Can cocaine kill you

How cocaine changes the brain and mind

Berkeley - Even after a single dose of cocaine, new spinous processes form on the dendrites of the neurons in the decision-making center of the frontal lobe. The experiments carried out on mice in Nature Neuroscience (2013; doi: 10.1038 / nn.3498) illustrate the rapid development of addiction to the drug.

Previous studies had shown that cocaine altered the dorsomedial prefrontal cortex. The region of the frontal lobe is one of the decision-making centers of the brain and is closely connected to the basal ganglia and other “deeper” brain regions that control behavior. Previous studies had shown that cocaine use leads to changes here.

This includes the formation of new spinous processes in layer 5, an upper layer of the pyramidal cells in the aforementioned dorsomedial prefrontal cortex. Spinous processes are button- or mushroom-shaped protuberances, at the tip of which synapses are usually formed. New spinous processes are therefore an indication of a functional change in the hardware of the brain.

The changes can be made visible in living animals using two-photon fluorescence microscopy. For this purpose, the special microscope is placed directly over the dorsomedial prefrontal cortex via trepanation. Linda Wilbrecht's team from the University of California at Berkeley carried out the study on mice that were given cocaine in various experiments.

In a first experiment, the animals were examined one day after the administration of cocaine or table salt. After the drug, there was a significant increase in the spinous processes. In a second study, the researchers observed that the formation of the new nerve connections began just two hours after exposure to cocaine.

In a third experiment, the formation of the spinous processes was linked to the behavior of the animals. The animals were in a cage with two differently equipped rooms. After a while, the animals develop a preference for one of the two rooms. They were then given the cocaine in the room, which they did not like to be in that much.

Shortly after the coca intake, the animals' preference turned. They preferred to stay in the room they had previously avoided because there they hoped for the next dose of cocaine. Wilbrecht put this preference in connection with the development of the spinous processes. Most of the spinous processes were observed in the animals that were most controllable in their spatial preference by the drug.

The experiments show that cocaine has a rapid “learning effect” in a brain region that is central to behavior. They confirm the clinical experience of addiction experts who ascribe cocaine a strong and rapidly onset of addiction potential. © rme / aerzteblatt.de