Biopsychology Flashcards
In the early 19th century what did scientists support
The holistic theory of the brain - all parts were involved in the process of thought and action
What is the localisation theory
Theory that different areas of the brain are responsible for different behaviours, processes or activities
What is the brain divided into
Two symmetrical halves called left and right hemispheres
What is lateralisation
Idea that two halves of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other
What is the left hand side of the body controlled by
The right hemisphere
What is the right hand side of the body controlled by
The left hemisphere
Characteristics of the cerebral cortex
Covers inner parts of the brain.
3mm thick and is what separates us from lower animals as it is highly developed.
Appears grey.
What does the cerebral cortex appear grey
Due to the location of cell bodies (‘grey matter’)
What is the cortex of both hemispheres divided into
Four loves: frontal, parietal, occipital and temporal
What is at the back of the frontal lobe
The motor area which controls voluntary movement on the other side of the body
What does damage to the motor area result in
A loss of control over fine motor movements
What is at the front of both parietal lives
Somatosensory area where sensory information from the skin is represented (touch, heat, pressure)
What denotes a particular body parts sensitivity
Amount of somatosensory area devoted to that area
What is in the occipital area at the back of the brain
The visual area. Each eye sends information from the right visual field to the left visual cortex and from the left visual field to the right visual cortex
What is the visual area/cortex
Part of the occipital love that receives and processes visual informtistionn
What is the frontal lobe
Area of the brain responsible for logical thinking and making decisions
What is the motor cortex
Part of the brain responsible for controlling movement
What csn damage to the occipital lobe in the left hemisphere result in
Produce blindness in part of the right visual field of both eyes
What is in the temporal lobe
Auditory area which analyses speech-based information
What can damage to the temporal lobe result in
Partial hearing loss, the more extensive the damage the more serious the loss
Who identified a small area in the left frontal lobe responsible for speech production
Broca
What did broca find
Broca’s area - an area in the frontal lobe of the brain in the left hemisphere responsible for speech production
What does damage to Broca’s areas cause
Brocas aphasia which is characterised by speech that is slow, laborious and lacking in fluency. Patients may have difficultly finding words and naming certain objects or difficultly using prepositions and conjunctions ( small words that link sentences)
Who identified an area in the back of the temporal lobe important for language comprehension
Wernicke
What did Wernicke find
Wernickes area in the back of the temporal lobe. Patients with damage in this area had no problem producing language but severe difficulties understanding it - speech was fluent but meaningless.
What do patients that have Wernickes aphasia often produce
Nonsense words (neologisms) as part of the content in their speech
Strength of localisation theory (evidence)
Brain scan evidence to support. Supports that many neurological functions are localised particularly in related to language and memory. Tulving did a study on memory and revealed that semantic and episodic are located in different parts of the frontal cortex. This provides sound scientific evidence of localisation.
Limitation of localisation of function
Existence of contradictory research. Lashley suggests that higher cognitive functions such are processes involved in learning are not localised but distributed more holistically. Lashley remover areas of the cortex in rats that were learning a maze. No areas were shown to be more important in the rats ability to learn the maze. Process of learning seemed to require every part of the cortex rather than being confined to a single area. Suggests learning is too complex to be localised and is more holistic
Limitation of localisation theory (neural plasticity)
Argument against localisation is neural plasticity. When the brain has become damaged and a particular function has been compromised, the brain appears able to reorganise itself in an attempt to recover the lost function. Lashley describes this as the law of equipotentiality where surviving brain circuits chip in so the same neurological action can be achieved. This does not happen every time but there are several documented cases of stroke victims being able to recover abilities that were seemingly lost
Strength of localisation of function (case studies)
Support form case studies.
Phineas Gage received brain damage in an accident.
He went from someone who was calm and reserved to someone who was rude and quick tempered.
Change in gages temperament suggest that the front lobe may be responsible for regulating mood
During infancy what does the brain experience
A rapid growth in synaptic connections. This peaks at approx 15,000 at age 2-3 years
What is synaptic pruning
As we age rarely used connections are deleted and frequently used connections are strengthened
What does more recent restful into synaptic connections suggest
That neural connections can change it be formed at any time in life as a result of learning and experience
What is neural plasticity
Describes the brains tendency to change and adapt (functionally and physically) as a result of experience and new learning
What is plasticity also referred to as
Cortical remapping
Key study into the concept of neural plasticity
Maguire et al
What did maguire study
The brain of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than a matched control group. Appears learning through experience alters the structure of the taxi drivers brains.
What is the posterior hippocampus sssocsted with
The development of spatial and navigational skills
As part of their training, what do London cabbies have to take
A complex test called ‘the Knowledge’ which assesses their recall of the city streets and possible routes
What did Maguire find about the taxi drivers brains in relation to how long they’ve worked
The longer they’d been in the job the more pronounced the structural difference
Secondary study into plasticity
Draganski
What did Draganski find
He imaged the brains of medical students three months before and after their final exams. Learning-induced changes were seen to have occurred in the posterior hippocampus and the parietal cortex, presumably as a result of the exam
What is functional recovery
Form of plasticity. Following damage through trauma, the brains ability to redistribute or transfer functions usually performed by a damaged area to other undsmshed areas
Example of neural plasticity
Functional recovery
What is spontaneous recovery in relation to functional recovery
Neuroscientists suggest the process of functional recovery can occur very quickly after trauma which is spontaneous recovery.
It then slows down at which point the person may require rehabilitative therapy.
How does the brain rewire and reorganise itself after damage
It forms new synaptic connections close to the area of damage. Secondary neural pathways that would not typically be used to carry out certain functions are activitsted and enables functioning to continue
Three ways structural changes may happen
Axonal sprouting
Reformation of blood vessels
Recruitment of homologous areas on the opposite side of the brain to perform specific tasks
What is axonal sprouting
The growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways
Strength of research into pasticisty and functional recovery
Practical applications.
Understanding the processes in pasticity has contributed to the field of neurorehabilitstion.
This make include electrical stimulation of the brain to counter the defecits that may be experienced following a stroke for example.
This shows that the research has been used to help people after trauma
Limitation of neural plasticity (negative consequences)
Negative consequences. 60-80% of amputees develop phantom limb syndrome, these sensations are usually unpleasant and painful and thought to be due to reorganisation in the somatosensory cortex. Such evidence suggests that the structural and physical processes in functional recovery may not always be beneficial
Strength of plasticity (case studies)
Documentated cases of people developing echo location after losing their sight. After losing sight at a young age some people are able to compensate by learning echo location - not usually a synaptic connections we have access to. This suggests that there has been rewiring in the brain to create the neural pathway supporting the theory of functional recovery.
What is an example of hemispheric lateralisation
Ability to reproduce and understand language.
Which hemisphere controls language
Left hemisphere
Who investigated split brain respect
Sperry
What is Spit brain research
A series of studies involving epileptic patients who have experienced a surgical separation of the hemispheres of the brain. Allows researchers in investigate the extent to which brain function is based
Who did Sperrys split brain reaerch involve
Participants who had undergone the same surgical procedure ( a commisuortomy). In this operation the corpus callosum which connects the two hemispheres is cut to control epileptic seizures. The Consequence is the hemisphere can no longer communicate with each other.
What did Sperrys research allow him to see
This allowed Sperry to see the extent to which the two hemispheres were specialised for certain functions and how they perform tasks independently from one and other
What was Sperrys procedure
An image or word could be projected to a patients right visual field (processes by left hemisphere) and the same or different image could be projected to the left visual field (processes by right hemisphere). In the split brain the information could not be conveyed from the chosen hemisphere to the other like a normal brain would do
Findings of Sperrys study (describing what was seen)
Whena picture was shown to a patients right visual field the patient could describe it. However if the picture was shown to the left visual field the patient couldn’t describe what was seen. Patients inability to describe objects in the left visual field (processes by right hemisphere) is because of the lack of language centres in the right hemisphere in most people. In normal brain the messages received by the RH would be relayed via the corpus callosum to the language centres in the LH
What is the connection between teo hemispheres called
Corpus callosum
Findings of Sperrys respect (recognition by touch)
They couldn’t attach verbal labels to objects (as left hemisphere is needed for this) but could select a matching object from a bag using their left hand (connected to the right hemisphere which receives information from the left visual field). Objects placed behind a screen so couldn’t be seen.
Left hand also able to select objects that were closely associated with the picture like an ashtray in response to a cigarette.
Findings of Sperrys research (composite words and matching faces)
Two words presented in either side of the visual field. If key was presented to left and ring to the right the patient would select a key with their left hand (left hand controlled by right hemisphere linked to left visual field) and day the word ring (right visual field linked to left hemisphere)
Why does the right hemisphere appear to be dominant in terms of matching faces
When patients asked to match a face from a series of other faces he picture processes by the right hemisphere (left visual field) was consistently selected.
In Sperrys study when a compost Ute picture made up of two different halves of a face was presented what happened
The left hemisphere dominated in terms of verbal description whereas the right hemisphere dominated in terms of selecting a matching picture
Strength of Sperrys work
Prompted a debate about the nature of the brain. Some say that the two hemispheres are so functionally different they repsresenr a form of duality in the brain - that in effect we are two minds. In contrast, others argue that they hemispheres are a highly integrated system and work together during most takes. The value of Sperrys work is promoting this debate
Limitation of Sperrys work
Issues with generalisation. Many researchers have said that split brain studies can not be widely accepted as the patients are an unusual sample of people. There were only 11 pettiness who took part in the procedure all of whom had a history of epileptic seizures. Could be argued this caused unique changes in the brain that may have influenced findings. Limits he extent to which the findings can be generalised to normal brains reducing the validity
Strength and weakness of Sperrys work
Demonstrates lateralised brain functions. Left hemisphere is geared towards analytic and verbal tasks whilst the right is more adept at performing spatial and music showing the lateralised function. However recent research has suggested that even this distinctions may be overly simplified and that several tasks are associated with one hemisphere cns be successfully carried by the other
What are four ways of investigating the brain
FMRI
EEG
ERPs
Post mortem
Why do psychologists use medical techniques
So they can investigate localisation in the brain
How does FMRIS work
They detect changes in blood oxygenation and flow that occurs due to neural activity in specific brain areas. When a brain is more active it consumes more oxygen and blood flow is directed to the active area. FMRI produce a 3D image showing which part of the brain are involved in particular mental processes
What is the name for blood flow being directed to the active area
Haemodynamic response
How do EEGs work
Measures electrical activity within the brain via electrodes using a skull cap. The scan recording represents overall brain activity. EEG is often used as a diagnostic tool.
What is brain activity
The brain wave pattern generated from millions of neurons
What may unusual arrhythmic patterns of brain activity indicate
Abnormalities such as epilepsy, tumours or sleep disorder
How to ERPS work
Using a statistical technique, all extraneous brain activity from an EEG recording is filtered out leaving only the responses that relate to for example the presentation of a specific stimulus. What remains are ERP.
What are ERPS
Event related potentials - types of brainwave that are triggered by particular events.
What has research revealed about ERP
There are many different forms and how these are linked to cognitive processes such as perception and attention
What is a post mortem examination
Technique involving the analysis of a persons brain following their death. Areas of the brain are examined to establish the likely cause of someone’s death - this may involve comparison with a neurotypical brain in order to assess the extent of difference
Strengths of FMRI
- unlike other scanning techniques like PET it does not reply on the use of radiation so it is safe
- it is non invasive
- produces high spatial resolution showing detail to the millimetre which means it can provide a clear picture of his brain activity is localised
Weakness of FMRI
- expensive
- can only capture a clear image if the person stays still
- poor temporal reduction because there is around a 5 second lag time behind the image on the screen and the initial firing of neural activity. Means it may not truest represent moment to moment brain activity
Strengths of EEG
- proved invaluable in diagnosing conditions such as epilepsy
- contributed to our understanding of the stages in sleep
- extremely high temporal resolution (can accurately detect brain actuary at a resolution of a single millisecond)
Weaknesses of EEG
- not useful for pinpointing the exact source of neural activity
- does not allow researchers to distinguish between activity coming from different but adjacent locations
Strength of EPR
- produce specific measurements of neural processes
- much more specific than using raw EEG data
- excellent temporal resolution like EEGS. Especially good wen compared to FMRI and this has led to widespread use in the measurement of cognitive functions and deficits
Weakness of ERPS
- lack of standardisation in ERP methodology between studies
- this makes it difficult to confirm findings in studies involving ERPS
- in order to establish pure data in ERP studies background noise and extraneous material must be completely eliminated which is difficult to achieve
Strength of post mortem
- vital in producing a foundation for early understanding of key processes in the brain e.g Einstein’s brain was found to be different to everyone else’s
- broca and Wernicke relies on post mortem studies
- improve medical knowledge
- help generate hypotheses for further study
Weakness of post mortem
- causation may be an issue( observed damage may not be linked to deficits under review but another trauma)
- raise ethical issues of consent from the patient before death S they may not be able to produced informed consent
Example of patient where post mortem was done without consent
Patient HM who lost his ability to form memories and wasn’t able to provide full consent
What does standardisation mean
Using exactly the same formalised procedures and instructions for all participants in a research study
