1.4 Neurotransmitters + their effect on behaviour Cheat Sheet

A Education › Psychology cheat sheet in English by Sruby

- Synapse (how these relate to excitatory and inhibitory neurotransmitters) - Definition of agonist and antagonist - Explanation of the role of acetylcholine in memory - Antagonist/agonist: Antonova et al (2011) Acetylcholine in memory formation - Use of smart drugs - Role of culture in the formation of memories

Neurotransmitters

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Antonova (2011)


Aim:	wanted to see if scopolamine affected hippocampal activity in the creation of spatial memory.
Procedure
-	20 healthy male adults (mean age 28). were injected with either Scopolamine or a placebo
-	Pts were put into an fMRI and scanned whilst playing the "Arena task." A virtual reality game where the goal was to navigate around an "arena" to reach a pole.
-	After learning where the pole was located, the pts were told to actively rehearse how to get to the pole in the arena.
-	Repeated measures design - pts returned 3/4 weeks later and redid the test - receiving the opposite treatment
Research method	Experiment
IVs	Scopolamine/Placebo
DV	fMRI - Brain activity
Antagonist	Scopolamine
Agonist	Acetylcholine
Findings
1) When pts were injected with scopolamine, they demonstrated a significant reduction in the activation of the hippocampus compared to when they received a placebo.
2) They were also more accurate in the placebo group.

Counter-argument: Kulkofsky

Neuron

Neurons are cells within the nervous system that transmit information to other nerve cells, muscle, or gland cells. Most neurons have a cell body, an axon, and dendrites.

Explain synaptic transmission

Synaptic transmission is the biological process by which a neuron communicates with a target cell across a synapse. Chemical synaptic transmission involves the release of a neurotransmitter from the pre-synaptic neuron, and neurotransmitter binding to specific post-synaptic receptors.

Excitatory + Inhibitory

Neurotransmitters have either an excitatory or Inhibitory effect of the neighboring neuron.

= Excitatory neurotransmitters are released into an excitatory synapse causing a neuron to fire, leading to an action potential, this produces stimulating effects on the brain.

E.g E.g. Acetylcholine when in excitation it makes the receiving neuron positively charged and more likely to fire and is thought to be involved in the process of memory consolidation.

Neurotransmitter

Neurotransmitters are electrochemical messages that result in a vast array of behaviours. The effects of Neurotransmitters can be amplified or reduced.

*Human behaviour is highly complex, thus trying to determine cause and effect is difficult to prove.

Neurotransmission

Describe Neurotransmission

Neurotransmission is the process of nerve cell communication. The neurons that are interconnected communicate with each other by releasing chemicals called neurotransmitters into small gaps between the two nerve cells call the synapse gap (see above).

The process of electrochemical transmission starts in the dendrites that branch out from the cell body and these receive incoming impulses from neighboring neurons.

The impulse passes down the axon as action potential, down to the terminal buttons, containing synaptic vesicles (tiny sacs) filled with neurotransmitters which are released into the synapse.

A released neurotransmitter is available for the synapse gap for a short amount of time during which it may be destroyed, pulled back into the presynaptic axon terminal through reuptake (reabsorption), or reach the postsynaptic membrane and bind to one of the receptors on its surface.

If the neurotransmitter bind onto the receptor on the postsynaptic neuron, this process changes the membrane potential and so contributes to activating an electrical pulse in the postsynaptic neuron. Here the chemical mechanism becomes electrical again.

Conclusions (Antonova (2011)

It appears that acetylcholine may play an important role in memory consolidation - why do you think this?

Becausethe hippocampus was activated - so what??

It was demonstrated that neurotransmitters themselves can be affected by other chemicals - why?

Because drugs interfere with the way neurons send, receive, and process signals via neurotransmitters.

= Some drugs, such as marijuana and heroin, can activate neurons because their chemical structure mimics that of a natural neurotransmitter in the body. This allows the drugs to attach onto and activate the neurons.

Antagonist

Is a substance that fits into a receptor site on the postsynaptic neuron, preventing the neuron from firing by blocking access to it.

Agonist

Looks like the neurotransmitter and fits in the receptor site but it amplifies the behaviour. The reaction can be excitatory or inhibitory.

= Drugs are exogenous agonists.

= Neurotransmitters are endogenous agonists.

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