How General Is The Concept Of A Receptive Field? Gregg Rosenberg April 7, 2004 Towards A Science of Consciousness

Talk Outline Foundations The classic example of a receptive field The classic example of a receptive field A rough attempt at generalizing the classic definition of receptive field A rough attempt at generalizing the classic definition of receptive field An attempt at precision in the generalized definition An attempt at precision in the generalized definition The ontology of consciousness Hypothesis 1: The field of conscious experience is determined by the contents of a receptive field at the level of the whole person. Hypothesis 1: The field of conscious experience is determined by the contents of a receptive field at the level of the whole person. Hypothesis 2: The subjective phenomenal contents of consciousness are Russellian intrinsic contents within the receptive field. Hypothesis 2: The subjective phenomenal contents of consciousness are Russellian intrinsic contents within the receptive field. Summary Summary

The Classic Example of a Receptive Field

Definition(s) of the Classic Receptive Field For the prototypical retinal example: Proximate cause definition: A retinal cell’s receptive field is the area of the retina where stimulation elicits a response in the cell. Proximate cause definition: A retinal cell’s receptive field is the area of the retina where stimulation elicits a response in the cell. Ultimate cause definition: A retinal cell’s receptive field is the area in the visual field where a stimulus elicits a response in the cell. Ultimate cause definition: A retinal cell’s receptive field is the area in the visual field where a stimulus elicits a response in the cell.

Definition(s) of the Classic Receptive Field For the prototypical retinal example: Proximate cause definition: A retinal cell’s receptive field is the area of the retina where stimulation elicits a response in the cell. Proximate cause definition: A retinal cell’s receptive field is the area of the retina where stimulation elicits a response in the cell. Ultimate cause definition: A retinal cell’s receptive field is the area in the visual field where a stimulus elicits a response in the cell. Ultimate cause definition: A retinal cell’s receptive field is the area in the visual field where a stimulus elicits a response in the cell. For arbitrary neural cells: Proximate cause definition: A neuron’s receptive field is the map of neurons in the brain where stimulation elicits a response in the cell. Proximate cause definition: A neuron’s receptive field is the map of neurons in the brain where stimulation elicits a response in the cell. Ultimate cause definition: A neuron’s receptive field is the area or feature in the organism’s stimulus field where a stimulus elicits a response in the cell. Ultimate cause definition: A neuron’s receptive field is the area or feature in the organism’s stimulus field where a stimulus elicits a response in the cell.

Generalization of the concept of receptive field From here: I will focus on the Proximate Cause definition. For arbitrary kinds of entities: Proximate cause definition: An entity’s receptive field consists of the entities in its immediate environment whose interactions with the receiving entity elicit responses from it. Proximate cause definition: An entity’s receptive field consists of the entities in its immediate environment whose interactions with the receiving entity elicit responses from it.

An attempt at precision in the generalized concept What kinds of entities are candidates for having receptive fields? What kinds of entities are candidates for having receptive fields? What is a “response”? What is a “response”? What is an “immediate environment”? What is an “immediate environment”? What kinds of “interactions”? What kinds of “interactions”?

Defining characteristics of “entities” What kinds of entities? How are they identified? –A receptive entity must be an entity that can take on a “single” state. –CAS criteria relevant (Holland 1996, 1998): CAS mechanisms: Tags, building blocks, internal models. CAS mechanisms: Tags, building blocks, internal models. CAS properties: Aggregation, Flows, Diversity, Non- linearity. CAS properties: Aggregation, Flows, Diversity, Non- linearity.

Defining characteristics of “entities” Self/non-self recognition – Tagging that enables the aggregation of components within a boundary. Self/non-self recognition – Tagging that enables the aggregation of components within a boundary. Selectively permeable boundary – Tagging that enables selective interaction with environment. Selectively permeable boundary – Tagging that enables selective interaction with environment. Attractor states – A set of stable states towards which neighboring states in a given basin of attraction asymptotically approach in the course of the entity’s dynamic evolution. Attractor states – A set of stable states towards which neighboring states in a given basin of attraction asymptotically approach in the course of the entity’s dynamic evolution. Lever points – Points of interaction where small amounts of input can produce large, directed changes. Lever points – Points of interaction where small amounts of input can produce large, directed changes.

Defining characteristics of a “response” Stable state – Prior to the response the entity is evolving within the basin of attraction of an attractor state. Stable state – Prior to the response the entity is evolving within the basin of attraction of an attractor state. Controlled trigger – The response is a reaction to validly tagged signals received through the permeable boundary. Controlled trigger – The response is a reaction to validly tagged signals received through the permeable boundary. Detectable difference – The trigger causes the entity to move sharply away from the attractor it had been approaching in a way that makes a difference to its interactions with its environment. Detectable difference – The trigger causes the entity to move sharply away from the attractor it had been approaching in a way that makes a difference to its interactions with its environment. –Cycles through one or more limit cycles. –Jump to a new basin of attraction. –Jump to a qualitatively different traversal path within its existing basin.

Example: Persons Coarse grained stable states – At the most coarse grain, a living person has a limit cycle of two state attractors: Waking and sleeping. Coarse grained stable states – At the most coarse grain, a living person has a limit cycle of two state attractors: Waking and sleeping. Controlled trigger – Human beings cycle between these two states reliably in response to circadian rhythms or external stimuli. Circadian rhythms are good examples of hormones being injected into the system as tagged messages right at structured lever points. Controlled trigger – Human beings cycle between these two states reliably in response to circadian rhythms or external stimuli. Circadian rhythms are good examples of hormones being injected into the system as tagged messages right at structured lever points. Detectable difference – The response consists of the person moving sharply away from the attractor he or she had settled near. Detectable difference – The response consists of the person moving sharply away from the attractor he or she had settled near. –Person cycles from waking to sleeping or sleeping to waking.

Defining an “immediate environment” Community – Consists of other entities at the same level. Community – Consists of other entities at the same level. Flow – These entities send signals to the receiving entity that can pass its boundary. Flow – These entities send signals to the receiving entity that can pass its boundary. Immediateness – These signals reach the entity without being transformed by (flowing through) any other entity at the same level as the receiving entity. Immediateness – These signals reach the entity without being transformed by (flowing through) any other entity at the same level as the receiving entity. Potential lever points – Some of these signals can contribute to the activation of a response. Potential lever points – Some of these signals can contribute to the activation of a response. Summary – A set of other entity’s at the same level from which signals flow to the receiving entity without having to flow through any other entity at the same level as the receiving entity. Summary – A set of other entity’s at the same level from which signals flow to the receiving entity without having to flow through any other entity at the same level as the receiving entity.

Defining an “immediate environment” An entity’s immediate environment is the set of other entity’s at the same level from which signals flow to the receiving entity without having to flow through any other entity at the same level as the receiving entity. Receiving Entity Not Immediate Immediate

“Interactions” Token responses – Every token response by an entity is to a set of signals received through a receiving entity’s boundary. Token responses – Every token response by an entity is to a set of signals received through a receiving entity’s boundary. Perturbation fields – This set of signals constitute a perturbation field eliciting the response from the entity. Think of a perturbation field as a wave of influence flowing through the entity. Perturbation fields – This set of signals constitute a perturbation field eliciting the response from the entity. Think of a perturbation field as a wave of influence flowing through the entity. Generation – The proximate cause of each perturbation field is a set of entities in the receiving entity’s immediate environment. Generation – The proximate cause of each perturbation field is a set of entities in the receiving entity’s immediate environment.

What is received at the center of a receptive field? In one sense, signals. In one sense, signals. Problem: The idea of a signal can be understood two ways. Problem: The idea of a signal can be understood two ways. –As an information carrier. “One if by land and two if by sea.” –As a command. “Red means stop. Green means go.” Note: The second sense is both necessary and sufficient for understanding a response. Note: The second sense is both necessary and sufficient for understanding a response.

What is received at the center of a receptive field? The command sense of “signal” is probably the appropriate sense for understanding the subjectivity of a receptive field. –A perturbation wave usually cannot be decomposed into its constituents Vector addition is many-one. Vector addition is many-one. –A perturbation wave always can be decomposed into a structure of command/influence for the entity. –Its significance is that it “tells” the entity into which new state it should jump as it flows through the entity and sometimes gives guidance on the manner of getting there. –This is a kind of “command content” and can be contrasted with “representational content”.

The definition of a receptive field understood precisely Proximate cause definition (original): An entity’s receptive field consists of the entities in its immediate environment whose interactions with the receiving entity elicit responses from it. Proximate cause definition (original): An entity’s receptive field consists of the entities in its immediate environment whose interactions with the receiving entity elicit responses from it. Sharpening: An entity B is in the receptive field of an entity A at time t if, and only if, B is in the immediate environment of A at time t and is capable of contributing to a possible perturbation wave with respect to A. Sharpening: An entity B is in the receptive field of an entity A at time t if, and only if, B is in the immediate environment of A at time t and is capable of contributing to a possible perturbation wave with respect to A.

Example: Neural firing Token responses – Neural firings. A typical neural activation is a response to a set of convergent signals received through its dendritic boundary. Token responses – Neural firings. A typical neural activation is a response to a set of convergent signals received through its dendritic boundary. Perturbation waves – This set of signals constitutes a perturbation wave, a wave of tagged causal influence, eliciting a firing response from the neuron. Perturbation waves – This set of signals constitutes a perturbation wave, a wave of tagged causal influence, eliciting a firing response from the neuron. Immediate environment – Every perturbation wave must come through a set of entities in the receiving neuron’s immediate environment. Immediate environment – Every perturbation wave must come through a set of entities in the receiving neuron’s immediate environment.

How general? Example 1: Atoms? Entity – Entity – –Self/non-self recognition – The integrity of nuclear forces in a nucleus. –Selectively permeable boundary – Orbital shells. –Attractor states – Stable orbital configurations. –Lever points – Conditions under which orbital configurations can change. Responses – Changes in ionic configurations. Responses – Changes in ionic configurations. Immediate environment – Other atoms. Immediate environment – Other atoms. Perturbations – Collisions. Perturbations – Collisions.

How general? Example 2: Cells other than neurons? Entity – Entity – –Self/non-self recognition – The selectivity of transport and messenger proteins. –Selectively permeable boundary – Cell walls. –Attractor states – Energy production states and message release via proteins. –Lever points – Protein and ionic concentrations. Responses – Cell division? Release of proteins into bloodstream? Responses – Cell division? Release of proteins into bloodstream? Immediate environment – Other cells. Immediate environment – Other cells. Perturbations – Hormones and proteins absorbed through the cell wall. Perturbations – Hormones and proteins absorbed through the cell wall.

How general? Example 3: Neural columns and assemblies? Entity – Entity – –Self/non-self recognition – Harmony of wave characteristics. –Selectively permeable boundary – The cloud of neurotransmitter junctions associated with its dendrite and axon projections to other neural columns/assemblies. –Attractor states – Discrete frequency ranges in its group firing characteristics. –Lever points – Neurotransmitter imbalances. Responses – Changes in the group harmonics of its neural firings. Responses – Changes in the group harmonics of its neural firings. Immediate environment – Other neural columns/assemblies. Immediate environment – Other neural columns/assemblies. Perturbations – Waves with competing harmonics. Perturbations – Waves with competing harmonics.

Do Persons Have Receptive Fields? Entity – Entity – –Self/non-self recognition – Immune system. –Selectively permeable boundary – An epidermal layer with sensory receptors. –Attractor states – The Sleep/wake cycle. More importantly, the wakefulness attractor is a very complex landscape composed of a variety of sub-attractors and limit cycles we can identify with motor and attentional programming. –Lever points – An integrated control system with person level responses modulated by attentional focus & emotional salience within consciousness. Responses – Changes in the priming of motor programming. Responses – Changes in the priming of motor programming. Immediate environment – The array of perceptual and introspectible objects capable of being represented in the global workspace of consciousness. Immediate environment – The array of perceptual and introspectible objects capable of being represented in the global workspace of consciousness. Perturbations – High saliency changes in the contents of the global workspace. Perturbations – High saliency changes in the contents of the global workspace.

Ontology of Consciousness: Hypothesis 1 The field of conscious experience is determined by the contents of a receptive field at the level of the whole person.

Ontology of Consciousness: Hypothesis 2 The subjective phenomenal contents of consciousness are Russellian intrinsic contents within a person’s receptive field. –These intrinsic contents carry the convergent influences active at the personal level. –These perturbation waves are composed of signals defined by, and structured according to, their command content for the person, not their micro constitution. –The person receives perturbation waves as unified command structures converging on it through its receptive field. –There is no “combination problem”.

Summary –The concept of having a “receptive field” can be generalized so that it includes persons. –The contents of consciousness may be determined by the contents of a person’s receptive field. –The qualitative content of consciousness may be the Russellian intrinsic content of perturbation waves received by the person. –The metaphysics of how all this may occur is explained in detail in my book, A Place For Consciousness to be published by OUP later this year (2004).