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  V1 cortical reorganization revisited: fMRI and electrophysiology in macaque following retinal lesions

Smirnakis, S., Brewer, A., Schmid, M., Tolias, A., Augath, M., Inhoffen, W., et al. (2004). V1 cortical reorganization revisited: fMRI and electrophysiology in macaque following retinal lesions. In 34th Annual Meeting of the Society for Neuroscience (Neuroscience 2004).

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Smirnakis, SM, Author           
Brewer, AA, Author
Schmid, MC1, 2, Author           
Tolias, AS1, 2, Author           
Augath, M1, 2, Author           
Inhoffen, W, Author
Schüz, A1, 2, Author           
Wandell, BA, Author
Logothetis, NK1, 2, Author           
Affiliations:
1Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497794              
2Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497798              

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 Abstract: ntroduction. Electrophysiological studies (Chino, Calford, Heinen, Gilbert, Kaas, Rosa) suggest that adult V1 visual field maps reorganize after de-afferentiation. The reported electrophysiological reorganization appears inconsistent with cytochrome oxidase staining patterns after similar de-afferentiation (Horton amp;amp; Hocking, J Neurosci 1998). We are measuring macaque V1 responses with functional magnetic resonance imaging (fMRI) and electrophysiology to clarify the extent of V1 reorganization.
Methods. A retinal photocoagulation laser (GYC-2000, NIDEK) was used to lesion 5-8 degree homonymous visual field locations in four adult rhesus macaques. The retinal lesion creates a de-afferentiated V1 zone referred to as the lesion projection zone, or LPZ (Schmid et al., Cerebral Cortex 1996). As expected, following the lesion we found little or no response to visual stimulation inside the LPZ using functional magnetic resonance imaging (fMRI) at 4.7T in the anesthetized macaque preparation (Logothetis et al., Nat Neurosci 1999). The extent of V1 reorganization was quantified by repeatedly measuring the visual modulation in the BOLD signal near the border of the LPZ.
Results. Over the course of seven months, we found very little, if any, increase in BOLD activity within the LPZ apart from that expected by reduced retinal swelling. The boundary of the LPZ remained stable to within 1 mm. The stable scotoma persisted in the BOLD response in all four animals tested. Parallel electrophysiological experiments are in progress in these animals, allowing direct comparison between BOLD measurements and single unit responses.

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 Dates: 2004-10
 Publication Status: Published online
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 Identifiers: BibTex Citekey: 4503
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Title: 34th Annual Meeting of the Society for Neuroscience (Neuroscience 2004)
Place of Event: San Diego, CA, USA
Start-/End Date: 2004-10-23 - 2004-10-27

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Title: 34th Annual Meeting of the Society for Neuroscience (Neuroscience 2004)
Source Genre: Proceedings
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Pages: - Volume / Issue: - Sequence Number: 605.3 Start / End Page: - Identifier: -