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Behavioral Tracking and Neuromast Imaging of Mexican Cavefish
Published on: April 6, 2019
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Differences in behavior between surface and cave Astyanax mexicanus may be mediated by changes in catecholamine
Kathryn Gallman1, Eric Fortune1, Daihana Rivera1
1Biological Sciences, New Jersey Institute of Technology, New Jersey, USA.
The Journal of Comparative Neurology
|April 16, 2020
Summary
Cavefish exhibit altered brain chemistry, specifically in tyrosine hydroxylase distribution, linked to enhanced sensory perception and altered behaviors. These changes in dopamine and noradrenaline systems facilitate adaptation to nutrient-poor cave environments.
Area of Science:
- Neuroscience
- Evolutionary Biology
- Ichthyology
Background:
- Astyanax mexicanus, a teleost fish, is undergoing allopatric speciation.
- Surface-dwelling ancestral populations contrast with derived blind cave forms.
- Cave adaptation involves enhanced foraging and reduced defensive behaviors, potentially mediated by catecholaminergic systems.
Purpose of the Study:
- To investigate the distribution of tyrosine hydroxylase, a key enzyme in catecholamine synthesis.
- To compare tyrosine hydroxylase expression in the brains of surface and cave Astyanax.
- To correlate neurochemical differences with behavioral adaptations to cave environments.
Main Methods:
- Immunohistochemistry was used to visualize tyrosine hydroxylase.
- Brain tissues from surface and cave Astyanax were analyzed.
- Quantitative analysis of tyrosine hydroxylase immunoreactive soma size was performed in specific brain regions.
Main Results:
- Differences in tyrosine hydroxylase staining were observed between surface and cavefish.
- Cavefish showed significantly increased soma diameters for tyrosine hydroxylase immunoreactive neurons.
- Affected regions include the olfactory bulb, basal telencephalon, preoptic nuclei, ventral thalamus, posterior tuberculum, and locus coeruleus.
Conclusions:
- Altered catecholaminergic systems, involving dopamine and noradrenaline, are associated with cave adaptation in Astyanax mexicanus.
- Changes in tyrosine hydroxylase distribution suggest modifications in nonvisual sensory perception, motor control, and attention.
- These neurochemical shifts likely underlie the unique behavioral repertoire of cave-dwelling fish.
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