U1 AOS2 - Role of brain in mental processes and behaviours Flashcards
(15 cards)
Brain-heart debate
The debate questioned whether thoughts, feelings and behaviours arose from the brain or the heart.
- traced to 500 BC, ideas of heart continued to the 19th century
- Heart theory was argued by Aristotle and Empedocles
- Heart theory was opposed by Alcameon, Hippocrates, Herophilus and Galen
In modern-day, it is widely accepted that the brain houses mental functions, and is where instructions are sent to the rest of the body. However, researchers still acknowledge that the heart has some influence on thoughts, feelings and behaviours.
Mind-body problem
The debate questioned the relationship between the body and the mind, with 2 opposing viewpoints of monoism (singular, complete entity) and dualism (seperate and distinguishable entities). Whereby, the mind refers to an individual’s thoughts, mental processes and consciousness, and the body refers to an individual’s brain structure and neurons.
- traced to the 17th century, and still continues today
- Monoism supported by Aristotle and other 17th century Western philosophers
- Dualism introduced by Rene Descartes, suggesting a 2-way interaction where the pineal gland is the ‘seat of the soul’ (where all thoughts are formed)
In modern-day world, it is yet to receive an answer.
Phrenology
The study of the shape of the brain and skull to determine an individual’s personality traits, behaviours, and abilities. This was underpinned by 3 core principles:
- A person’s 27 mental facualties depend on the organisation of their brain
- If a facualty is more developed, that area of the brain would be larger
- This process is reflected on the skull, hence, somebody could feel the physical indentations and use that to analyse the inside of the brain
-Introduced in 1796, discredited in the 1850s
Developed by Franz Gall and Joham Spurzheim
In modern-day, this theory has been debunked, however, it is considered as one of the starting points to ‘localisation of function.’ This is where certain functions (such as language or memory), exist within specific areas of the brain.
3 brain experiments
Ablation: Specific tissues are surgically removed from the brain, destroyed, or disabled, performed on animals. Used to determine if this influences behaviour and mental functions - localisation of function. Performed primarily through use of a scalpel. This is sometimes called as lesioning, as it can cause irreversible brain damage.
discovered equipotentiality - healthy parts of brain can take on responsibilities of unhealthy parts
and mass action - major areas of brain complete different actions as a whole
Electric stimulation:
Weak electrical signals are generated continuously throughout the brain, which is either stimulated or detected by electrodes.
If this yields a specific bodily response, this region of the brain is assumed to be responsible for that action. Performed by Penfield.
Split-brain experiments - Patients who had undergone surgery for Epilepsy involving the severing of the corpus callosum, were studied, as they interacted with different objects with different sides of the body. This was used to support study of ‘hemispheric specialisation.’ It was performed by Roger Sperry.
Structural neuroimaging techniques - types + what they do + define + compare
Procedures and devices taking scans of the brain as individuals perform different functional tasks, providing information on how its’ structured.
Computerised Tomography (CT) - A combinations of a series of images, taken at different angles, to create cross-sectional images of the body. Patients are injected with contrast, to highlight the blood vessels of the brain. It can locate brain tumours, identify changes in the brain caused by different disorders, and determine the level of brain injury after a stroke.
Uses X-ray equipment
Magnetic Resonance Imagery (MRI) - Magnetic fields are used to activate and realign atoms in the water molecules of the brain, generating a full-colour image. They are more sensitive than CT’s, but also more detailed and complex then CT scans. It identifies cancerous tissue, subtle brain abnormalities and signs of a stroke.
Taken in long, metal cylinder where patient must sit still, but no radiation involved
Functional neuroimaging techniques - types + define + compare
Procedures and devices taking scans of the brain, as individuals perform different tasks, providing information on brain activity.
Positron Emission Tomography (PET) - Technique providing information on both brain structure and activity, through registering emissions of a glucose solution containing a radioactive tracer, when completing an activity. This is in full colour. It can associate different activities with different regions of the brain.
Increased blood flow = increased neuronal activity
Functional Magnetic Resonance Imagery (fMRI) - Technique displaying brain activity by measuring consumption of oxygen in the cells of the brain, whilst participants complete a particular activity.
Preferred to PET as:
- it does not expose participants to any radioactive tracers
- it can provide more detailed images, and can be captured more quickly and in succession (allowing detection of brain changes, moment to moment)
BLUE = LOWER ACTIVITY LEVELS
RED = HIGHER ACTIVITY LEVELS
Neuron - define + types
A neuron is a nerve cell, which receives, processes and transmits information throughout the nervous system
Sensory - Afferent, carries sensory information from environment to CNS
Motor- Efferent, carries messages from CNS to skeletal muscles, organs and glands (lower brain stem and spinal cord)
Interneuron - The link between sensory and motor neurons, within the CNS
Neuron - features and their purpose
Dendrities - branch extensions which detect and receive info from other neurons, activating a response
Soma / cell body - contains nucleus, integrates information from dendrites, sending it to the axon
Nucleus - contains genetic code
Axon - fibre which transmits the neural information away from the soma
Myelin sheath - fatty form of insulation and protection, fast-tracking process
Nodes of ranvier - gaps in myelin sheath
Axon terminal - contains terminal button, storing and secreting neurotransmitter chemicals to transfer information over to the next neuron
Sypnaptic gap - gap between neurons where neurotransmitters travel through and stimulate the dendrite of the next neuron
The organisation of the nervous system
Central Nervous System (processes information and coordinates a response)
- brain (coordinates bodily activity, behaviour, and mental functions),
- Spinal cord (connects brain to peripheral nervous system, activates spinal reflexes)
Peripheral nervous system (relays information from and to muscles, glands and organs, as a response to changes in internal and external environments)
- Autonomic nervous system (automatic life functions)
(Sympathetic - fight/flight/freeze, initial involuntary movements due to stressful situation - eg. increase in heart rate)
(Parasympathetic - rest and digestion, recovery from sympathetic system response - eg. lowering heart rate)
- Somatic nervous system (transmits sensory info, and coordinates voluntary motor movement)
The Hind Brain - it’s purpose, its location, and its’ structures
The Hindbrain is important for basic survival, regulating the sleep-wake cycle, autonomic functions and coordinating muscle movements. It is located at the back of the brain.
Cerebellum - coordinates voluntary movement, balance, and posture, (eg. riding a bike). Ensures that movement is smooth, and also involved in learning and memory associated with movement.
Medulla oblongata - controls autonomic vital life functions, such as heart rate, breathing, salivating and blood pressure. (eg. vomiting to remove harmful substance in stomach) - damage can prove fatal
Pons - Relays information between cerebellum and medulla oblongata, regulates sleep, dreaming and awaking (sleep-wake cycle).
The forebrain - its’ purpose, location and structures
The forebrain is important for coordinating complex mental functions, and regulating homeostasis. It is located at the top of the brain.
Hypothalamus - regulates hormone release to maintain homeostasis (temperature, hunger, thirst, sleep), member of limbic system (group of structures which govern emotional and motivated behaviour) (eg. sweating to cool body down)
Thalamus - motor-sensory relay centre for all senses except smell before it can be interpreted by the cerebral cortex, also regulating arousal, focus. (eg. noticing it’s bright outside, smelling food in kitchen)
Cerebrum - it contains 2 cerebral hemispheres, connected by the corpus callosum (a bundle of nerves allowing communication between the hemispheres), and is seperated into 4 lobes. It is responsible for high order mental processes like problem-solving, thinking, learning and perception. (eg. recalling information for an exam and determining the answer to the question)
The Midbrain - its’ purpose, location and structures
The midbrain is important for filtering and transmitting sensory information, managing arousal and alertness and relaying messages between the hind brain and forebrain. It is located between the forebrain and hindbrain.
The Substantia Nigra - collection of neurons which produce dopamine for movement and coordination, and also for reward processing - damage is associated with Parkinson’s disease (eg. gently pressing brake pedal)
The Recticular formation - maintains arousal, and in consciousness the form of neuron clumps. Contains recticular activation system, which can cause awakeness and alertness, and filter out unnecessary information. (eg. whilst sleeping, it filters out noises like birds or rustling, but awakes an individual due to fire alarms or shouting).
Left + Right hemispheres
Left:
- controls motor and sensory functions of the right side
- verbal language
- logic and planning
- analytical processing
Right
- controls motor and sensory functions of the left side
- spatial and visual thinking
- creativity
- emotional recognition and thought
4 lobes of the brain
Frontal lobe:
Contains pre-frontal cortex, which focuses on executive functioning, involving problem-solving, symbolic thinking, emotional regulation and decision-making.
Also contains the primary motor cortex, which executes and controls movement. It is contrilateraly organised, where the left hemisphere controls movement of the right side of the body, and vice versa. It also involves cortical representation, where the amount of cortex distributed to a key body part corresponds to the complexity of its’ movements.
Further contains Broca’s Area, which is responsible for production of clear and fluent speech.
Parietal lobe: Responsible for spatial awareness, spatial reasoning, attention and receiving and processing sensory information relating to touch, pain and temperature.
Contains the somatosensory cortex, which receives and processes somatosensory information, and is also contrilateraly organised, and involving cortical representation (the amount of sensitivity).
Occipital lobe: Responsible for vision, where the primary visual cortex receives and processes visual info from sensory receptors in the retina of the eye
Temporal lobe: receives and processes sound, and also assists in memory,
identifying objects and recognising faces, and responding emotionally to sensory information.
It contains Wernicke’s area, which understands the sounds that arrange to make up speech.
The ‘brain story’
At the forefront of our story, we live in a country that is hyper over keeping at homeostasis (requiring needs to be fulfilled and the temperature to be perfect). It is a member of the limbic system kingdom, a group of countries that are infamous for their regulation of emotions and behaviour. We meet protagonist Thalamus, a mailmain who is sorting through information about the celebrity “sensory” customers. He is not responsible, however, for dealing with the ‘smell’ member - nobody talks about him. This is challenging, and requires high levels of focus and arousal. Once ready, he goes and delivers the info to Cerebrum, the President of the country. Cerebrum is desperately making decisions, directing conscious motor movements and also has to interpret all of the info Thalamus has given him. Being the President is a big job.
Now, we move to the middle of the story, where Thalamus takes Cerebrum down to the Substantia Nigra factory, as a form of motivation. Here, there is a collection of neuron slaves which produce dopamine, for movement and coordination. They are always tired, and have to rely on the REC FORM alarm system, acting to keep them alert, awake and focused, filtering out unnecessary noises outside the factory.
Now, to the hind side, where Cerebrum accompanies Thalamus to his second job, as a pizza deliverer. He is dizzy from a day’s work, and struggles to maintain his balance, posture and movement at an adequate level, almost dropping the pizza. He is so tired, but the bright lights prevent his pons from secreting melatonin for sleep. Cerebrum displays a shocked facial expression, at all the stuff Thalamus must deal with on a day to day basis. He awards Thalamus a medal for his dedication, and says he withdraws from the limbic kingdom. But, Cerebrum’s political rival comes up from behind him and has a knife, preparing to sacrifice him for his sins against the kingdom. Cerebrum’s autonomic life functions go crazy, raising his heart rate and blood pressure. Just in time, Thalamus throws himself over him, and his heart stops. To be continued…
