Experience-dependent increase in spine calcium evoked by backpropagating action potentials in layer 2/3 pyramidal neurons in rat somatosensory cortex.
In spines on basal dendrites of layer 2/3 pyramidal neurons in somatosensory barrel cortex, calcium transients evoked by back-propagating action potentials (bAPs) were investigated (i) along the length of the basal dendrite, (ii) with postnatal development and (iii) with sensory deprivation during postnatal development. Layer 2/3 pyramidal neurons were investigated at three different ages. At all ages [postnatal day (P)8, P14, P21] the bAP-evoked calcium transient amplitude increased with distance from the soma with a peak at around 50 microm, followed by a gradual decline in amplitude. The effect of sensory deprivation on the bAP-evoked calcium was investigated using two different protocols. When all whiskers on one side of the rat snout were trimmed daily from P8 to P20-24 there was no difference in the bAP-evoked calcium transient between cells in the contralateral hemisphere, lacking sensory input from the whisker, and cells in the ipsilateral barrel cortex, with intact whisker activation. When, however, only the D-row whiskers on one side were trimmed the distribution of bAP-evoked calcium transients in spines was shifted towards larger amplitudes in cells located in the deprived D-column. In conclusion, (i) the bAP-evoked calcium transient gradient along the dendrite length is established at P8, (ii) the calcium transient increases in amplitude with age and (iii) this increase is enhanced in layer 2/3 pyramidal neurons located in a sensory-deprived barrel column that is bordered by non-deprived barrel columns.
Krieger
Patrik
P
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden. Patrik.Krieger@ki.se
D000200:Action Potentials / Q000502:physiology*; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D049229:Dendritic Spines / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009930:Organic Chemicals; D018408:Patch-Clamp Techniques / Q000379:methods; D010812:Physical Stimulation / Q000379:methods; D017966:Pyramidal Cells / Q000166:cytology* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012683:Sensory Deprivation / Q000502:physiology*; D013003:Somatosensory Cortex / Q000166:cytology*; D013223:Statistics as Topic; D014738:Vibrissae / Q000294:innervation
C417664:Alexa594; C403124:Oregon Green BAPTA-dextran; D009930:Organic Chemicals; D002118:Calcium