Glossary

1.3 Higher visual processing areas

9 min read•august 19, 2024

Higher visual processing areas are crucial for interpreting complex visual information. These regions, including the ventral and dorsal streams, work together to recognize objects, perceive motion, and process spatial information. Understanding these areas helps explain how we make sense of the visual world around us.

The brain's ability to process visual information goes beyond simple perception. Higher visual areas enable us to recognize faces, interpret color and depth, and even influence our aesthetic experiences. These complex processes shape our understanding of the visual environment and our interactions with it.

Ventral and dorsal streams

  • The , also known as the "what" pathway, is involved in and , processing visual information related to the identity and features of objects
  • The , also known as the "where" or "how" pathway, is involved in and visually guided actions, processing information about the location and motion of objects
  • These two streams originate from the primary visual cortex (V1) and diverge into separate pathways, with the ventral stream projecting to the temporal lobe and the dorsal stream projecting to the parietal lobe

Form and object recognition

Inferior temporal cortex

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  • The (IT) is a key region in the ventral stream involved in object recognition and categorization
  • IT neurons respond selectively to complex visual stimuli, such as faces, objects, and scenes
  • Damage to the IT can lead to , a condition characterized by the inability to recognize objects despite intact visual perception
  • The IT is organized in a hierarchical manner, with increasing complexity and specificity of visual representations as information flows from posterior to anterior regions

Face-selective regions

  • Within the IT, there are specialized regions that respond selectively to faces, such as the (FFA) and the (OFA)
  • These face-selective regions are involved in the perception and recognition of faces, processing information about facial features, identity, and expression
  • Damage to these regions can result in , a specific impairment in face recognition
  • Studies using functional magnetic resonance imaging () have shown increased activation in the FFA and OFA when participants view faces compared to other objects

Motion perception

Middle temporal area (MT/V5)

  • The , also known as MT or V5, is a key region in the dorsal stream involved in the perception of motion
  • MT neurons are highly sensitive to the direction and speed of moving stimuli
  • Damage to MT can lead to motion blindness, a condition characterized by the inability to perceive motion despite intact visual acuity
  • MT receives input from the primary visual cortex (V1) and projects to other areas in the dorsal stream, such as the (MST)

Medial superior temporal area (MST)

  • The medial superior temporal area (MST) is another region in the dorsal stream involved in
  • MST neurons respond to complex motion patterns, such as optic flow and self-motion
  • MST is involved in the integration of visual motion signals with vestibular and proprioceptive information, contributing to the perception of self-motion and navigation
  • Damage to MST can impair the ability to perceive heading direction and navigate through the environment

Visuospatial processing

Posterior parietal cortex

  • The (PPC) is a key region in the dorsal stream involved in visuospatial processing and attention
  • The PPC integrates visual, somatosensory, and proprioceptive information to create a unified representation of space
  • Damage to the PPC can lead to spatial neglect, a condition characterized by the inability to attend to and respond to stimuli in the contralesional side of space
  • The PPC is involved in the planning and execution of visually guided actions, such as reaching and grasping

Spatial attention networks

  • The PPC is part of a network of brain regions involved in , including the frontal eye fields (FEF) and the superior colliculus
  • These regions work together to allocate attentional resources to relevant locations in space and to guide eye movements
  • The dorsal attention network, which includes the PPC and FEF, is involved in the voluntary control of attention, such as when searching for a specific target
  • The ventral attention network, which includes the temporoparietal junction (TPJ) and the ventral frontal cortex, is involved in the automatic orienting of attention to salient or unexpected stimuli

Color perception

V4 and color processing

  • is a region in the ventral stream that is involved in and perception
  • V4 neurons are sensitive to color and respond selectively to different wavelengths of light
  • Damage to V4 can lead to , a condition characterized by the inability to perceive color despite intact visual acuity
  • V4 receives input from the primary visual cortex (V1) and projects to higher-order regions in the temporal lobe, such as the inferior temporal cortex (IT)

Color constancy mechanisms

  • Color constancy refers to the ability to perceive the color of an object as relatively stable despite changes in illumination
  • The visual system achieves color constancy through a combination of retinal and cortical mechanisms
  • Retinal mechanisms, such as chromatic adaptation and color opponency, help to maintain stable color perception under different lighting conditions
  • Cortical mechanisms, such as the integration of contextual information and the use of prior knowledge, also contribute to color constancy
  • The interaction between V4 and higher-order regions in the temporal lobe is thought to play a key role in color constancy

Depth perception

Binocular disparity cues

  • refers to the slight difference in the images projected onto the left and right retinas due to the horizontal separation of the eyes
  • The visual system uses binocular disparity cues to extract information about the relative depth of objects in the environment
  • Neurons in the primary visual cortex (V1) and other visual areas, such as V2 and V3, are sensitive to binocular disparity and respond selectively to different disparity values
  • The integration of binocular disparity information across multiple visual areas allows for the perception of stereoscopic depth

Monocular depth cues

  • are sources of depth information that can be extracted from a single retinal image, without the need for binocular vision
  • Examples of monocular depth cues include occlusion, relative size, linear perspective, and texture gradient
  • The visual system uses a combination of monocular and binocular depth cues to create a unified perception of depth and three-dimensional space
  • The integration of depth cues occurs in higher-order visual areas, such as the inferior temporal cortex (IT) and the posterior parietal cortex (PPC)

Visual memory

Parahippocampal place area

  • The (PPA) is a region in the ventral stream that responds selectively to scenes and landmarks
  • The PPA is involved in the encoding and recognition of spatial layouts and navigational cues
  • Damage to the PPA can lead to topographical disorientation, a condition characterized by the inability to navigate familiar environments
  • The PPA is thought to play a key role in the formation of cognitive maps and the representation of spatial context

Perirhinal cortex

  • The (PRC) is a region in the medial temporal lobe that is involved in object recognition memory
  • The PRC is critical for the encoding and retrieval of object-related information, such as the identity and features of objects
  • Damage to the PRC can impair the ability to recognize objects and faces, particularly when the discrimination requires fine-grained visual analysis
  • The PRC is thought to work in conjunction with the hippocampus and other medial temporal lobe structures to support long-term declarative memory

Artistic processing

Aesthetic experiences

  • Aesthetic experiences, such as the appreciation of beauty and the emotional response to art, involve a distributed network of brain regions
  • The ventral visual pathway, particularly the inferior temporal cortex (IT), is involved in the perceptual analysis of visual art, processing information about form, color, and composition
  • The prefrontal cortex (PFC) and the anterior cingulate cortex (ACC) are involved in the cognitive and emotional evaluation of art, integrating perceptual information with personal experiences and cultural knowledge
  • The reward system, including the orbitofrontal cortex (OFC) and the ventral striatum, is activated during aesthetic experiences, suggesting a link between art appreciation and pleasure

Creativity and visual imagery

  • Creativity and visual imagery involve the generation and manipulation of mental images in the absence of direct sensory input
  • The default mode network (DMN), which includes the medial prefrontal cortex (mPFC), the posterior cingulate cortex (PCC), and the inferior parietal lobule (IPL), is involved in self-generated thought and mental simulation
  • The frontoparietal control network (FPCN), which includes the dorsolateral prefrontal cortex (DLPFC) and the anterior inferior parietal lobule (aIPL), is involved in the top-down control and manipulation of mental images
  • The interaction between the DMN and the FPCN is thought to support creative cognition and the generation of novel ideas

Synesthesia

Types of synesthesia

  • Synesthesia is a neurological condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway
  • There are many different types of synesthesia, such as grapheme-color synesthesia (associating letters or numbers with specific colors), chromesthesia (associating sounds with colors), and lexical-gustatory synesthesia (associating words with tastes)
  • The most common form of synesthesia is grapheme-color synesthesia, which affects approximately 1-2% of the population
  • Synesthesia is thought to arise from increased connectivity or cross-activation between different sensory or cognitive regions in the brain

Neural basis of synesthesia

  • The neural basis of synesthesia is not yet fully understood, but several theories have been proposed
  • The cross-activation theory suggests that synesthesia arises from direct connections between sensory or cognitive regions that are normally separate, such as the visual word form area (VWFA) and the color processing area V4 in grapheme-color synesthesia
  • The disinhibited feedback theory proposes that synesthesia results from a reduction in the normal inhibitory feedback from higher-order regions to lower-order sensory areas, leading to the activation of additional sensory experiences
  • Neuroimaging studies have shown increased activation and connectivity in the sensory or cognitive regions associated with the specific type of synesthesia, supporting the idea of cross-modal interactions in the brain

Disorders of higher visual processing

Visual agnosia

  • Visual agnosia is a neurological condition characterized by the inability to recognize objects, faces, or scenes despite intact visual perception
  • There are different types of visual agnosia, such as apperceptive agnosia (difficulty in perceiving the form and structure of objects) and associative agnosia (difficulty in attributing meaning to objects despite intact perception)
  • Visual agnosia can result from damage to the ventral visual pathway, particularly the inferior temporal cortex (IT) and the fusiform gyrus
  • Patients with visual agnosia may be able to copy or match objects but fail to recognize them, suggesting a dissociation between perception and recognition

Balint's syndrome

  • is a rare neurological condition characterized by a triad of symptoms: simultanagnosia (inability to perceive multiple objects simultaneously), oculomotor apraxia (difficulty in initiating voluntary eye movements), and optic ataxia (difficulty in reaching for objects under visual guidance)
  • Balint's syndrome typically results from bilateral damage to the posterior parietal cortex (PPC), a key region in the dorsal visual pathway involved in visuospatial processing and attention
  • Patients with Balint's syndrome may experience a restricted "spotlight" of attention, being able to perceive only one object at a time and having difficulty in shifting their attention to other objects in the visual field
  • The oculomotor and reaching deficits in Balint's syndrome highlight the role of the PPC in the coordination of eye movements and visually guided actions

Top-down influences

Attention and visual processing

  • Attention is a top-down cognitive process that allows us to selectively focus on relevant information while ignoring irrelevant distractors
  • Attention can modulate visual processing at multiple stages, from early sensory areas to higher-order regions in the ventral and dorsal pathways
  • The frontoparietal attention network, which includes the frontal eye fields (FEF) and the posterior parietal cortex (PPC), is involved in the top-down control of attention and the allocation of attentional resources
  • Attention can enhance the neural responses to attended stimuli, increase the signal-to-noise ratio, and improve the efficiency of visual processing

Expectations and prior knowledge

  • Expectations and prior knowledge can influence visual processing in a top-down manner, shaping our perception and interpretation of visual information
  • The predictive coding framework suggests that the brain constantly generates predictions about incoming sensory input based on prior experience and updates these predictions based on the mismatch between expected and actual input
  • Top-down expectations can modulate activity in sensory areas, such as the primary visual cortex (V1), leading to a more efficient processing of expected stimuli and a suppression of responses to unexpected or irrelevant stimuli
  • The integration of bottom-up sensory information and top-down expectations is thought to occur in higher-order regions, such as the prefrontal cortex (PFC) and the posterior parietal cortex (PPC), which send feedback signals to sensory areas to guide perceptual processing.

Key Terms to Review (29)

Achromatopsia: Achromatopsia is a rare visual disorder characterized by an inability to perceive color, resulting in a world seen only in shades of gray. This condition stems from a dysfunction in the visual pathways and processing areas of the brain responsible for color vision, connecting it to the broader understanding of visual processing and perception.
Area V4: Area V4 is a region in the visual cortex of the brain associated with processing color information. It plays a critical role in higher visual processing, particularly in recognizing and interpreting color patterns and chromatic features of objects, enhancing our ability to perceive the visual world.
Balint's Syndrome: Balint's Syndrome is a rare neurological condition that results from bilateral damage to the parieto-occipital regions of the brain, leading to a triad of symptoms: simultanagnosia, optic ataxia, and oculomotor apraxia. This disorder significantly impacts visual processing and attention, highlighting how closely linked these cognitive functions are in interpreting visual stimuli and guiding movements.
Binocular disparity: Binocular disparity refers to the slight difference in the images perceived by each eye due to their horizontal separation. This difference plays a crucial role in depth perception, allowing the brain to interpret distance and three-dimensional structure from two slightly different perspectives. By analyzing these disparities, higher visual processing areas can construct a coherent perception of the environment.
Color processing: Color processing refers to the brain's ability to interpret and make sense of the various wavelengths of light that correspond to different colors. This complex process involves the detection of color by photoreceptors in the retina, followed by the transmission of this information to the brain, where it is further analyzed and integrated to allow us to perceive a rich spectrum of colors in our environment.
Dorsal Stream: The dorsal stream is a neural pathway in the brain that processes visual information related to motion and spatial awareness, often referred to as the 'where' pathway. It runs from the primary visual cortex in the occipital lobe to the parietal lobe and is crucial for understanding where objects are located and how they move in space. This pathway is distinct from the ventral stream, which focuses on object recognition and identification.
Electrophysiology: Electrophysiology is the study of the electrical properties of biological cells and tissues, particularly how they generate and respond to electrical signals. This field is crucial for understanding how neurons communicate with each other and how visual information is processed in the brain, revealing insights into various functions such as vision, color perception, and even the neural basis of beauty.
Face inversion effect: The face inversion effect refers to the phenomenon where individuals have more difficulty recognizing faces when they are presented upside down compared to when they are upright. This effect highlights how the brain processes faces in a unique way, involving specialized neural mechanisms that are more efficient when the face is oriented correctly. It illustrates the importance of higher visual processing areas in understanding and recognizing facial features, emphasizing how orientation affects our perception.
FMRI: Functional Magnetic Resonance Imaging (fMRI) is a neuroimaging technique that measures and maps brain activity by detecting changes in blood flow and oxygenation levels. This method provides insights into brain function and connectivity, helping researchers understand how different brain regions contribute to processes like visual perception, music appreciation, emotional responses, and artistic training.
Form perception: Form perception is the process by which the visual system interprets and organizes sensory information to recognize shapes, objects, and patterns in the environment. This ability enables individuals to perceive boundaries and the overall structure of objects, distinguishing them from their backgrounds, which is essential for understanding complex visual scenes.
Fusiform face area: The fusiform face area (FFA) is a region in the human brain that is primarily responsible for facial recognition and processing. It is located in the fusiform gyrus, which lies in the temporal lobe. The FFA plays a crucial role in how we perceive and interpret faces, making it essential for social interactions and emotional understanding.
Greeble studies: Greeble studies refer to research focused on how the human brain processes complex shapes and objects, particularly those that resemble but are not real objects. These studies often utilize novel objects, known as greebles, which are designed to be unfamiliar yet share features of common visual stimuli. This research is crucial for understanding how higher visual processing areas in the brain identify and categorize objects, contributing to our knowledge of visual perception and recognition.
Inferior temporal cortex: The inferior temporal cortex is a region in the brain located in the lower part of the temporal lobe, primarily involved in visual processing, particularly in recognizing and interpreting complex visual stimuli such as faces and objects. It plays a crucial role in higher-order visual processing by integrating information from earlier visual areas, contributing to our understanding of visual scenes and object recognition.
Medial superior temporal area: The medial superior temporal area (MST) is a region in the brain involved in the processing of visual motion, particularly related to the perception of movement and the direction of moving objects. It plays a critical role in integrating visual information with spatial awareness and is essential for understanding complex motion patterns, linking it to higher visual processing areas responsible for interpreting visual stimuli.
Middle temporal area: The middle temporal area, also known as MT or V5, is a region in the brain that plays a crucial role in processing motion information from visual stimuli. It is part of the higher visual processing areas and is particularly important for perceiving movement direction and speed, contributing significantly to how we understand dynamic visual scenes.
Monocular depth cues: Monocular depth cues are visual signals that allow us to perceive depth and distance using just one eye. These cues help us understand the spatial relationships between objects in our environment, contributing to our ability to navigate and interact with the world around us. They are essential for interpreting three-dimensional space on a two-dimensional surface, such as a painting or photograph.
Motion perception: Motion perception is the process by which the visual system interprets visual information to perceive movement in the environment. This capability is crucial for understanding dynamic scenes, allowing us to recognize objects in motion and anticipate their paths, which is essential for navigation and interaction with our surroundings.
Multisensory integration: Multisensory integration is the process by which the brain combines information from different sensory modalities, such as sight, sound, and touch, to create a unified perception of the environment. This process enhances our ability to understand and interact with the world, allowing for a more robust interpretation of sensory inputs, particularly in higher visual processing areas where complex visual stimuli are analyzed in conjunction with other sensory data.
Object recognition: Object recognition is the cognitive process through which the brain identifies and categorizes objects in the visual field. This ability is crucial for interpreting visual information and allows individuals to understand their environment by recognizing familiar items, distinguishing them from unfamiliar ones, and making sense of complex scenes. Understanding how object recognition works is closely tied to the mechanisms of visual processing, particularly in differentiating between two major pathways in the brain that handle different aspects of visual information.
Occipital Face Area: The occipital face area (OFA) is a specialized region in the human brain located in the occipital lobe that is primarily involved in the perception and processing of faces. It plays a critical role in recognizing facial features, such as identity and emotion, serving as an early stage in the visual processing pathway for face recognition. This area works closely with other higher visual processing areas to interpret complex visual stimuli, particularly those involving social cues.
Parahippocampal Place Area: The parahippocampal place area (PPA) is a region in the brain's medial temporal lobe that is specifically involved in the perception and recognition of scenes and places. This area plays a crucial role in spatial navigation and memory, helping to process visual information related to the environment. Its connections to both memory and visual processing make it an important area for understanding how we perceive and interact with our surroundings.
Perirhinal cortex: The perirhinal cortex is a region of the brain located in the medial temporal lobe, adjacent to the hippocampus, and plays a crucial role in object recognition and visual memory. It is involved in processing visual information and integrating it with memory, making it essential for recognizing objects and scenes. This area helps connect higher visual processing areas with memory systems, allowing for a cohesive understanding of visual stimuli.
Posterior parietal cortex: The posterior parietal cortex is a region of the brain located in the parietal lobe, playing a crucial role in integrating sensory information and guiding motor actions. This area helps in spatial awareness, visual processing, and the coordination of movements in response to visual stimuli, making it vital for higher visual processing areas that support complex visual tasks.
Prosopagnosia: Prosopagnosia, often referred to as face blindness, is a neurological condition characterized by the inability to recognize faces, even those of familiar individuals. This impairment arises due to dysfunctions in the brain's visual processing areas that specifically handle facial recognition, which can disrupt social interactions and personal relationships.
Spatial Attention: Spatial attention refers to the cognitive process of selectively focusing on a specific location in space to enhance perception and processing of visual information in that area. This type of attention is crucial for efficiently navigating and interacting with our environment, as it allows us to prioritize important stimuli while ignoring distractions. By directing our attentional resources spatially, we can improve our ability to detect objects, recognize faces, and perform complex visual tasks.
Spatial Processing: Spatial processing is the cognitive ability to perceive, analyze, and interpret spatial relationships among objects in the environment. This skill is essential for understanding and appreciating art, as it involves recognizing shapes, patterns, and spatial arrangements that contribute to visual experiences. It also plays a key role in higher-level visual processing areas that help us comprehend complex images and three-dimensional spaces.
Ventral stream: The ventral stream is a pathway in the brain that processes visual information related to object recognition and form representation, often referred to as the 'what' pathway. This stream runs from the primary visual cortex into the temporal lobe and is crucial for identifying and understanding objects, colors, and faces. It works closely with other visual processing areas to create a comprehensive perception of the visual environment.
Visual agnosia: Visual agnosia is a neurological disorder characterized by the inability to recognize objects, faces, or places despite having intact vision. This condition arises from damage to specific areas in the brain, particularly affecting the pathways that process visual information. It highlights the distinct roles of different visual processing systems and can reveal how disruptions in these systems may lead to changes in artistic expression and perception.
Visual Attention: Visual attention is the cognitive process of selectively concentrating on specific visual stimuli while ignoring others, enabling individuals to efficiently process relevant information in their environment. This mechanism is crucial for guiding perception and action, influencing how we navigate our surroundings and make sense of visual inputs. By directing our focus, visual attention helps filter out distractions and prioritize what we need to see or react to, impacting various visual pathways, the understanding of object motion and spatial awareness, and higher-order visual processing.
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