Spatial Learning Model Research Articles

Spatial inference without a cognitive map: the role of higher-order path integration.

The cognitive map has been taken as the standard model for how agents infer the most efficient route to a goal location. Alternatively, path integration - maintaining a homing vector during navigation - constitutes a primitive and presumably less-flexible strategy than cognitive mapping because path integration relies primarily on vestibular stimuli and pace counting. The historical debate as to whether complex spatial navigation is ruled by associative learning or cognitive map mechanisms has been challenged by experimental difficulties in successfully neutralizing path integration. To our knowledge, there are only three studies that have succeeded in resolving this issue, all showing clear evidence of novel route taking, a behaviour outside the scope of traditional associative learning accounts. Nevertheless, there is no mechanistic explanation as to how animals perform novel route taking. We propose here a new model of spatial learning that combines path integration with higher-order associative learning, and demonstrate how it can account for novel route taking without a cognitive map, thus resolving this long-standing debate. We show how our higher-order path integration (HOPI) model can explain spatial inferences, such as novel detours and shortcuts. Our analysis suggests that a phylogenetically ancient, vector-based navigational strategy utilizing associative processes is powerful enough to support complex spatial inferences.

Predictive Place-Cell Sequences for Goal-Finding Emerge from Goal Memory and the Cognitive Map: A Computational Model.

Hippocampal place-cell sequences observed during awake immobility often represent previous experience, suggesting a role in memory processes. However, recent reports of goals being overrepresented in sequential activity suggest a role in short-term planning, although a detailed understanding of the origins of hippocampal sequential activity and of its functional role is still lacking. In particular, it is unknown which mechanism could support efficient planning by generating place-cell sequences biased toward known goal locations, in an adaptive and constructive fashion. To address these questions, we propose a model of spatial learning and sequence generation as interdependent processes, integrating cortical contextual coding, synaptic plasticity and neuromodulatory mechanisms into a map-based approach. Following goal learning, sequential activity emerges from continuous attractor network dynamics biased by goal memory inputs. We apply Bayesian decoding on the resulting spike trains, allowing a direct comparison with experimental data. Simulations show that this model (1) explains the generation of never-experienced sequence trajectories in familiar environments, without requiring virtual self-motion signals, (2) accounts for the bias in place-cell sequences toward goal locations, (3) highlights their utility in flexible route planning, and (4) provides specific testable predictions.

Blocking spatial navigation across environments that have a different shape.

According to the geometric module hypothesis, organisms encode a global representation of the space in which they navigate, and this representation is not prone to interference from other cues. A number of studies, however, have shown that both human and non-human animals can navigate on the basis of local geometric cues provided by the shape of an environment. According to the model of spatial learning proposed by Miller and Shettleworth (2007, 2008), geometric cues compete for associative strength in the same manner as non-geometric cues do. The experiments reported here were designed to test if humans learn about local geometric cues in a manner consistent with the Miller-Shettleworth model. Experiment 1 replicated previous findings that humans transfer navigational behavior, based on local geometric cues, from a rectangle-shaped environment to a kite-shaped environment, and vice versa. In Experiments 2 and 3, it was observed that learning about non-geometric cues blocked, and were blocked by, learning about local geometric cues. The reciprocal blocking observed is consistent with associative theories of spatial learning; however, it is difficult to explain the observed effects with theories of global-shape encoding in their current form.

Sprouting of Nervous Fibers and Upregulation of C‐X‐C Chemokine Receptor Type 4 Expression in Hippocampal Formation of Rats with Enhanced Spatial Learning and Memory

Hippocampal mossy fiber sprouting following training in the Morris water maze (MWM) is associated with spatial learning, memory and neural plasticity. The C-X-C chemokine receptor type 4 (CXCR4) is the main receptor for stromal cell-derived factor-1 (SDF-1), which is a chemokine that can regulate axonal elongation. This study aimed to investigate the relationship between the morphological plasticity of hippocampal formation and CXCR4 expression. A model of spatial learning and memory was established in rats by training using the MWM. Mossy fiber sprouting in the striatum oriens of the CA3 area of the hippocampus was found in trained rats by Neo-Timm's method. As shown by immunohistochemistry, the CXCR4 immunopositive neurons were distributed in all layers and areas of hippocampal formation. There were no differences among groups regarding the distribution or shape of the immunopositive neurons. However, the immunoreactive staining intensity was increased in trained rats as compared with the control rats. Both CXCR4 gene transcription and translation were significantly upregulated in the trained group as compared with the control group (P < 0.01). Morphological plasticity in the form of axonal sprouting in the hippocampal formation can be induced by enhanced spatial learning and memory activity, and CXCR4 mRNA and protein expression is upregulated, indicating a positive correlation between CXCR4 expression and axonal sprouting.

Absence of overshadowing between a landmark and geometric cues in a distinctively shaped environment: A test of Miller and Shettleworth (2007).

Rats in the first 2 experiments, which were designed to test predictions from a model of spatial learning by N. Y. Miller and S. J. Shettleworth (2007), had to escape from a triangular pool by swimming to a submerged platform in a geometrically unique corner. A spherical landmark was suspended above the platform for an overshadowing group. A control group was trained with the same arrangement and with a second, identical landmark suspended in another corner. The platform could thus be found by reference to the landmark or the geometric cues in the overshadowing group, whereas the control group had to rely on geometric cues. There was no indication of overshadowing between the geometric cues and the landmark in the overshadowing group. The final 2 experiments revealed that the absence of overshadowing was not a consequence of the landmark being an ineffective cue for overshadowing. The results indicate either that the landmark and geometric cues were not in competition for the control they acquired over behavior or that an additional process compensated for any such competition that might have occurred in the overshadowing group. This additional process could involve between-cues associations or the provision of a stable spatial framework.

Effects of histamine H 3 receptor antagonists in two models of spatial learning

Despite the well-described attention and short-term memory enhancing effects of H 3 receptor antagonists, and evidence to suggest a close relationship between central histaminergic and cholinergic systems, there is a paucity of evidence for a role for H 3 receptor blockade in spatial learning. To address this, we investigated two H 3 receptor antagonists in a visual discrimination water maze in rats, and in a Barnes circular maze in mice. Thioperamide and ciproxifan significantly attenuated a scopolamine-induced deficit in the water maze task, while only ciproxifan showed a modest attenuation in the Barnes maze. Taken together, these data suggest a role for H 3 receptors in spatial learning that appears to be task-dependent.

The Opioid System and Magnetic Field Perception

The impact of Opilong—a dermorphine analog and μ-receptor agonist—on male Wistar rats' sensitivity to a static magnetic field (MF) of 38 ± 2 μT was studied using an original behavioral model of spatial learning in a multiple alternative maze. The 90° maze rotation with respect to the geomagnetic force lines caused disorientation in 80% of well-trained rats preconditioned by the Opilong treatment (0.05 mg/kg), but not in the control rats. Analysis of the behavioral patterns of the opioid–induced rats implied that the rats' orientations in the maze were initially established by taking the geomagnetic force lines into account. The internal maze cues were dominant for control rats' orientations. We conclude that modulation of the opioid system caused increased MF sensitivity and allowed perception of MF parameters. This could serve as an information factor for orientation in the maze, while self-organizing complicated goal–directed behavior in opioid-induced rats.

Corporate Space Preferences: A New Zealand Example

The paper demonstrates the problems encountered in the measurement of corporate space preferences which are not present in the residential space preference context—most notably the assignment of people to levels in a decisionmaking hierarchy, and the weighting that is necessary to reflect the contribution that each level makes to any final decision. The greater complexity of the corporate situation highlights the conceptual inadequacy of the principal components technique for the construction of mental maps, with a simple psychological scaling technique appearing to be conceptually more adequate and equally as effective. But, it is the number of items on which data are collected which emerges as the issue of greatest consequence in this type of study, the suggestion having been made that respondents should not be asked to select more than say nine or ten locations from a list of alternatives. The example of a corporate mental map, constructed in the light of the methodological discussion, was shown to have important implications for the spatial learning model proposed by Taylor (1975b), which had been derived from industrial linkage studies. Instead it was suggested that a metric reflecting the organisation of a national space economy into a series of hierarchically arranged and reasonably discrete regional space economies should replace simple euclidean measures of distance (that is, geographic space) within the model.