The Spatial Properties of L- and M-Cone Inputs to Electroretinograms That Reflect Different Types of Post-Receptoral Processing

Abstract

We studied the spatial arrangement of L- and M-cone driven electroretinograms (ERGs) reflecting the activity of magno- and parvocellular pathways. L- and M-cone isolating sine wave stimuli were created with a four primary LED stimulator using triple silent substitution paradigms. Temporal frequencies were 8 and 12 Hz, to reflect cone opponent activity, and 30, 36 and 48 Hz to reflect luminance activity. The responses were measured for full-field stimuli and for different circular and annular stimuli. The ERG data confirm the presence of two different mechanisms at intermediate and high temporal frequencies. The responses measured at high temporal frequencies strongly depended upon spatial stimulus configuration. In the full-field conditions, the L-cone driven responses were substantially larger than the full-field M-cone driven responses and also than the L-cone driven responses with smaller stimuli. The M-cone driven responses at full-field and with 70° diameter stimuli displayed similar amplitudes. The L- and M-cone driven responses measured at 8 and 12 Hz were of similar amplitude and approximately in counter-phase. The amplitudes were constant for most stimulus configurations. The results indicate that, when the ERG reflects luminance activity, it is positively correlated with stimulus size. Beyond 35° retinal eccentricity, the retina mainly contains L-cones. Small stimuli are sufficient to obtain maximal ERGs at low temporal frequencies where the ERGs are also sensitive to cone-opponent processing.

Avaliação das vias do sistema visual por eletrorretinograma e testes psicofísicos na Distrofia Muscular de Duchenne e na Diabetes Mellitus tipo 1

“…Figure 6 shows a linear regression at 36 Hz (upper graph). The slopes were between 1.1 and 1.6, similar to those found for cone isolating stimuli (Jacob et al, 2015).…”

“…mean chromaticity in the present study is an explanation for this. The present 12-Hz data and the results of Jacob et al (2015) also agree in that for stimuli larger than 108 in diameter, the response amplitudes and phases are relatively invariant. Our data further provide evidence for the notion that these responses reflect cone opponent processes.…”

“…The data therefore indicate that the retinal periphery contributes less to the ERG amplitude than the central retina. Jacob et al (2015) found that the L:M ratio in highfrequency responses is much larger with FF than with smaller stimuli, indicating that the responses that originate in the periphery are strongly L-cone dominated. This is confirmed in other ERG recordings (Challa et al, 2010;Kuchenbecker, Sahay, Tait, Neitz, & Neitz, 2008; and messenger ribonucleic acid analyses (Hagstrom, Neitz, & Neitz, 1997.…”

“…First, we wanted to compare the results of measurements with heterochromatic modulation of red and green lights with those using L-and M-cone isolating stimuli in a previous study with similar stimulus parameters (Jacob et al, 2015). Second, we wanted to study the dependency of the responses, particularly those reflecting activity of cone opponent mechanisms, on the size of circular stimuli in more detail by including smaller stimuli than used with the cone isolating stimuli.…”

“…As alterações na atividade da via visual OFF da retina em condição mesópica (cones e bastonetes em atividade), , Ricotti et al, 2016presente Portanto pode-se concluir que a alteração nas respostas geradas pela estimulação mesópica que ativa preferencialmente a via visual OFF está relacionada à via dos bastonetes cujo processamento (conforme descrito anteriormente) depende da ativação inicial da célula bipolar do tipo ON e cujo contato sináptico ocorre no interior da invaginação (Bloomfield &Dacheux, 2001, Zaghloul, Boahen, & Demb, 2003, Wässle, 2004 , Martins et al, 2016Jacob et al, 2015). O aumento da amplitude na resposta ao estímulo senoidal é observado com o bloqueio da via ON (Kondo & Sieving, 2002).…”