What is the neurophysiology of a thought? PURPOSE

1) To find out if there is evidence in favor of one of Hebb's claim. In is book "The Organization of Behavior" he claimed that cell assemblies are the physiological foundation of thought. According to Sebastian Seung, in his book "Connectome: How The Brain's Wiring Makes Us Who We Are", a  thought is an association of ideas. 


  Is there evidence that support Hebb's claim?


2) In addition to (1) I want to know in which other ways Hebb has contributed to neuroscience. I have provided some examples below. 


  So, please leave links to research papers that support any other claim he has made.


BACKGROUND

The Organization of Behavior

"The Organization of Behavior - A Neuropsychological Theory", by D.O. Hebb, is one of the classics in the field of neuroscience, as you may know.

Hebb wondered about the nature of thought, and how ideas might be represented in the brain.

He was puzzled as to why the intelligence of some individuals remained intact after brain surgeries, where  a large part of their brain was destroyed. 

In his book, it is suggested, that these high IQ scores were 


  "due to a conceptual development which brain damage does not easily reverse."


Given these observations, Hebb asked:


  "... what is a concept physiologically ...?"


Which then prompt Hebb to claim that cell assemblies were the physiological basis of a concept/thought.

Hence, my question:


  Is there any scientific evidence that support that the cell assembly is the basis of thought/a concept?


HEBB'S CONTRIBUTION TO NEUROSCIENCE

Some of his ideas have been confirmed; for example, in "Biological Psychology",Breedlove, Watson, Rosenzweig, teach that memory storage requires neuronal remodeling. This finding is grounded on Hebb's observation, which was confirmed by Kelso and Brown, 1986, that 


  "Ensembles of neurons, or cell assemblies, linked via synchronized activity of these Hebbian synapses, could then act together to store memory traces."


The above observation is related to the maxim:


  "cells that fire together wire together."


Hebb's hypothesis about how synaptic connections grow stronger or weaker in response to experience gave rise to the idea of Hebbian synapses. 

A Hebbian synapse is a synapse whose strength depends on its effectiveness in driving the postsynaptic cell; for example, cells during visual deprivation do not fire together; consequently, they do not drive the postsynaptic cells. In turn, the synapses get weaker, i.e., less sensitive.
In contrast, if cells are stimulated by the visual field, cells fire together, driving postsynaptic cells. This in turn strengths synapses. 

REFERENCES 

Biological Psychology: An Introduction to Behavioral, Cognitive, and Clinical Neuroscience, Sixth Edition, Breedlove

Organization of Behavior - A Neuropsychological Theory, Hebb

Connectome: How The Brain's Wiring Makes Us Who We Are, Sebastian Seung
Hence, my question: Is there any scientific evidence that support that the cell assembly is the basis of thought/a concept?

This paper Thinking in circuits reviews this matter in detail, and its references can provide more related scientific evidence.

Question: What is the neurophysiology of a thought?

I think the following papers can provide some current information about the neurophysiology of thought:

1.How neurons make meaning

2.Brain Networks and Cognitive Architectures

3.Language and thought are not the same thing