This study investigates the effects of environmental manipulations on the firing properties of head-direction cells in freely moving rats. Head-direction cells were recorded from rats moving in a 76-cm diameter cylinder, with a white card taped to the inside wall serving as the primary spatial cue. Rotating the card produced near-equal rotations in the preferred firing direction of the cells, with minimal changes in peak firing rate, directional firing range, or asymmetry. Removing the card had no effect on peak firing rate or range but caused a rotation in the preferred direction for 8/13 cells. Changing the environment to a rectangular or square enclosure also led to a rotation in the preferred direction for 8/10 cells in the rectangle and 3/8 cells in the square, with minimal changes in other firing properties. Hand holding the animals and moving them around the cylinder decreased the maximal firing rate in 7/9 cells but did not affect the preferred direction or firing range. Simultaneous recordings from two cells showed that the rotation of the preferred direction was consistent across cells. These findings suggest that head-direction cell firing is not a simple sensory response to visual cues but rather reflects more abstract information about the animal's spatial relationship with its environment. The results also indicate that the neural network involved in spatial navigation is not confined to the hippocampus.This study investigates the effects of environmental manipulations on the firing properties of head-direction cells in freely moving rats. Head-direction cells were recorded from rats moving in a 76-cm diameter cylinder, with a white card taped to the inside wall serving as the primary spatial cue. Rotating the card produced near-equal rotations in the preferred firing direction of the cells, with minimal changes in peak firing rate, directional firing range, or asymmetry. Removing the card had no effect on peak firing rate or range but caused a rotation in the preferred direction for 8/13 cells. Changing the environment to a rectangular or square enclosure also led to a rotation in the preferred direction for 8/10 cells in the rectangle and 3/8 cells in the square, with minimal changes in other firing properties. Hand holding the animals and moving them around the cylinder decreased the maximal firing rate in 7/9 cells but did not affect the preferred direction or firing range. Simultaneous recordings from two cells showed that the rotation of the preferred direction was consistent across cells. These findings suggest that head-direction cell firing is not a simple sensory response to visual cues but rather reflects more abstract information about the animal's spatial relationship with its environment. The results also indicate that the neural network involved in spatial navigation is not confined to the hippocampus.