Psych - the brain

• Heart hypothesis

  • ancient Egyptians believed the heart held the mind and soul
  • source of memory, emotion and personality
  • all mental abilities came from the heart
• brain hypothesis:

  • done through animal experimentation
  • nerves from sense organs went to the brain
  • brain injury affected behaviour
  • pressure parts to parts of the brain affected behaviour but pressure parts of the heart did not
• the mind body problem

  • most Greek philosophers believed that the mind and body were separated (mind could control the body but the body could not control the mind)
• pineal gland:

  enabled the brain and the mind to interact and produce sensations, thoughts, emotions, self-awareness and other experiences
• phrenology:

  Gall proposed that personality characteristics and mental abilities were located on its outer surface

  • the more bumps on each part indicated how strong those characteristics were
• localisation

  brain structures that are highly specialised to allows us to perform certain functions
• holistic view:

  different areas of the brain working together to perform complex functions
• brain ablation experiments:

  involves the removal of selected brain tissue followed by the observation of behavioural changes
• criticisms of brain ablation experiments:

  • he did not document his research in detail so it was difficult to replicate and support his hypothesis
  • his surgery techniques were not precise
• Electrical Stimulation of the brain

  • an electrical wire stimulates specific areas of the brain - which initiates or inhibits a certain behaviour - providing evidence that an area of the brain controls specific function
• contra lateral control:

  the left half of the brain controls the right side of the body and vice versa
• split brain experiment:

  • severing the two hemispheres by cutting the corpus colosseum
  • no loss of brain function was evident
• hemispheric specialisation:

  • the understanding that both the right and left cerebral hemisphere specialise in function
• functional:

  captures what the brain is doing whilst working on a task - dynamic
• structural:

  captures the anatomy or structure of a particular area of the brain - static
• CAT - structural

  • uses a contrast substance injected into the blood stream that highlights the brains blood vessels and allows images of the brain to be interpreted
  • used to locate brain abnormalities and brain injury
• CAT limitations

  • only shows structure
  • uses x-ray technology/radiation which ins’t good for repeated exposure
  • MRIs are now superior
• MRI - structural

  • magnetic field to vibrate atoms in the brains neurons to produce coloured, clear images
  • used to located brain abnormalities and brain injury
  • can display extremely small changes
• MRI limitations

  • can not be used with patients with ”metal parts”
  • difficult to use with children because you have to lie still
  • expensive
• PET - functional

  • produces colour images of brain function during brain activity as well as structure
  • provides images of brain function
  • patient is inject with radioactive tracer into the blood stream
  • uses a colour code to show areas of high to low brain activity
• PET limitations:

  • minor radiation exposure due to the tracing element
  • pet images less detailed than MRI images
  • specific task is limited by the size of the chamber
• fMRI - functional

  • detects and record brain activity by measuring oxygen consumption across the brain whilst undergoing a mental or physical task
  • does not use radioactive tracers
  • images show both structure and function as oxygenated areas of the brain become active
  • colour variations reflect level of activity
• fMRI limitations

  • oxygenated blood flow levels are dependent on cardiovascular responses
  • expensive
  • very few machines
• Central nervous system

  • consists of all nerves in the brain and spinal cord
• brain:

  • receives and interprets information from the sensory systems
  • sends motor messages out to all parts of the body so that an appropriate response can be made
• spinal cord:

  • connects the brain to other parts of the body
  • receives information from the PNS and transmits it to the brain
  • transmits motor messages from the brain to the PNS
• Peripheral nervous system:

  • compromised of all parts of the nervous system other than the brain and the spinal cord
  • carries information from the sensory organs and internal organs to the CNS
• somatic nervous system:

  • controls all voluntary movement of skeletal muscles
  • carry sensory information from the outside via the spinal cord to the cerebral cortex
  • carry motor information from the cerebral cortex via the spinal cord to the muscles, organs and glands
• autonomic nervous system:

  • network of nerves that carriers neural messages between the CNS and involuntary muscles, internal organs and glands
  • regulates the functioning of internal organs (homeostasis)
  • prepares our body to deal with situations (fight flight)
• sympathetic nervous system:

  • prepares the muscle/organs in the body and makes resources available during activity
  • responsible for fight flight response - allows us to physically respond to the threat as effectively as possible
• parasympathetic nervous system:

  • responsible for reversing the effect of the sympathetic NS
  • returns the body’s internal systems to their natural level of functioning
• enteric nervous system:

  • responsible for the digestive system processes in maintains it’s health, disposing of waste, nutrient management, regulating response to food and drink
  • functions autonomously
• sensory neurons - afferent

  • specialised cells that receive information from both the external environment and from within the body
  • detect and respond to specific information
  • transmit information to the CNS
• motor neurons - efferent

  • transmit messages from the CNS to the muscles, glands and organs
  • enables bodily actions
  • contains myelin sheath: helps to speed up transmission of motor neural impulses
• interneurons:

  • only within the CNS
  • carry and integrate messages between sensory and motor neurons
  • provide neural links between sensory and motor neurons
• Triune Brain Hypothesis:

  emphasises three key brain regions consisting of the brain stem, the limbic system, and the cortex that function relatively independently in coping with stress via fight or flight, emotion and cognition respectively
• triune brain hypothesis criticisms:

  • oversimplifies the evolutionary process as structures aren’t just added
• Cerebellum:

  • located at the base of the brain
  • coordinates fine muscle movements
  • regulates posture and balance
  • involved in learning and memory associated with movement
• if cerebellum is damaged:

  • difficult to co-ordinate control of movement
• Medulla

  • Continuation of the spinal cord
  • Controls automatic, vital bodily functions
  • Some parts involved in sensations (touch)