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This Article Full Text Full Text (PDF) All Versions of this Article: 586/9/2293    most recent jphysiol.2008.151795v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Gur, M. Articles by Snodderly, D. M. PubMed PubMed Citation Articles by Gur, M. Articles by Snodderly, D. M. Related Collections Neuroscience

¹ Department of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel
² Department of Ophthalmology and School of Graduate Studies, Medical College of Georgia, Augusta, GA 30912-3402, USA
³ Schepens Eye Research Institute, Boston, MA 02114, USA

The physiological literature does not distinguish between the superficial layers 2 and 3 of the primary visual cortex even though these two layers differ in their cytoarchitecture and anatomical connections. To distinguish layer 2 from layer 3, we have analysed the response characteristics of neurons recorded during microelectrode penetrations perpendicular to the cortical surface. Extracellular responses of single neurons to sweeping bars were recorded while macaque monkeys performed a fixation task. Data were analysed from penetrations where cells could be localized to specific depths in the cortex. Although the most superficial cells (depth, 145–371 µm; presumably layer 2) responded preferentially to particular stimulus orientations, they were less selective than cells encountered immediately beneath them (depth, 386–696 µm; presumably layer 3). Layer 2 cells had smaller spikes, higher levels of ongoing activity, larger receptive field activating regions, and less finely tuned selectivity for stimulus orientation and length than layer 3 cells. Direction selectivity was found only in layer 3. These data suggest that layer 3 is involved in generating and transmitting precise, localized information about image features, while the lesser selectivity of layer 2 cells may participate in top-down influences from higher cortical areas, as well as modulatory influences from subcortical brain regions.

(Received 28 January 2008; accepted after revision 3 March 2008; first published online 6 March 2008)
Corresponding author M. Gur: Department of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel. Email: mogi{at}bm.technion.ac.il