Self-Organized Attractor Dynamics in the Developing Head Direction Circuit.

Head direction (HD) cells are neurons found in an extended cortical and subcortical network that signal the orientation of an animal's head relative to its environment [1-3]. They are a fundamental component of the wider circuit of spatially responsive hippocampal formation neurons that make up the neural cognitive map of space [4]. During post-natal development, HD cells are the first among spatially modulated neurons in the hippocampal circuit to exhibit mature firing properties [5, 6], but before eye opening, HD cell responses in rat pups have low directional information and are directionally unstable [7, 8].

The development of the head direction system before eye opening in the rat.

Head direction (HD) cells are neurons found in the hippocampal formation and connected areas that fire as a function of an animal's directional orientation relative to its environment. They integrate self-motion and environmental sensory information to update directional heading. Visual landmarks, in particular, exert strong control over the preferred direction of HD cell firing.

Impaired head direction cell representation in the anterodorsal thalamus after lesions of the retrosplenial cortex.

The retrosplenial cortex (RSP), a brain region frequently linked to processes of spatial navigation, contains neurons that discharge as a function of a rat's head direction (HD). HD cells have been identified throughout the limbic system including the anterodorsal thalamus (ADN) and postsubiculum (PoS), both of which are reciprocally connected to the RSP. The functional relationship between HD cells in the RSP and those found in other limbic regions is presently unknown, but given the intimate connectivity between the RSP and regions such as the ADN and PoS, and the reported loss of spatial orientation in rodents and humans with RSP damage, it is likely that the RSP plays an important role in processing the limbic HD signal.

Lesions of the tegmentomammillary circuit in the head direction system disrupt the head direction signal in the anterior thalamus.

Head direction (HD) cells in the rodent limbic system are believed to correspond to a cognitive representation of directional heading in the environment. Lesions of vestibular hair cells disrupt the characteristic firing patterns of HD cells, and thus vestibular afference is a critical contributor to the HD signal. A subcortical pathway that may convey this information includes the dorsal tegmental nucleus of Gudden (DTN) and the lateral mammillary nucleus (LMN).

Path integration and lesions within the head direction cell circuit: comparison between the roles of the anterodorsal thalamus and dorsal tegmental nucleus.

Experiments were designed to determine whether 2 regions of the head direction cell circuit, the anterodorsal thalamic nucleus (ADN) and the dorsal tegmental nucleus (DTN), contribute to navigation. Rats were trained to perform a food-carrying task with and without blindfolds prior to receiving sham lesions or bilateral lesions of the ADN or DTN. ADN-lesioned rats were mildly impaired in both versions of the task.

Passive movements of the head do not abolish anticipatory firing properties of head direction cells.

Neurons in the anterior dorsal thalamic nucleus (ADN) of the rat selectively discharge in relation to the animal's head direction (HD) in the horizontal plane. Temporal analyses of cell firing properties reveal that their discharge is optimally correlated with the animal's future directional heading by approximately 24 ms. Among the hypotheses proposed to explain this property is that ADN HD cells are informed of future head movement via motor efference copy signals.

Persistent neural activity in head direction cells.

Many neurons throughout the rat limbic system discharge in relation to the animal's directional heading with respect to its environment. These so-called head direction (HD) cells exhibit characteristics of persistent neural activity. This article summarizes where HD cells are found, their major properties, and some of the important experiments that have been conducted to elucidate how this signal is generated.

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.