Biopsychology

• What are the two main divisions of the nervous system?

  Peripheral nervous system and central nervous system.
• The peripheral nervous system transmits information to and from the central nervous system.
• The central nervous system is concerned with all life functions and psychological processes.
• What are the two divisions of the peripheral nervous system?

  Somatic nervous system and automatic nervous system.
• The somatic nervous system transmits information to and from the senses and to and from the central nervous system. It is made up of sensory receptors. Motor pathways allow the brain to control movement. Essentially, the somatic nervous system carries sensory information from the outside world into the brain and provide muscle responses via motor pathways.
• The automatic nervous system transmits information to and from internal organs to sustain life processes. Plays an important role in homeostasis. The automatic nervous system only has motor pathways, no sensory pathways.
• What are the two divisions of the automatic nervous system?

  Sympathetic nervous system and parasympathetic nervous system.
• The sympathetic nervous system generally increases bodily activities. It initiates fight or flight response. Impulses travel from the sympathetic nervous system to organs in the body to prepare us for action. Heart rate, breathing rate and blood pressure increase in dangerous situations. Less important functions like salivation or desire to urinate are supressed.
• The parasympathetic nervous system generally maintains or decreases bodily activities. Returns us to a normal resting state. Involved in 'rest and digest'. Slows down heart rate and breathing rate and reduces blood pressure.
• What are the two divisions of the central nervous system?

  The spinal chord and the brain.
• The spinal chord receives and transmits information to and from the brain. It carries messages and reflex actions (nerve fibres that connect parts of the body with the brain).
• The brain maintains life. It is involved in higher functions and psychological processes.
• What are the three types of neuron?

  Sensory, motor and relay.
• What are neurons?

  Nerve cells. There are approximately 100 billion neurons in the brain. They transmit information as electrical impulses around the body to and from the central nervous system.
• Sensory neurons transmit electrical impulses from receptors to the central nervous system (taste, smell, etc). They travel to the spial chord or brain. Sensory neurons have a separate cell body.
• Relay neurons transmit electrical impulses between sensory neurons and motor neurons. These are only found in the brain. Relay neurons have no myelin sheath.
• Motor neurons transmit electrical impulses from the central nervous system to effectors (synapses with muscles) which leads to movement. When motor neurons are stimulated, they release neurotransmitters that bind to recpetors on muscles to trigger a response (movement).
• The endocrine system communicates chemical messages to the organs of the body. A network of glands manufacture and secrete chemical messengers in the form of hormones. This is done by using blood vessels to transfer messages to target sites to help regulate the activity of cells and organs. The system is controlled by the hypothalamus which acts as a thermostat for hormones.
• The pituitary gland works on feedback from the body. It produces the growth hormone, which regulates growth, metabolism and body composition, and it produces ACTH, which stimulates the adrenal cortex (which produces cortisol).
• The adrenal glands are above the kidneys and have two parts; the adrenal cortex and the adrenal medulla. The adrenal cortex produces cortisol which maintains functions (regulates stress response, blood pressure, blood sugar, etc). The adrenal medulla produces adrenaline which increases heart rate and blood flow.
• The testes are the male reproductive organ and they produce testosterone, which is linked with puberty and sex drive in men.
• The ovaries are the female reproductive organ and they produce progesterone, which gives women a heightened sense of social awareness and threat, especially during pregnancy.
• Explain synaptic transmission.

  When a nerve impulse arrives at the ending of a neuron, it triggers the release of neurotransmitters from vesicles in the pre-synaptic neuron. The neurotransmitters diffuse across the synaptic cleft and bind with receptors in the post-synaptic neuron. This triggers an electrical impulse (muscle contraction, hormone secretion). Excess neurotransmitters are removed from the synaptic cleft via reuptake, diffusion or being broken down by enzymes.
• Explain summation.

  Excitatory neurotransmitters cause an electrical change in the cell which results in excitatory post-synaptic potential (EPSP). Inhibitory neurotransmitters cause an electrical change in the cell which results in inhibitory post-synaptic potential (IPSP). In the post-synaptic neuron, summation occurs: if the overall result is excitatory, the cell will fire. If it is inhibitory, it will not.
• Examples of excitatory neurotransmitters.

  Noradrenaline: constricts blood vessels, increases blood pressure and blood glucose levels. Too much = schizophrenia. Too little = depression.

  Dopamine: affects movements, emotions and sensation of pleasure and pain. Too much = schizophrenia. Too little = depression and Parkinson's.
• Examples of inhibitory neurotransmitters.

  Serotonin: affects mood and social behaviours, appetite and digestion, sleep, memory and sexual desires. Too little = depression.

  GABA (gamma-aminobutyric acid): inhibits or reduces the activity of the neurons or cells. Too little = anxiety disorder.
• Explain the fight or flight response.

  The adrenal medulla secretes adrenaline which gets the body ready for fight or flight. Physiological responses occur such as increased heart rate. Adrenaline leads to arousal of the sympathetic nervous system and reduced activity of the parasympathetic nervous system. Adrenaline creates changes such as decreased digestion and increased sweating. Once the threat is over, the parasympathetic nervous system takes control and brings body back to balance.
• Brain lateralisation is the idea that two halves of the brain perform different functions. For example, the left hemisphere is responsible for language, the right is responsible for visual-motor tasks. The left hemisphere controls the right side, the right hemisphere controls the left side.
• The motor area in the frontal lobe controls voluntary movements. Regions are located logically (region controlling finger movements is next to the region controlling hand movements). Hitzig & Fritsch electrically stimulated the motor areas of dogs and found muscular contractions in different areas depending on where the probe was inserted. The left motor area controls the muscles on the right hand side of the body, and vice versa.
• The somatosensory area in the parietal lobe recieves incoming sensory information to produce sensations for pressure, pain, temperature, etc. Robertson found this area of the brain is highly adaptable as Braille readers have a larger somatosensory area for fingertips compared to normal-sighted people. The left somatosensory area receives sensory information from the right side of the body and vice versa.
• The auditory area in the temporal lobe analyses and processes accoustic information. The primary auditory area is involved in processing features of sound such as volume, speed and pitch. Information from the left ear goes primarily to the right hemisphere and vice versa.
• The visual area in the occipital lobe receives and processes visual information such as colour, shape and movement. Information from the right hand side of the body is processed in the left hemisphere and vice versa.
• The two language centres in the brain are Wernicke's area and Broca's area.
• Broca's area is located in the left frontal lobe and is responsible for speech production. Broca studied Patient Tan who could only say the word 'tan'. A post-mortem examination showed a lesion on the left-frontal lobe (Broca's area). Damage to this area causes Broca's aphasia (slow and inarticulate speech).
• Wernicke's area is located in the left temporal lobe and is the language comprehension centre. Wernicke found that patients who were unable to understand language had a lesion to the left temporal lobe. This area is vital for locating words from memory to express meaning. Damage to this area causes receptive or sensory aphasia (difficulty understanding written or spoken language. Can't produce meaningful sentences).
• Global aphaisis is where both Broca's and Wernicke's areas are damaged resulting in complete loss of language abilities.
• Strenghts of hemispheric lateralisation & localisation (Patient Tan).

  Patient Tan had left temporal lobe damage causing Broca's aphasia. Close to motor region that controls muscles needed for speech. Scanning techniques have shown damage to Broca's area in patients with motor aphasia. HOWEVER, Dronkers did an MRI on Tan's brain and found other areas may have contributed to speech loss.
• Research against hemispheric lateralisation & localisation (Dejerine).

  Dejerine reported a man with damage to visual cortex and Wernicke's area and as a result was unable to read, and suggested damage to connections between areas causes impairments that represent damage to the localised brain region associated with that function. This reduces credibility of the theory.
• Research against hemispheric lateralisation & localisation (Lashley).

  Lashley removed areas of the cortex in rats when they were learning a maze and found that no one area appeared more important in terms of the rat's ability to learn the maze. Suggests learning requires every area of the brain. The idea of strict localisation is biologically reductionist. Additionally, after brain injury, undamaged areas of brain can take over the functions of damaged areas.
• Research against hemispheric lateralisation & localisation (individual differences & beta bias).

  Herasty found women have a larger Broca and Wernicke's area than men, so the suggestion that everyone is the same in terms of areas of the brain is beta bias because variations weren't considered in original research. Further research is needed to properly apply the findings to a population.