Intrinsic optical signals in rat neocortical slices measured with near- infrared dark-field microscopy reveal changes in extracellular space

• DOI: 10.1523/jneurosci.16-08-02740.1996
• Publication Date: 2018-04-05T22:28:20Z
• Authors: K Holthoff; OW Witte
• Keywords: Cerebral Cortex; Male; 03 medical and health sciences; Time Factors; 0302 clinical medicine; Furosemide; Image Processing, Computer-Assisted; Animals; Rats, Wistar; Extracellular Space; Rats

In the last decade, measurement of activity-dependent intrinsic optical signals (IOSs) in excitable tissues has become a useful tool for collecting data about spatial patterns information processing mammalian brain and spread excitation. Although extent IOS correlates well with electrical excitation, its time course is much slower, suggesting that it does not directly monitor activity. The aim this study was to investigate mechanisms responsible generation IOSs. Coronal neocortical slices juvenile rats were electrically stimulated at border layer VI white matter. induced columnar-shaped IOSs recorded using dark-field video microscopy. At corresponding locations, alterations extracellular K+ concentration space (ECS) volume registered ion-selective microelectrodes. After stimulation, transient increase up 10 mM decrease ECS by approximately 4% could be observed. comparison courses these parameters yielded considerable differences between IOS, but obvious similarities IOS. To test hypothesis changes reflect ECS, concentration, we under conditions are known prevent activity-induced i.e., low Cl- solutions presence furosemide. Both treatments similarly decreased stimulation-induced ECS. However, effect on different did correspond We conclude rat measured near-infrared microscopy reveal Furthermore, pharmacological ion substitutional experiments make likely attributable cell swelling via net KCI uptake concomitant water influx.