Biomedical subjects

Jeffrey S Taube

Publications and source records attributed to Jeffrey S Taube.

3 recordsLinked to original sources

PubMed2003

Passive transport disrupts directional path integration by rat head direction cells.

A subset of neurons in the rat limbic system encodes head direction (HD) by selectively discharging when the rat points its head in a preferred direction in the horizontal plane. The preferred firing direction is sensitive to the location of landmark cues, as well as idiothetic or self-motion cues (i.e., vestibular, motor efference copy, proprioception, and optic flow). Previous studies have shown that the preferred firing direction remains relatively stable (average shift +/- 18 degrees ) after the rat walks from a familiar environment into a novel one, suggesting that without familiar landmarks, the preferred firing direction can be maintained using idiothetic cues, a process called directional path integration. This study repeated this experiment and manipulated the idiothetic cues available to the rat as it moved between the familiar and novel environment. Motor efference copy/proprioceptive cues were disrupted by passively transporting the animal between the familiar and novel environment. Darkening the room as the animal moved to the novel environment eliminated optic flow cues. HD cell preferred firing directions shifted in the novel environment by an average of 30 degrees after locomotion from the familiar environment with the room lights off; by an average of 70 degrees after passive transport from the familiar environment with the room lights on; and by an average of 67 degrees after passive transport with the room lights off. These findings are consistent with the view that motor efference copy/proprioception cues are important for maintaining the preferred firing direction of HD cells under conditions requiring path integration.

Action Potentials↗

PubMed2002

Differences between appetitive and aversive reinforcement on reorientation in a spatial working memory task.

Tasks using appetitive reinforcers show that following disorientation rats use the shape of an arena to reorient, and cannot distinguish two geometrically similar corners to obtain a reward, despite the presence of a prominent visual cue that provides information to differentiate the two corners. Other studies show that disorientation impairs performance on certain appetitive, but not aversive, tasks. This study evaluated whether rats would make similar geometric errors in a working memory task that used aversive reinforcement. We hypothesized that in a task that used aversive reinforcement rats that were initially disoriented would not reorient by arena shape and thus make similar geometric errors. Tests were performed in a rectangular arena having one polarizing cue. In the appetitive condition water consumption was the reward. The aversive condition was a water maze task with reinforcement provided by escape to a hidden platform. In the aversive condition rats returned to the reinforced corner significantly more often than in the dry condition, and did not favor the diagonally opposite corner. Results show that rats can use cues besides arena shape to reorient in an aversive reinforcement condition. These findings may also reflect different strategies, with an escape/homing strategy in the wet condition and a foraging strategy in the dry condition.

Animals↗

PubMed2002

Hippocampal spatial representations require vestibular input.

The hippocampal formation is essential for forming declarative representations of the relationships among multiple stimuli. The rodent hippocampal formation, including the entorhinal cortex and subicular complex, is critical for spatial memory. Two classes of hippocampal neurons fire in relation to spatial features. Place cells collectively map spatial locations, with each cell firing only when the animal occupies that cell's "place field," a particular subregion of the larger environment. Head direction (HD) cells encode directional heading, with each HD cell firing when the rat's head is oriented in that cell's particular "preferred firing direction." Both landmarks and internal cues (e.g., vestibular, motor efference copy) influence place and HD cell activity. However, as is the case for navigation, landmarks are believed to exert greater influence over place and HD cell activity. Here we show that temporary inactivation of the vestibular system led to the disruption of location-specific firing in hippocampal place cells and direction-specific discharge of postsubicular HD cells, without altering motor function. Place and HD cell activity recovered over a time course similar to that of the restoration of vestibular function. These results indicate that vestibular signals provide an important influence over the expression of hippocampal spatial representations, and may explain the navigational deficits of humans with vestibular dysfunction.

Animals↗