Designing Brains for Pain: Human to Mollusc

Area of Science:

• Neuroscience
• Comparative Cognition
• Animal Sentience

Background:

• Subjective experience of stimuli arises in the cerebral cortex in mammals.
• Cephalopods are claimed to be sentient based on complex behavior, but evidence for pain perception is lacking.
• Anthropometric assumptions about sentience increase with phylogenetic distance from humans.

Purpose of the Study:

• To investigate the evidence for pain perception in cephalopods.
• To define the computational processes and neural circuitry underlying subjective awareness.
• To propose a model for sensory awareness based on observer neural networks.

Main Methods:

• Analysis of avoidance learning behavioral paradigms.
• Review of classical brain lesion studies.
• Development of an algorithm based on parallel observer networks for sensory awareness.

Main Results:

• No evidence found for cephalopods feeling pain.
• Human cortical networks possess circuitry consistent with the proposed pain awareness algorithm.
• Cephalopod brains lack the necessary neural circuitry to implement the proposed awareness algorithm.

Conclusions:

• Cephalopods do not exhibit compelling behavioral, functional, or neuroanatomical evidence for pain perception.
• Subjective awareness is dependent on observer neural networks that introspect neural processing.
• The human brain's cortical regions align with the proposed circuitry for pain awareness, unlike cephalopods.