Spider Brain Morphology & Behavior

Spiders are ideal model animals for experimental and comparative studies of behavior, learning and perception. They display many complex behaviors, such as the multimodal mating dances of lycosid spiders, the stealthy hunting strategies of the jumping spider Portia sp., to the labile sociality of theridiids. Spiders also demonstrate a wide range of cognitive capabilities. Spiders perceive their environment using multiple sensory modalities including: chemosensory organs; lyriform and slit-sense organs and specialized hairs that detect vibration and air movement; and up to eight eyes that vary in function, some able to detect polarization and a broad spectrum of light, including ultraviolet. While much is known about the behavior and external morphology of spiders, little is known about the spider’s nervous system. Early in the 20th century researchers, such as Saint-Remy, Hanström and Legendre, began the process of cataloging the variety of form and function within the arachnid brain. Unfortunately, these studies were limited by techniques and sample quality and much of the information is difficult to access and place into a modern context. In modern research the focus on comparative studies of spider brain morphology disappeared and was replaced with more focused research on a single species, the wandering spider Cupiennius salei. While much has been learned from these studies, C. salei represents only a small fraction of the spectrum of behaviors and sensory system morphologies that may be reflected in brain morphology. Current advances in techniques and collecting methods, combined with the framework of knowledge gained from C. salei allow for meaningful comparative work on spider neurobiology. The four chapters of my dissertation explore spider behavior, learning and neuromorphology and present two novel protocols for their study. In Chapter 1, I present a behavioral study in which I explore the effect of firefly flashing on the predatory behavior of spiders. In Chapter 2, I present a novel protocol for aversive learning trials in spiders. In Chapter 3, I present a novel method for producing whole-head DiI stained spider cephalothorax sections. In Chapter 4, I describe the variation in the visual processing pathways in spiders representing 19 different families

Plasticity, Learning and Cognition

As is becoming increasingly clear, spiders are not entirely instinct driven and inflexible in their behaviour. Here we review evidence for behavioural plasticity, learning and other cognitive processes such as attentional priming and memory. We first examine these attributes in several natural contexts: predation, interactions with conspecifics and potential predators, and spatial navigation. Next we examine two somewhat more artificial experimental approaches, heat aversion and rearing in enriched versus impoverished environments. We briefly describe the neurobiological underpinnings of these behaviours. Finally, we point to areas where our knowledge gaps are greatest, and we offer advice for researchers beginning their own studies of spider learning

Plasticity, Learning and Cognition

As is becoming increasingly clear, spiders are not entirely instinct driven and inflexible in their behaviour. Here we review evidence for behavioural plasticity, learning and other cognitive processes such as attentional priming and memory. We first examine these attributes in several natural contexts: predation, interactions with conspecifics and potential predators, and spatial navigation. Next we examine two somewhat more artificial experimental approaches, heat aversion and rearing in enriched versus impoverished environments. We briefly describe the neurobiological underpinnings of these behaviours. Finally, we point to areas where our knowledge gaps are greatest, and we offer advice for researchers beginning their own studies of spider learning

Vibration as an effective stimulus for aversive conditioning in jumping spiders

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Gastrointestinal and liver diseases and atrial fibrillation: a review of the literature

Atrial fibrillation (AF) is the most common arrhythmia worldwide and is associated with significant morbidity and mortality. A number of risk factors have been associated with AF, though few studies have explored the association between gastrointestinal and liver diseases and AF. Additionally, AF and treatment for AF may predispose to gastrointestinal and liver diseases. We review the current literature on the bidirectional associations between gastrointestinal and liver diseases and AF. We highlight the gaps in knowledge and areas requiring future investigation