Aos 2: How are mental processes & behaviour influenced by the brain?

**DP1: different approaches over time in understanding the role of the brain in behaviour and mental processes**

Psychology

the scientific study of human mental states and behaviour

brain versus heart debate

a historical debate as to whether the heart or the brain is responsible for mental processes, such as thought, emotion, and behaviour

heart hypothesis

* The ancient Egyptians perceived the heart to contain and control all aspects of personality, logic, and emotion
* The heart was collectively viewed as the sacred key to the afterlife and was carefully preserved in the mummification process, whereas the brain was deemed to be a relatively useless organ and was often discarded after death.

brain hypothesis

* The ancient Greek philosophers believed that the brain was solely responsible for mental functions, including personality and logic.

Heart versus brain debate – solution

Although the brain hypothesis is most supported today, the brain versus heart debate and its key figures have meaningfully contributed to modern scientific findings.

mind-body problem

the complex philosophical question as to whether our mind is separate and distinguishable from our body or whether they are one integrated entity

dualism

the belief that the human mind and body are separate and distinguishable from one another

monism

the belief that the human mind and body are together a singular complete entity

mind-body problem answer

Although modern science tends to favour the ideologies of monism, there is still no definitive answer to the mind-body problem as our understanding of concepts, such as the workings of unconsciousness, are still incomplete.

phrenology

the study of the shape and size of the human skull to determine personality and mental functioning.

phrenology belief

a human’s personality, intelligence, and mental functioning could be measured by feeling the bumps, grooves, and shape of the skull.

phrenology – background

The practice of phrenology was established by German physician Franz Gall in 1796.

* Gall suggested that the human brain was a sum of 27 ‘mind organs’, each having a distinct physical location in the brain and its own mental function.

ablation

involves the surgical removal, destruction, or cutting of a region of brain tissue.

* irreversible procedure

ablation history

historically been used to treat neurological and psychological disorders, as well as to help researchers determine how the brain responds to damage and make inferences about localisations of function

ablation origin

Pierre Flourens, a French physiologist, was the first person to practice ablation in the 1820s as a way of studying the brain.

* Flourens is famous for conclusively ‘discovering’ that the ‘mind’ was in the organ of the brain and not the heart \n

brain lesioning

the practice of inducing and/or studying the effects of damage to an area of the brain

* damage can be surgically created or result of an illness or injury, such as a stroke

brain lesioning purpose

Similar to ablation, the study of brain lesions helps psychologists to make inferences about the functions of specific brain regions by observing how brain damage affects these functions.

split brain research

studies on the brain conducted by Roger Sperry and Michael Gazzaniga in the 1960s. Sperry and Gazzaniga worked with patients who had undergone ‘split-brain surgery’, by cutting the corpus callosum.

* This surgery was conducted to prevent the patients’ epileptic seizures

split-brain research – method

* split-brain patients were situated behind a screen with a black dot in the centre on which they focused their eyes.
* Words and objects were then projected on either the left or right side of the dot.
* patients were asked to describe what they saw.

split-brain research findings

* when images or words were presented to the right visual field, patients were able to verbally state what they had seen. and vice-versa with the left visual field.

left hemisphere specialisation

* language expression
* comprehension
* controlling right side of body

right hemisphere specialisation

* imagination
* creativity
* controlling left side of body

hemispheric specialisation

the difference in functioning between the left and right hemispheres of the brain when performing a specific behaviour or task

Neuroimaging

a range of techniques used to capture images of the brain’s structure, function, and activities

neuroimaging benefits

* less invasive
* more precise

Structural neuroimaging techniques

produce images of the brain’s structure and composition.

Computerised tomography (CT)

involves taking continuous two-dimensional x-ray images of the brain which are then stacked to create a comprehensive three-dimensional image of the brain.

CT process

* individual must first ingest a dye called ‘contrast’ which allows their brain to be visible in scans.
* The individual enters a gantry while lying horizontally on a bed.
* Successive x-ray images are taken in a spiralling motion as the individual in the bed moves slowly through the gantry.

CT use

disease detection

CT benefits

* Enables the detection of haemorrhages, blood clots, cancer, and the loss of brain mass that can reflect disorders.
* Do not need to be used as frequently as other kinds of neuroimaging techniques.

CT limitations

* Somewhat intrusive process for the patient.
* Are limited to black and white images
* Not as detailed
* X-rays use electromagnetic ionising radiation which has the potential to have biological consequences

Magnetic Resonance imaging (MRI)

uses magnetic and radio fields to take detailed two-dimensional and three-dimensional images of the brain.

MRI process

* A person enters a chamber device that contains a big magnet.
* The magnetic field generated by the device causes the brain’s atoms to move and organise in such a way that they send signals which can be captured as an image by a computer.

MRI use

disease and disorder detection

MRI benefits

* less harmful to patients
* Produce more detailed, coloured images of the brain.

MRI limitations

* MRI cannot be used on a person with internal screws, pacemakers, or other similar devices.

functional neuroimaging techniques

use images to show the the brain’s activity and functions.

Postitron emission tomography (PET)

uses a scanning device to take coloured images of the brain, showing its functional activity by tracing the levels of a radioactive substance in the brain.

process of a PET scan

* A person is injected with a special radioactive glucose substance before entering a chamber.
* The solution reaches the brain via the bloodstream and then lights up different areas of the brain when they are active.
* The substance releases emissions that help to trace the biochemical changes that accompany brain activity.
* Within this chamber, a person is then asked to perform a certain task

PET scan images

* A PET scan shows a range of colours and has a colour key on the side. Each colour represents a different level of activity, with red showing the most activity to purple showing the least activity.

functional magnetic resonance imaging (fMRI)

uses magnetic and radio fields to take two and three-dimensional images of the brain and record \n its activity levels.

fMRI process

* measures brain activity levels by tracing biochemical changes in the brain that are reflected using different colours and a key.
* Rather than tracing glucose levels fMRI traces oxygen levels in the brain.
* The more active a certain brain region is, the more oxygenated the blood will be in that area.
* fMRI uses the same methods as MRI to get detailed 2D and 3D images.

**DP2: the roles of the hindbrain, midbrain and forebrain, including the cerebral cortex, in behaviour and mental processes**

the brain

a complex organ contained within the skull that coordinates mental processes and behaviour, and regulates bodily activity

complexity of the brain

increasing complexity as you move up from the hindbrain to the forebrain

* less complex structures developed earlier evolutionary wise

brainstem

an extension of the spinal cord that is made up of the medulla, pons, and midbrain

hindbrain

a region at the base of the brain, located around and \n including some of the brainstem

* consists of the pons, medulla and cerebellum

hindbrain role

coordinating basic survival functions, including movement, breathing rate, heart rate, and digestion

cerebellum function

* balance + posture
* monitor & coordinate skeletal muscle movement
* controlling voluntary motor movement in relation to sequences

medulla function

* regulate autonomic processes such as heartrate
* initiating reflexive actions such as coughing
* connects the brain to the spinal cord

pons function

* relays information to different brain areas
* regulates respiratory system
* controls sleeping, dreaming and waking
* involuntary behaviours such as blinking

midbrain

a region at the centre of the brain, between the hindbrain and forebrain, and is part of the brainstem

midbrain function

* relay neural information between higher and lower areas of the brain
* processing sensory information
* coordinating motor movement relating to sensory stimuli such as eye movements.
* regulating sleep and physiological arousal

reticular formation function

* filters information and direct these messages to various areas and structures of the brain
* integrate and relay neural information relating to survival and reflexive functions
* regulate sleep, wakefulness, and consciousness
* regulate physiological arousal and alertness

forebrain

a large and prominent brain region that is located at the top and front of the brain

* consists of the hypothalamus, thalamus and cerebrum

forebrain function

integration and coordination of information that enables complex functions, including receiving and processing sensory information

cerebrum function

crucial role in complex mental processes, such as:

* coordinating sophisticated mental processes, including cognition, perception
* performing complex functions, including receiving and processing sensory information, and initiating voluntary \n motor movement.

hypothalamus function

* regulates homeostasis
* motivated and emotional behaviours

thalamus function

* filtering system for sensory information excluding olfactory information
* relays sensory and motor information to various brain areas
* regulates alertness, activity and arousal

cerebral cortex

the outer layer of the cerebrum that covers the brain

cerebral cortex function

\
* initiation of voluntary motor movements


* processing of sensory information
* it is involved in mental processes, including language, sensation

motor areas

\
regions of the cerebral cortex that have functions related to initiating and executing motor movements.

* made up of motor neurons.

sensory areas

regions of the cerebral cortex that have functions related to receiving and processing information from the five senses

* made up of sensory neurons.

association areas

regions of the cerebral cortex that integrate information from both motor areas and sensory areas to execute complex mental processes

four lobes of the cerebral cortex

* Frontal lobe
* Parietal lobe
* Occipital lobe
* Temporal lobe

Frontal lobe

the largest and frontmost lobe of the cerebral cortex that is composed of motor and association areas.

* composed of the premotor cortex, primary motor cortex, prefrontal cortex and broca’s area

Prefrontal cortex

* coordinating complex mental functions such as judgement, personality, decision making
* initiating voluntary motor movement
* association area

premotor cortex

* involved in voluntary motor movement through organised sequences
* motor area

primary motor cortex

* involved in initiating voluntary motor movements through communication with the cerebellum
* motor area

primary motor cortex organisation

* top of the cortex controls lower regions of the body and vice versa.
* The amount devoted to different body parts is proportional to the number of neurons required to move them.
* body parts that are capable of fine motor movements, such as the hands take up a large proportion and vice versa with body parts that are not capable of fine motor movements such as the legs.

Broca’s area

* responsible for the production of speech
* association area
* localised to the left hemisphere

parietal lobe

the lobe of the cerebral cortex, located behind the frontal lobe, and is composed of sensory and association areas

* consists of the primary somatosensory cortex

primary somatosensory cortex

* receiving and processing sensory information
* sensory area

primary somatosensory cortex organisation

* top of the cortex controls lower regions of the body and vice versa.
* The amount devoted to different body parts is proportional to the number of neurons required to move them.
* body parts that are more sensitive such as the lips take up a large proportion and vice versa with body parts that are not as sensitive such as the back

association areas of the parietal lobe

* involved in attention, spatial awareness and reasoning

occipital lobe

the rearmost lobe of the cerebral cortex, located behind the parietal lobe, and is composed of sensory and association areas

* composed of the primary visual cortex

primary visual cortex

* receives and processes visual information


* sensory area

association areas of the occipital lobe

* involved in perception and interpretation of visual information

temporal lobe

the lowest lobe of the cerebral cortex, located beneath the parietal lobe, and is composed of sensory and association areas

* composed of the primary auditory cortex and wernicke’s area

primary auditory cortex

* receiving and processing auditory information
* left hemisphere processes verbal sounds while right hemisphere processes non-verbal sounds


* sensory area

wernicke’s area

* involved in comprehension and production of speech
* association area
* localised to the left hemisphere

association areas of the temporal lobe

* involved in memory
* expression of appropriate emotional responses

**DP3: the capacity of the brain to change in response to experience and brain trauma, including factors influencing neuroplasticity and ways to maintain and/or maximise brain functioning**

\

neuron

a nerve cell that receives and transmits neural information

structure of the neuron

* dendrites
* axon
* soma/cell body
* axon terminal
* myelin sheath
* synapse

the synapse

the region that includes the axon terminals of the presynaptic neuron, the synaptic gap, and the dendrites of the postsynaptic neuron

neuroplasticity

the ability of the brain to change in response to experience or environmental stimulation.

* the brain changes occur as a result of neurons communicating and creating connections

developmental plasticity

changes in the brain that occur in response to ageing and maturation

synaptogenesis

the formation of synapses between neurons as axon terminals and dendrites grow

* synapses are made to retain learning
* occurs most during infancy

synaptic pruning

the elimination of underused synapses

* allows space to strengthen frequently used neurons
* occurs most during infancy and adolescence

myelination

the formation and development of myelin around the axon of a neuron

* facilitates efficient communication
* allows for no disturbances = quick and smooth communication

Neuroplasticity trends in infancy

* Large amounts of information to learn therefore synaptogenesis and myelination will be required for the foundation of skills learnt.
* Skills refine at 2-3 therefore pruning occurs

Neuroplasticity trends in adolescence

* Individuals still continue to learn as they grow older, synaptogenesis and myelination are vital for higher mental processes and complex functions
* Synaptic pruning occurs rapidly during adolescence to refine skills learnt throughout childhood and to remove unused neural connections

brain trauma

damage to the brain that is caused by an external force

adaptive plasticity

the brain’s ability to restore adequate neural functioning over time after sustaining injury

sprouting

a neuron’s ability to develop new branches on the dendrites or axons

* allows for new neural connections to be made where depleted

rerouting

a neuron’s ability to form a new connection with another undamaged neuron

* allows for cognitive functioning to be re-developed

ways to maximise brain functioning

* diet
* physical activity
* social support
* mental stimulation

**DP4: the impact of an acquired brain injury (ABI) on a person’s biological, psychological, and social functioning**