Biopsychology

• The sensory neuron carries messages from the peripheral nervous system to the CNS
• The relay neuron transfers messages from sensory neurons to other relay neurons or motor neurons. They are the only type of neuron found in the centre nervous system and are thought to aid processes and decision making.
• The motor neuron carries messages from the central nervous system to the peripheral nervous system in order to instruct effectors such as muscles and glands to carry out the decisions of the CNS.
• The process of synaptic transmission:

  • Action potentials carry a neurotransmitter e.g. serotonin, through the transmitter neuron to the presynaptic terminal
  • This electrical impulse then triggers the release of the neurotransmitter into the synaptic cleft (1/3)
• The process of synaptic tranmission:

  • The neurotransmitter then crosses the synapse and binds to receptor sites on the postsynaptic membrane.
  • The stimulation of the postsynanptic receptor results in either excitation or inhibition of the postsynaptic membrane. If the neurotransmitter is excitatory then the postsynaptic is more likely to fire an impulse. (2/3)
• The process of synaptic transmission:

  • Any leftover neurotransmitter in the synapse will be re-uptaken into the transmitter neuron by the reuptake transporter so that they can be reused, or else they are broken down into an enzyme.
  • If the neurotransmitter is inhibitory then the postsynaptic neuron is less likely to fire an impulse
• If a neurotransmitter is inhibitory then the post synaptic neuron is less likely to fire an impulse. If it is excitatory then it is less likely. The influences are summed together (summation) and the total effect will influence the outcome.
• Broca's area (bottom of left frontal lobe) is responsible for speech. This was discovered after Broca did a post-mortem on a patient who could understand language but was only able to say one word due to a lesion on the brain in this area. Slow and inarticulate speech caused by damage to this area is known as Broca's aphasia.
• Wernicke's area (bottom of left parietal lobe and top of left temporal lobe) is involved in understanding language. Patients with lesions in this area are able to fluent but meaningless sentences (Wernicke's aphasia) and have trouble understanding language.
• 1 - Frontal lobe

  2 - Temporal lobe

  3 - Parietal lobe

  4 - Occipital lobe

  
• The brain is divided into left and right hemispheres which control the opposite sides of the body. The left hemisphere is responsible for language and logical/analytical thought. The right hemisphere is responsible for face recognition, spatial tasks, empathy and emotion.
• Sperry saw 11 epileptic patients being treated at a hospital with split brains. He conducted an experiment where the patients had to name a word that appeared on one side of a cross that they were focusing on. If the word appeared on the left visual field then the patient could not name it, but if it appearedd on the right visual field they could. This is because the left hemisphere is responsible for language.
• Sperry did another split brain experiment based on touch. Participants were asked to feel a wooden number that they could not see. If they used their left hand they were unable to name the number as the right hemisphere is incapable of speech. However they were able to accurately gesture the correct number using their hands.
• Brain plasticity refers to the brain's ability to change and adapt in reaction to the environment and through experience.
• Maguire et al studied the brains of London taxi drivers and found a greater volume of grey matter in the back of the hippocampus than with a matched control group.
• neural reorganisation can happen when the brain is damaged due to a stroke or accident and other undamaged parts of the brain adapt and compensate for these areas.
• neural regeneration or axonal sprouting can happen after brain damage occurs. This is where healthy axons sprout new nerve endings that connect to other pathways in the nervous system. This can restore damaged neural pathways to full functionality.
• neuronal unmasking is when previously dormant synapses open connections to compensate for a nearby damaged area of the brain.
• Jodi Miller suffered from frequent and severe epileptic seizures at a young age that originated from the right side of her brain which also led to paralysis on the left side of her body. She underwent a surgery to remove the right hemisphere of her brain. This cured her seizures and the left part of her brain was able to regain a majority of the right half's functions through neural plasticity. This was in part due to her being a young child at the time which means her brain was more plastic.
• The ovaries release oestrogen which is responsible for puberty in women and parts of the menstrual cycle.
• The pancreas secretes hormones such as insulin that help to regulate blood sugar.
• The adrenal gland secretes adrenaline which is responsible for regulating visceral functions which can be a part of the fight or flight response.
• An Ultradian rhythm occurs more than once a day. An example is sleep cycles which occur about 5 times a night and usually last for about 90 minutes. The stages of sleep cycles are awake, REM, non-REM 1, non-REM 2, and non-REM 3. Between 1 and 3 you begin to sleep more deeply and brainwave patterns become deeper and slower. As you process through the night stage 3 tends to get shorter and REM longer meaning longer and more detailed dreams.
• Circadian rhythms occur once every 24 hours. An example is the sleep-wake cycle. This lasts 25 hours if purely impacted by our biology but because of light and dark it is 24 hours.
• Falling asleep is influenced by the indogenous pacemaker the SCN (suprachiasmatic neucleus). This is a cluster of neurons in the hypothalamus that is connected to the optic nerve. When light levels fall the SCN sends signal to the pineal gland which excretes the sleep hormone melatonin. This inhibits brain mechanisms that promote wakefulness.
• When the SCN detects rising light levels it tells the pineal gland to stop producing melatonin which causes our brain to become disinhibited. The adrenal glands also secrete cortisol based on our internal body clock.
• Light acts as an exogenous zeitgeber which influences the production of melatonin from the pineal gland. This is due to evolutionary factors as we would have been more likely to find food during the daytime and less likely to detect predators during the night. There can also be other external factors that affect the sleep/wake cycle such as noise and comfort levels.
• An infradian rhythm lasts for longer than a day. An example is the menstrual cycle in women which lasts around 28 days. This can be altered exogenously through birth control or exposure to other women's pheromones.
• Stages of the Menstrual cycle (1/2):

  • 1: menstruation because the egg is not fertilised
  • 2: the pituitary gland releases FSH which prepares a follicle in the ovary to mature
  • 3: when the follicle is ready, the ovaries release oestrogen which causes the uterus walls to thicken.
• Stages of the Menstrual cycle (2/2):

  • 4: the pituitary gland secretes LH which causes the egg to be released and travel to the uterus
  • 5: ovaries produce progesterone which maintains the thickness of the uterus lining
  • 6: If the egg is unfertilised progesterone and oestrogen levels drop and the egg is flushed out via menstruation.
• Changes to sleep schedule mean the endogenous pacemakers try to impose an inbuilt rhythm of sleep but are now out of synch with the zeitgeiber of light. Also the disruption of biological rhythms can lead to anxiety, impaired focus and irritability.
• Rogers did research into split brain lateralisation in chickens. He found that it was associated with an increased ability to perform two tasks simultaneously (finding food and being vigilant for predators). This supports the idea that lateralisation increases neural processing capacity.
• Biernaskie et al did research into functional recovery where he damaged the motor cortex of rats. During the rehabilitation process the left hemisphere picked up the job of moving the left limb which the right hemisphere motor cortex was no longer able to do.
• Morgan did research into circadian rhythms. He removed the SCN of hamsters and then gave them a transplanted SCN from a mutant strain of hamster with a sleep cycle of 20 hours. Their circadian rhythms disappeared completely with the removal of the SCN, and they adopted the same sleep patterns as the donor animals. This suggests that the sleep wake cycle is entirely based on internal zeitgebers.
• When stress/a threat is percieved (fight/flight):

  1. hypothalamus is alerted and activates the SAM pathway
  2. this causes the sympathetic nervous system to become activated
  3. this leads to the stimulation of a part of the adrenal gland called the adrenal medulla
  4. when the adrenal medulla is stimulated, it releases adrenaline
  5. adrenaline prepares the body for fight or flight by causing many physiological changes6. when the stressful thing has gone, the parasympathetic branch of the autonomous nervous system is automatically activated to return the body to its normal state.
• physiological responses to fight/flight:

  • pupils dialate to let in more light
  • heart rate and blood pressure increase to pump more blood carrying oxygen around the body
  • digestion slows down so blood supply can be used for muscles/energy instead
• Taylor et al. (2002) suggest that females adopt a 'tend and befriend' response in stressful/dangerous situations. Women are more likely to protect their offspring (tending) and form alliances with other women (befriend), rather than fight an adversary or flee.
• Electro-encephalogram (EEG) AO1:

  • General Function only – not in relation to a task.
  • Electrodes are put on the scalp and detect electrical neuronal activity directly below where they are placed.
  • The scan recording represents the brainwave patterns that are generated from the area under each electrode.
  • Diagnostic tool as unusual patterns of activity may indicate neurological abnormalities such as epilepsy, tumours or disorders of sleep.
• Electro-encephalogram (EEG) AO3:

  • EEGs are cheaper compared to fMRI and so can be more widely used in research resulting in greater population validity.
  • Unlike fMRI, EEG technology has extremely high temporal resolution. Today’s EEG technology can accurately detect brain activity of a single millisecond.
  • EEGs have poor spatial resolution due to the generalised nature of the information received: The whole area under the electrode. The EEG signal is not useful for pinpointing the exact source of neural activity, as activities originating in different but adjacent locations can become muddled.
• Event Related Potentials (ERPs) AO1:

  • Function in relation to a task (not structure).
  • Similar to EEG’s but rather than general brain waves, they are designed to measure activity in response to a specific stimuli.
  • Using an averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to the presentation of a specific stimulus or performance of a specific task.
  • What remains are event-related potentials: types of brainwave that are triggered by particular events.