diff --git a/.gitignore b/.gitignore index d800ef9..c65df40 100644 --- a/.gitignore +++ b/.gitignore @@ -17,8 +17,8 @@ data/* *.cb *.cb2 .*.lb -*.bbl -*.bcf +*.bbl* +*.bcf* *.blg *-blx.aux *-blx.bib @@ -28,4 +28,4 @@ data/* *.synctex(busy) *.synctex.gz *.synctex.gz(busy) -*.pdfsync \ No newline at end of file +*.pdfsync diff --git a/cite.bib b/cite.bib index 44e88a1..1df10ef 100644 --- a/cite.bib +++ b/cite.bib @@ -253,7 +253,7 @@ volume={154}, pages={837--846}, year={1984}, -}# Cited +} @article{helversen1988interaural, title={Interaural intensity and time discrimination in an unrestraint grasshopper: a tentative behavioural approach}, diff --git a/main.pdf b/main.pdf index 6b961b7..3c8293f 100644 Binary files a/main.pdf and b/main.pdf differ diff --git a/main.tex b/main.tex index d815ae1..87ba146 100644 --- a/main.tex +++ b/main.tex @@ -1,7 +1,7 @@ \documentclass[a4paper, 12pt]{article} \usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm,includeheadfoot]{geometry} -\usepackage[onehalfspacing]{setspace} +% \usepackage[onehalfspacing]{setspace} \usepackage{graphicx} \usepackage{svg} \usepackage{import} @@ -106,95 +106,71 @@ \newcommand{\pclp}{p(c,\,\tlp)} % Probability density (lowpass interval) \newcommand{\muf}{\mu_{f_i}} % Average feature value -\section{Exploring a grasshopper's sensory world} +\section{Introduction} % Why functional models of sensory systems? -Our scientific understanding of sensory processing systems results from the -distributed accumulation of anatomical, physiological and ethological evidence. -This process is undoubtedly without alternative; however, it leaves us with the -challenge of integrating the available fragments into a coherent whole in order -to address issues such as the interaction between individual system components, -the functional limitations of the system overall, or taxonomic comparisons -between systems that process the same sensory modality. Any unified framework -that captures the essential functional aspects of a given sensory system thus -has the potential to deepen our current understanding and fasciliate systematic -investigations. However, building such a framework is a challenging task. It -requires a wealth of existing knowledge of the system and the signals it -operates on, a clearly defined scope, and careful reduction, abstraction, and -formalization of the underlying structures and mechanisms. +Our scientific understanding of sensory processing systems is based on the +distributed accumulation of specific anatomical, physiological, and ethological +evidence. This leaves us with the challenge of integrating the available +knowledge fragments into a coherent whole in order to address more and more +far-reaching questions, from the interaction between individual processing +steps to comparisons between similar systems across different species. One way +to deal with this challenge is to build a unified framework that captures the +essential functional aspects of a sensory system. However, building such a +framework is a challenging task in itself. It requires a wealth of existing +knowledge of the system and the stimuli it operates on, a clearly defined +scope, and careful abstraction of the underlying structures and mechanisms. % Why the grasshopper auditory system? % Why focus on song recognition among other auditory functions? -One sensory system about which extensive information has been gathered over the -years is the auditory system of grasshoppers~(\textit{Acrididae}). Grasshoppers -rely on their sense of hearing primarily for intraspecific communication, which -includes mate attraction~(\bcite{helversen1972gesang}) and +One sensory system that has been extensively studied over the years is the +auditory system of grasshoppers~(\textit{Acrididae}). Grasshoppers rely on +their sense of hearing for intraspecific communication --- including mate +attraction~(\bcite{helversen1972gesang}) and evaluation~(\bcite{stange2012grasshopper}), sender localization~(\bcite{helversen1988interaural}), courtship -display~(\bcite{elsner1968neuromuskularen}), rival -deterrence~(\bcite{greenfield1993acoustic}), and loss-of-signal predator -alarm~(SOURCE). In accordance with this rich behavioral repertoire, -grasshoppers have evolved a variety of sound production mechanisms to generate -acoustic communication signals for different contexts and ranges using their -wings, hindlegs, or mandibles~(\bcite{otte1970comparative}). Among the most -conspicuous acoustic signals of grasshoppers are their species-specific calling -songs, which broadcast the presence of the singing individual --- mostly the -males of the species --- to potential mates within range. These songs are -usually more characteristic of a species than morphological +display~(\bcite{elsner1968neuromuskularen}), and rival +deterrence~(\bcite{greenfield1993acoustic}) --- and have evolved a variety of +acoustic signals for different behavioral +contexts~(\bcite{otte1970comparative}). The most conspicuous acoustic signals +of grasshoppers are their species-specific calling songs, which broadcast the +presence of the singing individual to potential mates within range. These songs +are usually more characteristic of a species than morphological traits~(\bcite{tishechkin2016acoustic}; \bcite{tarasova2021eurasius}), which can vary greatly within species~(\bcite{rowell1972variable}; \bcite{kohler2017morphological}). The reliance on songs to mediate reproduction -represents a strong evolutionary driving force, that resulted in a massive +represents a strong evolutionary driving force that resulted in a massive species diversification~(\bcite{vedenina2011speciation}; -\bcite{sevastianov2023evolution}), with over 6800 recognized grasshopper -species in the \textit{Acrididae} family~(\bcite{cigliano2024orthoptera}). It -is this diversity of species, and the crucial role of acoustic communication in -its emergence, that makes the grasshopper auditory system an intriguing -candidate for attempting to construct a functional model framework. As a -necessary reduction, the model we propose here focuses on the pathway -responsible for the recognition of species-specific calling songs, disregarding -other essential auditory functions such as directional -hearing~(\bcite{helversen1984parallel}; \bcite{ronacher1986routes}; -\bcite{helversen1988interaural}). +\bcite{sevastianov2023evolution}), with over 6800 recognized species in the +\textit{Acrididae} family~(\bcite{cigliano2024orthoptera}). +% Could go lower to concluding part: +% Its evolutionary significance makes the grasshopper auditory system --- +% specifically, the pathway responsible for species-specific song recognition +% --- an intriguing candidate for attempting to construct a functional model +% framework. -% What are the signals the auditory system is supposed to recognize? -% Why is intensity invariance important for song recognition? -% (Obviously, split this paragraph) -To understand the functional challenges faced by the grasshopper auditory -system, one has to understand the properties of the songs it is designed to -recognize. Grasshopper songs are amplitude-modulated broad-band acoustic -signals. Most songs are produced by stridulation, during which the animal pulls -the serrated stridulatory file on its hindlegs across a resonating vein on the -forewings~(\bcite{helversen1977stridulatory}; \bcite{stumpner1994song}; -\bcite{helversen1997recognition}). Every tooth that strikes the vein generates -a brief pulse of sound. Multiple pulses make up a syllable; and the alternation -of syllables and relatively quiet pauses forms a characteristic, through noisy, -waveform pattern. Song recognition depends on certain temporal and structural -parameters of this pattern, such as the duration of syllables and +% What are the signals that the auditory system is supposed to recognize? +Grasshopper songs are amplitude-modulated broad-band acoustic signals. They +consist of a series of noisy syllables and relatively quiet pauses, which form +a characteristic repetitive pattern~(\bcite{helversen1977stridulatory}; +\bcite{stumpner1994song}). Song recognition depends on certain structural +parameters of this pattern --- such as the duration of syllables and pauses~(\bcite{helversen1972gesang}), the slope of pulse onsets~(\bcite{helversen1993absolute}), and the accentuation of syllable onsets relative to the preceeding pause~(\bcite{balakrishnan2001song}; -\bcite{helversen2004acoustic}). The amplitude modulation of the song is -sufficient for recognition~(\bcite{helversen1997recognition}). However, the -essential recognition cues can vary considerably with external physical -factors, which requires the auditory system to be invariant to such variations -in order to reliably recognize songs under different conditions. For instance, -the temporal structure of grasshopper songs warps with -temperature~(\bcite{skovmand1983song}). The auditory system can compensate for -this variability by reading out relative temporal relationships rather than -absolute time intervals~(\bcite{creutzig2009timescale}; -\bcite{creutzig2010timescale}), as those remain relatively constant across -different temperatures~(\bcite{helversen1972gesang}). Another, perhaps even -more fundamental external source of song variability lays in the attenuation of -sound intensity with increasing distance to the sender. Sound attenuation -depends on both the frequency content of the signal and the vegetation of the -habitat~(\bcite{michelsen1978sound}). For the receiving auditory system, this -has two major implications. First, the amplitude dynamics of the song pattern -are steadily degraded over distance, which limits the effective communication -range of grasshoppers to~\mbox{1\,-\,2\,m} in their typical grassland -habitats~(\bcite{lang2000acoustic}). Second, the overall intensity level of -songs at the receiver's position varies depending on the location of the -sender, which should ideally not affect the recognition of the song pattern. +\bcite{helversen2004acoustic}) --- which are sufficiently conveyed by the +amplitude modulation of the song alone~(\bcite{helversen1997recognition}). + +% Why is intensity invariance important for song recognition? +Grasshopper songs, like all acoustic signals, are subject to sound attenuation, +which depends on the distance from the sender, the frequency content of the +signal, and the vegetation of the habitat~(\bcite{michelsen1978sound}). The +amplitude dynamics of the song pattern degrade fairly quickly, which limits the +effective communication range of grasshoppers to~\mbox{1\,-\,2\,m} in their +typical grassland habitats~(\bcite{lang2000acoustic}). Moreover, the intensity +of a song at the receiver's position varies with the location of the sender, +which should ideally not affect the recognition of the song. + This neccessitates that the auditory system achieves a certain degree of intensity invariance --- a time scale-selective sensitivity to faster amplitude dynamics and simultaneous insensitivity to slower, more sustained amplitude @@ -1620,12 +1596,28 @@ natural song variation. \section{Conclusions \& outlook} +\textbf{The role of repetitive songs for the feature representation:} +Most grasshopper songs are produced by stridulation, which refers to the +pulling of the serrated stridulatory file on the hindlegs across a resonating +vein on the forewings~(\bcite{helversen1977stridulatory}; +\bcite{stumpner1994song}; \bcite{helversen1997recognition}). Every "tooth" that +strikes the vein generates a brief sound pulse; multiple pulses make up a +syllable; and the repetition of syllables and pauses results in a +characteristic amplitude-modulated waveform pattern. + +\textbf{Excursion into time-warp invariance:} +For instance, the temporal structure of grasshopper songs warps with +temperature~(\bcite{skovmand1983song}). The auditory system can compensate for +this variability by reading out relative temporal relationships rather than +absolute time intervals~(\bcite{creutzig2009timescale}; +\bcite{creutzig2010timescale}), as those remain relatively constant across +different temperatures~(\bcite{helversen1972gesang}). + \textbf{Song recognition pathway: Grasshopper vs. model:}\\ The model pathway includes a rather large number of Gabor kernels compared to the 15 to 20 ascending neurons in the grasshopper auditory system~(\bcite{stumpner1991auditory}). - \textbf{Definition of invariance (general, systemic):}\\ Invariance = Property of a system to maintain a stable output with respect to a set of relevant input parameters (variation to be represented) but irrespective