The medial entorhinal cortex is necessary for the stimulus control over hippocampal place fields by distal, but not proximal, landmarks.

A fundamental property of place cells in the hippocampus is the anchoring of their firing fields to salient landmarks within the environment. However, it is unclear how such information reaches the hippocampus. In the current experiment, we tested the hypothesis that the stimulus control exerted by distal visual landmarks requires input from the medial entorhinal cortex (MEC).

The stimulus control of local enclosures and barriers over head direction and place cell spatial firing.

Objective: Head direction cell and place cell spatially tuned firing is often anchored to salient visual landmarks on the periphery of a recording environment. What is less well understood is whether structural features of an environment, such as orientation of a maze sub-compartment or a polarizing barrier, can likewise control spatial firing.

Method: We recorded from 54 head direction cells in the medial entorhinal cortex and subicular region of male Lister Hooded rats while they explored an apparatus with four parallel or four radially arranged compartments (Experiment 1).

Mobile EEG identifies the re-allocation of attention during real-world activity.

The distribution of attention between competing processing demands can have dramatic real-world consequences, however little is known about how limited attentional resources are distributed during real-world behaviour. Here we employ mobile EEG to characterise the allocation of attention across multiple sensory-cognitive processing demands during naturalistic movement. We used a neural marker of attention, the Event-Related Potential (ERP) P300 effect, to show that attention to targets is reduced when human participants walk compared to when they stand still.

Lesions of the head direction cell system impair direction discrimination.

Previous results suggest that directional information from the head direction cell circuit may inform hippocampal place cell firing when an animal is confronted with visually identical environments. To investigate whether such information might also be essential for spatial behavior, we tested adult, male Lister Hooded rats that had received either bilateral lateral mammillary nuclei (LMN) lesions or sham lesions on a four-way, conditional odor-location discrimination in compartments arranged at 60° to one another. We found that significantly fewer rats in the LMN lesion group were able to learn the task compared to the Sham group.

A new perspective on the head direction cell system and spatial behavior.

The head direction cell system is an interconnected set of brain structures containing neurons whose firing is directionally tuned. The robust representation of allocentric direction by head direction cells suggests that they provide a neural compass for the animal. However, evidence linking head direction cells and spatial behavior has been mixed.

Navigation in Real-World Environments: New Opportunities Afforded by Advances in Mobile Brain Imaging.

A central question in neuroscience and psychology is how the mammalian brain represents the outside world and enables interaction with it. Significant progress on this question has been made in the domain of spatial cognition, where a consistent network of brain regions that represent external space has been identified in both humans and rodents. In rodents, much of the work to date has been done in situations where the animal is free to move about naturally.

Neuroethology of spatial cognition.

A key challenge for animals is recognising locations and navigating between them. These capacities are varied: we can remember where our car is parked at the mall, rats are able to remember where their nest location is while foraging for food morsels, and bats are able to fly directly to a favourite fruit tree 20 kilometers from their home cave. These spatial abilities, whether commonplace or remarkable, raise fundamental questions.

Lesions of the Head Direction Cell System Increase Hippocampal Place Field Repetition.

A central tenet of systems neuroscience is that the mammalian hippocampus provides a cognitive map of the environment. This view is supported by the finding of place cells, neurons whose firing is tuned to specific locations in an animal's environment, within this brain region. Recent work, however, has shown that these cells repeat their firing fields across visually identical maze compartments [1, 2].

Field repetition and local mapping in the hippocampus and the medial entorhinal cortex.

Hippocampal place cells support spatial cognition and are thought to form the neural substrate of a global "cognitive map." A widely held view is that parts of the hippocampus also underlie the ability to separate patterns or to provide different neural codes for distinct environments. However, a number of studies have shown that in environments composed of multiple, repeating compartments, place cells and other spatially modulated neurons show the same activity in each local area.

Understanding Minds in Real-World Environments: Toward a Mobile Cognition Approach.

There is a growing body of evidence that important aspects of human cognition have been marginalized, or overlooked, by traditional cognitive science. In particular, the use of laboratory-based experiments in which stimuli are artificial, and response options are fixed, inevitably results in findings that are less ecologically valid in relation to real-world behavior. In the present review we highlight the opportunities provided by a range of new mobile technologies that allow traditionally lab-bound measurements to now be collected during natural interactions with the world.

Place cells on a maze encode routes rather than destinations.

Hippocampal place cells fire at different rates when a rodent runs through a given location on its way to different destinations. However, it is unclear whether such firing represents the animal's intended destination or the execution of a specific trajectory. To distinguish between these possibilities, Lister Hooded rats (n = 8) were trained to navigate from a start box to three goal locations via four partially overlapping routes.

The head direction cell system and behavior: The effects of lesions to the lateral mammillary bodies on spatial memory in a novel landmark task and in the water maze.

The head direction system is composed of neurons found in a number of connected brain areas that fire in a sharply tuned, directional way. The function of this system, however, has not been fully established. To assess this, we devised a novel spatial landmark task, comparable to the paradigms in which stimulus control has been assessed for spatially tuned neurons.

Place field repetition and spatial learning in a multicompartment environment.

Recent studies have shown that place cells in the hippocampus possess firing fields that repeat in physically similar, parallel environments. These results imply that it should be difficult for animals to distinguish parallel environments at a behavioral level. To test this, we trained rats on a novel odor-location task in an environment with four parallel compartments which had previously been shown to yield place field repetition.

Place fields and the cognitive map.

The discovery of place cells by John O'Keefe in the early 1970s was a breakthrough not just for systems neuroscience, but also for psychology: place fields provided a clear neural substrate for the notion of a cognitive map, a construct devised to explain rat learning and spatial cognition. However, is the robust location-related firing of place cells still best conceptualised as a cognitive map? In this commentary, we reassess this view of hippocampus function in light of subsequent findings on place cells. We argue that as place fields encode local space, and as they are modulated by ongoing behavior, the representation they provide may be more cognitive than map-like.

Spatial cognition: a tabula rasa for the sense of direction.

Two recent studies have shown that neurons which fire in a compass-like way--head direction cells--are present before rat pups open their eyes. Upon eye opening, the firing direction of these cells is anchored rapidly to visual landmarks.

Hippocampus, delay discounting, and vicarious trial-and-error.

In decision-making, an immediate reward is usually preferred to a delayed reward, even if the latter is larger. We tested whether the hippocampus is necessary for this form of temporal discounting, and for vicarious trial-and-error at the decision point. Rats were trained on a recently developed, adjustable delay-discounting task (Papale et al.

Think local, act global: how do fragmented representations of space allow seamless navigation?

In this commentary, we highlight a difficulty for metric navigation arising from recent data with grid and place cells: the integration of piecemeal representations of space in environments with repeated boundaries. Put simply, it is unclear how place and grid cells might provide a global representation of distance when their fields appear to represent repeated boundaries within an environment. One implication of this is that the capacity for spatial inferences may be limited.

The postsubiculum and spatial learning: the role of postsubicular synaptic activity and synaptic plasticity in hippocampal place cell, object, and object-location memory.

Visual landmarks exert stimulus control over spatial behavior and the spatially tuned firing of place, head-direction, and grid cells in the rodent. However, the neural site of convergence for representations of landmarks and representations of space has yet to be identified. A potential site of plasticity underlying associations with landmarks is the postsubiculum.

Functional connectivity between the thalamus and postsubiculum: analysis of evoked responses elicited by stimulation of the laterodorsal thalamic nucleus in anesthetized rats.

The laterodorsal nucleus (LDN) of the thalamus provides a prominent afferent projection to the postsubiculum (dorsal presubiculum). To characterize synaptic transmission in this pathway, we placed stimulating electrodes in the LDN and recorded fEPSPs elicited in the postsubiculum of urethane-anesthetized rats. LDN stimulation elicited a source-sink dipole between the deep and superficial layers of the postsubiculum, respectively, consistent with anatomical evidence for the termination of thalamic afferents in the superficial layers of the structure, and the existence of deep layer neurons with apical dendrites extending into these layers.

The neural substrates of deliberative decision making: contrasting effects of hippocampus lesions on performance and vicarious trial-and-error behavior in a spatial memory task and a visual discrimination task.

Vicarious trial-and-errors (VTEs) are back-and-forth movements of the head exhibited by rodents and other animals when faced with a decision. These behaviors have recently been associated with prospective sweeps of hippocampal place cell firing, and thus may reflect a rodent model of deliberative decision-making. The aim of the current study was to test whether the hippocampus is essential for VTEs in a spatial memory task and in a simple visual discrimination (VD) task.

Animal models of working memory: a review of tasks that might be used in screening drug treatments for the memory impairments found in schizophrenia.

The Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) meeting on "Selecting Promising Animal Paradigms" focused on a consideration of valid tasks for drug discovery in non-humans. This consensus review is based on a break-out session with experts from academia and industry which considered tasks that tap working memory in animals. The specific focus of the session was on tasks measuring goal maintenance, memory capacity, and interference control.

The postsubiculum is necessary for spatial alternation but not for homing by path integration.

The postsubiculum is a structure of interest because it projects to the hippocampal formation and contains head direction cells, grid cells, and border cells. The aim of the current experiment was to test whether the postsubiculum is necessary for homing by path integration. Rats were trained on a homing task on a large circular platform.