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.
• A sensory neuro

  
• A relay neuron

  
• A motor neuron

  
• 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.
• The CNS (branch of the nervous system) contains the brain - receives and processes sensory info, initiates responses, stores memories, generates thoughts and emotions - and the spinal cord - conducts signals to and from the brain, controls reflex activities.
• The PNS (peripheral nervous system and branch of the nervous system) contains the Somatic nervous system - controls voluntary movements - and the autonomic nervous system - controls involuntary responses.
• The ANs contains the sympathetic division - Fight or flight - and the parasympathetic division - rest or digest.
• fMRIs measure brain activity whilst a person is performing a task vs a baseline task. They can see brain structure and live function. A large scanner uses a magnetic field to highlight blood oxygenation level as the magnet causes haemoglobin to release energy slightly differently. The scanner creates a 3D image.
• EEGs are placed on the scalp and detect electrical neuronal activity directly below where they are placed. There is no structural info, only brainwaves. They are used as a diagnostic tool, e.g. for epilepsy tumors or sleep disorders.
• ERPs function in relation to a task. They are similar to EEGs but measure activity in response to a stimuli. An averaging technique is used to filter out all extraneous brain activity except from in relation to the stimuli.
• Post-mortems show structure and not function. They can correlate abnormalities/damage with previous behaviour. Recent technology can show individual neurons.
• The motor cortex is the further forward of the two small brain areas located at the top of the brain. This controls voluntary movement. The amount of neurons for each part of the body depend on its level of movement. Damage to the motor cortex would result in paralysis.
• The somatosensory cortex is the further back of the two small areas located at the top of the brain. This area is where sensory information is represented. The amount of neurons for different parts of the body correlates with its sensitivity. This part of the brain is highly plastic. Damage to it could result in difficulty sensing temperature and feeling things.
• At the back of the brain there is the occipital area which contains the visual area. This recieves and processes visual information (info from the rhs visual field is processed in the left hemisphere and vice versa). There are different parts of the area to process different things like colour and shape.
• The auditory area is located in the temporal lobe and is responsible for processing aucoustic information. Information from the left ear primarily goes to the right hemisphere and vice versa. The area contains different parts, with the primary auditory area being responsible for volume, tempo and pitch.
• 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.
• Stages of Fight or Flight (1/2):

  • 1: a threat appears
  • 2: the brain processes the sensory input and the hypothalamus prepares the body for action
  • 3: the hypothalamus sends the neurotransmitter noradrenaline down the sympathetic branch of the ANS until it reaches the adrenal gland
• Stages of Fight or Flight (2/2):

  • 4: The adrenal medulla releases adrenaline into the bloodstream where it travels to relevant organs.
  • 5: Action occurs, either running or fighting.
  • 6: The threat has passed so the parasympathetic branch of the ANS turns on to return our body to normal.
• 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.