Neural representations of space in the hippocampus of a food-caching bird
Spatial memory in vertebrates requires brain regions homologous to the mammalian hippocampus. Between vertebrate clades, however, these regions are anatomically distinct and appear to produce different spatial patterns of neural activity. We asked whether hippocampal activity is fundamentally different even between distant vertebrates that share a strong dependence on spatial memory. We studied tufted titmice – food-caching birds capable of remembering many concealed food locations. We found mammalian-like neural activity in the titmouse hippocampus, including sharp-wave ripples and anatomically organized place cells. In a non-food-caching bird species, spatial firing was less informative and was exhibited by fewer neurons. These findings suggest that hippocampal circuit mechanisms are similar between birds and mammals, but that the resulting patterns of activity may vary quantitatively with species-specific ethological needs.
Chapter 2. The Origin of Vertebrates: Invertebrate Chordates and Cyclostomes
What transcriptomics tells us about retinal development, disease and evolution
Classification of neurons, long viewed as a fairly boring enterprise, has emerged as a major bottleneck in analysis of neural circuits. High throughput single cell RNA-seq has provided a new way to improve the situation. We initially applied this method to mouse retina, showing that its five neuronal classes (photoreceptors, three groups of interneurons, and retinal ganglion cells) can be divided into 130 discrete types. We then applied the method to other species including human, macaque, zebrafish and chick. With the atlases in hand, we are now using them to address questions about how retinal cell types diversify, how they differ in their responses to injury and disease, and the extent to which cell classes and types are conserved among vertebrates.
Fish Feelings: Emotional states in larval zebrafish
I’ll give an overview of internal - or motivational - states in larval zebrafish. Specifically we will focus on the role of the Oxytocin system in regulating the detection of, and behavioral responses to, conspecifics. The appeal here is that Oxytocin has likely conserved roles across all vertebrates, including humans, and that the larval zebrafish allows us to study some of the general principles across the brain but nonetheless at cellular resolution. This allows us to propose mechanistic models of emotional states.
Young IBRO NextInNeuro Webinar - The retinal basis of colour vision: from fish to humans
Colour vision is based on circuit-level comparison of the signals from spectral distinct types of photoreceptors. In our own eyes, the presence of three types of cones enable trichromatic colour vision. However, many phylogenetically ‘older’ vertebrates have four or more cone types, and in almost all their cases the circuits that enable tetra- or possibly even pentachromatic colour vision are not known. This includes the majority of birds, reptiles, amphibians, and bony fish. In the lab we study neuronal circuits for colour vision in non-mammalian vertebrates, with a focus on zebrafish, a tetrachromatic surface dwelling species of teleost. I will discuss how in the case of zebrafish, retinal colour computations are implemented in a fundamentally different, and probably much more efficient way compared to how they are thought to work in humans. I will then highlight how these fish circuits might be linked with those in mammals, possibly providing a new way of thinking about how circuits for colour vision are organized in vertebrates.