Cerebral hierarchies: predictive processing, precision and the pulvinar

Abstract

This paper considers neuronal architectures from a computational perspective and asks what aspects of neuroanatomy and neurophysiology can be disclosed by the nature of neuronal computations? In particular, we extend current formulations of the brain as an organ of inference—based upon hierarchical predictive coding—and consider how these inferences are orchestrated. In other words, what would the brain require to dynamically coordinate and contextualize its message passing to optimize its computational goals? The answer that emerges rests on the delicate (modulatory) gain control of neuronal populations that select and coordinate (prediction error) signals that ascend cortical hierarchies. This is important because it speaks to a hierarchical anatomy of extrinsic (between region) connections that form two distinct classes, namely a class of driving (first-order) connections that are concerned with encoding the content of neuronal representations and a class of modulatory (second-order) connections that establish context—in the form of the salience or precision ascribed to content. We explore the implications of this distinction from a formal perspective (using simulations of feature–ground segregation) and consider the neurobiological substrates of the ensuing precision-engineered dynamics, with a special focus on the pulvinar and attention.

Model-Based Approaches to Active Perception and Control

“…For example, an agent's generative model can be composed of a simple dynamical system [117,118] (e.g., a pendulum) that guides the active sampling of information, in analogy to rodent whisking behaviour. In this example, the pendulum may jointly support the control of a simple whisker-like sensor and the prediction of a sensory event following its protraction (with a certain amplitude)-or a sensorimotor contingency between whisker protraction and the receipt of sensory stimuli.…”

Predictive processing and the representation wars: a victory for the eliminativist (via fictionalism)

“…However, I contend that enough theorists use the concept in a manner which is best understood as involving the tracking of mere causal changes [e.g. (Clark 2016;Hohwy 2013;Kanai et al 2015;Seth 2014)] that the initial premise of my conditional argument is substantive and its adoption is motivated. My thanks to an anonymous reviewer for both: bringing this potential objection to my attention; and, suggesting the adoption of the above conditional argument in order to avoid it.…”

Introduction to the theme issue ‘Cerebral cartography: a vision of its future’

“…One of the pioneers of magneto-encephalography and her colleague (Hari and Parkkonen) address this here [14] as does (Zeki) [15] in his discussion of the asynchronous brain. The time factor is also critical in the papers by another pioneer of imaging studies, Karl Friston and his co-workers [16], which looks at brain activity computationally, emphasizing in particular attention and the ubiquitously important predictive coding, as well as in the paper by Gollo et al [17], which looks at the synchronization of activity that is critical in mood and introspection. Finally, the overall and seemingly intractable problem of consciousness, never far in any profound thinking about the brain, is covered here by two central figures (Tononi and Koch) in the study of consciousness [18] in the context of Integrated Information Theory.…”