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ON and OFF field potentials in the rat superior colliculus during development
S Fortin1, S K Itaya, S Chemtob
1Département de Sciences Biologiques, Université de Montréal, Québec, Canada.
Vision Research
|February 17, 1998
Summary
Visually evoked ON and OFF responses in rat superior colliculus develop early, with OFF responses showing increasing frequency oscillations. This suggests maturation of synaptic connections during this critical developmental period.
Area of Science:
- Neuroscience
- Developmental Biology
- Visual System Research
Background:
- The superior colliculus is crucial for visual processing.
- Understanding the developmental trajectory of visual responses is key to comprehending visual system maturation.
Purpose of the Study:
- To characterize the development of ON and OFF visually evoked responses in the rat superior colliculus.
- To investigate the emergence and characteristics of OFF oscillatory activity during early development.
Main Methods:
- Electrophysiological recordings of field potentials in the rat superior colliculus.
- Depth profiling to analyze responses across different layers.
- Local cobalt injections to probe the origin of oscillations.
- Fast Fourier Transform (FFT) analysis to quantify oscillatory frequency.
Main Results:
- ON and OFF visually evoked responses are present by postnatal day 13 (P13).
- OFF field potentials exhibit oscillatory activity starting at P15, with increasing frequency during development.
- Cobalt injections abolish OFF oscillations, indicating a postsynaptic origin.
- Polarity inversion of responses suggests adult-like synaptic organization early on.
Conclusions:
- The rat superior colliculus displays mature ON and OFF response characteristics early in development.
- Emerging OFF oscillatory activity increases in frequency, likely reflecting synaptic stabilization and myelination.
- This study provides the first report of OFF oscillatory responses in the developing superior colliculus.