CNS essay

• A01: 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. 
• A01: 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). 

   
• Subcortical structures below the cortex include:

  • Thalamus: the brain's relay station receiving info from all senses except smell, passing it to the cerebral cortex, and filtering info
  • Hypothalamus: controls motivational behaviors like hunger, plays a key role in the body's fight or flight stress response, maintains balance in bodily functions (e.g., temperature in homeostasis), and regulates the endocrine system
  • Limbic system: composed of structures like the amygdala, regulates emotional responses (e.g., aggression), and plays a role in memory and learning
  • Cerebellum: coordinates posture, balance, and movement by receiving and integrating info from the spinal cord
  • Corpus callosum: a dense collection of nerve cells connecting the two brain hemispheres below the cerebral cortex
• A03 main point: Raine et al investigated the glucose metabolism in different areas of the brain in 41 murderers using PET scans. The results showed that the murderers had reduced glucose metabolism in their prefrontal cortex
• a03: suggesting that the area is less active than in controls.  

  Therefore this research is a strength as it supports the explanation of the CNS controlling human behaviour as a correlation was found between having a less active prefrontal cortex and engaging in violent actions causing people to become murderers. Therefore there is strong evidence that the CNS is involved in our conscious awareness, able to inhibit aggression but this fails, it could explain murderers etc.
• A03 counter argument: However, the internal validity is limited through the PET scanning technique as it may have given misleading results. This is because the technique sometimes provides results that are not easy to interpret and the precise location of active areas in relation to brain structure is often difficult to pinpoint.
• A03 counter argument: For example, PET scans on people doing the same task have shown different brain activity in different people. This is a weakness as it may be as a result of individual differences providing misleading results as not everyone’s brain is identical. This makes it difficult to draw conclusions about which brain areas are linked to which behaviors
• The cerebral cortex of both hemispheres is subdivided into four lobes:
• Frontal lobe:

  • Located at the front of the brain
  • Controls high-level cognitive functions such as thinking, planning, problem solving, decision making
  • Contains the motor cortex
• Parietal lobe:

  • Found on the other side of the central sulcus, further back in the brain
  • Processes sensory information from the skin e.g. touch, temperature, pressure
  • Necessary for perceiving touch, pain, body position
  • Helps 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
  • Affects brain functions such as memory and emotion
• Occipital lobe:

  • Located at the back of the brain
  • Processes visual information, needed for vision
  • Damage to this lobe can cause blindness even if eyes are healthy
• A03: Raine et al investigated the glucose metabolism in different areas of the brain in 41 murderers using PET scans. The results showed that the murderers had reduced glucose metabolism in the parietal and occipital lobes, suggesting that the area is less active than in controls.
• A03: Raine et al found that there were specific regions in the brain with less activity than others. This is useful as it suggests that the CNS does plays a role in human behavior because it shows that different parts of the brain control individual behaviors. This is because the brain is divided into many sections with specific functions including the frontal lobe which controls high-level cognitive functioning and the occipital love which processes visual information.
• Counter argument: However Raine et al’s research on aggression showed a correlation between the brains of people who had been found guilty of murder and reduced glucose metabolism in the prefrontal, parietal and occipital lobes. However, due to ethical guidelines Raine et al weren’t able to alter the reduced glucose metabolism of the brains of people then see whether they commit violent crimes. Therefore, this reduces the usefulness because the research only shows correlation but a causal relationship cannot be established.
• There are many regions in the brain for example, in the frontal lobe the prefrontal cortex controls of impulses and design making takes place below the cortex and subcortical structures, such as the thalamus which recovers info from the senses, the lambic system which is made up of several structures
• several structures e.g the amygdala and regulates emotional responses e.g aggression, the cerebellum (primary role is to coordinate posture, balance and movement by receiving and integrating information from the spinal cord) and the corpus colosseum, a dense collection of nerve cells connecting the two hemispheres of the brain below the cerebral cortex.
• Raine supports the ideas that separate areas of the brain have different functions as results from Raines PET scanning on the brains of 41 non murderers and 41 murderers he found that the amygdala can be linked to aggression, this is because the results of the scan showed that there was less glucose metabolisms in the murders amygdala compared with non murderers, showing they are more aggressive. Therefore the results of Raines research increases the validity of the functions of the components of the brain.
• use of PET scans lowers the validity of research suggestint that results of Raines study may be misleading. This refutes Raines research because the PET, scanned the brain in 10mm intervals relative to the canthomeatal line. the canthomeatal line can vary between individuals making it harder to precisely locate different brain areas which have different functions. this reduces internal validity as results may not be accurate due to varied location of canthomeatal line and PET scanning. this is a weakness as information of the function of the amygdala linking to aggression may be inaccurate 
• The cerebral cortex of both hemispheres is subdivided into four lobes which control different aspects of human behaviour

  • in addition to the frontal love which controls high level cognitive functions such as thing=king, planning, problem solving and decision making
  • The parietal lobe - found further back in the brain, processes sensory information from the skin e.g touch, temperature, pressure
  • The temporal lobes - on the side of the brain, processes auditory informaton, and the occipital lobe - located at the back of the brain, processes visual information, is needed for vision 
• Raine et al 1997 also found that the murders had reduced glucose metabolism in the parietal and occipital lobes than the control group suggesting that the area is less active in murders than non murders

  This supports the explaination of the different lobes of the brain controlling different ascpects of behaviour, as they have activity in these lobes for example the under activity of the parietal lobe could lead to poor or faulty processing of sensory information from the body which could lead to misinterpretation by the brain and inappropriate behaviour in response
• However, often research on aggression is correlational research due to ethical guidelines which means a cause and effect relationship cannot be established. This is because it would not be ethical to create damage to brain regions to test whether this caused differences in behaviour, so only correlational research is conducted. This means that if the research is just a correlation we cannot infer that low brain activity in the parental lobes has caused aggression seen in Raines participants and can only conclude that there is an association between this low brain activity and aggression.
• Therefore, due to the nature of the supporting research, we cannot infer that under activity of the parietal and occipital lobes causes violence, as other factors may be involved and the role of the CNS in affecting behaviour responses to stimuli may not be accurate. This limits the predictive validity of the brain lobes explaining human behaviour such as aggression  
• The nervous system is a specialized and complex network of cells in the human body.
• • the cerebral cortex of both hemispheres is decided into four lobes which controls differnt aspects of human behaviour
• • In addition to the frontal lobe which controls high level cognitive functions such as thinking, planning, problem solving and decision making the parietal lobe foun d further back in the brain, processes sensory information from the skin e.g touch, temperature, pressure 
• • The temporal lobes on the sides of the brain, processes auditory information, and occipital lobes located at back of brain, processes visual information is needed for vision