For example, if one looks at a waterfall for about a minute and then looks at the stationary rocks at the side of the waterfall, these rocks appear to be moving upwards slightly. The illusory upwards movement is the motion aftereffect.
This video illustrates that effect nicely, i usually point to it when i'm trying to explain the "morphing" experienced in psychedelic trips, it's not quite the same thing, but its the closest i can show to a non-user.
It's also a good reminder that psychonautics isn't about taking drugs, it's about exploring the mind with several tools, besides, inducing this effect is fun!
This video is best viewed in full screen and HD, you can ignore the letters, its suggested that you read them out loud only to help you focus on the right part of the screen
But how does it work?
Neurons coding a particular movement reduce their responses with time of exposure to a constantly moving stimulus; this is neural adaptation. Neural adaptation also reduces the spontaneous, baseline activity of these same neurons when responding to a stationary stimulus. One theory is that perception of stationary objects is coded as the balance among the baseline responses of neurons coding all possible directions of motion. Neural adaptation of neurons stimulated by downward movement reduces their baseline activity, tilting the balance in favor of upward movement.
An alternative explanation for the MAE is based on an increase in excitability of neurons having a preference for a direction that is opposite to the adapting direction.
This video is best viewed in full screen and HD, you can ignore the letters, its suggested that you read them out loud only to help you focus on the right part of the screen
But how does it work?
Neurons coding a particular movement reduce their responses with time of exposure to a constantly moving stimulus; this is neural adaptation. Neural adaptation also reduces the spontaneous, baseline activity of these same neurons when responding to a stationary stimulus. One theory is that perception of stationary objects is coded as the balance among the baseline responses of neurons coding all possible directions of motion. Neural adaptation of neurons stimulated by downward movement reduces their baseline activity, tilting the balance in favor of upward movement.
An alternative explanation for the MAE is based on an increase in excitability of neurons having a preference for a direction that is opposite to the adapting direction.
Adapting direction-selective neurons hyperpolarize due to long duration intracellular sodium and calcium ion accumulation. This causes extracellular imbalances and an increase in brain tissue excitability; which spreads via ionic diffusion in extracellular space and glial assisted mechanisms. This causes the opposite direction neurons to spike when a stationary stimulus is presented, because these neurons have no hyperpolarizing intracellular imbalances but get surrounded by depolarizing extracellular imbalances. This explanation is supported by experimental data showing increases in neural excitability with motion adaptation.
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