title: Correlated activity of cortical neurons survives extensive removal of feedforward sensory input.
abstract: A fundamental property of brain function is that the spiking activity of cortical neurons is variable and that some of this variability is correlated between neurons. Correlated activity not due to the stimulus arises from shared input but the neuronal circuit mechanisms that result in these noise correlations are not fully understood. Here we tested in the visual system if correlated variability in mid-level area V4 of visual cortex is altered following extensive lesions of primary visual cortex (V1). To this end we recorded longitudinally the neuronal correlations in area V4 of two behaving macaque monkeys before and after a V1 lesion while the monkeys fixated a grey screen. We found that the correlations of neuronal activity survived the lesions in both monkeys. In one monkey, the correlation of multi-unit spiking signals was strongly increased in the first week post-lesion, while in the second monkey, correlated activity was slightly increased, but not greater than some week-by-week fluctuations observed. The typical drop-off of inter-neuronal correlations with cortical distance was preserved after the lesion. Therefore, as V4 noise correlations remain without feedforward input from V1, these results suggest instead that local and/or feedback input seem to be necessary for correlated activity.
authors.affiliation: Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck Society, 60528 Frankfurt, Germany.
authors.forename: Katharine A
authors.initials: KA
authors.lastname: Shapcott
authors.affiliation: Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck Society, 60528 Frankfurt, Germany.
authors.forename: Joscha T
authors.initials: JT
authors.lastname: Schmiedt
authors.affiliation: Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892, USA.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Saunders
authors.affiliation: Vanderbilt University, Department of Psychology, Nashville, Tennessee 37240, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Maier
authors.affiliation: Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892, USA.|Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, and National Eye Institute, Bethesda, Maryland 20892, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Leopold
authors.affiliation: Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck Society, 60528 Frankfurt, Germany.|Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Schmid
mesh_terms: D000818:Animals; D005260:Female; D008253:Macaca mulatta; D009474:Neurons / Q000502:physiology*; D064926:Neurophysiological Monitoring / Q000379:methods; D010775:Photic Stimulation; D014793:Visual Cortex / Q000166:cytology* / Q000502:physiology*