In this engaging discussion, Eli Sennesh, a postdoctoral researcher at Vanderbilt University, sheds light on predictive coding and its implications for understanding brain functions. He navigates the intriguing concept of 'divide-and-conquer predictive coding' and its experimental applications. The conversation also touches on the relationship between neuroscience and AI, emphasizing the need for biologically plausible computational models. They explore the complexities of decision-making, consciousness, and the humor in our perceptions of task difficulty, offering a delightful blend of research insights and personal anecdotes.
The divide-and-conquer approach in predictive coding seeks to simplify complex brain computations while reflecting interrelated neural dependencies.
A major theme highlights the need for biological plausibility in computational models to accurately represent neural processes and enhance understanding.
The conversation critiques simplistic definitions of artificial general intelligence, emphasizing the complex interactions that govern human cognition beyond mere performance metrics.
Deep dives
Understanding Behavior through Predictive Coding
Predictive coding is a framework suggesting that the brain constantly tries to predict incoming sensory information and adjusts its predictions based on the sensory input it receives. This adjustment process utilizes the discrepancies between expected and actual sensory information to refine future predictions, which forms a core part of how the brain functions. The discussion emphasizes the significance of this predictive mechanism not just in sensory contexts but also in how organisms decide their actions. By applying predictive coding to cognitive processes, it provides insights into how behavior emerges from these interactions.
Divide and Conquer Strategy
The episode introduces the concept of 'divide and conquer predictive coding,' which aims to provide a biologically plausible method for how predictive coding functions in the brain. This approach implies breaking down complex variables into simpler components while maintaining their interrelatedness, allowing for local updates that reflect their mutual dependencies. It is crucial because it challenges conventional assumptions in predictive coding theories that rely on independent variables, which may not accurately represent neural computations. The divide and conquer strategy thus seeks to offer a more realistic representation of neural processing in the brain.
Challenges of Transitioning to Experimental Neuroscience
Transitioning from theoretical to experimental neuroscience presents a myriad of challenges, including the difficulty of connecting abstract theories to practical experimental designs. The discussion touches on the anticipation of null results when conducting experiments, highlighting the unpredictable nature of biological systems and the problems encountered when trying to test specific theories. Eli describes the rigors of adapting to the experimental environment, revealing how initial expectations can clash with the complexities of real-world data. This experience underlines the notion that experimental neuroscience requires both rigorous planning and the flexibility to navigate unexpected outcomes.
The Necessity of Biological Plausibility
A central theme of the conversation is the importance of biological plausibility in computational models of brain function. The dialogue suggests that any model attempting to capture the brain's processes must accurately reflect how biological systems operate, including the types of neural signals involved. It emphasizes that while mathematical models and algorithms can be insightful, they must also align with the structural and functional realities of the brain to provide meaningful insights. This insistence on biological fidelity can ultimately enhance our understanding of both normal brain function and neurological disorders.
Rethinking the Concept of AGI
The discussion also delves into the evolving understanding of artificial general intelligence (AGI) and its relationship to biological systems, particularly the human brain. It critiques the tendency to define AGI simplistically based on performance benchmarks rather than depth of understanding, suggesting that equating capability with intelligence can be misleading. The brain is seen as an intricate system far more complex than the benchmarks often used in AI research, with behaviour and cognition deriving from nuanced interactions among various neural processes rather than a straightforward computation. This perspective encourages a more integrated approach to studying intelligence, balancing engineering goals with foundational scientific inquiry.
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The Transmitter is an online publication that aims to deliver useful information, insights and tools to build bridges across neuroscience and advance research. Visit thetransmitter.org to explore the latest neuroscience news and perspectives, written by journalists and scientists.
Eli Sennesh is a postdoc at Vanderbilt University, one of my old stomping grounds, currently in the lab of Andre Bastos. Andre’s lab focuses on understanding brain dynamics within cortical circuits, particularly how communication between brain areas is coordinated in perception, cognition, and behavior. So Eli is busy doing work along those lines, as you'll hear more about. But the original impetus for having him on his recently published proposal for how predictive coding might be implemented in brains. So in that sense, this episode builds on the last episode with Rajesh Rao, where we discussed Raj's "active predictive coding" account of predictive coding. As a super brief refresher, predictive coding is the proposal that the brain is constantly predicting what's about the happen, then stuff happens, and the brain uses the mismatch between its predictions and the actual stuff that's happening, to learn how to make better predictions moving forward. I refer you to the previous episode for more details. So Eli's account, along with his co-authors of course, which he calls "divide-and-conquer" predictive coding, uses a probabilistic approach in an attempt to account for how brains might implement predictive coding, and you'll learn more about that in our discussion. But we also talk quite a bit about the difference between practicing theoretical and experimental neuroscience, and Eli's experience moving into the experimental side from the theoretical side.
0:00 - Intro
3:59 - Eli's worldview
17:56 - NeuroAI is hard
24:38 - Prediction errors vs surprise
55:16 - Divide and conquer
1:13:24 - Challenges
1:18:44 - How to build AI
1:25:56 - Affect
1:31:55 - Abolish the value function
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