Pribram’s Holonomic Brain Theory

Neurosurgeon/neuroscientist Karl Pribram's Holonomic Brain Theory is the novel idea that human consciousness comes about via quantum effects in or between brain cells such that the brain acts as a holographic storage network (building on theories of holograms formulated by Dennis Gabor). (“Holonomic” refers to representations in a Hilbert phase space defined by both spectral and space-time coordinates.) (“Holonomic brain theory,” 2023).

Holograms and Memory Storage

Holograms are three-dimensional images encoded on two-dimensional surfaces, and Pribram's claim is that this counterintuitive capacity is fundamental in explaining consciousness. (There is precedent in that the holographic principle in quantum cosmology describes black hole entropy and information, with applications in string theory and quantum gravity [“Holographic principle,” 2024].)

Holograms are generated from patterns of interference produced by superimposed wavefronts, created by split beams of coherent radiation (i.e., lasers) that are recorded and later reconstructed. A prime characteristic is that every part of the stored information is distributed over the entire hologram. Even if most parts of the hologram are damaged, as long as any part of the hologram is large enough to contain the interference pattern, that part can recreate the entirety of the stored image (but if the image is too small it will be noisy, blurry).

The application of holographic models to consciousness was inspired by this non-locality of information storage within the hologram. It was Karl Pribram who first noted the similarities between an optical hologram and memory storage in the human brain, extrapolating what psychologist Karl Lashley had discovered about the wide distribution of memory in the cerebral cortex of rats following diverse surgical lesions.

Pribram had worked with Lashley on Lashley's engram experiments, which sought to determine exact locations of specific memories in primate brains by making small lesions. The surprising result was that these targeted extirpations had little effect on memory. In contrast, removing large areas of cortex caused multiple serious deficits in memory and cognitive function. The conclusion was a milestone in neuroscience: memories are not stored in a single circuit or exact location but are spread over the entirety of a neural network. Thus, according to Holonomic Brain Theory, memories are stored in holographic-like fashion within certain general regions but stored non-locally within those regions. This enables the brain to maintain function and memory even after it is damaged. (This can explain why some children retain normal intelligence when large portions of their brains—in some cases, half—are removed.) (“Holonomic brain theory,” 2023).

Quantum Processes and Consciousness

More fundamentally, Holonomic Brain Theory conjectures that consciousness is formed by quantum events within or between neurons. This early theory of quantum consciousness, which Pribram developed initially with physicist David Bohm, combines quantum biology with holographic storage. Pribram suggests these processes involve electric oscillations in the brain's fine-fibered dendritic webs, which differ from the commonly accepted action potentials along axons and traversing synapses. These oscillations are waves and create wave interference patterns in which memory is encoded such that a piece of a long-term memory is similarly distributed over a dendritic arbor.

The remarkable result is that each part of the dendritic network contains all the information stored over the entire network—a mechanism that maps well onto laser-generated holograms. Thus, Holonomic Brain Theory is said to enable distinctive features of consciousness, including the fast associative memory that connects different pieces of stored information and the non-locality of memory storage (a specific memory is not stored in a single location; there is no dedicated group or circuit of specific neurons) (“Holonomic brain theory,” 2023).

Although Holonomic Brain Theory has not come to threaten mainstream neuroscience, it has intriguing features that should be explored. I don't hold it against the theory that it has stimulated unusual and creative speculations; for example, holographic duality and the physics of consciousness (Awret, 2022); holographic principle of mind and the evolution of consciousness (Germine, 2018); and quantum hologram theory of consciousness as a framework for altered states of consciousness research (Valverde et al., 2022). In fact, for a theory to have a shot at explaining consciousness, if it does not stimulate strange ideas, it probably doesn't have the disruptive firepower that is surely required.

Extensions and Speculations

For example, physicist Uziel Awret's dual-aspect information theory of consciousness—holographic-duality—is motivated by certain anti-physicalist problem intuitions associated with representational content and spatial location and attempts to provide these with a topic-neutral, consciousness-independent explanation—which, he says “is ‘hard’ enough to make a philosophical difference and yet ‘easy’ enough to be approached scientifically.” This is achieved by, “among other things, showing that it is possible to conceive of physical scenarios that protect physicalism from the conceivability argument without needing to explain all the other anti-physicalist problem intuitions.” Awret argues that “abstract algorithms are not enough to solve this problem and that a more radical ‘computation’ that is inspired by physics and that can be realized in ‘strange metals’ may be needed” (Awret, 2022).