Dataset Information

Coherence among head direction cells before eye opening in rat pups.

ABSTRACT: Mammalian navigation is thought to depend on an internal map of space consisting of functionally specialized cells in the hippocampus and the surrounding parahippocampal cortices. Basic properties of this map are present when rat pups explore the world outside of their nest for the first time, around postnatal day 16-18 (P16-P18). One of the first functions to be expressed in navigating animals is the directional tuning of the head direction cells. To determine whether head direction tuning is expressed at even earlier ages, before the start of exploration, and to establish whether vision is necessary for the development of directional tuning, we recorded neural activity in pre- and parasubiculum, or medial entorhinal cortex, from P11 onward, 3-4 days before the eyelids unseal. Head direction cells were present from the first day of recording. Firing rates were lower than in adults, and preferred firing directions were less stable, drifting within trials and changing completely between trials. Yet the cells drifted coherently, i.e., relative firing directions were maintained from one trial to the next. Directional tuning stabilized shortly after eye opening. The data point to a hardwired attractor network for representation of head direction in which directional tuning develops before vision and visual input serves primarily to anchor firing direction to the external world.

SUBMITTER: Bjerknes TL

PROVIDER: S-EPMC4291142 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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Coherence among head direction cells before eye opening in rat pups.

Bjerknes Tale L TL Langston Rosamund F RF Kruge Ingvild U IU Moser Edvard I EI Moser May-Britt MB

Current biology : CB 20141126 1

Mammalian navigation is thought to depend on an internal map of space consisting of functionally specialized cells in the hippocampus and the surrounding parahippocampal cortices. Basic properties of this map are present when rat pups explore the world outside of their nest for the first time, around postnatal day 16-18 (P16-P18). One of the first functions to be expressed in navigating animals is the directional tuning of the head direction cells. To determine whether head direction tuning is e ...[more]

PMID: 25466682

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Project description:Head direction (HD) cells fire when the animal faces that cell's preferred firing direction (PFD) in the horizontal plane. The PFD response when the animal is oriented outside the earth-horizontal plane could result from cells representing direction in the plane of locomotion or as a three-dimensional (3D), global-referenced direction anchored to gravity. To investigate these possibilities, anterodorsal thalamic HD cells were recorded from restrained rats while they were passively positioned in various 3D orientations. Cell responses were unaffected by pitch or roll up to ~90° from the horizontal plane. Firing was disrupted once the animal was oriented >90° away from the horizontal plane and during inversion. When rolling the animal around the earth-vertical axis, cells were active when the animal's ventral surface faced the cell's PFD. However, with the rat rolled 90° in an ear-down orientation, pitching the rat and rotating it around the vertical axis did not produce directionally tuned responses. Complex movements involving combinations of yaw-roll, but usually not yaw-pitch, resulted in reduced directional tuning even at the final upright orientation when the rat had full visual view of its environment and was pointing in the cell's PFD. Directional firing was restored when the rat's head was moved back-and-forth. There was limited evidence indicating that cells contained conjunctive firing with pitch or roll positions. These findings suggest that the brain's representation of directional heading is derived primarily from horizontal canal information and that the HD signal is a 3D gravity-referenced signal anchored to a direction in the horizontal plane. NEW & NOTEWORTHY This study monitored head direction cell responses from rats in three dimensions using a series of manipulations that involved yaw, pitch, roll, or a combination of these rotations. Results showed that head direction responses are consistent with the use of two reference frames simultaneously: one defined by the surrounding environment using primarily visual landmarks and a second defined by the earth's gravity vector.

Dataset Information

Coherence among head direction cells before eye opening in rat pups.

Publications

Coherence among head direction cells before eye opening in rat pups.

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