Biopsychology

• Neurotransmitters


  Chemical messengers within the brain that transmit information from one neuron to another
• Synaptic transmission


  1. Action potentials sent down the axon of the presynaptic neuron

  2. Neurotransmitters stored in vesicles released into the synaptic cleft

  3. Neurotransmitters diffuse across the synapse and bind to receptor sites on the postsynaptic neuron

  4. Neurotransmitters have excitatory or inhibitory effect, or are recycled through reuptake
• Synaptic transmission


  • Allows communication between neurons
  • Enables actions and emotional responses
• Neurotransmitters are ONLY located in the presynaptic neuron</b>
• Receptor sites for neurotransmitters are ONLY present on the postsynaptic neuron
• Neurotransmitters diffuse across the synapse from high to low concentration
• Neurotransmitters bind to their specific receptor sites on the postsynaptic neuron
• Enough neurotransmitters binding to receptor sites on the postsynaptic neuron can lead to the next neuron firing an impulse or the neurotransmitters being recycled through reuptake
• Synaptic transmission


  1. Neurotransmitters

  2. Excitation

  3. Inhibition

  4. Summation
• Neurotransmitters

  Chemical messengers in the brain that can have an excitatory or inhibitory effect on the next neuron
• Excitatory neurotransmitter


  A chemical messenger that makes it more likely that the next neuron will fire so an impulse will travel down its axon, increasing brain activity
• Excitatory neurotransmitter


  • Noradrenaline
• Inhibitory neurotransmitter


  A chemical messenger that prevents or reduces the likelihood that the next neuron will fire, decreasing brain activity
• Inhibitory neurotransmitter

  • Serotonin
• Summation


  When the excitatory and inhibitory influences on a neuron are added together, if the overall effect is mainly inhibitory it reduces the likelihood the neuron will fire an impulse, if it is mainly excitatory the impulse will fire
• Drugs can be used to increase or decrease levels of neurotransmitters and work by affecting the transmission of neurotransmitters
• The inhibitory signal from one neuron is stronger than the excitatory signal from another, the neuron will not fire an impulse
• Noradrenaline


  Low levels cause low mood, high levels cause depression, plays a role in attention and arousal
• Serotonin


  Involved in regulating mood, appetite, sleep, and other bodily functions
• Functions of the endocrine system

  • Provides a chemical system of communication within the blood stream to regulate the activity of cells and organs in the body
  • Slower than the nervous system but its effects are more widespread and powerful
• Glands

  Organs that secrete/release hormones that control/regulate functions in the body
• Major glands in the endocrine system


  • Adrenal gland
  • Pineal gland
  • Ovaries
  • Testes
• Adrenal gland

  Produces adrenaline which causes physiological changes involved in the fight or flight response e.g. increased heart and breathing rate
• Pineal gland


  Secretes the hormone melatonin, which is involved in regulating the sleep-wake cycle by making the person feel tired and ready to sleep
• Ovaries

  Produce oestrogen which controls development of female physical features e.g. breast development, also control menstruation
• Testes

  Produce testosterone which controls development of male physical features e.g. facial hair, deepening of voice
• Exam top tip: Know the role of the endocrine system and at least two glands, which hormone they release and what that hormone does within the body
• Localisation of function


  Specific areas of the brain are specialised for certain functions (jobs)
• Hemispheric lateralisation


  The two different hemispheres of the brain are responsible for different mental processes
• Holistic theory


  Original view that all parts of the brain are involved in the processing of thought and action, contrasts with localisation and lateralisation
• Broca's area


  Left hemisphere area involved in production of spoken and written language, damage can cause Broca's aphasia
• Motor cortex


  Involved in the creation of voluntary motor movements, each hemisphere controls the opposite side of the body
• Somatosensory cortex


  Processes information from the senses including touch, pain and temperature
• Split brain


  Patients have had surgery (normally to treat epilepsy) to cut the area that connects the two hemispheres of the brain (corpus callosum)
• Split brain patients


  • The two hemispheres become functionally separate (they act as two separate, independent brains)
• Sperry's split brain research

  1. Participants sit in front of a screen, fixating their gaze

  2. Participants were presented with visual information to either their right visual field or left eye visual field for 1/10 of a second

  3. Objects seen in right visual field would be processed by the language centres in the left side of the brain

  4. Objects seen in the left visual field, the patient could not describe and typically reported there was nothing there
• Recognition by touch

  Participants could not attach verbal labels to objects projected in the left visual field, but they were able to select a matching object from a grab bag of different objects using their left hand linked to the right hemisphere
• This piece of research can also be used as a STRENGTH of hemispheric lateralisation because it is research to support
• Strengths of hemispheric lateralisation research

  • It has scientific evidence from controlled laboratory settings which use objective and empirical techniques
  • Sperry's procedure was standardised and well controlled
• Auditory cortex

  Associated with analysing speech-based information, damage can cause hearing loss