Gamma Oscillations in the Mouse Primary Visual Cortex as an Endophenotype of Schizophrenia

Gamma oscillations (20-50 Hz) are a robust component of brain activity associated with information processing, but are also part of the background spontaneous activity during various brain states including sleep and anesthesia. Our goal was to examine the changes in gamma oscillations that result from pharmacological and genetic manipulations of glutamatergic transmission which produce endophenotypes of schizophrenia. We recorded local field potentials (LFP) and single units through the depth of the mouse primary visual cortex in vivo and examined the alterations in gamma frequency activity under both normal and pathological conditions. Our results indicate that both in awake and anesthetized animals, baseline gamma frequency power in the LFP is increased throughout the cortical lamina, and the signal-to-noise ratio of gamma oscillations produced by a visual stimulus is diminished, most notably in the superficial layers. In addition, the entrainment of single units to the local oscillations in the LFP is reduced in the supragranular (L2/3) and infragranular (L5/6) layers. This work supports the hypothesis that alterations in glutamatergic transmission result in changes to gamma oscillations in primary sensory areas and is consistent with the hypothesis that these changes are associated with disrupted sensory perception

Hypothetical sample sizes of crossover () and parallel () experimental designs as a function of the effect size.

<p>CPM: conditioned pain modulation. NWR: nociceptive withdrawal reflex. Note that, despite the actual values obtained, the minimum recommended sample size for a group is 10 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100241#pone.0100241-Hopkins1" target="_blank">[44]</a>.</p

Reliability of the assessment measures before and during conditioned pain modulation.

<p>LoA: limits of agreement. CV: coefficient of variation. ICC: intraclass correlation coefficient. CPT: cold pressor test. NWR: nociceptive withdrawal reflex.</p

Thresholds before and after the cold pressor test (CPT).

<p>Nociceptive withdrawal reflex (NWR) thresholds, electrical pain detection thresholds and pain intensity ratings to suprathreshold stimulation are shown for both sessions. **: <i>p</i><0.01, ***: <i>p</i><0.001.</p

Reliability of the conditioned pain modulation effect.

<p>LoA: limits of agreement. CV: coefficient of variation. ICC: intraclass correlation coefficient. CPT: cold pressor test. NWR: nociceptive withdrawal reflex. ΔCPM: magnitude of the conditioned pain modulation effect.</p

Variations in the assessment measures due to conditioned pain modulation.

<p>CPT: cold pressor test. ΔCPM: magnitude of the conditioned pain modulation effect. NWR: nociceptive withdrawal reflex. Values are presented as mean ±SD.</p