navigating with fingers and feet: comparative analysis of human and rat movement kinematics during...
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Navigating with fingers and feet: Comparative analysis of human and rat movement kinematics during non-visual spatial tasks
J.R. Raines, N.D. McNeal, J.L. Jones, S.S. Winter, M.M. Martin, P.S. Wallace, D.G. Wallace*Dept Psychology, Northern Illinois Univ., DeKalb, IL, USA
Human subjects were blindfolded while seated at a rectangular table, instructed to follow a string attached to the surface of the table, and, upon reaching the end, instructed to return to the start location. Three groups followed two string segments (25cm) that were subtended by an Acute, Right, or Obtuse angle.
Female Long Evans rats were trained to track a scented string to locate a 1 gram banana food pellet. Upon locating the food item, rats carried it back to the refuge to consume it. Each rat experienced two legs (100 cm) of a scented string subtended by various angles.
Figure 2: Topographic and kinematic profiles are plotted for one rat’s outward segments (top panels). Distance traveled (bottom left) on each leg of the outward segment did not differ between acute and obtuse angles. Max speeds (bottom right) observed on each leg of the outward segment did not differ between acute and obtuse angles.
Maintaining spatial orientation is essential for an animal to survive; therefore, it is not surprising that animals have evolved multiple navigational strategies to maintain spatial orientation. Use of self-movement cues appears to be one navigational strategy that is conserved across many animal species. For example, both humans and rats have been shown to accurately return to a start location in the absence of visual cues after searching for a hidden item. In general, both species organize their searching movements into periods of fast linear speed with limited changes in heading or slow linear speed with large changes in heading; however, disruption of this pattern of movement organization in humans has been shown to decrease return accuracy. The current study adapted the triangle completion paradigm to investigate the role of movement organization on self-movement cue processing in humans and rats.
Correspondence:
D.G. Wallace [email protected]
Web: www.niu.edu/user/tj0dgw1
Figure 3: Outward segment topographic and kinematic profiles are plotted for one human subject in each group (top panels). Distance traveled (bottom left) on each leg of the outward segment did not differ among groups. Max speed (bottom right) observed on each leg of the outward segment did not differ among groups.
Figure 1: A single trial is plotted for the human string following task (left-hand panel) and the rat scent tracking task (right-hand panel).
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Figure 4: Homeward segment topographic and kinematic profiles are plotted for one rat (top panels). Rats traveled a longer distance on the homeward segment after following an obtuse angle relative to an acute angle (bottom left). In addition, homeward segment maximum speeds were significantly faster after following an obtuse angle relative to an acute angle (bottom right).
Figure 5: Topographic and kinematic profiles are plotted for one human subject’s homeward segment in each group (top panels). Distance traveled on the homeward segment significantly increased as the angle followed on the outward segment increased (bottom left). In addition, homeward segment maximum speeds significantly increased as groups followed larger angles (bottom right).
• Movement organization contributes to both human and rat spatial orientation.
• The relationship between movement organization and spatial orientation observed in humans’ large scale dead reckoning was observed in the table top string following task.• Rat scent tracking disrupted movement organization typically observed during dead reckoning tasks and resulted in more variable performance.
• This work provides the foundation for translational research examining spatial orientation in animal models of neurodegenerative disorders.
Abstract
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Figure 6: Homeward segment heading directions are plotted for rats (top left) and humans (bottom left). Although rats’ heading direction concentration did not vary as a function of outward segment angle, humans’ heading direction concentration increased as the outward segment angle increased.
Figure 7: Relationship between linear and angular speeds on a single outward segment are plotted for a rat and human (left hand panels). Average linear / angular correlations and heading direction concentrations are for angles experienced by humans and rats.
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