Jerry H. Jacobson

Distinct spike discharges in the evoked cortical response of the light adapted cat.

Abstract Following adaptation to white background illumination, photic stimulation produced several spike-like discharges situated between the primary and secondary complexes. With fixed stimulus intensity and serially augmented levels of light adaptation these discharges were found to increase in amplitude. The potentials may be divided into two groups: early and late spikes. The former were produced at higher levels of light adaptation, the latter at a low levels of adaptation. Bilateral, ipsilateral and contralateral stimulation and light adaptation studies indicated that the discharges occurred only when the stimulus and adapting light were presented to the same eye. The discharges were affected by Nembutal administration.

Luminance-Duration Relationship in the Human ERG

The Bunsen-Roscoe law, which refers to photochemical effects of light and its subjective visual correlate, Bloch’s law, indicate that when a light stimulus is shorter than a defined critical duration, the product of the intensity and the duration of the stimulus determines whether the stimulus is perceived. The product, intensity (I) x time (t) is a constant.

The effect of local light on the diffuse off-response of the excised frog retina

Abstract This paper concerns the off-response to diffuse light of the excised retina of Rana pipiens. The response was recorded by a 250 μ Pt-Ir electrode on receptor side and a silver plate electrode covering the vitreous side, receptor side placed upward toward the air. The electrical response to a diffuse light going off was negative, receptor relative to vitreous side. It has been found that if a local light, considerably more intense than the diffuse light, is being applied to the retina in the region of the Pt electrode, at the time the diffuse light is turned off, the electrical response of the retina is now positive, receptor relative to vitreous side. Changes in this effect with changes in intensity of local and diffuse lights have been observed. The possible significance of this effect is discussed. This paper serves to report an effect observed in the course of studying the off-response of the excised frog retina.