hide
Free keywords:
-
Abstract:
We previously reported that the activity of primary visual cortex (V1) transmits information about complex naturalistic video stimuli in two distinct frequency bands: a low frequency band (1-24 Hz), and a high frequency (60-100 Hz) gamma oscillation range, with each range carrying its own independent information about the visual stimuli [1]. Here we ask whether these independent frequency channels originate from distinct cortical laminae. We used laminar electrodes with 150 micron spacing spanning the whole cortical depth to record extracellular field potentials from the primary visual cortex of opiate-anaesthetised macaques during presentation of a 2 minute long Hollywood colour movie clip. Using the recorded Local Field Potential (LFP), we computed the Current Source Density (CSD) for each trial. From the time-resolved power of the CSD in each trial, we estimated the mutual information that the power at each frequency carries about which section of the movie is being presented, and how much information there is in frequency bands about different spatial resolutions of changes in luminance. We found, across depth and frequency, two distinct regions carrying large amounts of independent information about the movie stimulus: the low frequency (4-16 Hz) band had high information at depths corresponding to layers 4-6, whereas the high frequency (64-250 Hz) band had high information in layers 1-3. This suggests that different laminae of cortical circuits generate independent information channels that code information in separate frequency ranges. Furthermore, we found the low frequency band contained information about low spatial frequencies changes in luminance (<1 cycle per degree), whilst the high frequency band contained information about finer spatial details (1-6 cycles per degree). This suggests information about these two spatial frequency components arises through two different cortical mechanisms within V1, and information about them is encoded separately in two different frequency bands. References [1] Belitski, A., et al. (2008). J Neuroscience, 28(22), 5696-709.
