Navigating with fingers and feet: analysis of human (Homo sapiens) and rat (Rattus norvegicus) movement organization during nonvisual spatial tasks.

The current set of studies examines the contribution of movement segmentation to self-movement cue processing for estimating direction and distance to a start location in humans and rats. Experiments 1 and 2 examined the extent that ambulatory dead reckoning tasks can be adapted to the manipulatory scale in humans. Experiments 3 and 4 investigated the performance of rats in similar tasks at their ambulatory scale. Movement segmentation had differential effects on absolute heading error for humans and rats when only comparing performance on specific tasks; however, movement segmentation had similar effects for both species when performance was examined across all tasks. In general, magnitude of movement segmentation was associated with absolute heading error in both humans and rats. In contrast, both species modified homeward segment kinematics based on the distance to the start location in all tasks, consistent with the use of self-movement cues to estimate distance. The current study provides evidence for a role of movement segmentation in processing self-movement cues selective to direction estimation and develops a foundation for future studies investigating the neurobiology of spatial orientation.

Organization of food protection behavior is differentially influenced by 192 IgG-saporin lesions of either the medial septum or the nucleus basalis magnocellularis.

Converging lines of evidence have supported a role for the nucleus basalis magnocellularis (NB) in attentional mechanisms; however, debate continues regarding the role of the medial septum in behavior (MS). Recent studies have supported a role for the septohippocampal system in the online processing of internally generated cues. The current study was designed to investigate a possible double dissociation in rat food protection behavior, a natural behavior that has been shown to depend on external and internal sources of information. The study examined the effects of intraparenchymal injections of 192 IgG-saporin into either the MS or NB on the organization of food protection behavior. NB cholinergic lesions reduced the number of successful food protection behaviors while sparing the temporal organization of food protection behavior. In contrast, MS cholinergic lesions disrupted the temporal organization of food protection behavior while sparing the ability to successfully protect food items. These observations are consistent with a double dissociation of NB and MS cholinergic systems' contributions to processing external and internal sources of information and provide further evidence for the septohippocampal system's involvement in processing internally generated cues.