Secondary Visual Cortex is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
The secondary visual cortex, also known as V2 or the prestriate cortex, is a critical region in the ventral visual stream of the mammalian brain. Located immediately posterior to the primary visual cortex (V1), V2 receives processed visual information from V1 and performs more complex visual processing, including the analysis of object features, spatial relationships, and contextual information. This page provides a comprehensive overview of V2 anatomy, function, connectivity, and its relevance to neurodegenerative diseases. [1]
| Property | Value | [2]
|----------|-------| [3]
| Category | Visual Cortex, Ventral Stream | [4]
| Location | Occipital lobe, surrounding primary visual cortex (V1) | [5]
| Brodmann Areas | BA 18 (secondary), BA 19 (associative visual cortex) | [6]
| Function | Complex visual feature processing, form perception, depth analysis | [7]
| Key Inputs | Primary visual cortex (V1) | [8]
| Key Outputs | V4, IT cortex, posterior parietal cortex |
The secondary visual cortex represents approximately 10-15% of the total neocortex in primates and contains a highly organized columnar architecture similar to V1. V2 is essential for constructing our perceptual experience of the visual world, integrating basic visual features into coherent representations of objects and scenes.
V2 occupies the banks of the lunate sulcus and the superior and inferior occipital sulci in the occipital lobe:
Boundaries:
Thickness:
V2 exhibits a six-layered neocortical organization with some distinctive features:
Layer I (Molecular Layer):
Layer II (External Granular Layer):
Layer III (External Pyramidal Layer):
Layer IV (Internal Granular Layer):
Layer V (Internal Pyramidal Layer):
Layer VI (Multiform Layer):
V2 maintains a columnar organization similar to V1:
Orientation Columns:
Ocular Dominance Columns:
Blob/Interblob Domains:
V2 is a critical hub in both the ventral ("what") and dorsal ("where") visual streams:
Ventral Stream (V1 → V2 → V4 → IT):
Dorsal Stream (V1 → V2 → MT → VIP/MST):
V2 neurons have larger receptive fields than V1 neurons:
Simple Cells:
Complex Cells:
End-stopped Cells:
V2 neurons are tuned to more complex visual features than V1:
Curvature and Contour:
3D Surface Properties:
Figure-Ground Segmentation:
V2 receives input from multiple sources:
From V1:
From Thalamus:
From Other Cortical Areas:
V2 projects to several higher visual areas:
Major Targets:
Subcortical Outputs:
V2 has extensive horizontal connections:
Intrinsic Connections:
Functional Implications:
V2 is crucial for processing complex shapes:
Contour Integration:
Shape Recognition:
V2 contributes to 3D vision:
Binocular Disparity:
Monocular Depth Cues:
While V4 is primary for color, V2 contributes:
Color Processing:
Brightness Perception:
Posterior Cortical Atrophy (PCA), often due to Alzheimer's disease, prominently affects V2:
Symptoms:
Pathology:
V2 involvement in AD extends beyond PCA:
Early Changes:
Clinical Correlates:
V2 dysfunction may contribute to visual hallucinations in Lewy body disease:
Mechanisms:
Occipital lobe strokes affecting V2 cause characteristic deficits:
Deficits:
Recovery:
Single-unit recordings in primates have revealed V2 properties:
Feature Selectivity:
Receptive Field Sizes:
fMRI in humans has confirmed V2 organization:
** retinotopic Mapping:**
Functional Activation:
Tracing studies have mapped V2 connectivity:
Hierarchical Position:
V2 develops over an extended postnatal period:
Critical Period:
Maturation:
V2 retains some capacity for modification:
Training Effects:
Recovery from Injury:
V2 activity can be used to decode visual experiences:
Brain-Machine Interfaces:
Cognitive Neuroscience:
V2 is a focus of computational neuroscience:
Neural Network Models:
Theoretical Frameworks:
The study of Secondary Visual Cortex has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science. 2013. ↩︎
Goodale MA, Milner AD. Separate visual pathways for perception and action. 1992. ↩︎
Ungerleider LG, Mishkin M. Two cortical visual systems. 1982. ↩︎
Zeki S. The visual cortex: descriptions and the machine. 2004. ↩︎
Nassi JJ, Callaway EM. Parallel processing strategies of the primate visual system. 2009. ↩︎
Livingstone M, Hubel D. Segregation of form, color, movement, and depth: anatomy, physiology, and perception. 1988. ↩︎
Schott GD, ed. Imaging the Brain in Neurological and Psychiatric Disorders. Oxford University Press; 2014. 2014. ↩︎
Crutch SJ, Lehmann M, Schott JM, Rabinovici GD, Rossor MN, Fox NC. Posterior cortical atrophy: discordant neurodegenerative and psychiatric symptoms. 2012. ↩︎