Psychology - Biopsycholgy Flashcards
1
Q
The nervous system
A
is the main system that controls the mind and body. It takes in information from the environment and elsewhere in the body (transmitted across neurons) and co-ordinates a wide range of conscious functions such as thinking and movement, as well as unconscious functions like the control of organs (e.g. heart rate, digestion) and glands.
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Q
Central nervous system
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Main control system for life functions, plus conscious psychological processes
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CNS - Two parts
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Brain and spinal cord
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Brain
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Higher psychological processes (e.g. thinking, behaviour), and regulates bodily processes based on information from peripheral nervous system
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Spinal cord
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Transmits information between the brain and peripheral nervous system
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Peripheral nervous system
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Transmits information between the CNS and external world/organs
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PNS - two parts
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Autonomic and somatic
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Q
Autonomic
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Transmits information betwen organs and CNS responsible for involuntary bodily activities e.g. heart rate
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Somatic
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Transmits information between senses and CNS directs voluntary movement e.g. walking
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Q
Autonomic - two parts
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sympathetic and parasympathetic
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Q
Parasympathetic
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Decreases bodily functions to conserve energy (calm and rest)
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Sympathetic
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Increases bodily functions to prepare for action (fight or flight)
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Q
Brain - functions
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Perception (i.e. translating information from the senses so it can be understood and processed)
Motor control (i.e. sending commands to muscles to move)
Regulating bodily processes and maintaining homeostasis (e.g. maintaining temperature and hormone levels based on information from the peripheral nervous system)
Sleep
11
Q
Spinal cord -functions
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The spinal cord connects the brain with the peripheral nervous system. In other words, it connects the brain with the rest of the body and with the external world. The spinal cord is also responsible for some unconscious movements, such as reflexes (e.g. the one where you get hit on the knee and your leg kicks).
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PERIPHERAL NERVOUS SYSTEM - function
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The peripheral nervous system goes beyond the central nervous system to connect it with the rest of the body and the external world. It consists of two parts: the somatic nervous system and the autonomic nervous system.
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Q
Somatic - function
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It transmits information between the central nervous system and the senses (i.e. it connects the brain to the external world) and is under conscious control.
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Autonomic - functions
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The autonomic nervous system is responsible for transmitting information between the central nervous system and the internal organs (i.e. it connects the brain to the rest of the body). Unlike the somatic nervous system, it is involuntary and not under conscious control.
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Q
Organ - Heart - Sympathetic
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Increase heart rate
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Organ - Digestive system - Sympathetic
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Decrease stomach acid and digestion
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Organ - Eyes (iris) - Sympathetic
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Dilate pupils
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Organ -Lungs -Sympathetic
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Dilate bronchioles
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Organ - Heart - Parasympathetic
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Decrease heart rate
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Organ - Digestive system - Parasympathetic
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Increase stomach acid and digestion
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Q
Organ - Eyes (iris) -Parasympathetic
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Constrict pupils
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Organ -Lungs -Parasympathetic
Constrict bronchioles
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Neurons
Are the main components of the nervous system. They are how information is transmitted from one part of the nervous system to another. There are around 100 billion neurons in the brain and another 1 billion in the spinal cord.
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General structure of a neuron
The dendrite (receptor) receives a signal
The signal is carried towards a cell body (which contains the nucleus)
The signal travels along an axon (which is protected by myelin sheaths) towards the axon terminal
Terminal boutons at the end of the axon pass the electrical signal to the next neuron in the chain
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Direction of impulse
Signals are passed within neurons electrically. At rest, the neuron is negatively charged but becomes positively charged when activated, which sends an electrical impulse through the axon. Once this electrical signal reaches the axon terminal, synaptic transmission enables the signal to pass along to the next neuron in the chain.
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SYNAPTIC TRANSMISSION
Neurons are separated by small gaps called synapses, and synaptic transmission is the process of sending information from one neuron to another. The gap between two neurons is called the synaptic cleft (or synapse). When the electrical signal within a neuron reaches the axon terminal of that neuron, neurotransmitters are released from vesicles and cross over the synapse where they are taken up by receptors in the dendrites of the other neuron.
Whereas signals within neurons are transmitted electrically, signals between neurons are transmitted chemically. In other words, neurotransmitters are chemicals. When a neurotransmitter is taken up by the receptor of the next neuron, it is converted back to an electrical signal which passes along the axon of that neuron until it reaches the axon terminal where the chain can continue.
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Excitatory
Increase the likelihood of the neuron firing
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Inhibitory
Decrease the likelihood of the neuron firing
For example, serotonin has a generally inhibitory effect. When serotonin binds to the receptor of a neuron, it increases the negative charge of that neuron, making it less likely to fire. In contrast, glutamate has an excitatory effect. So, if glutamate outweighs serotonin in a neuron, the net effect is increased likelihood of that neuron firing.
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Sensory neurons
Transmit information from the senses (e.g. the eyes or fingertips) to the central nervous system
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Motor neurons:
Transmit information between the central nervous system and the organs and muscles (e.g. an instruction to the adrenals to produce adrenaline)
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Relay neurons
Connect neurons to other neurons (e.g. motor neurons to sensory neurons) and transmit information within the central nervous system (also called interneurons)
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The endocrine system
The endocrine system is a system of glands that are responsible for the release of hormones. The pituitary gland (the ‘master gland’) of the endocrine system is linked to the nervous system via the hypothalamus, which co-ordinates and regulates the release of hormones from glands.
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Hormones
are chemicals that communicate information throughout the body. Different hormones are produced and released by different glands in the body.
The effects of hormones are significant and affect growth, sleep, mood, metabolism, and just about every other process in the body. They flow through the body and bind to specialised receptors in cells (a bit like how neurotransmitters bind to receptors in neurons). When a hormone binds to a receptor, it can cause an effect in that cell.
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Gland - Pituitary - hormone and effect?
Growth hormone: Stimulates growth and cell division
Prolactin: Stimulates milk production (females
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Gland - Testes - hormone and effect?
Testosterone: Responsible for male secondary sex characteristics (e.g. body hair, deeper voice, bigger bone structure), sperm cell production, increases aggression and muscle size
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Gland - Ovaries - hormone and effect?
Oestrogen: Responsible for female secondary sex characteristics (e.g. breast development, wider hips), egg maturation
Progesterone: Regulates uterus for pregnancy
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Gland - Thyroid - hormone and effect?
Thyroxine: Increases metabolism, regulates growth and temperature
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Gland - Pineal - hormone and effect?
Melatonin: Regulates circadian rhythm and sleep
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AREAS OF THE BRAIN
Early scientists tended to see the brain in a holistic way, meaning they saw all areas of the brain as used for all functions.
frontal, parietal, temporal, and occipital lobes
cerbellum
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ADRENALINE: FIGHT OR FLIGHT
Adrenaline is responsible for the fight or flight response: an activation of the sympathetic side of the autonomic nervous system to prepare the body for action. The process for this is as follows:
The brain (specifically the hypothalamus) senses a threat
The hypothalamus sends a message to the adrenal glands (specifically the adrenal medulla) to release adrenaline
Adrenaline increases bodily activities to either fight or flee from the threat
For example, heart rate increases to improve blood flow, the bronchioles of the lungs dilate to increase oxygen intake, and the pupils dilate to increase vision. Other bodily activities that are not essential for fighting or fleeing are reduced, such as digestion
Once the brain senses that the threat has passed, the parasympathetic nervous system reduces these activities and returns the body to a resting state (rest and digest rather than fight or flight).
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Gland - Adrenal - hormone and effect?
Cortisol: Maintains blood sugar, regulates inflammation and immune response
Adrenaline: is responsible for the fight or flight response
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HEMISPHERIC LATERALISATION
left and right brain hemispheresThe first way the brain can be divided is laterally, i.e. a left half and a right half. These halves are called hemispheres. Each of the two hemispheres can be further divided into four lobes: frontal, parietal, occipital, and temporal. The two hemispheres are not symmetrical – they do different things. For example, the left hemisphere tends to be more involved in language processing, whereas the right hemisphere tends to be more involved in processing spatial relationships.
As a general rule, information from the left side of the body is processed by the right hemisphere and vice versa (contralateral). For example, damage to the motor cortex in the right hemisphere will affect the person’s ability to move their left side, and damage to the auditory cortex in the left hemisphere will affect a person’s hearing in their right ear.
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Split-brain research
The two hemispheres of the brain are connected by a bundle of nerve fibers called the corpus callosum. In rare cases of extreme epilepsy, a surgeon may cut the corpus callosum (corpus callosotomy), separating the right and left hemispheres from each other. This contains any epileptic seizures to just one side of the brain, reducing their severity.
Despite the dramatic nature of the procedure, patients who’ve undergone a corpus callosotomy (split-brain patients) are able to live relatively normal lives. However, there are some effects on functioning, as observed in Sperry (1968):
When split-brain patients were shown an image to their right visual field, they were able to describe in words what they saw. However, when they were shown the same image to their left visual field, they were not able to describe what they saw. This is likely because visual information from the left side is processed in the right hemisphere (the visual cortex is contralateral) and language processing primarily occurs in the left hemisphere. So, the visual data in the right hemisphere could not be shared to the language processing areas in the left hemisphere in order for the split-brain patient to describe what they saw.
However, despite not being able to describe in words the image shown to the left visual field, the split-brain patients could use their hands to pick an object associated with that image. For example, if the split brain patient was shown a cigarette to their left visual field, they could use their left hand to pick an ashtray. This can be explained by the fact that the left hand is controlled by the right hemisphere (again, the motor cortex is contralateral) and the image that was shown to the left visual field would have been processed in the same (right) hemisphere.
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Localisation of function
refers to identifying specific areas of the brain that correspond to specific functions.
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Somatosensory cortex (touch)
The somatosensory cortex of the brain is responsible for sensing physical sensations on the skin, like pressure and heat. It is located in the parietal lobes of each hemisphere. The number of neurons in the somatosensory cortex differs according to body part. For example, there are many more neuronal connections dedicated to processing information from the hands than the ankles because people use their hands to feel things much more commonly than they do their ankles.
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Motor cortex (voluntary movement)
The motor cortex of the brain is responsible for voluntary movement, such as walking. It is located in the frontal lobes of each hemisphere. However, basic involuntary movements (like coughing) are controlled by other parts of the brain.
So, damage to the motor cortex may limit a person’s motor skills. For example, a person with a damaged motor cortex may have difficulty holding a pen.
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Visual cortex (seeing)
The visual cortex of the brain is responsible for processing visual information from the eyes. It is located in the occipital lobes of each hemisphere. The visual cortex is contralateral: The right hemisphere processes data from the left of a person’s field of vision (both eyes) and vice versa. So, damage to the visual cortex of the right hemisphere may make it difficult for a person to perceive objects to the left of them.
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Auditory cortex (hearing)
The auditory cortex of the brain is responsible for processing sound. It is located in the temporal lobes of each hemisphere. The auditory cortex is also contralateral: The right hemisphere processes sound from a person’s left ear and vice versa. So, damage to the auditory cortex of the left hemisphere may cause hearing difficulties in a person’s right ear.
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Language centres
language processing primarily happens in the left hemisphere. There are two areas that are particularly important for language: Broca’s area and Wernicke’s area.
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Broca’s area (speech production)
The Broca’s area is the main area where speech is produced. It is located in the frontal lobe of the left hemisphere.
The Broca’s area was identified by and named after Pierre Paul Broca in the mid 19th Century. From post-mortem autopsies, Broca observed that patients who’d had difficulty producing words had lesions (damage) in this area of the brain.
Damage to the Broca’s area causes Broca’s aphasia (also called expressive aphasia), a condition characterised by slow speech, lack of fluency, and an inability to find the right words. Despite difficulties producing speech, people with Broca’s aphasia often have normal language comprehension – i.e. they understand what others are saying.
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Wernicke’s area (speech comprehension)
Another important (but separate) area for language is Wernicke’s area. The Wernicke’s area is primarily responsible for language comprehension (both written and spoken). It is located in the temporal lobe.
Damage to the Wernicke’s area causes Wernicke’s aphasia (also called receptive aphasia). Patients with Wernicke’s aphasia typically have no problems producing speech – they speak in a fluent and effortless way – but the content of what they say often lacks meaning.
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NEUROPLASTICITY
Neuroplasticity is this ability of the brain to change its physical structure to perform different functions.
In childhood, the brain is highly plastic. This plasticity enables infants and children to quickly learn new skills, adapt to their environment, and recover from brain injury. Neuroplasticity reduces with age, but still remains: Unused pathways are removed, commonly used pathways are strengthened, and new pathways can be formed.
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FUNCTIONAL RECOVERY AFTER TRAUMA
Neuroplasticity enables people to recover function after trauma (e.g. brain damage caused by stroke or accident). To recover function, the brain restructures itself in the following ways:
Other areas of the brain adapt to take over the function of damaged areas: For example, Danelli et al (2013) describes a case study of a boy who had his entire left hemisphere removed at age 2 and a half. As described above, language function is primarily localised in this hemisphere, and the boy was initially unable to speak. However, his language skills recovered after 2 years, suggesting the right hemisphere adapted to take over this function.
Unused neural pathways are recruited: Wall (1977) observed that the brain contains many dormant neural connections. When healthy neural connections are damaged, these previously dormant synapses activate and form new connections to compensate for the damaged ones.
Axon sprouting: Damage to the axon of a neuron can break its connections to neighbouring neurons. When this happens, the neighbouring intact neurons may grow (‘sprout’) extra nerve endings to reconnect with these damaged neurons.
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FMRI
Functional magnetic resonance imaging (fMRI) is a form of brain scanning. It uses magnetic fields to measure blood flow and oxygenation in the brain.
When an area of the brain is highly active, that area needs more oxygen and greater blood flow to provide this oxygen. By measuring blood flow and oxygenation, fMRI scanners enable researchers to identify which areas of the brain are activated during certain tasks.
The example fMRI scans above are from Ovaysikia et al (2011). In this study, the researchers measured brain activity during two tasks: Reading words and recognising facial expressions. As can be seen from the fMRI scan above, the different tasks increased brain activity in different areas.
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ELECTROENCEPHALOGRAM
An electroencephalogram (EEG) is a scan of the brain’s electrical activity. An EEG scan is performed by attaching electrodes to the scalp or by using a hat with electrodes attached.
The electrodes detect electrical activity in the brain cells beneath them. So, the more electrodes that are used in an EEG, the more complete a picture of brain activity the EEG can provide.
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ERPS
Event-related potentials (ERPs) are closely related to EEG scans.
They use the same equipment but use statistical techniques to measure changes in brain activity in response to a stimulus. For example, the EEG could initially provide a baseline picture of brain activity, then researchers could introduce a stimulus (e.g. giving a subject some food to eat) and use ERPs to determine how brain activity changed in response.
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POST-MORTEM
A post-mortem is a physical examination of the brain after a person has died. By physically analysing a brain (for example, by weighing it, dissecting parts of it, and comparing it to neurotypical (‘normal’) brains) and cross-referencing this with the person’s behaviour in life (e.g. any psychological disorders the person had) the examiner can learn more about the causes of behaviours and psychological disorders. An example of this is described above: From post-mortem analysis of the brains of patients with speaking difficulties, Pierre Paul Broca identified that the Broca’s area of the brain is important for speech production.
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Biological rhythms
The activities of the mind and body follow various cycles, which are known as biological rhythms
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Circadian - length - example
24 hours
Sleep and wake cycle
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Infradian - length - example
More than 24 hours
Female menstrual cycle
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Ultradian - length - example
Less than 24 hours
Stages of sleep
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Endogenous pacemakers
Things within the body that regulate biological rhythms (your ‘body clock’).
E.g. The suprachiasmatic nucleus of the hypothalamus
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Exogenous zeitgebers
Cues in the external environment that inform endogenous pacemakers to regulate biological rhythms. E.g. Sunlight and darkness prompt the body to release hormones that control sleep and wake cycles
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Circadian rhythms
Are biological cycles lasting approximately 24 hours. An example of a circadian rhythm is the sleep/wake cycle: You might cycle between sleeping for 8 hours when it gets dark and being awake for 16 hours during the day, for instance.typical circadian rhythm
Examples of endogenous pacemakers that control circadian rhythm include systems that release hormones such as melatonin, systems that regulate body temperature, and systems that control metabolism and digestion. The main system that controls circadian rhythms is the suprachiasmatic nucleus (SCN).
These internal processes are influenced by exogenous zeitgebers – perhaps the most obvious of which is sunlight. For example, the darkness of night is thought to trigger melatonin release, which makes you feel tired and want to go to bed.
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Infradian rhythms
are biological cycles lasting more than 24 hours. An example of an infradian rhythm is the human menstrual cycle: Women typically ovulate once every 28 days.
As with circadian rhythms, infradian rhythms are controlled by endogenous pacemakers. For example, hormones such as estrogen and progesterone are crucial to the menstrual cycle.
Infradian rhythms can also be influenced by exogenous zeitgebers. For example, Stern and McClintock (1998) demonstrated that women’s menstrual cycles change when exposed to pheromones from other women.
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Ultradian rhythms
Are biological cycles lasting less than 24 hours. An example of an ultradian rhythm is the different stages of sleep: During the night, a sleeping person will typically cycle between five stages. One complete sleep cycle through all these stages will typically take around 90 minutes. So, during a full night’s sleep, a person may repeat this cycle four or five times.
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Stage 1 of sleep - length , description
5-15 minutes
Light sleep. Alpha waves increase and brain activity starts to reduce. Heart rate slows and muscles relax.
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Stage 3 of sleep - length , description
5-15 minutes
Deep sleep. Delta brain waves increase and brain activity is greatly reduced.
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Stage 2 of sleep - length , description
5-15 minutes
Light sleep. Brain activity reduces but with occasional bursts of activity.
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Stage 5 of sleep - length , description
Rapid eye movement (REM)
>15 minutes
High level of brain activity. Dreams are likely to occur. Body is completely relaxed.
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Stage 4 of sleep - length , description
~40 minutes
Deep sleep. Delta waves peak, lowest level of brain activity during the sleep cycle.
