biopsychology 2 Flashcards
What is Localisation of Function?
Broca and Wernicke discovered that there were specific parts of the brain associated with different
Functions
If a certain area of the Brain get Damaged it will impair the Function of that area
What are the Hemispheres of the Brain?
We have a Left Hemisphere and a Right Hemisphere
- Left side of the Body is controlled by Right Hemisphere
- Right side of the Body is controlled by Left Hemisphere
What is the Cereberal Cortex?
The Outer Layer of Both Hemispheres
How is the Brain Divided?
Both Hemispheres are Divided into 4 ‘Lobes”
- Frontal Lobe
- Parietal Lobe
- Occipital Lobe
- Temporal Lobe
Each lobe is associated with a different function
What is the Frontal Lobe’s Function?
Contains the Motor Area
- Controls Voluntary movement in the Opposite Side of the Body
- Damage to this area may lead to the loss of Control over Fine Movements
What is the Parietal Lobe’s Function?
Contains the Somatosensory Area
- Is where Sensory Information is processed
- The amount of area devoted to a particular Body Part Denotes it Sensitivity (e.g. Hands are very sensitive = Large Area)
What is the Occipital Lobe’s Function?
Contains the Visual Area
- Information from the Right Visual Field goes to the Left Visual Cortex
- Information from the Left Visual Field goes to the Right Visual Cortex
What is the Temporal Lobe’s Function?
Contains the Auditory Area
- Damage to this area may cause Hearing Loss
- Damage to specific areas may cause specific consequences
What Happens if Wernicke’s Area suffers Damage?
Damage to Wernicke’s area can lead to an inability to comprehend Language
- Wernicke’s area is responsible for Language Comprehension
- Wernicke’s Aphasia can cause someone to speak in Gibberish (Neologisms)
What Happens if Broca’s Area suffers Damage?
Damage to Broca’s area can lead to an inability to produce Language
- Broca’s area is responsible for Language Production
- Broca’s Aphasia can cause someone to speak Very Slowly and Lack Fluency
Strength of Localisation of Function
Evidence from Brain Scans
- Petersen et al used Brain Scans to show that Wernicke’s area was Active during Listening Tasks and Broca’s area during Reading Tasks
- Buckner and Petersen found that Semantic and Episodic Memories reside in Different parts of the Prefrontal Cortex
- Therefore there is Scientific Evidence for the Brains Function
Limitations of Localisation of Function
Individual and Gender Differences
- Bavellier found Variation in both Left & Right Temporal Lobe, and Left Frontal & Occipital Lobes
- Harasty found Women’s Broca’s Area & Wernicke’s Area were Larger than Mens
Equipotentiality
- Plaza found that slow destruction of Broca’s Area by Brain Tumors can leave Speech relatively Intact
- This Suggests that its Function can Shift to Nearby Brain Areas
- Idea that the Localisation isn’t Permanent and can be in Different Areas
What is Hemispheric Lateralisation?
The idea that the 2 Halves of the Brain are Functionally Different and that each Hemisphere has Different Dominances
- The Left is Dominant for Language Tasks
- The Right is Dominant for Motor Tasks
What is Split Brain Research?
A Split Brain operation is the severing of Connections between the Left Hemisphere and the Right Hemisphere
- This is done by Cutting the Corpus Callosum
- This is often done to Treat Seizures
What was Sperry’s Split Brain Research?
- 11 People with Split Brains were studied by putting an image in their Right Visual Field (Processed by Left Hemisphere) and then putting an image in their Left Visual Field (Processed by Right Hemisphere)
- Found that when something was shown to the RVF the participant could Describe what was seen
- When something was in the LVF they could not Describe what was seen
- Participants could match and object out of sight in their Left Hand (Right Hemisphere)
Strength of Split Brain
Related to Increased Neural Capacity
- By using 1 Hemisphere to do a Task the other is Free to do another function
- Rogers et al Found that in a Chicken Brain Lateralisation is associated with Enhanced Ability to Perform 2 Tasks Simultaneously
Limitations of Split Brain
Associated Disadvantages
- Left Handed people are more likely to suffer from Allergies and Problems with Immune System
- Tonnessen et al found that Genetic processes for Lateralisation are also for Immune System Development
Gender Differences
- Females have Bilateral Brain Usage during Linguistic Tasks whereas Men have more Left Brain Only
- Females have Bilateral Brain Usage in Spatial Tasks whereas Men have more Right Brain Only
- Studies Suggests Women have a Thicker Corpus Callosum
what is Brain Plasticity?
The brains Ability to Change and Adapt because of Experience
What is an Example of Brain Plasticity?
Maguire et al
- The role of the Hippocampus is to facilitate Spatial Memory
- Black Cab drivers undergo Extensive Memory Training (‘The Knowledge’) which makes them an ideal Test Group
- 16 Right Handed Male Black Cab drivers and 50 Right Handed Non-Black Cab drivers given MRI scans
- Found Increased Grey Matter in Hippocampi of Taxi Drivers compared to controls
- Found Increased Volume in Posterior Hipocampi of Cab Drivers
Strengths of Brain Plasticity
Supportive Evidence
- Kempermann studied Rats to see whether Enriched Environments could Alter Neurones in the Brain
- Found that Rats housed in a Complex Environement Showed increased amount of Neurones in the Hippocampus
- Supports idea that Life Experiences can affect Brain Plasticity
Supportive Evidence
- Boyke taught a group of 60 Year Olds to Juggle and found increased Grey Matter in their Visual Cortex
- However this Reversed when they Stopped Juggling
Limitation of Brain Plasticity
Negative Plasticity
- 60-80% of Amputees develop ‘Phantom Limb Syndrome’ which is Painful and Unpleasant
- Ramachandran and Hirstien found that this was due to Cortical Reorganisation in the Somatosensory Cortex
What is Functional Recovery?
The Transfer of Functions from a Damaged Area of the brain after Trauma to other Undamaged Areas
What is Neuronal Unmasking in Functional Recovery?
Where the Brain is able to ‘Rewire’ itself and Create Alternative Pathways around Damaged Areas and Taking over Functions that were Lost
What are Stem Cells in Functional Recovery?
A Treatment that involves Functional Recovery as Stem Cells can Replace Dead / Dying cells in the Brain
- Stem Cells can also help the Regeneration of Damaged Cells or Link an Undamaged Brain Site with a Damaged one
Strengths of Functional Recovery
Stem Cell Evidence
- Tajiri gave Rats with Traumatic Brain Injuries a Stem Cell Solution
- After 3 Months they had Recovered better than a Control Group
Real-World Application
- Has been involved in Neurorehabilitation and the Development of New Therapies (E.g. Constraint Induced Movement Therapy)
Limitations of Functional Recovery
Cognitive Reserve
- Schnieder found that those with a Higher Education Level (indicated of Cognitive Reserve) were more likely to Recover
- 40% of those who achieved a Disability-Free Recovery (DFR) had over 16 Years of Education Compared to 10% for people with 10 Years of Education
- Could be Socially Sensitive
What are the Methods of Brain Imaging?
- fMRI
- EEG
- ERG
- Post Mortem
What is a fMRI?
It Measures Blood Flow in the Brain when a person performs a Task
- Neurones in the Brain that are the Most Active require the Most Energy & Oxygen / Blood
Strength of fMRI
Good Spatial Resolution
- Within 1-2mm
Limitations of fMRI
Inference
- Blood flow = Brain activity is only Correlational
Low Temporal Resolution
- Approx 1-4 secs
- Slow in Terms of the Brain
What is an EEG?
Measures Electrical Activity through Electrodes attached to the Scalp
- Information is Processed in the Brain as Electrical Activity in the form of Action Potential
Strength of EEG
Applicable to Medicine
- Can be used to detect Illnesses like Epilepsy and Sleep Disorders
Limitations of EEG
Bad for Localisation of Function
- Hard to Locate Activity due to Size and Placement of Nodes
Low Mundane Realism
- Not Representative of Normal Sleep
What is an ERP?
Similar Equipment to EEG
- Stimulus presented to participant (E.g. Picture or Sound) & Researcher looks for Activity
- Stimulus is presented Hundreds of Times and an Average Response is Graphed
Strength of ERP
Good Temporal Resolution
- 1-10 milliseconds
Limitation of ERP
Bad Spatial Resolution
- not as good
What is a Post Mortem Scan?
Studying a Physical Brain of a Person who displayed a particular Behaviour when they were Alive
Strength of Post Mortem
Vital for Early Discoveries
- Broca and Wernicke relied on this for their Discoveries
Limitation of Post Mortem
Ethical Issues
- Hard to gain Informed Consent before the persons death
Limitation of Brain Scans
Lack of Causation
- not enough Explanation of why in:
- fMRI (only blood flow changes)
- Post Mortem
- EEG (Hard to Pinpoint)
What is the Circadian Rhythm
Our 24 hour ‘Body Clock’ that is reset by Light
- Light provides the Primary Input to this system
- When Light is first detected it sends a message to the Suprachiasmatic Nuclei
- the Circadian Rhythm dips Energy Levels at 2-4am and 1-3pm
What was Siffre’s Research into Circadian Rythyms?
- He spent prolonged amounts of time Underground to study his own Biological Rhythms
- He was deprived of Light but had supplies of Food and Water
- In these Experiments his Circadian Rhythm settled on a 25 Hour Cycle rather than 24 Hour
What was Aschoff and Weber’s Research into Circadian Rhythms?
- Studied participants living in a Bunker with no Windows and only Artificial Light
- Found that Participants settled into a longer Sleep / Wake Cycle of 24-25 hours (other than one who was 29 hours)
- Demonstrates the Importance of Light for a Circadian Rhythm
Strengths of Circadian Rhythms
Chronotheraputics
- The time that Medicine is taken can have an effect on the success of the Treatment
- Heart Disease Medication has been designed to be Taken before bed but to be Released in the Morning (the most likely time for a Heart Attack)
Supportive Evidence
- Hughes studied and Antarctic Station where there was 3 months of Continuous Darkness
- Found that Cortisol peaked at Noon (makes you wake up)
- But the participants were not Alone and had access to other cues about time
Limitation of Circadian Rhythms
Individual Differences
- The Studies done for this were on very Small Samples and may not be Generalisable
- Duffy et al found that there were people with a Preference for Going to Bed Early and Rising Early, and those who Went to Bed Late and Rose Late
What are Ultradian Rhythms?
Cycles that occur under 24 hours
- Best shown in the Sleep Cycle
What is the Sleep Cycle?
5 Stages
- Roughly 90 min cycle
- 5x a night
What is Stage 1 of the Sleep Cycle?
- Muscle Activity Slowed Down
- Occasional Muscle Twitching
- Light Sleep
What is Stage 2 of the Sleep Cycle?
- Breathing Patterns and Heart Rate slows
- Decrease in Body Temp
What is Stage 3 of the Sleep Cycle?
- Deep Sleep Begins
- Brain begins to generate slow Delta waves
What is Stage 4 of the Sleep Cycle?
- Very Deep Sleep
- Rhythmic Breathing
- Limited Muscle Activity
- Delta Waves
What is Stage 5 of the Sleep Cycle?
- Rapid Eye Movement (REM)
- Supposedly Dreaming
- Paralysed
- Desynchronised Brain Waves
Strengths of Ultradian Rhythms?
Dement and Kleitman
- Made link between dreaming and REM sleep
- Sample of 5 Participants in Sleep Lab with EEG machine
- Woken as Specific Intervals to ask if they were Dreaming
- Found Positive Correlation between REM and Dreaming
Kleitman
- Support for 90 min Cycles
- Found we have 90 min Cycles when awake too called BRAC (Basic Rest Activity Cycles)
- Supported by Ericson who found violinists will practice in 90 min Sessions
Limitation of Ultradian Rhythms
Individual Differences with Age
- Van Cauter et al did study of 149 men
- Found reduction in amount of Deep Sleep as the men got older
- Can be explained by reduction in Growth Hormones with Age
Dement and Kleitman Counterpoint
- Based on Correlation
- Sleep lab not representative of Real Life Sleep
What are Infradian Rhythms?
Cycles longer than 24 hours
- E.g the Menstrual Cycle - Regulated by Hormones (Oestrogen peaks at Ovulation)
- E.g Seasonal Affective Disorder - Regulated by Seasons (Lack of Sunlight causes Higher Melatonin and Lower Serotonin - leading to Depression)
Infradian Rhythms Strengths
Rosen et al
- Large scale American Study into Seasonal Affective Disorder
- Measured prevalence rates of SAD
- Found Winter SAD rates were higher in Northern America where it would be darker and colder
Reinburg
- Examined a Women who spent 3 months in a cave
- Her Menstrual Cycle went from 28 days to 27.5 dyas
Infradian Rhythms Limitaion
Russel et al
- Could be External Factors
- Females Menstrual Cycles could be synchronised when exposed to the smell of the sweat of another group of women
