OCR 21 st Century Science Unit B6b Revision Learning and memory

Drugs and the nervous system Drugs are classed as “a substance that affects the central nervous system, causing changes in psychological behaviour and possibly addiction”. They do this by affecting the transmission of impulses. Consider Ecstasy for example: Ecstasy (MDMA) blocks the sites in the brain’s synapses where the transmitter substance serotonin is removed. Beta blockers and Prozac can also affect the transmission of impulses.

Some drugs stop the impulse from passing across the ……………………… Drugs such as strychnine cause all the muscles in the body to go into a continuous spasm of contraction. This also stops the person from ………………………. Serotonin is a chemical released in the brain that gives feelings of pleasure. Lack of this chemical can lead to feelings of ………………………. Prozac is an ……………………… ……………drug that causes serotonin concentration to build up in synapses. The Prozac molecule blocks the re-uptake of serotonin from a synapse. Beta blockers are drugs that can help people who suffer from angina (chest pain due to a ……………………… condition). They work by blocking the receptor sites on heart muscle cells so impulses from nerves which would speed up the heart are ……………………… from passing to the heart. WORDS: synapse. Breathing depression anti-depressant heart prevented Drugs and the nervous system summary

The cerebral cortex The cerebral cortex is the part of our brain most concerned with intelligence, memory and consciousness. By studying the effects (e.g. memory/sight loss) when different parts of the brain are damaged scientists have been able to identify which parts of the brain control which functions.

EEG and MRI 1) An electroencephalogram (EEG) is a visual record of the electrical activity generated by neurons in the brain. It works by amplifying and detecting the electrical signals from the brain. 2) Magnetic resonance imaging (MRI) scanning is a new technique that produces images of different cross sections of the brain and uses colours to represent activity.

Conditioning- Pavlov’s dogs Ivan Pavlov, I won the Nobel Prize in 1904 and am most famous for investigating “conditioned responses”: 1)Steak + dog = saliva 2)Steak + bell + dog = saliva 3)Bell + dog = saliva Notice that the final response (saliva) has no direct relation to the stimulus (the bell). Conditioned reflexes can increase an animal’s chance of survival!

Bird finds a black caterpillar and tastes it. It tastes good so it is eaten Bird finds a black and orange caterpillar and tastes it. It is poisonous and tastes bad so it is not eaten Bird finds a black and orange caterpillar but avoids it because it is poisonous Bird finds a hairy black and orange caterpillar, this one is harmless but the bird still avoids it. Underline the primary stimulus Circle the secondary stimulus Put a box round the conditioned response Extension: Answer the following questions in your exercise book: 1.Which organisms benefit? For each one explain how. 2.Which caterpillar would you expect to find in the highest numbers? Explain your answer.

Complex behaviour When the brain is asked to do certain tasks different areas are “activated”. New experiences cause new neuron pathways to develop, while pathways that are not used are eventually destroyed. This is why we become better at certain tasks when we practice them more often. PET scan showing areas “activated” by doing algebra.

Memory Our memory is divided into two types: short term and long term. Short-term memory lasts for about 30 seconds. This is why, when you look up a new telephone number, by the time the call has ended you have forgotten the number. If more information arrives than can be held in the short-term memory then some is lost (forgotten). Long-term memory may last the whole of your life. When you sing the words of a favourite song, you are using your long- term memory. Although we often complain about how hard it is to learn new things, there is no limit to how much information you can store in your long-term memory. Ways of improving short term memory, e.g. a phone number Ways of improving long term memory e.g. exam revision

Multistore model Scientists have produced models to help explain how memory works. So far, none of these models has provided an exact explanation. The multistore memory model can be used to help explain some steps involved in long-term and short-term memory.