The mouse visually evoked potential : neural correlates and functional applications

The visually evoked potential (VEP) is a local field potential (LFP) evoked in visual cortex in response to visual stimuli. Unlike extracellular single unit recordings, which allow us to probe the function of single spiking cells acutely, the chronic VEP technique gives us insight into ensemble synaptic activity. However, while action potentials are easily interpreted as the output of the recorded neuron, LFPs are difficult to interpret because they may reflect the sum of activity occurring at or beyond the site of recording. The goal of this study was to use the current source density (CSD) method to derive information about synaptic activity occurring at the site of recording and to determine how this activity relates to the concurrent LFP. The mouse has recently become a widely-used experimental model for studying the mechanisms of plasticity and there has been an increase in the use of VEP recordings to study experience-dependent changes in mouse primary visual cortex (V1). These studies typically focus on changes occurring in the layer 4 VEP after a variable period of visual deprivation. Layer 4 of mouse V1 receives heavy direct input from the lateral geniculate nucleus. This initial input is followed by strict hierarchical connectivity from cortical layer 4 to superficial layers 2/3 and from 2/3 to deep layers 5/6. Using a method for silencing cortical activity without affecting geniculate input activity in conjunction with CSD analyses, we found that the laminar flow of activity in mouse V1 in response to various grating stimuli was consistent with the anatomical connectivity going from layer 4 ?? 2/3 ?? 5/6. To determine if the layer 4 VEP is indeed reflecting synaptic activity occurring in layer 4, we applied the CSD method to field potentials recorded from mouse V1. Our results indicate that changes in the layer 4 VEP strongly and significantly covaries with changes in layer 4 current sink activity suggesting that the layer 4 VEP is indeed reflecting local layer 4 synaptic activity.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Brain and Cognitive Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Muhammad, Rahmat

Advisor dc:contributor.advisor

• Morgan Sheng and Mark F. Bear.

• Brain and Cognitive Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/46388

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/46388