What part of the brain is responsible for processing visual signals?

The lateral geniculate nucleus (LGN) is a critical component of the brain's visual processing system. It acts as a relay center in the thalamus for visual information received from the retina of the eye. The LGN receives input from the optic nerve and processes visual signals before they are sent to the primary visual cortex in the occipital lobe.

The structure of the LGN is organized into layers that correspond to different types of visual information, such as colors and motion. This organizational feature allows the brain to integrate and interpret complex visual stimuli effectively.

In contrast, the other options are involved in different functions. The hippocampus is primarily associated with memory and learning, the substantia nigra is crucial for movement and reward processing, and the hypothalamus regulates various autonomic processes and homeostasis, such as temperature and hunger. Thus, the lateral geniculate nucleus is the correct answer for the processing of visual signals.