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Questions and Answers
The optic disk is located in the temporal part of the retina.
The optic disk is located in the temporal part of the retina.
False
Approximately 60% of ganglion cell axons cross at the optic chiasm.
Approximately 60% of ganglion cell axons cross at the optic chiasm.
True
The optic nerve is composed of fibers from both eyes.
The optic nerve is composed of fibers from both eyes.
False
The primary visual cortex is also known as Brodmann's area 18.
The primary visual cortex is also known as Brodmann's area 18.
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Damage to the retinogeniculate pathway can lead to severe visual impairment.
Damage to the retinogeniculate pathway can lead to severe visual impairment.
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The pretectum is larger than the lateral geniculate nucleus.
The pretectum is larger than the lateral geniculate nucleus.
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The optic radiation is part of the internal capsule.
The optic radiation is part of the internal capsule.
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The pupillary light reflex is coordinated by the lateral geniculate nucleus.
The pupillary light reflex is coordinated by the lateral geniculate nucleus.
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The Edinger–Westphal nucleus is primarily responsible for the sympathetic innervation of the iris.
The Edinger–Westphal nucleus is primarily responsible for the sympathetic innervation of the iris.
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The temporal visual fields of both eyes are larger than the nasal visual fields due to the size of the retinas.
The temporal visual fields of both eyes are larger than the nasal visual fields due to the size of the retinas.
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Pretectal neurons increase their activity in response to decreased light conditions, stimulating the Edinger–Westphal nucleus.
Pretectal neurons increase their activity in response to decreased light conditions, stimulating the Edinger–Westphal nucleus.
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The optic tract contains the axons of ganglion cells that represent the ipsilateral field of view.
The optic tract contains the axons of ganglion cells that represent the ipsilateral field of view.
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Binocular vision results from overlapping visual fields of both eyes aligning on a single target.
Binocular vision results from overlapping visual fields of both eyes aligning on a single target.
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Changing the color or shape of a stimulus affects the discharge of different parts of the cortex.
Changing the color or shape of a stimulus affects the discharge of different parts of the cortex.
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AIP is primarily responsible for integrating auditory features for hand-motor schemas.
AIP is primarily responsible for integrating auditory features for hand-motor schemas.
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The statement that the inferotemporal cortex is unrelated to the limbic and prefrontal areas is accurate.
The statement that the inferotemporal cortex is unrelated to the limbic and prefrontal areas is accurate.
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The neurons in the parietal lobe that are involved in sensory integration are known as unimodal neurons.
The neurons in the parietal lobe that are involved in sensory integration are known as unimodal neurons.
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Neurons in the inferior temporal cortex change their firing pattern with respect to the object's distance from the observer.
Neurons in the inferior temporal cortex change their firing pattern with respect to the object's distance from the observer.
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Perceptual constancy allows for object recognition under varying viewing conditions, despite different retinal images.
Perceptual constancy allows for object recognition under varying viewing conditions, despite different retinal images.
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Neurons in the inferotemporal cortex increase their firing pattern when the position of the object is changed.
Neurons in the inferotemporal cortex increase their firing pattern when the position of the object is changed.
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Neglect syndrome can occur due to lesions in the left parietal or frontal lobe.
Neglect syndrome can occur due to lesions in the left parietal or frontal lobe.
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Categorical perception allows for the distinction between objects of different categories even if they are very similar.
Categorical perception allows for the distinction between objects of different categories even if they are very similar.
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The term 'hypercolumn' refers to columns of neurons that represent distinct patterns, such as different faces.
The term 'hypercolumn' refers to columns of neurons that represent distinct patterns, such as different faces.
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Patients with neglect syndrome may omit objects located on their right side during tasks.
Patients with neglect syndrome may omit objects located on their right side during tasks.
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Earl Miller found that firing rates of neurons in the prefrontal cortex did not vary when distinguishing cats from dogs.
Earl Miller found that firing rates of neurons in the prefrontal cortex did not vary when distinguishing cats from dogs.
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Connections between VIP and F4 facilitate the integration of visual information with motor responses.
Connections between VIP and F4 facilitate the integration of visual information with motor responses.
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Position constancy means recognizing objects as the same regardless of the distance from which they are viewed.
Position constancy means recognizing objects as the same regardless of the distance from which they are viewed.
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Space coding is not relevant to the processing happening in AIP.
Space coding is not relevant to the processing happening in AIP.
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Invariant attributes of an object include the spatial and chromatic relationships between image features.
Invariant attributes of an object include the spatial and chromatic relationships between image features.
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The prefrontal cortex is not involved in processing visual information.
The prefrontal cortex is not involved in processing visual information.
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An example of size constancy is perceiving an object as the same size when viewed from different distances.
An example of size constancy is perceiving an object as the same size when viewed from different distances.
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The left and right sides of the visual field are equally processed in individuals without brain lesions.
The left and right sides of the visual field are equally processed in individuals without brain lesions.
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Visual memory can influence the processing of incoming visual information.
Visual memory can influence the processing of incoming visual information.
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A fractal object was used to train the monkey by associating it with a reward mechanism.
A fractal object was used to train the monkey by associating it with a reward mechanism.
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Optical image studies can conclusively determine the exact functioning of all regions in the anterior inferior temporal cortex.
Optical image studies can conclusively determine the exact functioning of all regions in the anterior inferior temporal cortex.
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The parietal lobe is involved in encoding peripersonal space based on body-centered references.
The parietal lobe is involved in encoding peripersonal space based on body-centered references.
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An example of perceptual constancy can include recognizing a zebra and an unrelated image connected to it, like a football team.
An example of perceptual constancy can include recognizing a zebra and an unrelated image connected to it, like a football team.
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Neurons in the prefrontal cortex primarily operate in a retinotopic manner.
Neurons in the prefrontal cortex primarily operate in a retinotopic manner.
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Hand positioning for grabbing objects does not take into account the physical features of those objects.
Hand positioning for grabbing objects does not take into account the physical features of those objects.
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The activity of inferotemporal neurons does not connect with the prefrontal cortex.
The activity of inferotemporal neurons does not connect with the prefrontal cortex.
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Attentional focus during movement planning is influenced by connections between LIP and FEF.
Attentional focus during movement planning is influenced by connections between LIP and FEF.
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When an object recognized by a monkey starts moving, the neuron firing rate decreases.
When an object recognized by a monkey starts moving, the neuron firing rate decreases.
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Categorical perception is limited to the inferotemporal cortex only.
Categorical perception is limited to the inferotemporal cortex only.
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Study Notes
Visual Stream - Central Computation
- Ganglion cell axons exit the retina at the optic disk, bundling to form the optic nerve.
- Approximately 60% of optic nerve fibers cross at the optic chiasm; the remaining 40% continue to the thalamus and midbrain on the same side.
- The optic tract, formed after the chiasm, contains fibers from both eyes.
- The optic chiasm's decussation allows corresponding retinal points to be processed in the same cortical hemisphere.
- The optic tract axons reach diencephalon and midbrain structures.
- The major diencephalon target is the lateral geniculate nucleus of the thalamus.
- Thalamic neurons transmit signals to the primary visual cortex (V1, striate cortex) via the optic radiation of the internal capsule.
- The retinogeniculostriate pathway (primary visual pathway) is crucial for vision.
- The pretectum, a midbrain region, coordinates the pupillary light reflex (pupil dilation/constriction).
Pupillary Light Reflex Pathway
- Light striking the retina triggers a bilateral projection to the pretectum.
- Pretectal neurons project to the Edinger-Westphal nucleus in the midbrain.
- The Edinger-Westphal nucleus contains preganglionic parasympathetic neurons.
- Oculomotor neurons (cranial nerve III) carry axons to the ciliary ganglion.
- Ciliary ganglion neurons innervate the iris's constrictor muscle, reducing pupil diameter.
Visual Functions and Structures
- The suprachiasmatic nucleus (SCN) in the hypothalamus regulates circadian rhythms, influenced by light levels.
- The superior colliculus coordinates head and eye movements in response to visual stimuli (and other targets).
Visual Field and the Retina
- The binocular field in humans comprises two symmetrical hemifields.
- The left hemifield includes the right eye's nasal and the left eye's temporal visual field.
- The right hemifield includes the right eye's temporal and the left eye's nasal visual field.
- Peripheral vision is monocular, relying on the most medial part of the nasal retina.
- The optic tracts contain axons representing the contralateral field of view.
- There are well-ordered maps of the contralateral field in the lateral geniculate nucleus of the thalamus, maintained in cortical projections.
- The upper and lower visual fields are mapped in the striate cortex, in the posterior and anterior halves respectively, below and above the calcarine sulcus.
- The macular region displays a high cortical magnification, reflecting its importance in visual acuity.
Visual Pathway impairments
- Lesions in the visual pathways can cause different impairments, including:
- Homonymous quadrantanopsia (partial loss of a visual quadrant)
- Homonymous hemianopsia (partial loss of a visual half field)
- Macula sparing (preservation of central vision even with broad lesions).
Visual Cortex Organization
- Neurons in the lateral geniculate nucleus and retina are organized in center-surround receptive fields.
- Cortical neurons (particularly in V1) are highly responsive to oriented bars of light rather than simple spots.
- These neurons are characterized as orientation selective, meaning they respond most strongly to bars of light at a specific orientation within their receptive field (preferred orientation).
- The visual cortex is organized in columns for neurons with similar properties (orientation, binocularity, and color).
- Layers IV of primary visual cortex receives inputs from the lateral geniculate nuclei.
Other Important Visual Structures
- The optic nerve transmits visual information from the retina to the brain.
- The optic chiasm is a point of crossover for some optic nerve fibers.
- The lateral geniculate nucleus (LGN) is a primary relay station for visual information in the thalamus.
- Different visual pathways (magnocellular, parvocellular, and koniocellular) transmit diverse types of visual information to different cortical areas.
- Extrastriate visual areas (beyond V1) further process visual information.
- The ventral stream is associated with object recognition.
- The dorsal stream is associated with spatial awareness and actions.
- Visual agnosia (inability to recognize objects) occurs with lesions in the inferior temporal cortex.
- Prosopagnosia (face blindness) is a type of agnosia.
- The inferotemporal cortex (IT) contains neurons sensitive to specific shapes and objects.
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Description
Test your knowledge on the neuroanatomy related to vision, including the optic nerve, visual cortex, and related pathways. This quiz covers essential concepts such as the optic chiasm, retinogeniculate pathway, and pupillary light reflex.
