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Space-Specific Deficits in Visual Orientation Discrimination Caused by Lesions in the Midbrain Stimulus Selection
Eric I Knudsen1, Jason S Schwarz1, Phyllis F Knudsen1
1Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Current Biology : CB
|July 4, 2017
Summary
Midbrain lesions severely impair chickens' visual orientation discrimination. The optic tectum (OT) and nucleus isthmi pars parvocellularis (Ipc) are crucial for routing visual information to decision-making areas.
Area of Science:
- Neuroscience
- Animal Behavior
- Visual Perception
Background:
- Perceptual decisions involve sensory analysis and information routing.
- In birds, visual orientation analysis occurs in the forebrain Wulst, unlike mammals' V1.
- The midbrain, receiving retinal input, poorly encodes orientation but is vital for stimulus selection.
Purpose of the Study:
- To investigate the midbrain's role in visual perception and orientation discrimination in chickens.
- To determine the specific contributions of the optic tectum (OT) and nucleus isthmi pars parvocellularis (Ipc) to visual gating.
Main Methods:
- Chickens were trained on an orientation discrimination task.
- Focal electrolytic lesions were made in the optic tectum (OT) and nucleus isthmi pars parvocellularis (Ipc).
- Performance was assessed with and without distracting stimuli.
Main Results:
- OT lesions caused severe, space-specific orientation discrimination deficits, exacerbated by distractors.
- Ipc lesions resulted in similar but more transient impairments.
- These deficits suggest a role in information routing rather than solely sensory processing.
Conclusions:
- The optic tectum (OT) likely transmits space-specific signals to gate Wulst-processed orientation information for behavioral decisions.
- The nucleus isthmi pars parvocellularis (Ipc) plays a critical role in this visual information gating process.
- This midbrain network function is analogous to the superior colliculus (SC) in primates.
Keywords:
attentionbehaviorbirdchickencognitionoptic tectumperceptual decisionsuperior colliculusvisionMore Related Videos
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