Why Visual Performance Matters: Foundations for Occupational Therapy Practice — participation guide

3 contact hours · 0.3 AOTA CEUs · Module 2 — follow along, take notes, and complete the reflection prompts.

Module 2

The Visual Pathways

Anchor concept

Different visual jobs travel different routes. Identifying what something is and knowing where it is in space are separate demands, and students can be strong in one and weak in the other.

Follow along

What this module covers

What a ventral-stream (parvocellular) signature looks like in class
What a dorsal-stream (magnocellular) signature looks like in class
We do not treat tracts — we treat the functional components

Key ideas

Capture these as you listen

Ventral stream = "what" (object identity, detail, recognition); dorsal stream = "where" (spatial mapping, posture, movement guidance).
Classroom signatures differ: ventral problems look like recognition errors; dorsal problems look like spatial, navigation, and postural errors.
OTs describe the behavioral signature in occupational terms, not as a neurological diagnosis.
Both streams feed Level 3 of a structured visual performance framework; observations must be tied to functional performance.

Notes

My notes for this module

Reference figures

Keep these for practice

Two streams, one retina

Retina → optic nerve → chiasm → LGN → primary visual cortex (V1), then divergence: the dorsal stream travels superiorly to parietal cortex, the ventral stream inferiorly to temporal cortex.

Parvocellular and magnocellular tracts

	Parvocellular	Magnocellular
Cell body size	Small (parvo = “small”)	Large (magno = “large”)
LGN layers	Layers 3–6	Layers 1–2
Best at	Fine spatial detail, color (red/green)	Motion, low contrast, coarse form
Temporal response	Sustained, slower conduction	Transient, fast conduction
Contrast sensitivity	Needs higher contrast	Responds to very low contrast
Feeds primarily	Ventral “what” stream	Dorsal “where/how” stream
Functional signature	Slow letter/word ID, detail errors, color-cue reliance	Place loss, spatial/postural errors, motion-guided reach errors

Parvocellular and magnocellular tracts carry different information from retina to cortex — they explain transmission, not treatment. OT addresses the functional components in the bottom row; we never treat or train a tract.

Vision's Two Highways

The retina sends two parallel “highways” to the LGN: the magnocellular tract handles motion, contrast, and spatial-action cues; the parvocellular tract handles detail, color, and object recognition. Both pass through the LGN, then split into the dorsal (where/how) and ventral (what) streams.

Apply it

Case prompt

A third-grade student reads words accurately in isolation but cannot find her place after looking up from the page and frequently loses items on a busy desk. Which stream pattern does this sound more consistent with, and how would you phrase it for the teacher without using stream terminology?

Practice

Mini exercise

Write a one-sentence present-level statement that names a stream-related observation and ties it to a Level 3–5 classroom task.

Take it to work

Action step this week

Pick one student on your caseload. List three visual observations and sort them by whether they look like "what" (identification) or "where" (spatial/movement) problems.