Temporal aspects of contrast visual evoked potentials in the pigmented rat: Effect of dark rearing

Tommaso Pizzorusso, Michela Fagiolini, Vittorio Porciatti, Lamberto Maffei

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Cortical visual evoked potentials (VEPs) in response to gratings temporally modulated in counterphase were recorded in normal and dark-reared pigmented rats. Temporal modulation was either sinusoidal (0.25-15 Hz, steady state condition) or abrupt (0.5 Hz, transient condition). In normals, the amplitude spectrum of contrast VEPs has two peaks (at about 0.5 and 4 Hz) and a high temporal frequency cut-off of the order of 11 Hz. The VEP phase lags with temporal frequency, showing two different linear slopes for separate frequency ranges (0.25-1 Hz and 1-7 Hz) centred on the peaks of the curve. The different slopes correspond to apparent latencies of 500 and 136 msec, respectively. Dark rearing reduced the cut-off frequency by about 3 Hz and increased apparent latencies by about 42 msec in the low temporal frequency range and 30 msec in the high temporal frequency range. The latency of the first peak of transient VEPs was increased by about 47 msec. Results indicate that the frequency response of rat contrast VEPs is qualitatively similar to that of other mammals (including human), albeit shifted to a lower range of temporal frequencies. Dark rearing significantly alters the VEP temporal characteristics, suggesting that visual experience is necessary for their correct development.

Original languageEnglish (US)
Pages (from-to)389-395
Number of pages7
JournalVision Research
Issue number4
StatePublished - Feb 1997
Externally publishedYes


  • Critical period
  • Plasticity
  • Visual cortex
  • Visual deprivation

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems


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