Biopsychology Flashcards
(13 cards)
The central and peripheral nervous system
Nervous system - a network of nerves cells that transmit messages between different body parts, allowing communication to take place. It is divided into 2 main components: 1) the central nervous system; 2) the peripheral nervous system (PNS).
Central nervous system - the CNS comprises the brain and the spinal cord. The brain provides conscious awareness and is involved in all psychological processes. It consists of many regions which are responsible for different functions.
Peripheral nervous system - the role of the PNS is to relay messages (nerve impulses) from the CNS (brain and spinal cord) to the rest of the body. The PNS consists of 2 main components: 1) the somatic nervous system; 2) the autonomic nervous system.
Neurons and neurotransmission: Sensory, relay and motor neurons
There are 3 main types of neurone: sensory, relay and motor. Each has a different function, depending on its location in the body and its role within the nervous system.
Sensory neurons - found in receptors such as the eyes, ears, tongue and skin, and carry nerve impulses to the spinal cord and brain. When these nerve impulses reach the brain they are translated into ‘sensations’, such as vision, hearing, taste and touch. However, not all sensory neuron impulses reach the brain, as some stop at the spinal cord, allowing for quick reflex actions.
Relay neurons - found in the brain between sensory input neurons and motor output/response neurons, allowing them to communicate.
Motor neurons - found in the central nervous system (CNS) and control muscle movements. When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which leads to movement.
Neurons and neurotransmission: Synaptic transmission - excitation and inhibition
Synaptic transmission is the process by which one neuron communicates with another. Information is passed down the axon of the neuron as an electrical impulse known as action potential. Once it reaches the end of the axon it crosses the synaptic gap between the presynaptic neuron and post-synaptic neuron. When the electrical impulse (action potential) reaches the synaptic vesicles in the axon terminal they release their neurotransmitters, which cross the synaptic gap and bind to receptor sites on the post-synaptic cell, thereby completing the process of synaptic transmission.
Excitatory - if an excitatory neurotransmitter like noradrenaline binds to the post-synaptic receptors it will cause an electrical charge in the cell membrane which results in an excitatory post-synaptic potential (EPSP), making the post-synaptic cell more likely to fire.
Inhibitory - if an inhibitory neurotransmitter like GABA binds to the post-synaptic receptors it will result in an inhibitory post-synaptic potential (IPSP), which makes the post-synaptic cell less likely to fire.
Glands and hormones: the function of the endocrine system
The endocrine system works alongside the nervous system. It is a network of glands across the body that secrete chemical messages called hormones. Instead of using nerves (sensory and motor neurons) to transmit information, this system uses blood vessels. Different glands produce different hormones, which in turn have a variety of effects (behaviours).
Examples: E.g. the main hormone released from the pineal gland is melatonin, which is important for biological rhythms, including the sleep-wake cycle. The adrenal gland is divided into two parts and releases three hormones. The adrenal medulla is responsible for releasing adrenaline and noradrenaline, which play a key role in the fight or flight response. The adrenal cortex releases cortisol, which stimulates the release of glucose to provide the body with energy while suppressing the immune system.
The role of adrenaline: the fight or flight response
Stressful situation: when someone enters and potentially stressful situation, the amygdala (part of the limbic system) is activated. The amygdala responds to sensory input (what we see, hear, smell, etc) and connects sensory input with emotions associated with the fight or flight response (e.g. fear, anger). The amygdala then stimulates the hypothalamus to activate the sympathomedullary pathway, which is the pathway running to the adrenal medulla and the sympathetic nervous system (SNS).
Adrenaline: The SNS stimulates the adrenal medulla to secrete the hormones adrenaline and noradrenaline into the bloodstream, where adrenaline causes a number of physiological changes to prepare the body for fight or flight. These include increase heart rate to increase the blood flow and the transportation of adrenaline around the body; increased respiration, to raise oxygen levels; dilation of pupils to increase light entry into the eye and enhance vision (especially in the dark).
Localisation of function
The idea that certain functions (e.g. language and memory) are correlated with certain locations within the brain.
Areas of the brain - e.g. the motor area is responsible for voluntary movements by sending signals to the muscles in the body, and the somatosensory area receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature, etc. The visual area receives and processes different types of information including colour, shape or movement, while the auditory area is responsible for analysing and processing acoustic information.
Language centres - Broca’s area is found in the left frontal lobe and is thought to be involved in language production and Wernicke’s area is found in the left temporal lobe and is thought to be involved in language processing/comprehension.
Split brain research
Hemispheric lateralisation
Lateralisation is the fact that the two halves of the brain are functionally different and that each hemisphere has functional specialisations, e.g. the left is dominant for language, and the right excels at visual motor tasks. Both halves of the brain are connected by a bundle of nerve fibres called the corpus callous.
Split-brain patients - individuals who have undergone a surgical procedure where the corpus callous is cut. This procedure, which separates the two hemispheres, was used as a treatment for severe epilepsy.
Sperry and Gazzaniga (1967) - conducted research using split-brain patients to examine the extent to which the two hemispheres are specialised for certain functions. They found a number of key differences between the two hemispheres. Firstly, the left hemisphere is dominant in terms of speech and language. Secondly, the right hemisphere is dominant in terms of visual-motor tasks. This demonstrated the lateralisation of brain functions.
Recovery of the brain after trauma
Brain plasticity refers to the brain’s ability to change and adapt in reaction to the environment and through experience. An example of this is when learning a new skills develops neuronal connections in the related area of the brain.
Kuhn et al. found a significant increase in grey matter in various regions of the brain after ups played video games for 30 mins a day over a two-month period. This highlights the idea of plasticity and the brain’s ability to adapt as a result of new experience, like playing video games.
Functional recovery - the transfer of functions from a damaged area of the brain after trauma, to other undamaged areas. Functional recovery can take place through a process called neuronal unmasking, where ‘dormant’ synapses (which have not received enough input to be active) open connections to compensate for a damaged area of the brain.
Ways of studying the brain: fMRI and Post-mortem examination
Functional Magnetic Resonance Imaging (fMRI) - brain-scanning technique that measures blood flow in the brain when a person performs a task. It works on the premise that neutrons in the brain that are most active (during a task) use the most energy. An fMRI creates a dynamic (moving) 3D map of the brain, highlighting which areas are involved in different neural activities.
Post-mortem examination - studying the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage. E.g. the work of Broca who examined the brain of a man who displayed speech problems when he was alive. It was then discovered that he had a lesion in the area of the brain important for speech production that later became known as Broca’s area.
Ways of studying the brain: EEG and ERP
Electroencephalogram (EEG) - information is processed in the brain as electrical activity in the form of action potentials or nerve impulses, transmitted along neurone. EEG scanners measure this electrical activity through electrodes attached to the scalp. Small electrical charges are detected by the electrodes, and are graphed over a period of time, indicating the level of activity in the brain.
Event-related potentials (ERP) - electrodes are attached to the scalp, but a stimulus is presented to a pp (e.g. a picture or sound), and the researcher looks for activity related to that stimulus.
Biological rhythms: circadian, infradian and ultradian rhythms
Cyclical patterns in biological systems that have evolved in response to environmental influences, e.g. day and night.
Circadian rhythm - 24 hour rhythm (A.K.A body clock), which is reset by levels of light. ‘Circadian’ comes from the Latin ‘circa’ meaning ‘about, and ‘dian’ meaning ‘day’. Examples of circadian rhythms include the sleep-wake cycle and body temperature.
Infradian rhythm - can be weekly, monthly or annually. Monthly infradian rhythm is the female menstrual cycle, which is regulated by hormones that either promote ovulation or stimulate the uterus for fertilisation.
Ultradian rhythm - less than 24 hours. Can be found in the pattern of human sleep. It alternates between REM (rapid eye movement) and NREM (non-rapid eye movement) sleep and consists of 5 stages.
Biological rhythms: endogenous pacemakers
Internal mechanisms that govern biological rhythms, especially the circadian sleep/wake cycle.
Although they are internal biological clocks, they can be affected by the environment. The most important endogenous pacemaker is the suprachiasmatic nucleus which is closely linked to the pineal gland, both of which are influential in maintaining the circadian sleep-wake cycle.
Biological rhythms: exogenous zeitgebers
External mechanisms that govern biological rhythms, especially the circadian sleep/wake cycle.
They can include social cues, e.g. meal times and social activities, but the most important zeitgeber is light, which is responsible for resetting the body clock each day, keeping it on a 24-hour cycle.
