The utricle and saccule are :

Options

A. involved in lateral integration of visual signals
B. visual centres in the cortex
C. part of the vestibular apparatus responsible for positional information about the head
D. semicircular canals that respond to head rotation

Explanation

### Step-by-Step Solution:

1. **Understanding Utricle and Saccule**:
- The utricle and saccule are structures located in the inner ear of vertebrates. They are part of the vestibular system, which is crucial for maintaining balance and spatial orientation.

2. **Location**:
- These organs are found within the vestibular cavity of the bony labyrinth of the inner ear.

3. **Function**:
- The saccule is responsible for detecting vertical (dorsal-ventral) movements, while the utricle detects horizontal movements and head tilts in all directions.

4. **Analyzing the Options**:
- **Option 1**: Involved in lateral integration of visual signals - This is incorrect as the utricle and saccule are not related to visual processing.
- **Option 2**: Visual centers in the cortex - This is also incorrect since these structures are located in the inner ear, not in the visual cortex.
- **Option 3**: Part of the vestibular apparatus responsible for positional information about the head - This is correct, as the utricle and saccule provide information about the position and movement of the head.
- **Option 4**: Semicircular canals that respond to head rotation - This is incorrect because while semicircular canals do respond to head rotation, the utricle and saccule are not located in the semicircular canals.

5. **Conclusion**:
- The correct answer is that the utricle and saccule are part of the vestibular apparatus responsible for providing positional information about the head.