Object Processing & Dysfunction I

Flashcards covering key concepts from Lecture 7: Object Processing & Dysfunction I, including the 'What' vs. 'Where' pathways, their origins, and processing beyond V1.

Geniculo-striate pathway

The cortical parallel path from the retina, involved in object processing.

Retino-tectal pathway

A non-striate, subcortical parallel path from the retina.

Cortical 'What' pathway (Ventral stream)

A cortical pathway primarily responsible for object identification and recognition, ending in the Inferior Temporal Lobe.

Cortical 'Where' pathway (Dorsal stream)

A cortical Pathway primarily responsible for spatial location and motion processing, ending in the Posterior Parietal Lobe.

Inferior Temporal Lobe

The brain region that serves as the endpoint for the ventral stream, processing object identity (the 'what' pathway).

Posterior Parietal Lobe

The brain region that serves as the endpoint for the dorsal stream, processing spatial location (the 'where' pathway).

Object discrimination task

A task used by Ungerleider & Mishkin (1982) to test the 'what' pathway, involving studying and selecting a familiar object.

Landmark discrimination task

A task used by Ungerleider & Mishkin (1982) to test the 'where' pathway, involving picking a location relative to a landmark.

Single dissociation

A result where damage to one brain area impairs a specific function, but not another, indicating some specialization.

Double dissociation

When damage to two different brain areas each causes a different distinct deficit, providing strong evidence for separate and independent brain systems.

P cells (Parvocellular retinal ganglion cells)

Retinal ganglion cells with small, foveal receptive fields, providing input to the parvocellular pathway.

M cells (Magnocellular retinal ganglion cells)

Retinal ganglion cells that integrate across multiple cones, providing input to the magnocellular pathway.

Parvocellular pathway

A visual pathway originating from retinal P-cells, projecting to parvocellular layers of the LGN and dominant to the ventral 'what' path; characterized by slow conduction, color selectivity, and high acuity.

Magnocellular pathway

A visual pathway originating from retinal M-cells, projecting to magnocellular layers of the LGN and dominant to the dorsal 'where' path; characterized by fast conduction, no color code, and low acuity.

Lateral Geniculate Nuclei (LGN)

Thalamic nuclei in each hemisphere with 6 layers, where superior 4 layers are parvocellular and inferior 2 are magnocellular, receiving input from each eye.

Primary Visual Cortex (V1)

Also known as striate cortex or Area 17; the first cortical processing area for visual information from the LGN.

Extrastriate cortex

Secondary sensory visual cortex (V2, V3, V4, V5) beyond V1, involved in more complex visual processing.

Cytochrome oxidase stain

A stain that reveals subregions like blobs and interblobs within V1, indicating segregation of magnocellular and parvocellular pathways.

Blobs (in V1)

Subregions in V1 (layers II and III) that primarily receive parvocellular input and are involved in color processing.

Interblobs (in V1)

Subregions in V1 (layers II and III) that primarily receive parvocellular input and are involved in orientation and form processing.

Visual receptive fields (progression)

As one ascends the visual processing hierarchy, receptive fields increase in size, cross the midline, increase in complexity, and become sensitive to specific features like colors, direction, objects, and faces.

V2 (Thick stripe)

A subregion of V2 associated with the dorsal pathway, primarily involved in processing speed, direction, and motion-related information.

V2 (Thin stripe)

A subregion of V2 associated with the ventral pathway, primarily involved in processing color information.

V2 (Interstripe)

A subregion of V2 associated with the ventral pathway, primarily involved in processing edges, illusory edges, and form.

MT (V5)

A key area in the dorsal stream, highly specialized for processing speed, direction, and global motion.

V4

A key area in the ventral stream, specialized for processing angles, curvature, perceived color, and kinetic contours.

MST (Medial Superior Temporal area)

A visual area involved in processing complex motion patterns such as expansions, contractions, rotations, and optic flow, crucial for self-motion perception.

TE/AIT (Anterior Inferior Temporal cortex)

A high-level area in the ventral stream involved in processing complex shapes, body parts, object recognition, and object invariance.