Oxygenation of the cat primary visual cortex

Abstract

Tissue [Formula: see text] was measured in the primary visual cortex of anesthetized, artificially ventilated normovolemic cats to examine tissue oxygenation with respect to depth. The method utilized 1) a chamber designed to maintain cerebrospinal fluid pressure and prevent ambient[Formula: see text] from influencing the brain, 2) a microelectrode capable of recording electrical activity as well as local[Formula: see text], and 3) recordings primarily during electrode withdrawal from the cortex rather than during penetrations. Local peaks in the [Formula: see text] profiles were consistent with the presence of numerous vessels. Excluding the superficial 200 μm of the cortex, in which the ambient[Formula: see text] may have influenced tissue[Formula: see text], there was a slight decrease (4.9 Torr/mm cortex) in [Formula: see text] as a function of depth. After all depths and cats were weighted equally, the average [Formula: see text] in six cats was 12.8 Torr, with approximately one-half of the values being ≤10 Torr. The kurtosis of the [Formula: see text] histogram, with all depths and cats weighted equally, was 3.61, and the skewness was 1.70.