Key Terms & Definitions

Conscious – Unconscious Aspects

For the time being, we will refer to our common sense meanings of conscious and unconscious brain functions. During waking, we experience the world consciously, during sleep, we do not. That is our first overview.

Conscious Brain

Sensory consciousness is profoundly embedded in biology, anatomy, physiology, and above all, in adaptive brain functions that serve us in every second of waking life. This is not some philosophical speculation. It is now supported by numerous empirical findings published in peer-reviewed journals that are easily found in web archives.

Adaptive Resonance

It is a remarkable fact that almost all the connections in the cortex go in two directions, like the world wide web. The signals, therefore, travel back and forth very freely. This used to baffle brain scientists, but it is now clear that “resonant signaling” is key to the adaptive genius of the cortex. Resonance is an enormously powerful information processing style of the cortex.

Resonance is responsible, perhaps, for the near criticality of the trajectory of cortex — the ability cortex has to respond, almost instantly, to any stimulus in any modality — and, of course, from endogenous stimulation from the cortex itself.

Near Criticality

Another scientific puzzle has been the very fast switching in cortex between stable states and disorganized states, called “chaos.” In engineering, this is called “near critical functioning.” A tightrope walker stays safe in a very delicate balance, so as to move forward toward a goal, while not falling off. The dynamical cortex runs in much the same way, ready to adapt in a moment, while moving towards its goal.

Oscillations

The instantaneous operations of the brain are reflected in their electrical signature, which can be recorded, either from outside, or from implanted electrodes. These oscillations tell us about signal processing in the brain.

Corpus Callosum

The two hemispheres of the brain look separate, but so do the two neighborhoods of a city divided by a river. Geography tells us of appearance, but the traffic flow shows how things actually work. This is a distinction between visible anatomy and the actual functioning of the system. The corpus callosum is an enormous bridge between the two giant hemispheres. The healthy brain looks divided, like a city, but it works as a unified system.

Composed of about 200 million axons interconnecting the brain’s two hemispheres. Its primary function is to integrate motor, sensory, and cognitive performances between the cerebral cortex on one side of the brain to the same region on the other side.

Bidirectional Traffic Flow in cortex

Bidirectional traffic signaling is the standard working mode for the waking cortex; both the outer cortical helmet of the neocortex and the inner double-horned hippocampus, which is wrapped in the two temporal lobes at the sides of the brain.

Connectome

The connectome is the city map of the brain, which has emerged in science quite recently. It is a very important new sight.

We can think of the connectome as a “wiring diagram.” An organism’s nervous system is made up of neurons which link through synapses.

Excitatory & Inhibitory Neurons

Over a hundred billion neurons in the brain are either excitatory or inhibitory. An excitatory neuron signals the next nerve cell to fire. An inhibitory neuron tells the next nerve cell not to fire. Every state of the brain is a balance between excitation and inhibition.

Neural Darwinism

The late Nobelist Gerald M. Edelman proposed that “Neural Darwinism” describes brain functioning at many, many levels, from fetal development of the waking brain to life-long learning.

Another term is to call the brain a “Selectionist” organ, like the evolution of life itself.

Synchrony

Scientists in recent years have been amazed to find many kinds of synchrony among populations of brain cells. These have helped to answer questions that have emerged with the discovery of the EEG a century ago. 

Synchrony means that many neurons are dancing in step, or in sync. Neurons constantly move in and out of synchrony with each other, allowing new functional dances to emerge. When we use two hands to hold one object, two body maps in the cortex are dancing together.

Brain Rhythms

A century ago, scientists were baffled to observe electrical rhythms radiating from the brain. Today we know that brain rhythms can range from very slow to very fast, much like radio waves. The slowest waves are about the pace of a heartbeat, and the fastest waves go up to a thousand times per second. Most signaling in the brain is somewhere in the middle.

We are still learning about the different functions of various waveforms.

Term

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Term

Aptent felis blandit cursus gravida sociis eleifend lectus nullam conubia mauris dapibus netus feugiat. Lorem ipsum dolor sit amet, consectetur adipiscing elit.