Unifying low-level mechanistic and high-level Bayesian explanations of bistable perceptions: neuronal adaptation for cortical inference
✍ Scribed by David P Reichert; Peggy Series; Amos J Storkey
- Publisher
- BioMed Central
- Year
- 2011
- Tongue
- English
- Weight
- 143 KB
- Volume
- 12
- Category
- Article
- ISSN
- 1471-2202
No coin nor oath required. For personal study only.
✦ Synopsis
Ambiguous images such as the Necker cube evoke bistable perceptions in observers, where the conscious percept alternates between the two possible image interpretations. One classic explanation is that mechanisms like neuronal adaptation underlie the switching phenomenon [1]. On the other hand, one possible high-level explanation [2] is that in performing Bayesian inference, the brain might explore the multimodal posterior distribution over possible image interpretations. For example, sampling from a bimodal distribution could explain the perceptual switching [2], and probabilistic sampling might be a general principle underlying cortical inference [3]. In this computational study of bistable perceptions, we show that both views can be combined: Neuronal adaptation such as changes of neuronal excitability and synaptic depression can be understood to improve the sampling algorithm the brain might perform.
We use Deep Boltzmann Machines (DBMs) as models of cortical processing [4]. DBMs are hierarchal probabilistic neural networks that learn to generate or predict the data they are trained on. For doing inference, one can utilize Markov chain Monte Carlo methods such as Gibbs-sampling, corresponding to the model's neurons switching on stochastically. The model then performs a random walk in state space, exploring the various learned interpretations of an image, thus potentially explaining bistable perceptions (cf. [5]). However, in machine learning one often finds that exploring multi-modal posterior distributions in high-dimensional spaces can be problematic, as models can get stuck in individual modes ('the Markov chain does not mix'). Very recent machine learning work [6,7] has devised a class of methods that