Available Sensory Input Determines Motor Performance and Strategy in Early Blind and Sighted Short-Tailed Opossums

Abstract

Summary The early loss of vision results in a reorganized neocortex, affecting areas of the brain that process both the spared and lost senses, and leads to heightened abilities on discrimination tasks involving the spared senses. Here, we used performance measures and machine learning algorithms that quantify behavioral strategy to determine if and how early vision loss alters adaptive sensorimotor behavior. We tested opossums on a motor task involving somatosensation and found that early blind animals had increased limb placement accuracy compared with sighted controls, while showing similarities in crossing strategy. However, increased reliance on tactile inputs in early blind animals resulted in greater deficits in limb placement and behavioral flexibility when the whiskers were trimmed. These data show that compensatory cross-modal plasticity extends beyond sensory discrimination tasks to motor tasks involving the spared senses and highlights the importance of whiskers in guiding forelimb control.

Conserved visual capacity of rats under red light

“…Red illumination is often used in reverse light cycle conditions in animal husbandry settings with the assumption that it will not affect rodent circadian rhythms (Emmer et al, 2018). Furthermore, experiments done under red light are believed to place the animal in dark conditions while allowing the experimenter to observe the preparation directly or by video recording (Cloke et al, 2015; Englund et al, 2020; van Goethem et al, 2012; Harris and Diamond, 2000; Harris et al, 1999; Jacklin et al, 2016; Nikbakht et al, 2012; Pacchiarini et al, 2020; Reid et al, 2014; Salaberry et al, 2017; Sieben et al, 2015; Vasconcelos et al, 2011; Winters and Reid, 2010). But from the inability to see red as a color, it does not necessarily follow that rodents cannot absorb red light through their rod-dominated retina to support form vision.…”

Kinematic analysis of sensorimotor behavior during variable ladder rung walking in short-tailed opossums (Monodelphis domestica)

“…The camera lens and ladder rungs must be at the same height (vertical red lines) to capture footage at a zero-degree angle, ensuring accurate limb tracking data is collected. Figure reprinted with permission from Englund et al., 2020 . (B) For the standard rung pattern, rungs are placed in every other slot.…”

“…This protocol produces a single, organized data-frame of body position information from multiple trials, animals, and experimental conditions which can then be analyzed in many different ways (step 32). Average limb waveforms should show little variation within-subject across trials due to the constraints of the musculoskeletal system during locomotion and waveform alignment by peak (see Englund et al., 2020 , Figures 2 D and 3 A). Correct forelimb placements of a single subject should cluster into few stereotypical waveform types due to these constraints.…”

“…This pipeline implements aspects of machine learning and signal processing, allowing for rapid data analysis that provides insight into how animals perform this task. For complete details on the use and execution of this protocol, please refer to Englund et al. (2020) .…”

“…For complete details on the use and execution of this protocol, please refer to Englund et al. (2020) .…”