Brain Info

Basic and advanced information in a digestible format.

The basics of the brain

The brain is posited to be a highly evolved biological probability machine that adjusts our internal model of the world to a perceived reality. Activation of different areas within this probability machine create emergent properties of subconcious processing, conscious thought and action.

The processors

Patterns of activation within the brain are a result of orchestrated cell activity. There are two primary cell types in the brain, neurons and glia. Neurons are primarily the signalers and glial cells are the governers that modulate and prune connections.

How do signals spread?

Cell to Cell

The brain is comprised of many cells arranged in a carefully connected circuit.

Signals spread from cell to cell in an electro-chemical manner. First, neurons 'fire' by propagating an electrical wave (action potential) from their main cell body to the end of their long arm (axon). How? By sequential opening of 'floodgates' (voltage-gated ion channels). When open, these gates let positively charged sodium ions in, causing the next gate to open. Each subsequent opening of a floodgate causes the next to open in a wave like manner. When the wave reaches the end of the axon, it triggers the release of chemical neurotransmitters - signals in physical form that flow across gaps (synapses) between connected neurons. These signals are captured by tree-branch like structures (dendrites) on other nerve cells. Some axons are short and connect neighbouring cells. Some are very long. Collections of neurons with long axons form bundles and tracts that connect different areas of the brain.

Network wide dynamics

On a wider level, scientists have observed traveling wave patterns across the brain . These patterns are marked by neuronal oscillations - activity at certain frequencies that move around the brain dynamically. Such patterns, which have spatial, temporal and directional qualities, are hypothesized to be the mechanism through which the brain quickly coordinates activity and shares information across multiple regions. Some sets of brain areas that work together in unison have already been characterized as 'functional networks' responsible for attention or self embodiment and daydreaming etc. The level and frequency of activity in combination with the direction of spread are all valuable pieces of information that when encapsulated, allow researchers and clinicians to discover new brain patterns linked to different healthy functions, abnormal functions and disease.

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Chopra, S., Zhang, X.H. and Holmes, A.J., 2023. Wave-like properties of functional dynamics across the cortical sheet. Neuron, 111(8), pp.1171-1173.

Muller L, Chavane F, Reynolds J, Sejnowski TJ. Cortical travelling waves: mechanisms and computational principles. Nat Rev Neurosci. 2018 May;19(5):255-268. doi: 10.1038/nrn.2018.20. Epub 2018 Mar 22. PMID: 29563572; PMCID: PMC5933075.

Sato, N. Cortical traveling waves reflect state-dependent hierarchical sequencing of local regions in the human connectome network. Sci Rep 12, 334 (2022). https://doi.org/10.1038/s41598-021-04169-9