Sample response

Neurotransmitters play an important role in human behaviour.  Neurotransmitters are released from the terminal buttons of a neuron and then travel across a synapse where they attach to receptor sites on the postsynaptic membrane. Some neurotransmitters are seen as more inhibitory - that is, they make the target neuron less likely to "fire" an action potential. A neurotransmitter can sometimes have either an excitatory or an inhibitory effect, depending on the receptor sites that it binds to.

One example of how a neurotransmitter binds to inhibitory receptor sites is the role of GABA in memory formation. Prevot carried out a study to see if using a benzodiazepine to stimulate GABA receptor sites would improve memory.  GABA receptor sites in the hippocampus are inhibitory, decreasing neural activity.

The study was done using older mice that showed memory impairment.  They were placed into a  ‘Y’ shaped maze.  The researchers carried out a double-blind experiment with a pre-test/post-test design. The mice were either allocated to the placebo condition (the control condition) or to drug condition.  You can see below the results in both the chronic stress and aged mice samples.  The older mice treated with the drug showed significantly higher levels of performance on the task than does those that received the placebo. In other words, the GABA agonist increased the memory retention of the maze.

This study is relevant to human behaviour. Porges found a correlation between higher concentrations of GABA receptors in the frontal lobe of an elderly sample and superior cognitive performance. It appears that inhibition of activity in the hippocampus plays a role in the creation of memory.