Search Results

In this interlude, Tougaw examines two major cultural responses to advances in neuroscience: neurodiversity politics and the U.S.-European race to “map” the brain in the hope of creating a dynamic digital “brain atlas.” While neurodiversity activists emphasize the difference from one human brain to another, the brain atlas projects aim to create a composite of the human brain. The interlude examines the inevitable contradictions that arise from both points of view, arguing that both are valuable but that neurodiversity politics and scientific efforts to map the composite brain would benefit from more mutual dialogue.

The human brain is a fine-tuned and balanced structural, functional, and dynamic electrochemical system. Any alterations, from slight slowing of partial brain networks to severe disruptions in structural, functional, and dynamic connectivity across local and large-scale brain networks will result in slight to severe changes in cognitive ability, awareness, and consciousness. Using future noninvasive technologies, the common goal is to relate typical or atypical resting-state, sensory-motor functions, cognition, and consciousness to underlying typical or altered quantified brain structure, biochemistry, pathways, functional brain networks, and connectivity. This will pose enormous ethical challenges of quantitative diagnostic and prognostic strategies in future neurologic and psychiatric clinical practice.

Turning human brains into soup; 86 billion neurons in the average human brain; the human brain as a large primate brain; numbers of brain neurons in human ancestors; great apes as outliers in the body x brain size relationship

Larger organisms explore a wider world and live longer, thereby expanding their possibilities for foraging but also their exposure to danger. Now a bigger brain becomes essential for sensing the environment and guiding behaviour. Behaviour must satisfy an animal’s internal systems, and internal systems must support behaviour. Thus the brain’s core tasks are to adapt behaviour to conditions and to match internal systems to these conditions, thereby using resources efficiently. These tasks involve gathering and transmitting information, defined by Shannon’s equations and quantified as the unit, bit. To capture, send, or store a bit costs space and energy, and for fundamental reasons higher rates are disproportionately expensive. Therefore neurons are constrained by three principles: send only information that is needed; send it at the lowest possible rate; minimize “wire” (minimize length and diameter of all neural processes). These few principles explain many design features of bigger brains – as exemplified in Chapter 4.