Title
How the Brain Represents Language and Answers Questions? Using an AI System to Understand the Underlying Neurobiological Mechanisms.
Abstract
To understand the computations that underlie high-level cognitive processes we propose a framework of mechanisms that could in principle implement START, an Al program that answers questions using natural language. START organizes a sentence into a series of triplets, each containing three elements (subject, verb, object). We propose that the brain similarly defines triplets and then chunks the three elements into a spatial pattern. A complete sentence can be represented using up to 7 triplets in a working memory buffer organized by theta and gamma oscillations. This buffer can transfer information into long-term memory networks where a second chunking operation converts the serial triplets into a single spatial pattern in a network, with each triplet (with corresponding elements) represented in specialized subregions. The triplets that define a sentence become synaptically linked, thereby encoding the sentence in synaptic weights. When a question is posed, there is a search for the closest stored memory (having the greatest number of shared triplets). We have devised a search process that does not require that the question and the stored memory have the same number of triplets or have triplets in the same order. Once the most similar memory is recalled and undergoes 2-level dechunking, the sought for information can be obtained by element-by-element comparison of the key triplet in the question to the corresponding triplet in the retrieved memory. This search may require a reordering to align corresponding triplets, the use of pointers that link different triplets, or the use of semantic memory. Our framework uses 12 network processes; existing models can implement many of these, but in other cases we can only suggest neural implementations. Overall, our scheme provides the first view of how language-based question answering could be implemented by the brain.
Year
DOI
Venue
2019
10.3389/fncom.2019.00012
FRONTIERS IN COMPUTATIONAL NEUROSCIENCE
Keywords
Field
DocType
theta-gamma code,episodic memory,short-term (working) memory,memory retrieval,question and answer
Semantic memory,Pointer (computer programming),Episodic memory,Question answering,Computer science,Working memory,Chunking (psychology),Artificial intelligence,Natural language processing,Sentence,Machine learning,Encoding (memory)
Journal
Volume
ISSN
Citations 
13
1662-5188
0
PageRank 
References 
Authors
0.34
6
5
Name
Order
Citations
PageRank
Marco Idiart18411.23
Aline Villavicencio228635.24
Boris Katz317916.09
César Rennó-Costa4143.47
John E. Lisman5203.16