scholarly journals Blind cavefish retain functional connectivity in the tectum despite loss of retinal input

2021 ◽  
Author(s):  
Evan Lloyd ◽  
Brittnee McDole ◽  
Martin Privat ◽  
James B. Jaggard ◽  
Erik Duboué ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Neural Circuit ◽  
Astyanax Mexicanus ◽  
Evolutionary Selection ◽  
Environmental Perturbation ◽  
Multiple Components ◽  
Correlated Activity ◽  
Retinal Input ◽  
Hybrid Fish ◽  
Blind Cavefish

AbstractSensory systems display remarkable plasticity and are under strong evolutionary selection. The Mexican cavefish, Astyanax mexicanus, consists of eyed river-dwelling surface populations, and multiple independent cave populations which have converged on eye loss, providing the opportunity to examine the evolution of sensory circuits in response to environmental perturbation. Functional analysis across multiple transgenic populations expressing GCaMP6s showed that functional connectivity of the optic tectum largely did not differ between populations, except for the selective loss of negatively correlated activity within the cavefish tectum, suggesting positively correlated neural activity is resistant to an evolved loss of input from the retina. Further, analysis of surface-cave hybrid fish reveals that changes in the tectum are genetically distinct from those encoding eye-loss. Together, these findings uncover the independent evolution of multiple components of the visual system and establish the use of functional imaging in A. mexicanus to study neural circuit evolution.

scholarly journals Thalamic Functional Connectivity during Spatial Long-Term Memory and the Role of Sex

2020 ◽  
Vol 10 (12) ◽  
pp. 898
Author(s):  
Dylan S. Spets ◽  
Scott D. Slotnick
Keyword(s):  
Sex Differences ◽  
Functional Connectivity ◽  
Region Of Interest ◽  
Brain Regions ◽  
Long Term Memory ◽  
Thalamic Nuclei ◽  
Term Memory ◽  
Correlated Activity ◽  
Abstract Shapes

The thalamus has been implicated in many cognitive processes, including long-term memory. More specifically, the anterior (AT) and mediodorsal (MD) thalamic nuclei have been associated with long-term memory. Despite extensive mapping of the anatomical connections between these nuclei and other brain regions, little is known regarding their functional connectivity during long-term memory. The current study sought to determine which brain regions are functionally connected to AT and MD during spatial long-term memory and whether sex differences exist in the patterns of connectivity. During encoding, abstract shapes were presented to the left and right of fixation. During retrieval, shapes were presented at fixation, and participants made an “old-left” or “old-right” judgment. Activations functionally connected to AT and MD existed in regions with known anatomical connections to each nucleus as well as in a broader network of long-term memory regions. Sex differences were identified in a subset of these regions. A targeted region-of-interest analysis identified anti-correlated activity between MD and the hippocampus that was specific to females, which is consistent with findings in rodents. The current results suggest that AT and MD play key roles during spatial long-term memory and suggest that these functions may be sex specific.

scholarly journals Gene flow and population structure in the Mexican blind cavefish complex (Astyanax mexicanus)

2012 ◽  
Vol 12 (1) ◽  
pp. 9 ◽  
Author(s):  
Martina Bradic ◽  
Peter Beerli ◽  
Francisco J García-de León ◽  
Sarai Esquivel-Bobadilla ◽  
Richard L Borowsky
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Astyanax Mexicanus ◽  
Blind Cavefish

scholarly journals Circadian rhythms in Mexican blind cavefish Astyanax mexicanus in the lab and in the field

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Andrew Beale ◽  
Christophe Guibal ◽  
T. Katherine Tamai ◽  
Linda Klotz ◽  
Sophie Cowen ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Astyanax Mexicanus ◽  
Blind Cavefish

scholarly journals Morphogenetic and patterning defects explain the coloboma phenotype of the eye in the Mexican cavefish

2019 ◽  
Author(s):  
Lucie Devos ◽  
Florent Klee ◽  
Joanne Edouard ◽  
Victor Simon ◽  
Laurent Legendre ◽  
...  
Keyword(s):  
Morphological Evolution ◽  
Developmental Defects ◽  
Optic Stalk ◽  
Astyanax Mexicanus ◽  
Cellular Processes ◽  
Tightly Coupled ◽  
Vertebrate Eye ◽  
Blind Cavefish ◽  
Epithelium Cells ◽  
Type Specification

AbstractThe morphogenesis of the vertebrate eye consists of a complex choreography of cell movements, tightly coupled to axial regionalization and cell type specification processes. Any disturbance in these events can lead to developmental defects and blindness. Here we have deciphered the sequence of defective events leading to coloboma phenotype in the embryonic eye of the blind cavefish of the species Astyanax mexicanus. Using comparative live imaging on targeted enhancer-trap Zic1:hsp70:GFP reporter lines of both the normal, river-dwelling morph and the cave morph of the species, we identified major defects in initial optic vesicle size and optic cup invagination in cavefish. Combining these results with gene expression analyses, we also discovered defects in axial patterning affecting mainly the temporal retina, in optic stalk tissue specification, and in the spreading processes involving the retinal pigmented epithelium cells. Based on these results, we propose a developmental scenario to explain the cavefish phenotype and discuss developmental constraints to morphological evolution. The cavefish eye appears as an outstanding natural mutant model to study molecular and cellular processes involved in optic region morphogenesis.

scholarly journals Processing of motion boundary orientation in macaque V2

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Heng Ma ◽  
Pengcheng Li ◽  
Jiaming Hu ◽  
Xingya Cai ◽  
Qianling Song ◽  
...  
Keyword(s):  
Neural Circuit ◽  
Neuronal Response ◽  
Critical Role ◽  
Neural Mechanisms ◽  
Orientation Discrimination ◽  
Boundary Orientation ◽  
Area V2 ◽  
Correlated Activity ◽  
Object Based ◽  
Motion Boundaries

Human and nonhuman primates are good at identifying an object based on its motion, a task that is believed to be carried out by the ventral visual pathway. However, the neural mechanisms underlying such ability remains unclear. We trained macaque monkeys to do orientation discrimination for motion boundaries (MBs) and recorded neuronal response in area V2 with microelectrode arrays. We found 10.9% of V2 neurons exhibited robust orientation selectivity to MBs, and their responses correlated with monkeys’ orientation-discrimination performances. Furthermore, the responses of V2 direction-selective neurons recorded at the same time showed correlated activity with MB neurons for particular MB stimuli, suggesting that these motion-sensitive neurons made specific functional contributions to MB discrimination tasks. Our findings support the view that V2 plays a critical role in MB analysis and may achieve this through a neural circuit within area V2.

A Theoretical Analysis of the Influence of Fixational Instability on the Development of Thalamocortical Connectivity

2006 ◽  
Vol 18 (3) ◽  
pp. 569-590 ◽  
Author(s):  
Antonino Casile ◽  
Michele Rucci
Keyword(s):  
Receptive Fields ◽  
Simple Cells ◽  
Second Order Statistics ◽  
Response Characteristics ◽  
Correlated Activity ◽  
Retinal Input ◽  
Before And After ◽  
Eye Opening ◽  
Cortical Receptive Fields ◽  
Analytical Expressions

Under natural viewing conditions, the physiological instability of visual fixation keeps the projection of the stimulus on the retina in constant motion. After eye opening, chronic exposure to a constantly moving retinal image might influence the experience-dependent refinement of cell response characteristics. The results of previous modeling studies have suggested a contribution of fixational instability to the Hebbian maturation of the receptive fields of V1 simple cells (Rucci, Edelman, & Wray, 2000; Rucci & Casile, 2004). This letter examines the origins of such a contribution. Using quasilinear models of lateral geniculate nucleus units and V1 simple cells, we derive analytical expressions for the second- order statistics of thalamocortical activity before and after eye opening. We show that in the presence of natural stimulation, fixational instability introduces a spatially uncorrelated signal in the retinal input, which strongly influences the structure of correlated activity in the model. This input signal produces a regime of thalamocortical activity similar to that present before eye opening and compatible with the Hebbian maturation of cortical receptive fields.

scholarly journals Shh and forebrain evolution in the blind cavefish Astyanax mexicanus

2008 ◽  
Vol 100 (3) ◽  
pp. 139-147 ◽  
Author(s):  
Sylvie Rétaux ◽  
Karen Pottin ◽  
Alessandro Alunni
Keyword(s):  
Astyanax Mexicanus ◽  
Blind Cavefish
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