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Central Nervous System - Coggle Diagram
Central Nervous System
Central Nervous System (CNS) which includes the nerves running down the spine. The brain and spinal cord together make up the CNS.
The Peripheral Nervous System, which stretches out from your brain and spinal cord into every other part of your body. The Peripheral Nervous System includes sensory nerves (which carry information back to the brain as sensations - the "five senses") and motor nerves (which carry messages from the brain, telling muscles to move and glands to release their hormones).
Two hemispheres
The two hemispheres are linked by a "bridge" of nerve fibres called the corpus callosum. The corpus callosum allows the left and right hemispheres to communicate with each other.
This is because the left and right hemispheres specialise in different things. The way different sides of the brain have different functions is called brain lateralisation.
An obvious example of brain lateralisation is that each hemisphere controls a different side of the body. However, it's not as you think: the left hemisphere controls most of the right side of the body, while the right hemisphere controls most of the left side. So if you raise your left hand, that's your right hemisphere controlling the hand.
The two hemispheres have other differences too that are revealed when people suffer brain damage to one side of the brain only (such as a stroke). The brain's language centre is in the left hemisphere and damage to this takes away the power to speak or write (but not to understand language - the right hemisphere can do that). The left hemisphere seems to specialise in reasoning and numbers and more abstract thought; spatial awareness (like reading maps or judging distances) is based in the right hemisphere as is musical ability and artistic creativity.
Cerebral Cortex- The cortex handles a lot "higher" brain functions, such as conscious thought and interacting with the world around us. It is divided into a number of areas with different functions, the most important being the four lobes.
Lobes
Frontal Lobe- Handles most of our conscious planning, especially an important part of it called the pre-frontal cortex. Because it is important for self-control and decision-making, it has a big role to play in handling aggression, which is why it was studied by Raine et al. (1997) in the Classic Biological Study. Raine observed murderers showed less activity in the frontal lobe compared to a non-criminal control group.
Temporal Lobe- Handles most of our memory functions,
Occipital Lobe- Is at the back of the brain, but it processes sight and our sense of our environment.
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The Limbic System
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The limbic system handles memory but also raw appetites and desires - sleep, hunger, aggression and sex. It is thought to be the source of all our basic emotions. Is sometimes called "the brain's switchboard", since it handles all the messages coming in from the brain and routes them to where they need to go.
Amygdala- Is the shape of an almond. It is the brain's "emotion centre". It handles emotional responses to things, especially anger and fear. If it is working properly, we should only fear things that are dangerous. Raine et al. (1997) noticed that the amygdala in murderers functioned erratically; this suggests they might not have felt fear or aggression at appropriate times. Other studies on animals have shown that, when the amygdala is damaged, the animal stops showing fear of threatening stimuli.
Hypothalamus- Is the shape and size of a pea. It regulates hunger, thirst, sexual arousal and sleep. Animals with damage to the hypothalamus have been known to lose all interest in food or else to start eating compulsively. It's also part of the endocrine system: it regulates hormone production in the body.
Hippocampus- Is shaped like a sea horse (it's name means "sea horse"). It is important for forming new memories: it is the brain's "memory factory". Damage to the hippocampus destroys the ability to form new long term memories. A famous example of someone with this problem was H.M. (Henry Molaison), whose hippocampus was removed during brain surgery. Schmolck et al. (2002) found that semantic long term memory was located outside the hippocampus, in the medial temporal lobe.