265
behavioural and physiological techniques may actually measure an integrated
response from the lateral line and ears.
Fish of course can be using their auditory systems for much more than just conspecifi c communication and it has been cogently argued elsewhere (Popper and Fay
1993 , 1997 ; Fay 2009 ) that “hearing” in fi sh may have evolved to function for auditory scene analysis rather than just conspecifi c communication. Under this model, the
fi sh auditory system works to extract a range of relevant signals out of the background
noise, forming a sensory gestalt of the entire acoustic landscape. While there is little
direct evidence for this hypothesis, it does make intuitive sense and it is in analysis of
the broader range of sounds that auditory and lateral line inputs may be separated. For
nearfi eld communication sounds however, and especially for sound fi elds in laboratory tanks, it is likely that central processing of both auditory and lateral line inputs is
combined in integration centres to form an integrative picture of sound stimuli. Until
this central integration is better understood it will not be clear exactly what roles the
ear and lateral line play in sound detection, although for a fi sh it may not matter what
system predominates as long as the appropriate response is elicited.
10 Conclusions and Recommendations
Popper and Fay have had an outsized infl uence on the general fi eld of vertebrate
hearing through their superb compendium of Springer-Verlag volumes, their strong
individual scientifi c work, and their training and mentoring of numerous students,
postdoctoral fellows and visiting researchers and, for fi sh hearing in particular, in
their excellent series of review papers (Popper and Fay 1973 , 1993 , 1999 ; Fay and
Popper 2012 ) laying out the state of the fi eld and major research questions still to be
addressed. While we are far from their status as ‘senior bioacousticians’ (Fay and
Popper 2012 ), we wish to end this review by emulating their model and offer three
suggestions where we feel the research community could helpfully progress. As we
hope we outlined above, we are not the fi rst to suggest these research foci but by
laying them out explicitly below we urge the fi eld to consider new approaches that
will better elucidate how the ear and lateral line work together to form a central
image in response to sound stimuli.
1. In other vertebrates, especially mammals, the study of multisensory integration
has become well established but researchers studying fi sh sensory function have
predominantly studied sensory systems in isolation. We feel an enhanced emphasis on truly integrative physiology has the potential to advance the fi eld in signifi -
cant ways. Both single- and multi-unit recordings from integrative centres such
as the torus semicircularis in response to sound stimuli as well as more natural
stimuli (e.g. conspecifi cs or prey stimuli presented in the recording chamber, e.g.
Wysocki and Ladich 2003 ; Maruska et al. 2007 ) would better inform us as to
how fi sh encode and process sensory stimuli at the central level and turn that
processing into behavioural responses. This physiological work would ideally be
The Potential Overlapping Roles of the Ear and Lateral Line in Driving “Acoustic”…
behavioural and physiological techniques may actually measure an integrated
response from the lateral line and ears.
Fish of course can be using their auditory systems for much more than just conspecifi c communication and it has been cogently argued elsewhere (Popper and Fay
1993 , 1997 ; Fay 2009 ) that “hearing” in fi sh may have evolved to function for auditory scene analysis rather than just conspecifi c communication. Under this model, the
fi sh auditory system works to extract a range of relevant signals out of the background
noise, forming a sensory gestalt of the entire acoustic landscape. While there is little
direct evidence for this hypothesis, it does make intuitive sense and it is in analysis of
the broader range of sounds that auditory and lateral line inputs may be separated. For
nearfi eld communication sounds however, and especially for sound fi elds in laboratory tanks, it is likely that central processing of both auditory and lateral line inputs is
combined in integration centres to form an integrative picture of sound stimuli. Until
this central integration is better understood it will not be clear exactly what roles the
ear and lateral line play in sound detection, although for a fi sh it may not matter what
system predominates as long as the appropriate response is elicited.
10 Conclusions and Recommendations
Popper and Fay have had an outsized infl uence on the general fi eld of vertebrate
hearing through their superb compendium of Springer-Verlag volumes, their strong
individual scientifi c work, and their training and mentoring of numerous students,
postdoctoral fellows and visiting researchers and, for fi sh hearing in particular, in
their excellent series of review papers (Popper and Fay 1973 , 1993 , 1999 ; Fay and
Popper 2012 ) laying out the state of the fi eld and major research questions still to be
addressed. While we are far from their status as ‘senior bioacousticians’ (Fay and
Popper 2012 ), we wish to end this review by emulating their model and offer three
suggestions where we feel the research community could helpfully progress. As we
hope we outlined above, we are not the fi rst to suggest these research foci but by
laying them out explicitly below we urge the fi eld to consider new approaches that
will better elucidate how the ear and lateral line work together to form a central
image in response to sound stimuli.
1. In other vertebrates, especially mammals, the study of multisensory integration
has become well established but researchers studying fi sh sensory function have
predominantly studied sensory systems in isolation. We feel an enhanced emphasis on truly integrative physiology has the potential to advance the fi eld in signifi -
cant ways. Both single- and multi-unit recordings from integrative centres such
as the torus semicircularis in response to sound stimuli as well as more natural
stimuli (e.g. conspecifi cs or prey stimuli presented in the recording chamber, e.g.
Wysocki and Ladich 2003 ; Maruska et al. 2007 ) would better inform us as to
how fi sh encode and process sensory stimuli at the central level and turn that
processing into behavioural responses. This physiological work would ideally be
The Potential Overlapping Roles of the Ear and Lateral Line in Driving “Acoustic”…