Lecture 21 Flashcards
What are extrastriate areas, and how do they relate to the visual cortex?
Extrastriate areas are higher-order visual areas that contain representations of the retina and are located beyond the striate cortex in the visual cortex.
What is the concept of a receptive field in the context of single cell recording in visual neuroscience?
A receptive field refers to the limited region of space within which a visually sensitive neuron responds to stimuli.
Describe the results and conclusions of the single cell recording study in area MT regarding direction of motion.
Neurons in area MT were found to be selective for the direction of motion. They fired vigorously when the stimulus moved in a specific direction, indicating direction selectivity.
Explain the concept of speed tuning in the context of single cell recording in area MT.
Speed tuning refers to the selectivity of neurons in area MT for the speed of motion. Neurons in this area respond most vigorously to motion at a particular speed.
How was positron emission tomography (PET) used to study specialization of function in human visual cortex?
PET measured regional cerebral blood flow to identify which parts of the brain are involved in the perception of different visual stimuli, such as colored stimuli or moving stimuli.
What functional differences were observed between the dorsal and ventral pathways in the PET study?
The PET study demonstrated that different areas of human extrastriate visual cortex are involved in processing different attributes of vision. The dorsal stream codes motion and location, while the ventral stream processes detailed stimulus features and object identity.
How is topography preserved in different visual areas of the cortex, and what determines the type of information represented in each area’s map?
Topography is preserved as one area projects to another, and the type of information represented in each area’s map is determined by the response properties of the neurons in that area.
What is the role of V4 in visual processing, and what types of stimuli are neurons in this area selective for?
V4, located along the “ventral stream,” was initially thought to be selective for color. However, it was later discovered that some cells in V4 respond to combinations of color and form.
Describe the functions and selectivity of neurons in V5 (Area MT) within the dorsal stream.
Neurons in V5 are selective for the direction of motion and the speed of motion. Damage to V5 can disrupt motion perception, such as the ability to discriminate the direction of a stimulus’s movement.
