title: Stimulus-induced changes of reflectivity detected by optical coherence tomography in macaque retina.
abstract: OBJECTIVE
  To investigate the properties and origin of retinal intrinsic signals by functional optical coherence tomography (fOCT) in macaque retinas.
  
  
  METHODS
  We modified a spectral domain OCT system to be able to give short-duration flashes or continuous light stimulation to the retina of three adult macaque monkeys (Macaca mulatta) under general anesthesia. Changes in the intensities of the OCT signals following the stimulus were determined.
  
  
  RESULTS
  Stimulus-evoked decreases or increases in the OCT signals were observed in the photoreceptor inner segment ellipsoids and outer segments, respectively. Experiments with focal and colored stimuli confirmed that these fOCT signals originated from the photoreceptors. No diffuse changes in the OCT signals were detected in the inner retinal layers; however, there were slow changes in small discrete areas where the retinal vessels were located. The polarity of the fOCT signals in the inner retinal layer was dependent on each activated region, and one of the possible sources of the reflectance changes was the light-scattering changes of the retinal vessels.
  
  
  CONCLUSIONS
  The fOCT signals in the macaque retina consist of at least three components: light-scattering changes from the photoreceptor inner segment ellipsoids, light-scattering changes from the outer segments, and slow light-scattering changes from the blood vessels in the inner retina. This technique has the potential of mapping local neuronal activity three-dimensionally and may help in the diagnosis of retinal disorders of different retinal origins.
authors: Laboratory of Visual Physiology, National Institute of Sensory Organs, Tokyo, Japan.
authors: Wataru
authors: W
authors: Suzuki
authors: Kazushige
authors: K
authors: Tsunoda
authors: Gen
authors: G
authors: Hanazono
authors: Manabu
authors: M
authors: Tanifuji
mesh_terms: D000818:Animals; D008253:Macaca mulatta; D010775:Photic Stimulation / Q000379:methods*; D010786:Photoreceptor Cells / Q000166:cytology / Q000502:physiology; D012160:Retina / Q000166:cytology / Q000502:physiology*; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: OCT; functional OCT; intrinsic signal; macaque; retina