This book came out in 2005. It is a very difficult text, starting with anatomy and physiology of the brain and neuronal networks, considering consciousness and how the brain perceives the outside world, ending with some comments on the processes of science. I am a neurologist these past 40 years, and struggled at times with the material.
One of the first revelations was the existence of constant neuronal activity generated by pacemaker cells in the brain. The early 20th century physiologist thought that electrical activity was evoked only by external stimuli. “The brain behaves as an autonomous system that constantly transmits energy to the outside world, rather than passively receiving the impression of external stimuli”. Spontaneous activity develops early in the development to the embryonic nervous system. (p 25)
“J.Z. Young, developing an idea originally due to Claude Bernard, suggested that living organisms are “homeostats”; that is, that they must be able to devise a representation of the world that favors their survival” (p. 27)
On addictive drugs, Changeux notes that they usually resemble chemically endogenous neurotransmitters, and produce adaptive changes in there targets that with the results that the brain circuits involved can function normally only in the presence of the drug. In withdrawal the discomfort arises from the disruption of the urge to engage in self stimulation. This is in a discussion of mouse self stimulation experiments. (p 46)
The discussion of “states of consciousness” includes extensive information about electrical activity of the brain, in thalamocortical circuits, and the activation of the brain by neurotransmitters released from the reticular formation. “Local high frequency firings (about 40 cycles per second) are also recorded in alert subjects in attentive states related to the processing of representations in the brain” (p 77). On thalamic specific and non-specific nucleii: “Neurons of the specific nucleii receive afferent inputs from the environment through sensory (and motor) pathways and establish connections with a particular layer of cerebral cortex, layer IV” (p 77). Nonspecific nuclei are not connected to the external world, mobilize different cortical circuits. Damage produces disorders of alertness, and petit mal epilepsy is associated with abnormally low frequency of nonspecific thalamocortical activity. Depolarization of thalamic neurons are associated with the 40 Hz oscillations. “Reticular neurons of the brainstem exhibit great biochemical and topological diversity” (p 80). They project widely in the cortex, and release acetylcholine, norepinephrine, and serotonin. Acetylcholine release is associated with alertness.
Neuronal workspace hypothesis for consciousness suggests that during conscious effort, pyramidal cells in layers V and VI that have long axons spanning the hemispheres, and are abundant in prefrontal, dorsolateral and inferoparietal areas, are spontaneously and jointly activated, forming discrete but variable spatiotemporal patterns. These a reciprocally linked to multiple sensory and motor processor and reward neurons. “A pre-representation that has been selected as a representation in the workspace may remain active, in an autonomous manner, and resist changes as long as it receives positive reward signals. If, however, signals are negative or attention is no longer sustained, this pre-representation can be revised or replaced, through trial and error, by another discrete combination of workspace neurons” (p 93).
On FMRI studies of consciousness, “Focusing attention for short periods of time - on auditory stimuli, for example - leads to increased activity in the prefrontal cortex (frontopolar, dorsolateal and orbitofrontal), the parietal cortex, and the secondary auditory cortex (superior temporal gyrus) without producing any significant interference with the operation of the arousal network, which has its principle source in the thalamus” (p 97)
“Brain imaging studies have shown that a dramatic change occurs, when in the course of carrying out a given task, the subject shifts from a perceptual mode that is undemanding but prone to error to a more active deductive mode requiring greater effort. ... a very clear swing from a posterior pattern of activation in the brain including ventral and dorsal visual pathways to a left prefrontal pattern involving notably the medial frontal gyrus, Broca’s area, the anterior insula and the presupplementary motor area” (p 105-106)
“A distinction is also made between aphasic patients who are no longer able to arrange words of a sentence in correct order and those who produce words with anomalous endings (or without endings at all)” (p 121)
“The mobilization of the prefrontal cortex under conditions of complete understanding [of a spoken story] suggests that efficient communication of contextualized knowledge involves the concerted activity of many more cortical areas than the “language areas” identified by Broca and Wernicke” (p 123)
“In the conscious workspace of the actor’s brain there is a splitting of representational schemas between what pertains to his true identity and what pertains to the role he plays” (p 131)
“The ancient Greek word symbolon meant both “to throw together” and “to put back together”. A symbol was a token of recognition constituted by two halves of a broken object that was handed down within families as proof of ancient bonds of hospitality” (p 134)
“...the relation between the total number of genes and the evolution of brain structure reveals a surprising absence of linearity” (p 156)
“Genes such as Otx2 and its homologues are therefore necessary for the formation of the head in both the mouse and the fruitfly” (p 161)
Complex interactions of transcription factors explain some of morphogenesis.
“Many genes whose alteration is responsible for neurological disorders have prior homologues in Drosophila, including the genes that create predispositions to Tay-Sachs, Duchenne muscular dystrophy, lissencephaly, and “Fragile X” mental retardation” (p 178)
“Although the ability to read and write is a classic example of culturally acquired behavior, there exist specific familial reading disabilities that have been attributed to localized alterations in the histocompatibility region (21.3) of chromosome 6p and perhaps also in chromosome 15.” (p 181)
Differences in handedness, the size of the planum temporale, and language dominance have been discovered in monozygotic twins (p 186)
On regressive phenomena in development, inactivation of caspases responsible for programmed cell death in mice results in increase in the surface of the cerebral cortex, but also epileptic seizures. (p 191)
[Donald] Hebb’s rule is that the strength of synaptic connections increases when there is temporal coincidence between pre and post synaptic activities (p 198)
Illiterates repeat meaningful words easily, but cannot easily repeat words without meaning “pseudo-words” and there are very different brain activation patterns. (p 205). This points to the epigenetic ability of the developing brain to learn new skills (p 204)
A very small number of genetic determinants (? Transcription factor genes) governed the development of the brain of Homo Sapiens over the last few million years.
“A remarkable and non linear transformation occurred in the morphogenesis and connectional complexity of the human cerebral phenotype on the basis of a relatively stable genetic endowment”
The striking development of the brain’s conscious workspace, allowing development of mental objects in unlimited combinations, whose capacity to truthfully represent the world could be evaluated. (p 209) ( )

Good attention to human process rather than projection and wish-full fhinking. ( )