). This M-cell escape response has been frequently
used to test directional orientation to acoustic stimuli (reviewed in Eaton et al. 2001 )
and has been said to form a defi ned linkage between the ear and the trunk musculature (Moulton and Dixon 1967 ; Eaton and Popper 1995 ; Canfi eld and Rose 1996 ).
While it is clear that the ear is involved in this behavioural response, the lateral line
can also play an integrative role. Chemical ablation of the lateral line improves the
ability of goldfi sh ( Carassius auratus ) to respond to sound stimuli while blocking
the response of cichlids ( Astatotilapia burtoni ) (Canfi eld and Rose 1996 ) so both
systems play a role in the M-cell response. The lateral line has been further implicated in both the directionality of this response and its interaction with environmental obstructions (i.e. tank walls) (Mirjany et al. 2011 ), showing that at least lower
frequency sound stimuli are detected and processed by both auditory and lateral line
systems.
9 Particle and Pressure Detection
To date there is only one published paper that has directly compared the contribution of particle motion and pressure sensitivity in fi sh (Radford et al. 2012 ). This
paper compared the hearing thresholds of three species of fi sh ( C. auratus , Pempheris
adspersa , and Forstergyian lappilum ) using a shaker table stimulus and an in-tank
speaker stimulus. The results showed that all fi sh have the same basal hearing ability
to particle motion and it is the fi sh’s ability to detect the pressure stimulus that differentiates hearing ability between different groups, and likely drove evolutionary
diversifi cation in this modality. In a behavioural assay, female plainfi n midshipman
fi sh ( Porichthys notatus ) use particle velocity paths to directly guide their movement toward a vocalizing male with the response likely due to both hearing and
lateral-line inputs (Zeddies et al. 2012 ). Radford and Mensinger ( 2014 ) have also
shown that the toadfi sh ( O. tau ) can use their anterior lateral line to respond to a
speaker stimulus using chronic recordings. Thus both the lateral line and inner ear
may play in sound source localisation and, depending how the stimulus is presented,
D.M. Higgs and C.A. Radford
be an integrative response between these two acoustic modalities. Unless the role of
each system can be explicitly identifi ed, we would recommend that future wholebrain physiological work be identifi ed as acousticolateralis evoked potentials rather
than the current ABR/AEP terminology.
8 “Hearing” as a Behavioural Response
In a more behavioural setup, there is also good evidence that lateral line afferents
can also drive “hearing” responses, although the effect seems to vary with species.
The Mauthner-mediated (M-cell) escape response is a reliable behavioural measure
of reaction to aversive stimuli in fi sh that is driven by M-cell innervation of trunk
musculature (Eaton et al. 1977 ). This M-cell escape response has been frequently
used to test directional orientation to acoustic stimuli (reviewed in Eaton et al. 2001 )
and has been said to form a defi ned linkage between the ear and the trunk musculature (Moulton and Dixon 1967 ; Eaton and Popper 1995 ; Canfi eld and Rose 1996 ).
While it is clear that the ear is involved in this behavioural response, the lateral line
can also play an integrative role. Chemical ablation of the lateral line improves the
ability of goldfi sh ( Carassius auratus ) to respond to sound stimuli while blocking
the response of cichlids ( Astatotilapia burtoni ) (Canfi eld and Rose 1996 ) so both
systems play a role in the M-cell response. The lateral line has been further implicated in both the directionality of this response and its interaction with environmental obstructions (i.e. tank walls) (Mirjany et al. 2011 ), showing that at least lower
frequency sound stimuli are detected and processed by both auditory and lateral line
systems.
9 Particle and Pressure Detection
To date there is only one published paper that has directly compared the contribution of particle motion and pressure sensitivity in fi sh (Radford et al. 2012 ). This
paper compared the hearing thresholds of three species of fi sh ( C. auratus , Pempheris
adspersa , and Forstergyian lappilum ) using a shaker table stimulus and an in-tank
speaker stimulus. The results showed that all fi sh have the same basal hearing ability
to particle motion and it is the fi sh’s ability to detect the pressure stimulus that differentiates hearing ability between different groups, and likely drove evolutionary
diversifi cation in this modality. In a behavioural assay, female plainfi n midshipman
fi sh ( Porichthys notatus ) use particle velocity paths to directly guide their movement toward a vocalizing male with the response likely due to both hearing and
lateral-line inputs (Zeddies et al. 2012 ). Radford and Mensinger ( 2014 ) have also
shown that the toadfi sh ( O. tau ) can use their anterior lateral line to respond to a
speaker stimulus using chronic recordings. Thus both the lateral line and inner ear
may play in sound source localisation and, depending how the stimulus is presented,
D.M. Higgs and C.A. Radford