Neurobiology of Addiction Mark L. Carlson, MD, MPH Cox Center for Addictions October 11, 2018

etymology Neuro from Greek νευρον meaning sinew or tendon

pathos Greek for suffering

logos Heraclitus 535-475 BC A principle of order and knowledge the stoic philosophers identified the term with the divine animating principle pervading the universe

Herophilus 325 to 255 BC He was one of the first anatomist to differentiate nerves from blood vessels and tendons

Sagittal image of the brain

Forel Axis

Three Simple Parts to the Brain Thinking part—cerebral hemispheres Wanting part—limbic system Breathing part--brainstem

Sagittal image of the brain with the Meynert Axis

“Neural science must continually confront certain fundamental questions. Is a particular mental process carried out in specific parts of the brain, or does it involve the brain as a whole? page 5 in Eric R. Kandel et al: Principle of Neural Science, Fifth edition, McGraw Hill Medical, New York, 2013

C-shaped Limbic structures Cingulate gyrus, medial and longitudinal striae, indusium griseum, corpus callosum, fornix, stria terminalis, caudate nucleus, hippocampus, dentate gyrus, olfactory tract, habenular triangle, medullary stria

Nerve drawing by Santiago Ramon y Cajal

Camillo Golgi

Controversy Reticular theory of Golgi Neuron theory of Ramon y Cajal

resolution We are talking about the synapse. This structure was not clearly seen until the development of the electron microscope in the 1950’s

Grand parts of humans

Body functions Instinct of self-preservation Continuing of the human race

Soul Functions Thought and intellectual work—the brain Feelings—the heart (more correctly the limbic system) Desires—the will, but no body part is known to correspond to this function

Spirit functions The theological issues regarding conscience Should not be overlooked

The synapse This is where we can change our feelings by the addition of chemicals

But addiction is a choice Electric thought experiment 1 mA—not perceptible, probable tingling sensation 3-5 mA—”Let go” current for an average child 7 mA—”Let go” current for an adult 20-50 mA—paralysis of respiratory muscles Match the above with a worm, a bunny, a baby or yourself

What does it feel like to be in opioid withdrawal? Very bad.