Adaptation 1.Adaptation – examples and definitions 2.Adaptation as efficient coding 3.A tradeoff between sensitivity and efficiency 4.Adaptation and perception 5.Adaptation occurs over multiple timescales 6.Adaptation involves multiple mechanisms

Mori, Sasakura, & Kuhara, 2007 Adaptation with 302 neurons C. elegans

Adaptation with thousands (?) of neurons

Rhodes, Jeffery, Watson, Clifford, & Nakayama 2003 human psychophysics exposed to compressive distortionexposed to expansive distortion Adaptation with millions (?) of neurons

How does this explain that? Why might this be useful? stimulus Smirnakis & Meister, 1997

Adaptation 1.Adaptation – examples and definitions 2.Adaptation as efficient coding 3.A tradeoff between sensitivity and efficiency 4.Adaptation and perception 5.Adaptation occurs over multiple timescales 6.Adaptation involves multiple mechanisms

The idea of efficient coding 1. Each neuron should use all parts of its dynamic range with roughly equal frequency. 2. Information encoded in the spike train of one neuron should not be duplicated in the spike train of another neuron.

1. Each neuron should use all parts of its dynamic range with roughly equal frequency. The idea of efficient coding

Encoding a natural distribution efficiently Dunn and Rieke, 2006

Laughlin 1981 redrawn in Wark & Fairhall 2007 Encoding a natural distribution efficiently Equal areas of probability density should correspond to equal segments of dynamic range.

Laughlin 1981 redrawn in Wark & Fairhall 2007 Changing stimulus statistics

Laughlin 1981 redrawn in Wark & Fairhall 2007 Changing stimulus statistics

Laughlin 1981 redrawn in Wark & Fairhall 2007 Efficient coding of a changing distribution

Adaptation

1.Adaptation – examples and definitions 2.Adaptation as efficient coding 3.A tradeoff between sensitivity and efficiency 4.Adaptation and perception 5.Adaptation occurs over multiple timescales 6.Adaptation involves multiple mechanisms

Enroth-Cudgell & Lennie, 1975 An example: light adaptation in the retina cat RGC

spatial integrator high redundancy spatial edge detector low redundancy An adaptive change in receptive field low luminance (low signal-to-noise) high luminance (high signal-to-noise)

An adaptive change in receptive field temporal edge detector low redundancy high luminance (high signal-to-noise) temporal integrator high redundancy low luminance (low signal-to-noise)

Adaptation 1.Adaptation – examples and definitions 2.Adaptation as efficient coding 3.A tradeoff between sensitivity and efficiency 4.Adaptation and perception 5.Adaptation occurs over multiple timescales 6.Adaptation involves multiple mechanisms

Repulsive perceptual adaptation

Repulsive perceptual adaptation

Bacon & Murphey 1984 see The cricket cercal system

cell 1cell 2cell 3cell 4 wind direction (degrees) r / r max Theunissen & Miller 1991 Salinas & Abbott 1994 v

Attractive neural adaptation macaque MT adapting stimulus adapting stimulus ○ before ● after Kohn and Movshon, 2004

Attractive neural adaptation can explain repulsive perceptual adaptation

Adaptation 1.Adaptation – examples and definitions 2.Adaptation as efficient coding 3.A tradeoff between sensitivity and efficiency 4.Adaptation and perception 5.Adaptation occurs over multiple timescales 6.Adaptation involves multiple mechanisms

Adaptation on many timescales in the same neuron Smirnakis et al salamander RGC

Adaptation on many timescales in the same neuron velocity Fairhall et al blowfly H1

Adaptation on many timescales in the same neuron single exponential process cascade of exponential processes Drew and Abbott, 2006 model

Adaptation

1.Adaptation – examples and definitions 2.Adaptation as efficient coding 3.A tradeoff between sensitivity and efficiency 4.Adaptation and perception 5.Adaptation occurs over multiple timescales 6.Adaptation involves multiple mechanisms

Mechanisms of adaptation: intrinsic mechanisms Lancaster and Nicoll, 1987 VmVm I inj

Mechanisms of adaptation: synaptic mechanisms Tsodyks & Markram 1997

Mechanisms of adaptation: circuit mechanisms Hosoya et al., 2005

Costs of adaptation Adaptation worsens the ability of a system to encode the absolute magnitude of a stimulus. Noise in the signals controlling gain can produce noisy fluctuations in gain. inputoutput