Consistency behind trial-to-trial variation in intrinsic optical responses to single-whisker movement in the rat D1-barrel cortex.
We examined consistent characteristics behind the trial-to-trial variati on in intrinsic optical imaging of single barrel cortical responses to D 1-whisker movement in 2-5-week postnatal (2-5 W) and adul t (>9-weeks) Wistar rats, and we identified the effective are a of the neural response. The extent/size, configuration and orientation of the intrinsic optical response area varied from trial-to-trial with the same whisker stimulation. We argue that the trial-to-trial variation was due to cortical blood circulation related to the barrel neural activity. Subsequently, interpolating a family of the traces of the optical response area imaged with repeated stimulation for each animal, we extracted a centered circular area from the trial-to-trial response for each animal. Although the trial-to-trial variation decreased gradually with age, the spatial extent of the interpolated response area was consistently about 660 microm in diameter, in agreement with that measured morphologically and/or histochemically. A possible interpretation is that the optically defined area appears to image the actual effective single-barrel response area, as a first approximation. Furthermore, the constancy of the extracted area independent of age suggests that the barrel cortex is, in fact, virtually mature by 2 weeks of age. The extracted area was also nearly independent of the frequency (>/=5 Hz) of whisker movement.
Tanaka
T
T
Department of Physiology, Tokyo Medical and Dental University School of Medicine, Bunkyo-ku, Tokyo, Japan.
Yazawa
I
I
Sato
K
K
Momose-Sato
Y
Y
Kamino
K
K
D000818:Animals; D005260:Female; D005336:Fiber Optic Technology; D014644:Genetic Variation; D007091:Image Processing, Computer-Assisted; D008297:Male; D008959:Models, Neurological; D009038:Motion; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000502:physiology*; D013997:Time Factors; D014738:Vibrissae / Q000502:physiology*