PARTS OF THE BRAIN

Cerebrum= largest part of the brain. Divided into two hemispheres, into four lobes.

Cerebellum- not that. a lobe. controls motor skills and balance 

Peripheral Nervous System!

Autonomic= Involuntary movements such as breathing, heart beat, digestion, stress response . Carries commands from the brain stem.

Somatic= Voluntary muscle movement. Transmits info from the sensory receptors to CNS. Carries commands from the motor cortex. Only excitatory movement.

Autonomic: Sympathetic and Parasympathetic NS

FIGHT OR FLIGHT RESPONSE

Acute response:

When our  body sees a stressor, the AMYGDALA associates what we see with an emotion. The stressor sends a signal to the hypothalamus.

The hypothalamus sends nerve impulses along the SYMPA to prepare the body for immediate acions. It goes in several places, one is the adrenal medulla.

SO your adrenal medulla (in the pancreas) secretes adrenaline and nor-adrenaline into the bloodstream. This amplifies the effects of the normal sympathetic nervous system.

Your pupils dilate, heart-rate increases, salivary glands are inhibited, digestion inhibited, bronchi dilate, liver produces glucose.

Hormones and the endocrine system

Usually work in parallel with the autonomic NS.

The endocrine system controls the secretion and production of hormones to be sent to certain parts of the body via the bloodstream.

An important one is the PITUITARY GLAND, which releases hormones that controls the production of other hormones wow. Its controlled by the hypothalamus in the brain.

The anterior pituitary gland is responsible for the production of ACTH, which is the main stress hormone.

Its responsible for stimulating the adrenal cortex to release corticosteroids such as CORTISOL.

Cortisol is released under long -term stress.

It is responsible for: lowering sensitivity to pain, glucose production?, lowering immnue response,  

THEREFORE long-term stress can cause illness and possible coronary heart disease

NEURONSSSSS

Between Receptors and the CNS

Between muscles and the CNS to allow movement yo

Between sensory and motor!

Evaluation of Brain Localisation

A lot of supporting evidence-

e.g the case of Phineas Gage, who suffered a motor accident where a pole went through his head, his personality changed.

this provides evidence that the part of his brain that was damaged must have been related to mood regulation.

This is supportive, however the method used to research PG was questionable, they asked his friends how he was before the accident, may not be the most accurate way to determine personality change

Evaluation of Brain Localisation

We have better, more scientific ways of knowing how the brain works

COME BACK

Evaluation of Brain Localisation

There is evidence for Wernicke's and Broca's areas from brain scans.

Peterson and et al found that Broca's area was active during reading tasks whereas Wernicke's area was active during a listening task. This demonstrates that these areas of the brain have different/seperate functions.

What's more, damage to these areas specifically leads to aphasia

~explain how that works~

this demonstrates the validity of assigning function to parts of the brain.

Evaluation of Brain Localisation

HOWEVER

Evidence from Lashley suggests otherwise. Her theory of equipotentiality suggests that different parts of the brain can take over the function for those that are damaged.

This view is an opposing limitation that is supported by research into functional recovery. It has been found that in the brain of stroke victims, the brain can re-wire itself over time and that patients can regain some function.

This goes against the theory of localisation, and shows that different areas of the brain may be able to perform several fucntions

Split Brain Research 

Results and Conclusions?

Split Brain Research EVALUATION 

Ecological validity

- Apparatus and method were highly reliable, participants blindfolded etc.

- This is an issue because in real life, split brain patients use both eyes. the other eye usually compensates for the lack of corpus collosum

Split Brain Research EVALUATION 

Split Brain Research EVALUATION 

THE BRAIN AND TRAUMA 

Plasticity and functional recovery 

What is Trauma?

Traumatic brain injury occurs when an external mechanical force causes brain dysfunction. Traumatic brain injury usually results from a violent blow or jolt to the head or body.

Can result in cognitive, behavioural and psychological impairment

Resarch into Plasticity

GOPNICK ET AL- Found that the number of synaptic connections in the brain peaks at 15,000 around 2-3 YEARS OLD. 

Twice as many as the average adult brain. 

the decline is due to SYNAPTIC PRUNING , in which rarely used connections are deleted.

MAGUIRE + WOOLETT (The Knowledge)

Used MRI scans on 16 Black Cab drivers and 50 controls.

The cab drivers had all passed the Knowledge, which is an extensive memory test of thousands of roads and POIs around London. 

They found increased grey matter in the POSTERIOR HIPPOCAMPI in both hemispheres than the control group.

A positive correlation was seen between increase of size and time spent as a taxi driver.

This suggests that extensive time with spatial navigation can affect the hippocampus PHYSICALLY. 

DRAGANSKI

MRI SCANS at 3 different points of a medical students life lol.

3 months before, day after and 3 months after medical exam.

During the first three months, the grey matter increased significantly in the parietal cortex bilaterally

Changes remained after 3 months.

* Increased grey matter was more prononuced 3 months after than the day after, so volume continued to increase.

Learning a large amount of information can LEAD TO STRUCTURAL CHANGES IN THE BRAIN.

Applications in neurohabilitation

- Research shows that the brains ability to repair itself slows after a few weeks.

- We know now that further intervention is necessary: physio or electrical stimulation, to stimulate the growth of cells.

*important economic implications because it means that more elaborate, expensive solutions do not have to be considered.

Evaluation

There is evidence that plasticity occurs all throughout life, not just childhood.

Bezzola et al used ppts aged 40-60, found that there was reduced motor cortex activity during their swing after golf lessons compared to a novice control group. Shows that they learned, brains became more efficient - ADAPTED from an external stimulus.                                           Also supports the use of fMRI scans..

Evaluation

BUT there are individual differences in the brains ability for functional recovery.

SCHNEIDER found that the more time an individual spent in education, the more likely they were to have a DFR (disability-free recovery) after brain trauma.

People with university-level education were 7x more likely to achieve DFR.

This is evidence for a 'cognitive reserve', which occurs as a result of education.

However, DATA COLLECTION was retrospective and no IV was manipulated, so we cannot know if results are directly/only linked to education.

Support from animals studies

TAJIRI injected rats with brain trauma with stem cells.

Three months later they showed recovery and clear development of neuron-like cells. The same was not seen in the control group. This shows the effect of stem cells and demonstrates their usefulness.

However, stem cells are a controversial area of treatment, not easily come by, animals.

Evaluation

fMRI Scans

How does it work?

fMRI machines detect changes in blood oxygenation and blood flow that occurs in the brain as a result of neural activity.

When areas of the brain are active, they require more bloodflow for oxygen. This is known as the haemodynamic response

What Does it show?

A 3D image showing which part of the brain is active during activit 

For whom can you use it?

• For soft tissue (the brain for example)

• Bodies with no metal in them

• People who do not have claustrophobia

• If you wanna study internal mental processes

Advantages

• Provides a 3D image of bloodflow
• No radiation (unlike PET)
• Non-invasive
• Risk free
• High spatial image

Disadvantages

• Expensive
• Poor temporal resolution (5-second lag) between image on screen and firing of neurons
• Only shows bloodflow, not actual neural activity or individual neurons

Electroencephalograms 

EEGs

How Does it Work?

Electrodes are placed on the scalp.

Electrical activity in the brain is measured for a certain length of time.

Measures the activity of many electrons firing at once, not individual ones.

What does it show?

Shows overall electrical activity.

Patterns of waves are produced that represent levels of arousal or consciousness at different times and in response to different stimuli.

What is it used for?

• Used in sleep studies to measure the stages of sleep

• As a diagnostic tool: abnormal EEGs can be seen in patients with epilepsy, anorexia, depression and schizo.

Advant

• Valuable for detecting epilepsy
• Contributes to our understanding of sleep
• Has really good temporal resolution
• Non-invasive
• Cheaper than fMRI

Disadvant

• Doesnt show individual neurons firing
• Poor spatial resolution, unable to tell where the brain waves are coming from.

Event-Related Potentials

How does it work?

Using EEG's means ending up with a vague and general show of brain activity.

Within all the data however are waves that are specific to a certain stimuli.

Using a statistical averaging technique, researchers can ilter out the waves made from unwanted stimuli

What remains are the even-related potentials specific to a certain stimulus

Advantage?

They make it possible to see someone's response to something without them having to actually respond.

If the patient cannot respond due to inury 

But

Not all voltage channes across the scalp are recordable.

Electrical activity from deep in the brain is not recorded. This means that, at current, ERPs are restricted to the neocortex, the most recently evolved part of the brain

Post-Mortem Examinations

How is it done?

Involves removing the brain from the skull (after death) and dissecting it to look at abnormalities when compared to a neurotypical brain

It's usually done on people with rare disorders to see how their brains differ from a neurotypical one

Good

Allow for a more detailed examination of the brain than non-invasive techniques. Researchers can look at deeper parts of the brain such as the hypocampus and hypothalamus

THis is useful in cases such as that of HM, who's post-mortem showed his memory problems were due to lesions in the hippocampus

But

There can be lots of confounding influences on the brain,

cause of death, age, drug use, length o time between death and exam. these could all influence the anatomy of the brain and prevents us from establishing cause and effect between abnormalities in the brain and abnormal behaviour

ULTRADIAN RHYTHMS

Less than 24 hours

Eating, rest-activity cycle, stages of sleep

Research into Ultradian Rhythm

McClintock and Stern

10 year long longitudinal study 

29 women who had irregular periods. 9 of them had their sweat swabbed and put on the upper lip of the other 20 participants

68% of the time the participants who had recieved sweat found their cycles closer to that of the donors.

Infradian rhythms can be affected by external factors as well as internal ones.

Research into Ultradian Rhythm

 Seasonal Affective Disorder

SAD is a depressive disorder which has a seasonal pattern of onset – throughout the winter months. Its symptoms are general low mood and lack of interest in activity. At night, low light levels stimulate the production of melatonin, this is what triggers sleepiness. Therefore, you would expect the lower light levels of the winter months to have a similar effect. In areas where light levels are exceptionally low for prolonged periods, such as the Polar regions, you would expect the effects to be particularly noticeable. Terman (1988) found that SAD was five times more common in New Hampshire, a northern state of the USA, than in Florida, obviously a sunnier clime. SAD could also be considered a disruption of a circadian rhythm since it could be seen as due to disruption of the sleep/wake cycle during the darker winter months.

CIRCADIAN RHYTHMS

Last around 24 hours

Sleep wake cycle, core body temperature, hormone production (melatonin)

Circadian rythms are synchronised by an internal pacemaker, the suprachiasmatic nucleus (hypothalamus) (or SCN)

The pacemaker needs to be constantly reset so that it is in sync with the outside world. Light acts to provide that reset. 

Our 24 hour sleep cycle is influenced by patterns of daylight and darkness. These are exogenous zeitgebers.

These help to maintain the rhythm but are not necessary. Our circadian rythm is 'free-running' and does not require exogenouses in ourder to keeo a 24-25 hour cycle

Research into Circadian Rythms

Siffre was a cave spealist who lived in a cave for ~6 months so as to investigate the effect of having no exogenous zeitgebers.

He lived in a pitch dark cave with only a lamp, food water, a means of communicating with the outside world, but not clock or watch.

He slept and ate whenever he felt like it.

He found that his sleep-wake cycle settled on 25 hours naturally, showing that without light, his body ran its natural clock

Research into Circadian Rythms

Folkard

Had 12 participants stay in a cave for 3 weeks with no way of telling the time besides a large clock controlled by the experimenters.

The participants agreed to go to bed at 11 45pm and get up at 8 45pm.

At first the clock worked at a 24 hour pace and then they sped it up to a 22 hour pace

Only one of the participants adapted their cycle to the clock, the rest kept their 24 hour sleep-wake cycle.

so dont overestimate the role of the EXTERNAL crap, endogenous pacemakers are important too

Evaluation of Circadian Rhythm research

• Practical applications
• Research has shown that the risk of heart attack is the most in the morning so drugs have been developed that can be taken at night to be released in the morning 
• And, shift workers have been seen to have more accidents around 6am when their concentration reduces. Night shift workers are also 3 times as likely to develop heart disease due to the stress of trying to adjust to different sleep/wake cycle.

• Problem is that the sample sizes used for these studies is usually quite small, so cant apply results to general population or anything. Siffre himself said that his sleep/wake cycle slowed down as he aged, which shows that there can be individual differences between participants.

Evaluation of Circadian Rhythm research

Lack of control of extraneous variables

Siffre had a small source of artificial light with him, which could have acted as an exogenous zeitgeber. Czeisler found that even artifical light can affect circadian rhythms. So we cannoot e sure therefore if the circadian rhythm is free-runnning and 24/25 hours long