Medial superior temporal area

Medial Superior Temporal Area

TheMedial Superior Temporal Area (MST) is a region of the cerebral cortex located in the dorsal stream of the visual processing pathway. It is part of the extrastriate visual cortex and plays a crucial role in the perception of motion, particularly in the analysis of complex motion patterns such as optic flow, which is the pattern of apparent motion of objects, surfaces, and edges in a visual scene caused by the relative motion between an observer and the scene.

Anatomy and Location

The MST is situated in the superior temporal sulcus of the primate brain, adjacent to the middle temporal area (MT or V5). It is part of the dorsal stream, which is involved in processing spatial and motion information. The MST is divided into two subregions: MSTd (dorsal) and MSTl (lateral), each with distinct functional properties.

Function

The MST is primarily involved in the processing of visual motion. It receives input from the middle temporal area (MT), which is responsible for detecting basic motion signals. The MST further processes these signals to interpret more complex motion patterns, such as:

• Optic Flow: MST neurons are sensitive to the global motion patterns that occur when an observer moves through an environment. This includes expansion, contraction, rotation, and translation of the visual field.
• Heading Perception: The MST is involved in determining the direction of self-motion, which is crucial for navigation and balance.
• Pursuit Eye Movements: MST neurons contribute to the control of smooth pursuit eye movements, allowing the eyes to smoothly follow moving objects.

Neural Mechanisms

Neurons in the MST are highly specialized for motion processing. They exhibit selectivity for different types of motion patterns and are capable of integrating motion information over large areas of the visual field. This integration is essential for interpreting complex motion cues and for the perception of three-dimensional motion.

Clinical Significance

Dysfunction in the MST can lead to deficits in motion perception, which can affect an individual's ability to navigate through their environment. Research into the MST and its connections with other brain areas is ongoing, with implications for understanding disorders such as motion blindness (akinetopsia) and vestibular disorders.

Research Techniques

The study of the MST involves various techniques, including:

• Functional MRI (fMRI): Used to observe the activity of the MST in response to visual motion stimuli.
• Electrophysiology: Recording the electrical activity of neurons in the MST to understand their response properties.
• Lesion Studies: Examining the effects of damage to the MST on motion perception and behavior.

Also see

• Middle temporal area
• Dorsal stream
• Optic flow
• Visual cortex
• Motion perception