The optic radiation connects the lateral geniculate region with visual cortex around the calcarine sulcus. Here, gross thalamus and HCP parcel V1 provide reference objects at the two ends of that relationship.
Select each structure to light it on the atlas, then rotate until you can name what lies in front, behind and beneath it.
Targets
V1 · primary visual
Thalamus (gross)
OR · optic radiation
Compare
Find V1 with the structure button, then compare it with the thalamic mesh and the optic-radiation sample. Use the medial view to orient the occipital reference.
Read the neighbours
The geniculocalcarine pathway has a thalamic relay, a long white-matter course and a medial occipital cortical destination.
The lateral geniculate nucleus is not separately segmented inside this gross thalamus; use V1 to orient the calcarine destination.
Explain before revealing
Describe the three anatomical levels you would examine when localizing a retrochiasmal visual-pathway problem along the geniculocalcarine system.
Explanation
Consider the lateral geniculate relay, the optic radiation along its temporal and posterior course, and visual cortex around the calcarine sulcus. They are separated anatomical levels within one system. The gross thalamic mesh provides orientation here but cannot isolate the geniculate nucleus.
In a surgical discussion
For a posterior visual-pathway discussion, name the thalamic, white-matter and cortical levels separately. A field deficit requires localization beyond merely identifying the occipital lobe.
The anterior turn varies between people and reconstruction methods. A short or poorly visible atlas loop cannot establish anatomical absence or a resection margin. The temporal horn is not installed as a surface.
Ask the learner to answer before opening the explanation. Compare the answer with the named structures and the cited method. Teaching point: Consider the lateral geniculate relay, the optic radiation along its temporal and posterior course, and visual cortex around the calcarine sulcus. They are separated anatomical levels within one system. The gross thalamic mesh provides orientation here but cannot isolate the geniculate nucleus.
This relationship draws on 6 cited sources.
Relationship 2 of 5 · reconstruction
Follow the anterior turn before the posterior course
Orient
Meyer’s loop is the anterior sweep of the temporal optic radiation before it turns posteriorly. Learning the bend matters because an occipital destination does not imply a purely posterior course.
Select each structure to light it on the atlas, then rotate until you can name what lies in front, behind and beneath it.
Targets
OR · optic radiation
Hippocampus
Compare
Find the most anterior visible turn of this OR sample, then follow it posteriorly. The hippocampus is a medial temporal reference; a temporal-horn surface is not installed.
Read the neighbours
Dissection and MR correlation place the loop in a close relationship with the temporal horn.
Nilsson’s small DTI study found variable anterior extent. Those measurements depend on sample and method; a shallow atlas turn may reflect reconstruction or display limitations.
Explain before revealing
Why can an anterior temporal lesion affect a pathway whose cortical destination is occipital?
Explanation
Because some optic-radiation fibres sweep anteriorly before turning posteriorly toward visual cortex. Destination alone does not describe the course. The temporal horn is useful anatomical context but cannot be identified as a mesh in this viewer.
In a surgical discussion
Anterior temporal and temporal-stem discussions should include the optic radiation even when the occipital lobe is distant from the operative region.
The anterior turn varies between people and reconstruction methods. A short or poorly visible atlas loop cannot establish anatomical absence or a resection margin. The temporal horn is not installed as a surface.
Ask the learner to answer before opening the explanation. Compare the answer with the named structures and the cited method. Teaching point: Because some optic-radiation fibres sweep anteriorly before turning posteriorly toward visual cortex. Destination alone does not describe the course. The temporal horn is useful anatomical context but cannot be identified as a mesh in this viewer.
This relationship draws on 4 cited sources.
Relationship 3 of 5 · experimental anatomy
Compare the temporal-stem neighbours
Orient
The optic radiation shares the temporal region with association pathways. Add uncinate and inferior fronto-occipital samples and distinguish their courses rather than treating every temporal line as visual.
Select each structure to light it on the atlas, then rotate until you can name what lies in front, behind and beneath it.
Targets
OR · optic radiation
UF · uncinate fasciculus
IFOF · inferior fronto-occipital fasciculus
Compare
Follow OR, uncinate and IFOF individually from two views. Describe which reconstruction continues between frontal and occipital regions and which turns between anterior temporal and frontal regions.
Read the neighbours
Kier and colleagues correlated temporal-stem dissection with MR anatomy of these neighbouring pathways.
A crowded crossing in the render is a reason to inspect each structure separately, not to infer a common function.
Explain before revealing
Which association pathway in this comparison links anterior temporal and frontal regions?
Explanation
The uncinate fasciculus. IFOF has a longer frontal–occipital relationship, while OR belongs to the thalamic–visual cortical relationship. Identify each course before making a functional inference.
In a surgical discussion
Temporal-stem pathology can raise both visual and language-related anatomical questions. A single selected bundle gives an incomplete description of the neighbourhood.
The anterior turn varies between people and reconstruction methods. A short or poorly visible atlas loop cannot establish anatomical absence or a resection margin. The temporal horn is not installed as a surface.
Ask the learner to answer before opening the explanation. Compare the answer with the named structures and the cited method. Teaching point: The uncinate fasciculus. IFOF has a longer frontal–occipital relationship, while OR belongs to the thalamic–visual cortical relationship. Identify each course before making a functional inference.
This relationship draws on 5 cited sources.
Relationship 4 of 5 · association
Translate the temporal loop into a field question
Orient
A temporal optic-radiation injury raises concern for the contralateral superior visual field. Describe the side of the lesion and the affected field explicitly; the two eyes share the homonymous field relationship.
Rotate the atlas until you can name what lies in front, behind and beneath the displayed structures.
Compare
Identify the displayed hemisphere before answering. For a left temporal-loop injury in the vignette, state the side and quadrant of the expected field concern.
Read the neighbours
The cited resection study paired tractography with measured postoperative perimetry.
The range of field loss and loop position varies. Neither a fixed temporal-pole distance nor an atlas screenshot predicts an individual field outcome.
Explain before revealing
A left temporal-loop injury classically raises concern for which visual field?
Explanation
The right superior homonymous field, affecting corresponding parts of both eyes. The extent is not fixed by this vignette or by the template; actual perimetry characterizes the deficit.
In a surgical discussion
A visual-pathway presentation should distinguish an anatomical risk hypothesis from a documented deficit on perimetry. Use the actual pre- and postoperative field findings when available.
The anterior turn varies between people and reconstruction methods. A short or poorly visible atlas loop cannot establish anatomical absence or a resection margin. The temporal horn is not installed as a surface.
Ask the learner to answer before opening the explanation. Compare the answer with the named structures and the cited method. Teaching point: The right superior homonymous field, affecting corresponding parts of both eyes. The extent is not fixed by this vignette or by the template; actual perimetry characterizes the deficit.
This relationship draws on 4 cited sources.
Relationship 5 of 5 · reconstruction
Explain an unexpectedly short loop
Orient
Teaching vignette: one reconstruction appears to stop posterior to the anticipated anterior bend. The finding is a discrepancy to investigate, not proof that the pathway is anatomically absent.
Rotate the atlas until you can name what lies in front, behind and beneath the displayed structures.
Compare
Rotate the same sample and change cortical transparency. Restore the lesson view and distinguish a hidden segment from a segment that was never reconstructed.
Read the neighbours
Visibility and reconstruction completeness are separate questions.
Acquisition, orientation modelling and extraction choices can change which parts of a pathway appear.
Explain before revealing
If lowering cortical opacity reveals a segment, what changed?
Explanation
Its visibility changed. No new anatomical evidence was acquired and no fibres were reconstructed by moving the slider. If the segment remains absent, that still requires investigation of reconstruction and selection rather than a conclusion of anatomical absence.
In a surgical discussion
A short-looking loop should not be used to declare a larger resection margin. Separately, Nimsky’s pre-/intraoperative DTI study documented tract displacement during resection: preoperative location is not fixed intraoperatively. Brain shift does not explain a short static atlas sample; it adds another limitation when interpreting actual surgical anatomy.
The anterior turn varies between people and reconstruction methods. A short or poorly visible atlas loop cannot establish anatomical absence or a resection margin. The temporal horn is not installed as a surface.
Ask the learner to answer before opening the explanation. Compare the answer with the named structures and the cited method. Teaching point: Its visibility changed. No new anatomical evidence was acquired and no fibres were reconstructed by moving the slider. If the segment remains absent, that still requires investigation of reconstruction and selection rather than a conclusion of anatomical absence.
This relationship draws on 6 cited sources.
Recap
An expected anterior loop appears short in a reconstruction. What would you investigate first?
Connect the gross thalamic, white-matter and medial occipital levels of the account.
Distinguish optic radiation, uncinate and IFOF by their temporal courses.
Separate a display discrepancy from reconstruction limits, variation and individual anatomy.
Review the final explanation
Its visibility changed. No new anatomical evidence was acquired and no fibres were reconstructed by moving the slider. If the segment remains absent, that still requires investigation of reconstruction and selection rather than a conclusion of anatomical absence.
Control and temporal-resection cohorts studied with tractography and perimetry. Anterior extent and postoperative field loss vary; a template cannot supply an individual margin.
Provenance for the Melbourne Subcortex Atlas scale-1 meshes rendered here. Scale 1 is the coarsest level: anterior and posterior thalamus are merged and no brainstem nucleus is included.
HCP population reference built from converging cortical features. A parcel boundary here is a group boundary; it does not locate one person’s functional border and it has not been registered to any individual in this viewer.
Challenge dataset with a defined ground truth and many submitted pipelines. Its false-positive findings motivate caution; its error figures belong to that challenge and are not an error estimate for this atlas.
Provenance for the HCP1065 population-averaged bundles rendered here. Every displayed line is an average-space reconstruction sampled for display; it is not a patient’s pathway and carries no direction of conduction.
Neurosurgical comparison of tensor and higher-order fibre-orientation models. Demonstrates that the orientation model changes which pathways appear; a rendered bundle inherits its model’s failure modes.
Operative series using DTI tractography inside neuronavigation, reporting intraoperative displacement of the reconstructed tracts. A preoperative bundle position is not a position during the resection.