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Optic radiations: geniculocalcarine tract?
•Geniculocalcarine Tract
oGeniculate nucleus --> calcarine fissure (V1, striate cortex)
What is the relay station of the nucleus of the thalamus?
What is Lateral Geniculate Nucleus (LGN)?
What is the role of the lateral geniculate nucleus (LGN) in the visual pathway?
The lateral geniculate nucleus (LGN) is the relay station in the thalamus for visual information. It receives input from the optic nerve and sends the processed signals via the optic radiations to the primary visual cortex (V1) for interpretation.
In the Spinothalamic Tract, the first-order neurons synapse in the ________________ after entering the spinal cord.
Dorsal horn of the spinal cord
Which of the following visual deficits would most likely result from damage to the right optic tract?
Left homonymous hemianopia
The _____________ syndrome is characterized by a loss of pain and temperature sensation below the level of injury, with preserved touch and proprioception.
Anterior cord
In Brown-Séquard Syndrome, damage to one side of the spinal cord leads to loss of ____________ and ____________ sensation on the same side, and loss of pain and temperature sensation on the opposite side.
Proprioception, fine touch
What is the function of the Spinothalamic Tract?
The Spinothalamic Tract transmits pain, temperature, and crude touch sensations from the body to the brain. It crosses over (decussates) at the level of the spinal cord before ascending to the thalamus and then to the primary somatosensory cortex (S1).
What happens to the visual field if the optic chiasm is damaged?
Damage to the optic chiasm typically results in bitemporal hemianopia, where the outer (temporal) half of the visual field in both eyes is lost.
Describe the symptoms of Posterior Cord Syndrome.
Posterior Cord Syndrome results in a loss of proprioception, fine touch, and vibration sensation below the level of injury, while pain and temperature sensations are typically preserved.
The primary afferent fibers in the Spinothalamic Tract that transmit pain and temperature sensations are ________________ fibers.
C fibers
In the Dorsal Column-Medial Lemniscal (DCML) pathway, the first order neurons synapse in the ________________ of the medulla.
Gracile nucleus (for lower body) or Cuneate nucleus (for upper body)
Pain and temperature information from the right side of the body is processed in the ________________ thalamus, and then sent to the left S1 (primary somatosensory cortex).
Ventral posterolateral (VPL) nucleus
The loss of the ability to perceive one side of the body or space without visual loss is called ________________.
Hemi-neglect
The two major branches of the optic radiations are the ________________ and ________________ pathways.
Superior, inferior
The two branches of the optic radiations and what part of the visual field each branch carries?
Medial Superior Branch
●Carries information from inferior visual fields
●Fibers travel in the parietal lobe
Superior bank of calcarine sulcus
Lateral Inferior Branch
(i.e. Meyer Loop)
●Carries information from superior visual fields
●Fibers travel in the temporal lobe
●Inferior bank of calcarine sulcus
Explain the difference between hemi-neglect and hemianopia?
Hemi-Neglect-ignores
●Attention difficulty to one side of the body or environment
●Damage to PPC
●Unilateral inattention
●People are less aware of their neglect, difficult to teach compensatory strategies
Hemianopia-lose vision
●Physical loss of visual field due to visual pathway dysfunction
●People can use compensatory strategies
Primary visual cortex process what?
What is processes basic visual features (color, line orientation, edges, spacing, etc.?
•Multilayered, light receptors in the last layer (photoreceptors)
•Converts image from environment into electrical signals for the brain to interpret
What is the retina?
Dorsal column job?
The dorsal column is an important part of the nervous system, and its main job is to carry sensory information from the body to the brain. It helps you feel things like touch, pressure, vibration, and proprioception (which is the sense of where your body parts are in space).
•Results in loss of both temporal visual fields (loss of both nasal retinal fields)
•Example: Pituitary Tumor
Nonhomonymous bitemporal hemianopia
Loss of optic tract leads to?
Loss of right temporal retinal field and left nasal retinal field =
loss of left visual field in both eyes
Contralateral (left) homonymous hemianopia
Loss of optic radiations (both pathways) results in what?
Loss of right temporal retinal field and left nasal retinal field = loss of left visual field in both eyes
Contralateral (left) homonymous hemianopia
Loss of meyers loop (lateral inferior optic radiations) results in?
Loss of superior quadrant of contralateral visual hemifield of each eye
Pie in the sky
Superior contralateral homonymous quadrantanopia
Loss of medial aspect of optic radiations results in?
Loss of inferior quadrant of contralateral visual hemifield of each eye
Pie on the Floor
Inferior contralateral homonymous quadrantanopia