Biology & philosophy
January 1, 2015
Brian Key
115 citations
Feeling pain requires specific neural architecture that fish lack. While humans readily attribute subjective experience to animals that respond to noxious stimuli, the neural properties necessary for phenomenal consciousness—the subjective feeling of sensory stimuli—are present in mammals and birds but absent in fish. Fish respond to noxious stimuli reflexively and with limited behaviors, not through conscious awareness. The paper proposes a set of fundamental neural tissue properties required for experiencing affective states and concludes that fish do not feel pain.
Frontiers in systems neuroscience
January 1, 2022
Brian Key, Oressia Zalucki, Deborah J Brown
9 citations
Subjective experience—conscious awareness—requires a specific neural architecture, not merely activity in higher cortical regions. The authors propose that any system capable of subjective experience must implement stacked forward models that predict the output of neural processing from inputs, enabling prediction, error detection, and feedback control. They call this the hierarchical forward models algorithm. This framework defines a minimal but not sufficient neural architecture necessary for subjective experience. It implies that animals lacking this architecture cannot have subjective experience, regardless of behavior or brain similarities to humans. The approach shifts focus from which brain regions are active to what computations are performed.
Neuroscience of consciousness
January 1, 2024
Brian Key, Deborah J Brown
6 citations
Internal feeling states like pain, hunger, and thirst are often assumed to directly cause behaviors essential for survival, but this 'causal assumption' conflicts with the standard neuroscientific view of motor action. The authors argue that denying feelings cause behavior does not necessarily lead to epiphenomenalism, which would contradict evolutionary biology. Instead, they propose the 'sense making sense' hypothesis: the function of subjective experience is not to cause behavior but to explain it, in a restricted sense. This framework integrates neural computations for motor control, feelings, and explanatory processes to account for how feelings contribute to our understanding of why we act.
Neuroscience and biobehavioral reviews
October 1, 2025
Brian Key, Deborah J. Brown
1 citation
The commonsense idea that feelings such as pain cause behavior is challenged. No known mechanism explains how subjectively experienced pain could directly modulate neural activity or gate ion channels. The real cause of behavior is neural activity, not the feeling of pain itself. This raises whether pain has any causal function or is merely epiphenomenal. Epiphenomenalism struggles to explain why such an attention-consuming feeling would survive evolution. The authors infer from neuroscientific evidence that pain has a novel, non-causal function: it marks neural pathways that cause behavior as salient, serving as a ground but not a cause of decision-making and action. Decisions are caused by threshold detection of accumulated evidence of pain, not by pain per se.