Manipulations of start and food locations affect navigation on a foraging task

Self Cite

The head-direction (HD) signal is believed to originate in the dorsal tegmental nucleus (DTN) and lesions to this structure have been shown to disrupt HD cell firing in other areas along the HD cell circuit. To investigate the role of the DTN in spatial navigation, rats with bilateral, electrolytic (Experiment 1), or neurotoxic (Experiment 2) lesions to the DTN were compared with sham controls on two tasks that differed in difficulty and could be solved using directional heading. Rats were first trained on a direction problem in a water T maze where they learned to travel either east or west from two locations in the experimental room. DTN-lesioned rats were impaired relative to sham controls, both early in training, on the first block of eight trials, and on the total trials taken to reach criterion. In the food-foraging task, rats were trained to leave a home cage at the periphery of a circular table, find food in the center of the table and return to the home cage. Again, DTN-lesioned rats were impaired relative to sham rats, making more errors on the return component of the foraging trip. These data extend previous cell-recording studies and behavioral tests in which rats with electrolytic DTN lesions were used, and they demonstrate the importance of the direction system to spatial learning.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The effects of bilateral lesions to the dorsal tegmental nucleus on spatial learning in rats.

Dwyer¹,

Ingram²,

Snow³

et al. 2013

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“…After locating food, the rats tended to return to the correct location for that trial or to one of the two holes that had afforded escape on previous trials. This result was not unexpected as rats make more proactive interference errors when variable start locations are used in combination with variable reward locations (Martin et al, 2011). Although accurate performance on this task could reflect the use of allothetic (e.g., visual) or idiothetic cues, the fact that all rats made a high number of memory errors suggests that they were using allothetic cues to orient.…”

Section: Discussionmentioning

confidence: 89%

“…First choice errors were divided into three types. Adjacent-hole errors occurred when a rat nose-poked the hole 45° to the left or right of its start hole; memory errors consisted of exploration of start holes (1, 3, or 5) from a previous trial; and other errors included visits to any other hole (Martin, Evans, Harley, & Skinner, 2005; Martin et al, 2011). Because the rats often made more than one error per trial, we also analyzed total errors by the two groups.…”

Section: Methodsmentioning

confidence: 99%

The effects of lesions to the postsubiculum or the anterior dorsal nucleus of the thalamus on spatial learning in rats.

Peckford

Dwyer

Snow

et al. 2014

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To investigate the role of the head direction (HD) cell circuit in spatial navigation, rats with bilateral, neurotoxic lesions to the postsubiculum (PoS; Experiment 1) or the anterior dorsal nucleus of the thalamus (ADN; Experiment 2) were compared to sham controls on 2 tasks that could be solved using directional heading. Rats were first trained on a direction problem in a water T maze where they learned to travel either east or west from 2 locations in the experimental room. ADN lesioned rats were impaired relative to sham controls on the first block of 8 trials, but not on the total trials taken to reach criterion. This transient deficit was not observed in rats with lesions to the PoS. In the food-foraging task, rats were trained to leave a home cage at the periphery of a circular table, find food in the center of the table, and return to the home cage. Both PoS and ADN lesioned rats showed impairments on this task relative to sham rats, making more errors on the return component of the foraging trip. The spatial deficits produced by lesions to the PoS and the ADN, downstream structures in the HD cell circuit, are not as severe as those observed in earlier studies in rats with lesions to the dorsal tegmental nucleus.

“…Upon completion of the water maze tasks in Experiment 1, the same rats were trained on a food foraging task. We have previously shown that when rats are trained to leave a variable start location in search of food they often make errors on the return to the start location (Dwyer et al, 2013; Martin, Evans, Harley, & Skinner, 2005; Martin et al, 2011). The most common type of error seen in control animals is memory errors, where subjects return to a hole that was correct on a previous trial.…”

Section: Discussionmentioning

confidence: 99%

Lesions to the lateral mammillary nuclei disrupt spatial learning in rats.

Wasef¹,

Nixon²,

Bungay³

et al. 2019

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The head direction (HD) signal is thought to originate in the reciprocal connections between the dorsal tegmental nuclei (DTN) and the lateral mammillary nuclei (LMN) and lesions to these structures disrupt the HD signal in downstream structures. Lesions to the DTN also disrupt performance on spatial tasks where directional heading is thought to be important. In Experiment 1, rats with bilateral electrolytic lesions of the LMN and sham controls were trained on 2 tasks previously shown to be sensitive to DTN damage. Rats were first trained on either a direction or rotation problem in a water maze. LMN-lesioned rats were impaired relative to sham controls, on both the first block of 8 trials and on the total number of trials taken to reach criterion. In the food-foraging task, rats were trained to leave a home cage at the periphery of a circular table, find food in a food cup at the center of the table, and return to the home cage. Again, LMN-lesioned rats were impaired relative to sham rats, making more errors on the return component of the foraging trip. In Experiment 2, rats with electrolytic LMN lesions were also impaired on a dry land version of the direction and rotation problems and had difficulty discriminating between reinforced and nonreinforced locations on a 12-arm maze. These results build on previous behavioral and cell-recording studies and demonstrate the importance of the direction system to spatial learning.