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Baden T. The vertebrate retina: a window into the evolution of computation in the brain. Curr Opin Behav Sci 2024; 57:None. [PMID: 38899158 PMCID: PMC11183302 DOI: 10.1016/j.cobeha.2024.101391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 03/14/2024] [Accepted: 03/24/2024] [Indexed: 06/21/2024]
Abstract
Animal brains are probably the most complex computational machines on our planet, and like everything in biology, they are the product of evolution. Advances in developmental and palaeobiology have been expanding our general understanding of how nervous systems can change at a molecular and structural level. However, how these changes translate into altered function - that is, into 'computation' - remains comparatively sparsely explored. What, concretely, does it mean for neuronal computation when neurons change their morphology and connectivity, when new neurons appear or old ones disappear, or when transmitter systems are slowly modified over many generations? And how does evolution use these many possible knobs and dials to constantly tune computation to give rise to the amazing diversity in animal behaviours we see today? Addressing these major gaps of understanding benefits from choosing a suitable model system. Here, I present the vertebrate retina as one perhaps unusually promising candidate. The retina is ancient and displays highly conserved core organisational principles across the entire vertebrate lineage, alongside a myriad of adjustments across extant species that were shaped by the history of their visual ecology. Moreover, the computational logic of the retina is readily interrogated experimentally, and our existing understanding of retinal circuits in a handful of species can serve as an anchor when exploring the visual circuit adaptations across the entire vertebrate tree of life, from fish deep in the aphotic zone of the oceans to eagles soaring high up in the sky.
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Christenson MP, Sanz Diez A, Heath SL, Saavedra-Weisenhaus M, Adachi A, Nern A, Abbott LF, Behnia R. Hue selectivity from recurrent circuitry in Drosophila. Nat Neurosci 2024; 27:1137-1147. [PMID: 38755272 DOI: 10.1038/s41593-024-01640-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 04/04/2024] [Indexed: 05/18/2024]
Abstract
In the perception of color, wavelengths of light reflected off objects are transformed into the derived quantities of brightness, saturation and hue. Neurons responding selectively to hue have been reported in primate cortex, but it is unknown how their narrow tuning in color space is produced by upstream circuit mechanisms. We report the discovery of neurons in the Drosophila optic lobe with hue-selective properties, which enables circuit-level analysis of color processing. From our analysis of an electron microscopy volume of a whole Drosophila brain, we construct a connectomics-constrained circuit model that accounts for this hue selectivity. Our model predicts that recurrent connections in the circuit are critical for generating hue selectivity. Experiments using genetic manipulations to perturb recurrence in adult flies confirm this prediction. Our findings reveal a circuit basis for hue selectivity in color vision.
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Affiliation(s)
- Matthias P Christenson
- Zuckerman Institute, Columbia University, New York, NY, USA
- Center for Theoretical Neuroscience, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
| | - Alvaro Sanz Diez
- Zuckerman Institute, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
| | - Sarah L Heath
- Zuckerman Institute, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
| | - Maia Saavedra-Weisenhaus
- Zuckerman Institute, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
| | - Atsuko Adachi
- Zuckerman Institute, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
| | - Aljoscha Nern
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - L F Abbott
- Zuckerman Institute, Columbia University, New York, NY, USA
- Center for Theoretical Neuroscience, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
- Kavli Institute for Brain Science, Columbia University Medical Center, New York, NY, USA
| | - Rudy Behnia
- Zuckerman Institute, Columbia University, New York, NY, USA.
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA.
- Kavli Institute for Brain Science, Columbia University Medical Center, New York, NY, USA.
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Baden T. Ancestral photoreceptor diversity as the basis of visual behaviour. Nat Ecol Evol 2024; 8:374-386. [PMID: 38253752 DOI: 10.1038/s41559-023-02291-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 11/10/2023] [Indexed: 01/24/2024]
Abstract
Animal colour vision is based on comparing signals from different photoreceptors. It is generally assumed that processing different spectral types of photoreceptor mainly serves colour vision. Here I propose instead that photoreceptors are parallel feature channels that differentially support visual-motor programmes like motion vision behaviours, prey capture and predator evasion. Colour vision may have emerged as a secondary benefit of these circuits, which originally helped aquatic vertebrates to visually navigate and segment their underwater world. Specifically, I suggest that ancestral vertebrate vision was built around three main systems, including a high-resolution general purpose greyscale system based on ancestral red cones and rods to mediate visual body stabilization and navigation, a high-sensitivity specialized foreground system based on ancestral ultraviolet cones to mediate threat detection and prey capture, and a net-suppressive system based on ancestral green and blue cones for regulating red/rod and ultraviolet circuits. This ancestral strategy probably still underpins vision today, and different vertebrate lineages have since adapted their original photoreceptor circuits to suit their diverse visual ecologies.
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Affiliation(s)
- Tom Baden
- University of Sussex, Sussex Neuroscience, Sussex Center for Sensory Neuroscience and Computation, Brighton, UK.
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Nimpf S, Kaplan HS, Nordmann GC, Cushion T, Keays DA. Long-term, high-resolution in vivo calcium imaging in pigeons. CELL REPORTS METHODS 2024; 4:100711. [PMID: 38382523 PMCID: PMC10921020 DOI: 10.1016/j.crmeth.2024.100711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 11/05/2023] [Accepted: 01/26/2024] [Indexed: 02/23/2024]
Abstract
In vivo 2-photon calcium imaging has led to fundamental advances in our understanding of sensory circuits in mammalian species. In contrast, few studies have exploited this methodology in birds, with investigators primarily relying on histological and electrophysiological techniques. Here, we report the development of in vivo 2-photon calcium imaging in awake pigeons. We show that the genetically encoded calcium indicator GCaMP6s, delivered by the adeno-associated virus rAAV2/7, allows high-quality, stable, and long-term imaging of neuronal populations at single-cell and single-dendrite resolution in the pigeon forebrain. We demonstrate the utility of our setup by investigating the processing of colors in the visual Wulst, the avian homolog of the visual cortex. We report that neurons in the Wulst are color selective and display diverse response profiles to light of different wavelengths. This technology provides a powerful tool to decipher the operating principles that underlie sensory encoding in birds.
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Affiliation(s)
- Simon Nimpf
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilian-University Munich, Planegg-Martinsried, 82152 Munich, Germany.
| | - Harris S Kaplan
- Harvard University, Department of Molecular and Cellular Biology, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Gregory C Nordmann
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilian-University Munich, Planegg-Martinsried, 82152 Munich, Germany
| | - Thomas Cushion
- University of Cambridge, Department of Physiology, Development & Neuroscience, Downing Street, Cambridge CB2 3EG, UK
| | - David A Keays
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilian-University Munich, Planegg-Martinsried, 82152 Munich, Germany; University of Cambridge, Department of Physiology, Development & Neuroscience, Downing Street, Cambridge CB2 3EG, UK; Research Institute of Molecular Pathology, Vienna Biocenter, Campus-Vienna-Biocenter 1, Vienna 1030, Austria.
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Abstract
When vertebrates first conquered the land, they encountered a visual world that was radically distinct from that of their aquatic ancestors. Fish exploit the strong wavelength-dependent interactions of light with water by differentially feeding the signals from up to 5 spectral photoreceptor types into distinct behavioural programmes. However, above the water the same spectral rules do not apply, and this called for an update to visual circuit strategies. Early tetrapods soon evolved the double cone, a still poorly understood pair of new photoreceptors that brought the "ancestral terrestrial" complement from 5 to 7. Subsequent nonmammalian lineages differentially adapted this highly parallelised retinal input strategy for their diverse visual ecologies. By contrast, mammals shed most ancestral photoreceptors and converged on an input strategy that is exceptionally general. In eutherian mammals including in humans, parallelisation emerges gradually as the visual signal traverses the layers of the retina and into the brain.
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Affiliation(s)
- Tom Baden
- University of Sussex, Sussex Neuroscience, Sussex Center for Sensory Neuroscience and Computation, Brighton, United Kingdom
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