CNS

• Rain et al: 

  • investigated the glucose metabolism is different areas in the brain in 41 murders using PET scans. 
• Rain et al Study showed

  • that murders had reduced glucose metabolism in their prefrontal cortex suggesting that the area is less active than in controls
• Straiker and Mackie

  • used hippocampal neurons from mice with the human CB1 receptor in order to study the effects of cannabis 
• Straiker and Mackie

  • Study showed that mice exhibited similar addictive behaviours to humans when dosed with cannabis as excess dopamine was found in neural pathways 
• Jovanovic

  • jovanovic studied serotonin systems in women as low serotonin levels are linked with depression, They scanned women with and without pmdd before and after ovulation 
• Jovanovic

  • Results showed that women without pmdd showed differences in their synaptic receptors suggesting that synaptic receptors have a role in pmdd.
• The nervous system is a specialized and complex network of cells in the human body. It is our primary internal communication system and has two main functions: it collects, processes and responds to information in the environment and it coordinates the working of different organs and cells in the body. 
• The central nervous system is made up of the spinal cord (responsible for reflex actions and passing messages to and from the brain) and the brain (the source of our conscious awareness and where decision-making takes place). 
• Below the cortex are subcortical structures, such as – the thalamus (the brains relay station which receives info from all our senses but smell and passes it to the right areas of the cerebral cortex, filters info), the hypothalamus (controls motivational behaviours e.g. hunger, has a key role in body’s fight or flight stress response, maintains balance in bodily functions e.g temperature in homeostasis, and regulates endocrine system)
• the limbic system (made up of several structures e.g. amygdala, regulates emotional responses e.g. aggression, also has a role in memory and learning), the cerebellum (primary role is to coordinate posture, balance and movement by receiving and integrating info from the spinal cord), and the corpus collosum (a dense collection of nerve cells connecting the two hemispheres of the brain below the cerebral cortex). 
• The cerebral cortex of both hemispheres is subdivided into four lobes: frontal, parietal, occipital, and temporal
• Frontal lobe – located at the front of the brain, it controls high-level cognitive functions such as thinking, planning, problem solving and decision making. Also contains the motor cortex.
• Parietal lobe – found on the other side of the central sulcus, further back in the brain, it processes sensory information from the skin e.g. touch, temperature, pressure, it is necessary for perceiving touch, pain and body position. It also helps you understand symbols and the space around you.
• Temporal lobe – located beneath the lateral sulcus of each hemisphere, processes auditory information, needed to hear and understand sound. It also affects brain functions such as memory and emotion.
• Occipital lobe – located at the back of the brain, processes visual information, is needed for vision. Even if eyes are healthy damage to this lobe can cause blindness.
• A neuron is a nerve cell, the basic unit of the nervous system. Of the roughly 100 billion neurons in the human nervous system about 80% are located in the brain. Neurons allow the nervous system to fulfil its communication function by transmitting signals electrically and chemically. Neurons vary in size from less than a millimetre up to a metre long, but all share the same basic structure
• The cell body (soma) - includes a nucleus containing the genetic material of the cell. Branch like structures called dendrites stick out from the cell body – these carry impulses from neighbouring neurons towards the cell body.
• The axon is the tube-like structure that carries the impulses away from the cell body down the length of the neuron. The axon is covered by a fatty layer called the myelin sheath. 
• The myelin sheath both protects the axon and speeds up electrical transmission of the impulse. Gaps in the myelin sheath, called nodes of Ranvier, allow this increase in speed by forcing the impulses to jump across the gaps.
• At the end of the axon are the terminal buttons. These are not physically connected to the next neuron in the chain but are involved in communication across a gap known as a synapse.
• There are three main types of neuron: sensory neuron, motor neuron, and relay
• Sensory neurons – carry messages from sensory receptors along nerves in the peripheral nervous system (PNS) to the central nervous system (CNS). They have long dendrites and short axons.
• Motor neurons – carry messages from the CNS, along nerves in the PNS, to effectors in the body (e.g. muscles and glands). They have short dendrites and long axons. 
• Relay neurons – connects sensory and motor neurons together and also connects to other relay neurons. They have short dendrites and short axons and are only found in CNS.
• Neurons communicate with each other within groups known as neural networks. They do not physically touch but are separated by a gap called the synaptic cleft. So, although signals within neurons are transmitted electrically, signals between neurons have to be transmitted chemically across the synapse. 
• synaptic transmission is a chemical process using biochemical substances called neurotransmitters
• When the action potential reaches the end of the pre-synaptic neuron (the presynaptic terminal button) it triggers the release of neurotransmitters from tiny sacs called synaptic vesicles. Neurotransmitters diffuse across the synapse to the post synaptic neuron in the chain. When the neurotransmitter molecules cross the gap, they fit into matching receptor sites on the postsynaptic neuron. There are different receptors for different neurotransmitters. The chemical signal carried by the neurotransmitters is converted back into an electrical signal in the postsynaptic neuron.