229
techniques such as auditory evoked potentials (AEP; formerly called auditory
brainstem response, or ABR) (Kenyon et al. 1998 ; Ladich and Fay 2013 ), and more
invasive approaches such as saccular potentials (Furukawa et al. 1972 ; Enger et al.
1973 ; Fay 1974 ; Sisneros 2007 ; Vasconcelos et al. 2011 ), single neuron recordings
from auditory primary afferents (Fay 1978a , b ; Fay and Ream 1986 ; Lu et al. 2003 ;
Sisneros and Bass 2003 ) and single or multi-unit recordings from central auditory
nuclei in the brain (Lu and Fay 1993 , 1995 ; Bodnar and Bass 1997 , 1999 ; EddsWalton and Fay 1998 , 2003 , 2008 ; Kozloski and Crawford 2000 ; Maruska and
Tricas 2009b ). These electrophysiological methods typically require animal anesthetization and restraint, and depending on the method, are often focused on only a
specifi c subset of the auditory processing pathway, which will subsequently be integrated by the animal to display context-appropriate behaviors. Due to their quick
and relatively easy setup, however, electrophysiological methods are particularly
useful for testing auditory effects during ontogeny, before and after physiologically
relevant (e.g., steroids), acoustical (e.g. noise), or accessory auditory structure
(e.g., swim bladder) manipulations (Yan et al. 2000 ; Scholik and Yan 2001 ; Egner
and Mann 2005 ; Smith et al. 2006 ), and for comparing among species, sexes, social
status, and reproductive conditions (Kenyon et al. 1998 ; Maruska et al. 2007 , 2012 ;
Ladich and Fay 2013 ). Thus, while both behavioral and electrophysiological
approaches have advantages and disadvantages, their utility for examining auditory
abilities in fi shes is valuable but will vary based on the research question, species
used, and other experiment-dependent limitations. Recent advances in neural telemetry that permit simultaneous neural recordings in freely behaving fi shes will also
likely make important contributions towards fully understanding the relationships
between behavioral and electrophysiological measures of fi sh auditory and mechanosensory capabilities (Palmer and Mensinger 2002 ; Maruska and Mensinger 2015 ;
Radford and Mensinger 2014 ).
1.2 Comparisons of Auditory Capabilities Using Different
Methods within a Single Species
To understand the effi cacy of determining auditory capabilities in fi shes via these
diverse techniques, it is imperative to compare measures obtained via several methods within a single species under similar testing conditions. Unfortunately, the
existing comparative data on this topic are scant. Auditory abilities using both
behavioral and physiological AEP methods have been achieved for only a small
representative number of the >30,000 species of fi shes, and include the goldfi sh
( Carassius auratus ), oyster toadfi sh ( Opsanus tau ), Oscar cichlid ( Astronotus ocellatus ), little skate ( Raja ( Leucoraja ) erinacea ), perch ( Perca fl uviatilis ), red sea
bream ( Pagrus major ), and common carp ( Cyprinus carpio ) [reviewed in Ladich
and Fay 2013 ]. From these comparisons it is clear that there is no universal conversion between behavioral auditory thresholds and AEP-determined thresholds.
However, Ladich and Fay ( 2013 ) note the generalization that AEPs tend to produce
Comparison of Electrophysiological Auditory Measures in Fishes
techniques such as auditory evoked potentials (AEP; formerly called auditory
brainstem response, or ABR) (Kenyon et al. 1998 ; Ladich and Fay 2013 ), and more
invasive approaches such as saccular potentials (Furukawa et al. 1972 ; Enger et al.
1973 ; Fay 1974 ; Sisneros 2007 ; Vasconcelos et al. 2011 ), single neuron recordings
from auditory primary afferents (Fay 1978a , b ; Fay and Ream 1986 ; Lu et al. 2003 ;
Sisneros and Bass 2003 ) and single or multi-unit recordings from central auditory
nuclei in the brain (Lu and Fay 1993 , 1995 ; Bodnar and Bass 1997 , 1999 ; EddsWalton and Fay 1998 , 2003 , 2008 ; Kozloski and Crawford 2000 ; Maruska and
Tricas 2009b ). These electrophysiological methods typically require animal anesthetization and restraint, and depending on the method, are often focused on only a
specifi c subset of the auditory processing pathway, which will subsequently be integrated by the animal to display context-appropriate behaviors. Due to their quick
and relatively easy setup, however, electrophysiological methods are particularly
useful for testing auditory effects during ontogeny, before and after physiologically
relevant (e.g., steroids), acoustical (e.g. noise), or accessory auditory structure
(e.g., swim bladder) manipulations (Yan et al. 2000 ; Scholik and Yan 2001 ; Egner
and Mann 2005 ; Smith et al. 2006 ), and for comparing among species, sexes, social
status, and reproductive conditions (Kenyon et al. 1998 ; Maruska et al. 2007 , 2012 ;
Ladich and Fay 2013 ). Thus, while both behavioral and electrophysiological
approaches have advantages and disadvantages, their utility for examining auditory
abilities in fi shes is valuable but will vary based on the research question, species
used, and other experiment-dependent limitations. Recent advances in neural telemetry that permit simultaneous neural recordings in freely behaving fi shes will also
likely make important contributions towards fully understanding the relationships
between behavioral and electrophysiological measures of fi sh auditory and mechanosensory capabilities (Palmer and Mensinger 2002 ; Maruska and Mensinger 2015 ;
Radford and Mensinger 2014 ).
1.2 Comparisons of Auditory Capabilities Using Different
Methods within a Single Species
To understand the effi cacy of determining auditory capabilities in fi shes via these
diverse techniques, it is imperative to compare measures obtained via several methods within a single species under similar testing conditions. Unfortunately, the
existing comparative data on this topic are scant. Auditory abilities using both
behavioral and physiological AEP methods have been achieved for only a small
representative number of the >30,000 species of fi shes, and include the goldfi sh
( Carassius auratus ), oyster toadfi sh ( Opsanus tau ), Oscar cichlid ( Astronotus ocellatus ), little skate ( Raja ( Leucoraja ) erinacea ), perch ( Perca fl uviatilis ), red sea
bream ( Pagrus major ), and common carp ( Cyprinus carpio ) [reviewed in Ladich
and Fay 2013 ]. From these comparisons it is clear that there is no universal conversion between behavioral auditory thresholds and AEP-determined thresholds.
However, Ladich and Fay ( 2013 ) note the generalization that AEPs tend to produce
Comparison of Electrophysiological Auditory Measures in Fishes