Biopsychology Flashcards
BRAIN PLASTICITY - what is it?
The brain ability to change and adapt (functionally and physically) as a result of damage and new learning.
It was thought that changes were restricted to the developing brain within childhood and that the adult brain, having moved beyond a critical period, would remain fixed and static in terms of function and structure. However, more recent research suggests that existing neural connections can change and new ones can be formed.
INFANCY ( infancy the brain grows in the number of synaptic connections, peaks to 15 000 per neuron by 3 years old )
ADULTHOOD ( twice as many as infant )
FUNCTIONAL RECOVERY - what is it?
Functional recovery refers to the way in which the brain may recover following trauma. (form of neural plasticity).
The brain is able to rewire and reorganise itself by forming new synaptic connections to redistribute functions following damage through trauma.
SYNAPTIC PRUNING (functional recovery) - what is it?
As we age, rarely used neural connections are deleted and frequently used connections are strengthened.
AXONAL SPROUTING (functional recovery) - what is it?
Undamaged axons grow new nerve endings to reconnect neurons whose links were injured or severed following trauma.
DENERVATION SUPERSENSITIVITY (functional recovery) - what is it?
Axons that complete a similar job become aroused to compensate for those lost.
RECRUITMENT OF HOMOLOGOUS AREAS (functional recovery) - what is it?
regions on opposite hemispheres of the brain take on the function of damaged areas.
BRAIN PLASICITY AND FUNCTIONAL RECOVERY - what are the strengths and limitations?
(-) NEGATIVE PLASTICITY - 60-80% of amputees experience phantom limb syndrome, thought to be due to reorganisation in the somatosensory cortex that occurs as a result of limb loss. suggests that that brains ability to adapt to damage is not always beneficial.
As was as this, prolonged drug use leads to poorer cognitive functioning later in life.
(+) AGE AND PLASTICITY - in general plasticity reduces with age, but Bezzola’s study demonstrated that 40 hrs of golf training produced changes in neural representations of movement in PPs aged 40-60. fMRI scans were used by researchers, who found increased motor cortex activity in the novice golfers compared to a control group (suggests more efficient neural representations).
(+) PRACTICAL APPLICATION - contributed to the field of neurorehabilitation. Understanding axonal growth encourages the development of new therapies such as constraint-induced movement therapy used with stroke patients.
COUNTERPOINT - however research into the effectiveness of neurorehabilitation therapies are often based on small sample sizes with no control groups.
WAYS OF STUDYING THE BRAIN - what is functional magnetic resonance imaging (fMRI)?
fMRI detects changes in blood oxygenation and flow as a results of neural changes in certain sections of the brain.
when a brain area is more active, it consumes more oxygen, in order to meet this higher demand blood flow is directed to the active area.
fMRIs produce 3d images that help with understanding localisation of function as it shows which part of the brain is used in a particular mental process.
WAYS OF STUDYING THE BRAIN - what are the strengths and limitations of fMRI?
STRENGTHS -
*does not rely on radiation like other techniques
*non invasive and essentially risk free
*images have high spatial resolution (detail by the mm)
LIMITATIONS -
*expensive compared to other techniques
*poor temporal resolution (5 seconds time lag between image and actual neuronal activity)
WAYS OF STUDYING THE BRAIN - what is an electroencephalogram (EEG)?
An EEG measures electrical activity within the brain via a skull cap (electrodes fixed to a persons scalp). The scan recording represents the brainwave patterns generated from the action of thousands of neurons. Often used as a diagnostic tool by clinicians as arrhythmic patterns of activity may indicate neurological abnormalities (for example, epilepsy, tumours or sleep disorders).
WAYS OF STUDYING THE BRAIN - what are the strengths and limitations of EEG?
STRENGTHS -
*useful in studying the stages of sleep and the diagnosis in conditions such as epilepsy (random bursts of neural activity that can be detected on screen).
*high temporal resolution (within a millisecond)
LIMITATIONS -
*generalised nature of the information received.
* not useful for pinpointing the exact source of neural activity.
WAYS OF STUDYING THE BRAIN - what is event related potentials (ERP)?
within EEG data are all the neural responses associated with specific sensory, cognitive and motor events that may be of interest. As such, researchers have developed a way of isolating these responses using a statistical averaging technique (where all extraneous brain activity from the EEG is filtered out leaving only the responses to stimuli or performance).
EEG - type of brainwaves that are triggered by certain performances or stimuli.
FOR EXAMPLE - one form of ERP are linked to cognitive processes such as attention and perception.
WAYS OF STUDYING THE BRAIN - what are the strengths and limitations of ERP?
STRENGTHS -
*high temporal resolution (means they can be used to measure cognitive functions such as maintenance of working memory).
*useful for pinpointing the exact source of neural activity.
LIMITATIONS -
*Lack of standardisation between studies (difficult to confirm findings)
*not easy to achieve as extraneous material must be completely eliminated to get pure data.
HEMISPHERIC LATERISATION - what is it?
Lateralisation refers to the idea that some of our physical and psychological functions are controlled or dominated by a particular hemisphere.
*LANGUAGE - language is lateralised as the LH contains the two main language centres, the RH can produce rudimentary words but can add emotional context.
Many functions are not lateralised:
*MOTOR and SOMATOSENSORY - the brain is cross-wired
*VISUAL - each eye receives light from both the LVF and the RVF, enabling visual areas to compare perspectives and aids depth perception.
SPLIT BRAIN RESEARCH - what is this?
A split brain operation involves severing the connections between the LH and the RH, mainly the corpus collosum. (used to reduce the fits associated with epilepsy).
PROCEDURE - 11 people who had this operation were studied using a special set up. (image projected to a persons RVF and the same or different image was projected on to a persons LVF. Presenting the image to one hemisphere of a split brain PP meant info cannot be shared.
FINDINGS -
image shown to PP RVF = could describe what was seen.
image shown to PP LVF = could not give verbal labels to image but could identify image (or most closely associated image) using left hand.
