Karl Pribram: The Holographic Brain and the Mathematics of Consciousness

How a Neurosurgeon Discovered That Memory Is Stored as Interference Patterns, Not in Specific Neurons

Karl H. Pribram was one of the most distinguished neuroscientists of the twentieth century. A board-certified neurosurgeon, a professor at Stanford University for over thirty years, a former colleague of Karl Lashley (who spent his career searching for the “engram” — the physical trace of memory in the brain), and the author or editor of over thirteen books and hundreds of scientific papers. His conventional neuroscience credentials were impeccable.

And yet, the theory for which Pribram is most famous — the holographic model of the brain — remains one of the most radical proposals in the history of brain science. It suggests that the brain does not store memories in specific neurons or specific locations but encodes them as interference patterns distributed across neural networks, in a manner mathematically analogous to the way a hologram stores images.

This theory, developed over several decades and published in its most complete form in Brain and Perception (1991) and Languages of the Brain (1971), has implications that extend far beyond neuroscience. When combined with David Bohm’s implicate order model, it produces the Bohm-Pribram holographic model of reality — a framework in which the brain is a holographic decoder that translates the implicate order (a frequency domain of enfolded information) into the explicate order (the world of separate objects in space and time that we perceive).

Karl Lashley’s Enigma: Where Is Memory?

The origins of Pribram’s holographic model lie in the work of his mentor, Karl Lashley, who conducted some of the most famous experiments in the history of neuroscience during the first half of the twentieth century.

Lashley trained rats to navigate mazes, then surgically removed different portions of their cerebral cortex, and tested whether the rats could still remember the maze. His expectation — shared by virtually all neuroscientists of his era — was that memory was stored in a specific location in the brain (the “engram”), and that removing the right location would erase the memory.

The results were baffling.

No matter which part of the cortex Lashley removed, the rats retained some memory of the maze. Removing larger amounts of cortex produced greater memory impairment, but the impairment was proportional to the amount of tissue removed, not to the specific location. The engram — the specific site where a specific memory was stored — could not be found.

Lashley summarized his decades of engram-hunting with a famous quip: “I sometimes feel, in reviewing the evidence on the localization of the memory trace, that the necessary conclusion is that learning just is not possible.”

Pribram, who had worked in Lashley’s laboratory and inherited the engram problem, spent years trying to solve it within the conventional framework of neuroscience. He could not. The data was clear: memory was not stored in any specific location. It was distributed throughout the brain. But how? What physical mechanism could encode information in a distributed, non-localized manner?

The answer came to him in the mid-1960s, when he encountered the concept of holography.

The Holographic Insight

Dennis Gabor had invented holography in 1947 (for which he received the Nobel Prize in Physics in 1971). A hologram is created by recording the interference pattern produced when a coherent light beam (a laser) is split into two beams: one that illuminates the object (the object beam) and one that serves as a reference (the reference beam). The two beams meet at a photographic plate, where their interference pattern — the pattern of light and dark bands produced by the overlap of the two wave fronts — is recorded.

The recorded interference pattern looks nothing like the original object. It appears as a meaningless swirl of light and dark bands. But when the pattern is illuminated by the reference beam, it reconstructs a three-dimensional image of the original object — an image that can be viewed from different angles, that has depth and parallax, and that contains far more information than a conventional photograph.

The property of holograms that struck Pribram like a thunderbolt was this: every part of a holographic plate contains information about the whole image. If you break a holographic plate in half, each half still produces the complete image (though with reduced resolution). If you break it into quarters, each quarter still produces the complete image. The information is distributed throughout the plate, encoded in the interference pattern, not localized in any specific region.

This was exactly the property that Lashley’s experiments had revealed in the brain. Memory was distributed, not localized. Removing a portion of the cortex reduced the resolution of the memory (like breaking a piece off a holographic plate reduces the resolution of the image) but did not erase it. The analogy was precise.

Pribram proposed that the brain stores memory not in the connections between specific neurons but as interference patterns in the neural network — patterns generated by the interaction of incoming sensory signals with the brain’s ongoing electrical activity, analogous to the interference pattern generated by the interaction of the object beam and the reference beam in holography.

The Mathematics: Fourier Transforms in Neural Processing

Pribram’s holographic model is not merely a metaphor. It is a mathematical model grounded in a specific mathematical operation: the Fourier transform.

A Fourier transform is a mathematical technique that converts a signal from the “time domain” (a description of how the signal changes over time) to the “frequency domain” (a description of the frequencies that compose the signal). Any complex signal — a piece of music, a brain wave, a visual scene — can be decomposed into a set of simple sine waves of different frequencies, amplitudes, and phases. The Fourier transform performs this decomposition.

Holography is, mathematically, a Fourier transform. The holographic plate records the interference pattern of light waves, which is the Fourier transform of the spatial information in the object scene. Reconstructing the holographic image is an inverse Fourier transform — converting the frequency-domain information back into spatial information.

Pribram proposed that the brain performs Fourier transforms on incoming sensory data. Instead of processing information as a spatial map (a point-by-point representation of the visual field, for example), the brain first converts the spatial information into a frequency domain — an interference pattern. This frequency-domain representation is what is stored as memory. When the memory is retrieved, the brain performs an inverse Fourier transform, converting the frequency-domain representation back into a spatial image.

The evidence for this model came from several sources:

Dendritic processing. Pribram identified the dendrites — the branching input fibers of neurons — as the site of Fourier-like processing. Dendrites do not fire all-or-nothing action potentials (the digital signals of the axon). Instead, they generate slow, graded potentials that interact with the graded potentials of neighboring dendrites, producing interference patterns. The dendritic network, Pribram argued, performs the equivalent of a Fourier transform on incoming signals.

Receptive field structure. The receptive fields of visual cortex neurons — the spatial patterns of light that activate specific neurons — were found by David Hubel and Torsten Wiesel (Nobel Prize, 1981) to include spatial frequency selectivity. Some neurons respond preferentially to specific spatial frequencies (specific patterns of light and dark stripes) rather than to specific features (edges, corners). This is consistent with Fourier processing.

Lens-like optics in the neural network. In optical systems, a lens performs a Fourier transform — it converts a spatial image into a frequency-domain pattern at the focal plane. Pribram proposed that the neural architecture of the cortex performs an analogous function, with the layered structure of the cortex acting as a neural “lens” that transforms spatial information into frequency-domain representations.

The Bohm-Pribram Synthesis: The Holographic Universe

The meeting point of Bohm’s implicate order and Pribram’s holographic brain produces a model of reality of extraordinary scope.

In the Bohm-Pribram model:

1. Reality at its deepest level is a frequency domain — Bohm’s implicate order, a domain of enfolded information that is not organized in space or time but in frequencies and interference patterns.

2. The brain is a holographic decoder that translates the frequency domain into the explicate order — the world of separate objects in space and time that we perceive. The brain performs a Fourier transform (or something mathematically analogous) on the implicate order, converting frequency-domain information into the spatial-temporal representation that constitutes our conscious experience.

3. What we perceive as the “real world” is a decoded hologram — a reconstruction of the frequency-domain information of the implicate order, performed by the brain’s neural processing. The world “out there” is not an objective reality that we passively perceive. It is a constructed representation — a decoded hologram — that is shaped by the brain’s decoding algorithms.

4. Consciousness occurs at the interface between the implicate and explicate orders — at the point where frequency-domain information is transformed into spatial-temporal experience. Consciousness is not in the brain or outside the brain. It is the process of transformation itself — the act of decoding the implicate order into lived experience.

This model has several remarkable implications:

The hard problem of consciousness. The Bohm-Pribram model offers a framework for the “hard problem” — how physical processes give rise to subjective experience. In this model, subjective experience is not produced by physical processes. It is produced by the transformation from the implicate to the explicate order, a transformation that the brain mediates but does not generate. Consciousness, in this framework, is as fundamental as the implicate order itself.

Mystical experiences. If the brain normally decodes the implicate order into the explicate order (producing the ordinary perception of separate objects in space and time), then meditation, psychedelics, and other consciousness-altering practices may temporarily modify or bypass the decoding process, allowing direct perception of the implicate order — the undivided frequency domain. This would explain the recurring features of mystical experience: the dissolution of boundaries, the sense of unity, the perception of everything as interconnected, and the feeling that “this is more real than ordinary reality.”

Paranormal phenomena. If the implicate order is a domain where information is non-local (every part contains information about the whole), then telepathy, precognition, and remote viewing become theoretically possible. They represent the brain accessing implicate-order information that has not been through the normal decoding process — perceiving the wholeness directly rather than through the filtered, fragmented lens of ordinary perception.

Pribram’s Later Work: Toward a Spectral Theory of Cognition

In his later career, Pribram refined and extended his holographic model into what he called a “spectral” or “holonomic” theory of brain function. This refinement addressed some of the limitations of the original holographic metaphor.

The key refinement: the brain is not literally a hologram. It does not use laser light or optical interference patterns. What the brain does use is a mathematical process that is formally equivalent to holography: the decomposition of information into spectral components (frequencies) and the reconstruction of spatial patterns from spectral representations.

Pribram called this process holonomy — the mathematical framework that describes how a system can encode spatial information in a frequency domain and reconstruct it. Holonomy includes holography as a special case but is more general — it applies to any system that performs Fourier-like transformations, whether using light, sound, electrical potentials, or quantum processes.

The holonomic model makes specific, testable predictions about neural processing:

• Sensory systems should show spectral (frequency-domain) processing in addition to spatial (feature-detection) processing. This has been confirmed in the visual, auditory, somatosensory, and olfactory systems.
• Memory storage should be distributed, not localized. This is consistent with decades of lesion studies and modern neuroimaging data.
• Memory recall should involve a reconstruction process analogous to holographic reconstruction — not a simple “playback” of stored information. This is consistent with the well-documented constructive nature of memory recall.

Critics and Limitations

The holographic brain model has attracted significant criticism:

The metaphor critique. Critics argue that the holographic model is a metaphor, not a mechanism. The brain is not a hologram. It does not use laser light or photographic plates. Calling the brain “holographic” is, in this view, an analogy that may be misleading.

Pribram addressed this criticism directly by developing the holonomic theory, which is based on the mathematics of Fourier transforms rather than on the physical mechanism of holography. The argument is not that the brain is literally a hologram but that it performs mathematically equivalent operations.

The localization evidence. Modern neuroimaging (fMRI, PET) has identified specific brain regions associated with specific functions — the fusiform face area for face recognition, the hippocampus for spatial memory, Broca’s area for language production. This localization seems to contradict the holographic model’s emphasis on distributed processing.

Pribram’s response: both localization and distribution are real. Specific brain regions perform specific processing functions, but the information processed by these regions is encoded in a distributed, interference-pattern format. Localization and distribution are complementary, not contradictory — like the fact that a holographic plate has a specific location while the information it encodes is distributed throughout it.

The quantum requirement. The Bohm-Pribram model in its strongest form requires quantum coherence in the brain — the brain must maintain phase relationships between neural oscillations with a precision that approaches quantum levels. Whether the brain can maintain this level of coherence in its warm, noisy, biological environment is an open question.

Pribram in the Digital Dharma Framework: The Decoder Ring

Karl Pribram’s work provides the Digital Dharma framework with a specific model of how the biological hardware decodes consciousness into lived experience.

If the body is wetware, Pribram explains what the wetware computes: Fourier transforms. The brain is a spectral analyzer — it decomposes incoming information into frequency components, stores them as interference patterns, and reconstructs spatial-temporal experience from these patterns. The hardware is doing mathematics — specifically, the mathematics of wave interference and spectral decomposition.

If DNA is source code, the code specifies the construction of a biological Fourier transform engine — a neural network optimized for holonomic processing. The layered architecture of the cortex, the branching structure of dendrites, the oscillatory properties of neural ensembles — all of these are, in Pribram’s model, design features of a spectral processing system encoded in the genome.

If consciousness is the operating system, Pribram’s model explains how the OS interfaces with the hardware: through the transformation of frequency-domain information (the implicate order) into spatial-temporal experience (the explicate order). Consciousness is not produced by neural computation; it is the experiential aspect of the transformation process itself. The brain does not generate consciousness; it shapes it, like a lens shapes light.

The holographic model explains why meditation works: by quieting the brain’s habitual processing — its compulsive Fourier-transforming of the implicate order into the explicate order — meditation allows consciousness to rest in the frequency domain itself. The experience of unity, timelessness, and boundlessness reported by meditators is not an illusion; it is a direct experience of the implicate order, the domain from which ordinary experience is decoded.

The holographic model also explains the efficacy of shamanic diagnosis. If every part of the holographic system contains information about the whole, then any part of the body contains information about the entire organism — and any fragment of experience contains information about the entire life. The shaman who reads the client’s energy body, the acupuncturist who diagnoses through the pulse, the iridologist who reads the iris — all are accessing holographic information: the whole enfolded in the part.

Key Works

• Languages of the Brain: Experimental Paradoxes and Principles in Neuropsychology (1971) — The first comprehensive presentation of the holographic brain model
• Brain and Perception: Holonomy and Structure in Figural Processing (1991) — The mature holonomic theory
• The Form Within: My Point of View (2013) — Pribram’s intellectual autobiography
• Numerous papers in Science, Nature, Neuropsychologia, and other peer-reviewed journals

The Bottom Line

Karl Pribram solved the riddle that defeated Karl Lashley: how can memory be distributed throughout the brain without being stored in any specific location? The answer: holographic encoding. Memory is stored as interference patterns — frequency-domain representations distributed across neural networks — and reconstructed through a process mathematically equivalent to holographic image reconstruction.

This finding, combined with Bohm’s implicate order, produces one of the most profound models of reality ever proposed: a universe in which physical reality is a decoded hologram, the brain is the decoder, and consciousness is the process of decoding — the transformation of a frequency domain of infinite enfolded information into the spatial-temporal experience we call “the world.”

Pribram died on January 19, 2015, at the age of 95. He had spent seven decades investigating the relationship between brain and mind, and he concluded that the brain does not produce the mind. It decodes it. The signal is everywhere. The brain is the tuner.