Evoked responses to sinusoidal gratings in the pigeon optic tectum

V. Porciatti, R. Alesci, P. Bagnoli

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Tectal evoked potentials (TEPs) in response to sinusoidal gratings of different contrast, spatial and temporal frequency have been recorded from the tectal surface of the pigeon. Responses have been digitally filtered in order to isolate transient oscillatory (fast) potentials (50-150 Hz), transient slow potentials (1-50 Hz), and the steady-state second-harmonic component (16.6 Hz). Transient slow potentials, as well as the steady-state second-harmonic component, are band-pass spatially tuned with a maximum at 0.5 cycles/deg and attenuation at higher and lower spatial frequencies. The high spatial frequency cutoff is 4-5 cycles/deg. Both transient slow potentials and the steady-state second-harmonic component increase in amplitude as a function of log contrast and saturate at about 20% contrast. The contrast sensitivity, as determined by extrapolating TEP amplitude to 0 V is 0.1-0.2%. These characteristics of spatial-frequency selectivity and contrast sensitivity are similar to those reported for single tectal cells. Unlike slow potentials, oscillatory potentials are not band-pass spatially tuned. In addition, their contrast response function does not saturate at moderate contrast. These differences suggest that tectal evoked slow and fast potentials reflect the activity of different neuronal mechanisms.

Original languageEnglish (US)
Pages (from-to)137-145
Number of pages9
JournalVisual neuroscience
Volume2
Issue number2
DOIs
StatePublished - Feb 1989

Keywords

  • Evoked potentials
  • Optic tectum
  • Pigeons
  • Sinusoidal gratings

ASJC Scopus subject areas

  • Physiology
  • Sensory Systems

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