Biopsychology - Year 12

Question 1

The Nervous System Structure?

Answer 1

The nervous system is divided into the two main components:

1) the central nervous system (CNS)
2) the peripheral nervous system (PNS).

The nervous system has the following structure:
Nervous system —> CNS + PNS.
CNS —> Spinal Cord + Brain.
PNS —> Somatic Nervous System + Autonomic Nervous System (the autonomic splits further into sympathetic + parasympathetic).

Question 2

The CNS AO1?

Answer 2

The CNS (Central Nervous System) consists of the brain and the spinal cord.

The brain provides conscious awareness and consists of many regions, which are responsible for different functions.

For example, the brain consists of four main lobes: frontal lobe, parietal lobe, temporal lobe and occipital lobe.

(Include the roles of the different lobes here).

The brain stem connects the brain and spinal cord and controls involuntary processes, including our heartbeat, breathing and consciousness.

The role of the spinal cord is to transfer messages to and from the brain, and the rest of the body.

The spinal cord is also responsible for simple reflex actions that do not involve the brain, for example jumping out of your chair if you sit on a drawing pin.

Question 3

The Roles Of The Four Lobes?

Answer 3

This is AO1 for CNS.

The occipital lobe processes visual information.

The temporal lobe processes auditory information.

The parietal lobe integrates information from the different senses and therefore plays an important role in spatial navigation.

The frontal lobe is associated with higher-order functions, including planning, abstract reasoning and logic.

Question 4

The PNS AO1?

Answer 4

The role of the peripheral nervous system (PNS) is to relay messages (nerve impulses) from the CNS (brain and spinal cord) to the rest of the body.

The PNS consists of two main components:

1) the somatic nervous system and
2) the autonomic nervous system.

The somatic nervous system facilitates communication between the CNS and the outside world.

The somatic nervous system is made up of sensory receptors that carry information to the spinal cord and brain, and motor pathways that allow the brain to control movement.

Therefore, the role of the somatic nervous system is to carry sensory information from the outside world to the brain and provide muscle responses via the motor pathways.

The autonomic nervous system plays an important role in homeostasis, which maintains internal processes like body temperature, heart rate and blood pressure. The autonomic nervous system only consists of motor pathways and has two components: 1) the sympathetic nervous system and 2) the parasympathetic nervous system.

Question 5

The Autonomic Nervous System?

Answer 5

This is part of AO1 for the PNS.

The autonomic nervous system plays an important role in homeostasis, which maintains internal processes like body temperature, heart rate and blood pressure.

The autonomic nervous system only consists of motor pathways and has two components:

1) the sympathetic nervous system and
2) the parasympathetic nervous system.

The sympathetic nervous system is typically involved in responses that prepare the body for fight or flight.

Impulses travel from the sympathetic nervous system to organs in the body to help us prepare for action when we are faced with a dangerous situation.

For example, our heart rate, blood pressure and breathing rate increase, while less important functions like digestion, salivation and the desire to urinate are suppressed.

The role of the parasympathetic nervous system is to relax the body, and return us to our ‘normal’ resting state.

Consequently, the parasympathetic nervous system slows down our heart rate and breathing rate, and reduces our blood pressure.

Furthermore, any functions that were previously slowed down during a fight or flight reaction are started again (e.g. digestion).

Question 6

Types Of Neurones?

Answer 6

There are three main types of neurons, including: sensory, relay and motor.

Each of these neurons has a different function, depending on its location in the body and its role within the nervous system.

Question 7

Sensory Neurones?

Answer 7

Sensory neurons are found in receptors such as the eyes, ears, tongue and skin, and carry nerve impulses to the spinal cord and brain.

When these nerve impulses reach the brain, they are translated into ‘sensations’, such as vision, hearing, taste and touch.

However, not all sensory neurons reach the brain, as some neurons stop at the spinal cord, allowing for quick reflex actions.

Question 8

Relay Neurones?

Answer 8

Relay neurons are found between sensory input and motor output/response.

Relay neurons are found in the brain and spinal cord and allow sensory and motor neurons to communicate.

Question 9

Motor Neurones?

Answer 9

Motor neurons are found in the central nervous system (CNS) and control muscle movements.

When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which lead to movement.

Question 10

Structures Of Neurones?

Answer 10

The Dendrites: receive signals from other neurones or from sensory receptor cells. The dendrites are typically connected to the cell body, which is often referred to as the ‘control centre’ of the neuron, as it’s contains the nucleus.

The Axon: is a long slender fibre that carries nerve impulses, in the form of an electrical signal known as action potential, away from the cell body towards the axon terminals, where the neuron ends.

Myelin Sheath: Most axons are surrounded by a myelin sheath (except for relay neurons) which insulates the axon so that the electrical impulses travel faster along the axon.

The axon terminal connects the neuron to other neurons (or directly to organs), using a process called synaptic transmission.

Question 11

Sensory Neurone Structure?

Answer 11

They have one dendron that is often very long.

The dendron carries the impulse toward the cell body and then an axon carries the impulse away from the cell body.

Cell body in middle, in dorsal root ganglion.

Impulse travels from the nerve endings (dendron) at the skin to the axon.

Myelinated.

Impulse travels from the dendrites and cell body to the axon.

Question 12

Relay Neurone Structure?

Answer 12

Transmit impulses between neurones, for example, from sensory to motor neurones.

They have numerous short processes.

Cell body in middle.

Not myelinated.

Impulses travel from the dendrites inwards to the cell body in middle of neurone. They all travel inward (almost like a inward spiral).

Question 13

Motor Neurone Structure?

Answer 13

Transmit nerve impulses from an intermediate or relay neurone to an effector.

Effector examples: gland or muscle.

Motor neurones have a long axon and then lots of short dendrites.

Usually attached to some sort of muscle tissue.

Cell body at same side as dendrites.

Myelinated.

Question 14

Transmission Across A Synapse?

Answer 14

Different to the biology A-level way.

Synapses are between neurons or tissues. Synaptic transmission is an example of chemical transmission.

1. An electrical impulse is passed down axon (this is known as action potential).
2. Once the action potential reaches the end of the axon it needs to be transferred to another neuron or tissue.

3 Synaptic vesicles which contains chemical messengers, known as neurotransmitters. When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters (acetycholine).

4. Neurotransmitters then carry the signal across the synaptic gap. They bind to receptor sites on the post-synaptic neurone that then become activated.
5. Once the receptors are activated, they produce excitatory or inhibitory effects on the post-synaptic cell.
6. Some neurotransmitters are excitatory and some are inhibitory.

Serotonin is inhibitory in the receiving neuron. Adrenaline causes excitarory effects - increases positive charge in the neuron.

Question 15

Excitatory Or Inhibitory Effects On The Synapse?

Answer 15

Excitatory neurotransmitters (e.g. noradrenaline) make the post-synaptic cell more likely to fire.

Excitatory post-synaptic potential (EPSP) is caused when an excitatory neurotransmitter makes the post-synaptic cell more likely to fire.

Inhibitory neurotransmitters (e.g. GABA) make them less likely to fire.

If inhibitory neurotransmitters binds to the post-synaptic receptors it will result in an inhibitory post-synaptic potential (IPSP), which makes the post-synaptic cell less likely to fire.

Question 16

The Endocrine System - Glands?

Answer 16

The endocrine system works alongside the nervous system.

Glands release hormones.

It is a network of glands across the body that secrete chemical messages called hormones.

Instead of using nerves (sensory and motor neurons) to transmit information, this system uses blood vessels.

Different hormones produce different effects.

(Less important for essay): The word ‘hormone’ comes from the Greek work ‘hormao’ which means ‘excite’, as hormones excite (stimulate) a particular part of the body.

Question 17

Types Of Glands?

Answer 17

Glands release hormones - they are part of the endocrine system.

Types of glands:

1. Hypothalamus,
2. Pituitary gland,
3. Thyroid and parathyroid gland,
4. Pineal gland,
5. Thymus,
6. Ovary,
7. Testicle,
8. Pancras,
9. Adrenal gland,
10. Placenta (during pregnancy only).

Question 18

The Endocrine System - Hormones?

Answer 18

Pituitary gland releases:

• ACTH (adrenocortical trophic hormone) from anterior.
• Oxytocin from posterior.

Pineal gland releases:
- Melatonin.

Thyroid gland releases:
- Thyroxine,

Adrenal gland releases:

• Adrenaline and noradrenaline from adrenal medulla.
• Cortisol from adrenal cortex.

Ovaries release:
- Oestrogen.

Testes release:
- Testosterone.

Question 19

The Endocrine System - Sex Hormones?

Answer 19

Males and females have different sex organs, and in males the testes release androgens, which include the main hormone testosterone.

Testosterone is responsible for the development of male sex characteristics during puberty while also promoting muscle growth.

In females, the ovaries release oestrogen which controls the regulation of the female reproductive system, including the menstrual cycle and pregnancy.

Question 20

The Pineal Gland?

Answer 20

Pineal gland releases:
- Melatonin.

Melatonin is responsible for important biological rhythms, including the sleep-wake cycle.

Question 21

The Thyroid Gland?

Answer 21

Thyroid gland releases:
- Thyroxine.

Thyroxine regulates the metabolism.

Question 22

The Adrenal Gland?

Answer 22

Adrenal gland releases:
- Adrenaline and noradrenaline from adrenal medulla.
The key hormones in fight or flight.

• Cortisol from adrenal cortex.
  Stimulates the release of glucose to provide the body with energy, while suppressing the immune system.

Question 23

Fight Or Flight AO1?

Answer 23

When someone enters a potentially stressful situation, the amygdala (part of the limbic system) is activated. The amygdala responds to sensory input (what we see, hear, smell, etc.) and connects sensory input with emotions associated with the fight or flight response (e.g. fear and anger).
If the situation is deemed as stressful/dangerous, the amygdala sends a distress signal to the hypothalamus, which communicates with the body through the sympathetic nervous system. If the situation requires a short-term response the sympathomedullary pathway (SAM pathway) is activated, triggering the fight or flight response.
1. A person enters a stressful/dangerous situation.

2. The amygdala (part of the limbic system) is activated which sends a distress signal to
   the hypothalamus.
3. The hypothalamus activates the sympathomedullary pathway (SAM pathway) – the pathway running to the adrenal medulla and the sympathetic nervous system (SNS).
4. The SNS stimulates the adrenal medulla, part of the adrenal gland.
5. The adrenal medulla secretes the hormones adrenaline and noradrenaline into the
   bloodstream.
6. Adrenaline causes a number of physiological changes to prepare the body for fight or flight.

Following the fight or flight response, the parasympathetic nervous system is activated to return the body back to its ‘normal’ resting state.

Consequently, the parasympathetic nervous system slows down our heart rate and breathing rate and reduces our blood pressure. Any functions that were previously slowed down are started again (e.g. digestion).

Question 24

Adrenaline Causes What Psychological Changes And Why?

Answer 24

Increased heart rate - To increase blood flow to organs and increase the movement of adrenaline around the body.

Increased breathing rate - To increase oxygen intake.

Pupil dilation - To increase light entry into the eye and enhance vision (especially in the dark).

Sweat production - To regulate temperature.

Reduction of non-essential functions (e.g. digestive system, urination, salivation) - To increase energy for other essential functions.

Question 25

“Describe and evaluate scanning techniques as a way of investigating the brain?” - AO1?

Answer 25

Oxygen is carried by haemoglobin and deoxygenated for use by active neurons. Deoxygenated haemoglobin has a different magnetic quality from oxygenated haemoglobin. The functional magnetic resonance imaging (fMRI) detects the magnetic fields around deoxygenated blood in active areas of the brain. These measurements are used to create a dynamic 3D map of the brain.

Electroencephalogram (EEG) scanners detect nerve impulses through electrodes attached to the scalp. Information is then graphed over a period of time. EEG can be used to detect illnesses that affect brain activity (e.g. epilepsy) and understand REM sleep.

Event-Related Potentials (ERP) also use electrodes attached to the scalp and measure nerve impulses when a stimulus is presented to a participant (e.g. a sound). ERPs cannot separate background EEG data, therefore the stimulus is presented many times and an average response is graphed.

Post-mortem exams study the physical brain of a dead person. E.g. Broca examined the brain of Tan who displayed speech problems when he was alive and discovered that Tan had a lesion in the area of the brain important for speech production (Broca’s area). Post-mortem studies allow for a more detailed examination of deeper regions of the brain (e.g. hypothalamus/hippocampus).

Question 26

“Discuss research into circadian rhythms. Refer to evidence in your answer?” - AO1?

Answer 26

Circadian rhythms are 24-hour cycles (often known as the ‘body clock’), which are controlled by levels of light.
The word circadian is from the Latin ‘circa’, which means ‘about’, and ‘dian’, which means ‘day’. The sleep-wake cycle is an example of a circadian rhythm, which dictates when humans and animals should be asleep and awake.

During the sleep-wake cycle, light is provided as the primary input to the system through the eye (an external cue). This causes a signal to be sent involving the level of intensity of the light to the suprachiasmatic nuclei (SCN). The SCN then uses this information to coordinate the activity of the entire circadian rhythm. If the light intensity is low, the SCN will signal messages that the organism should be sleeping. When the light intensity is high, the SCN will signal messages for the organism to be awake.

Homeostasis is another circadian rhythm which is involved in the sleep-wake cycle. The homeostasis drive for sleep increases throughout the day, reaching its maximum in the late evening when most people fall asleep. This is due to energy consumption during the hours the organism is awake. When more energy is needed, the organism is signaled to sleep.

Question 27

Localisation of brain function - AO1?

Answer 27

Localisation of function is the idea that certain functions (e.g. language, memory, etc.) have certain locations within the brain.

The motor area is located in the frontal lobe and is responsible for voluntary movements. Hitzig and Fritsch electrically stimulated different areas of the motor cortex in dogs and concluded that different muscles contract when different areas of the motor cortex are stimulated. The regions of the motor area are arranged in a logical order (e.g. region that controls finger movement is located next to region controlling hand).

The somatosensory area is located in the parent lobe and receives sensory information from the skin to produce sensations (e.g. pressure/pain). Robertson found that this area of the brain is adaptable (e.g. Braille readers have larger areas in the somatosensory area for their fingertips compared to normal sighted participants).

The visual area is in the occipital lobe in the visual area; it receives and processes visual information. Information from the right-hand side visual field is processed in the left hemisphere, and information from the left-hand side visual field is processed in the right hemisphere. Different parts of the visual area process different types of information.

The auditory area is located in the temporal lobe and is responsible for analysing and
processing acoustic information. Information from the left ear is processed in the right hemisphere and vice versa.

The Broca’s area is named after Paul Broca, who discovered this region while treating a patient named Leborgne, who was more commonly referred to as ‘Tan’. Tan could understand spoken language but was unable to produce any coherent words, and could only say ‘Tan’.
Broca conducted a post-mortem examination on Tan’s brain and discovered that he had a lesion in the left frontal lobe. This led Broca to conclude that this area was responsible for speech production. People with damage to this area experience Broca’s aphasia, which results
in slow and inarticulate speech.

Carl Wernicke discovered another area of the brain that was involved in understanding language. Wernicke found that patients with lesions to Wernicke’s area were still able to speak, but were unable to comprehend language.
Wernicke’s area is found in the left temporal lobe, and it is thought to be involved in language processing/comprehension. People with damage to this area struggle to comprehend language, often producing sentences that are fluent, but meaningless (Wernicke’s aphasia).

Wernicke concluded that language involves a separate motor and sensory region. The motor region is located in Broca’s area, and the sensory region is located in Wernicke’s area.

Question 28

“Discuss research into infradian and/or ultradian rhythms?” - AO1?

Answer 28

Infradian rhythms and can be weekly, monthly or annually. An infradian rhythm is the female menstrual cycle (around 28 days). Ovulation occurs around day 14 of the cycle, when oestrogen levels are at their highest, and usually lasts for 16-32 hours. After ovulation, progesterone levels increase in preparation for the possible implantation of an embryo in the uterus. Another example of an infradian rhythm is seasonal affective disorder (a yearly cycle) in which the lack of light during the winter months results in a longer period of melatonin secretion, which has been linked to depressive symptoms.

Ultradian rhythms last fewer than 24 hours. For example, the cycle of human sleep which alternates between REM (rapid eye movement) and NREM (non-rapid movement) sleep and consists of five stages. Stages 1 and 2 consist of ‘light sleep’; brainwave patterns are slower and more rhythmic, starting with alpha waves which progress to theta waves. Stages 3 and 4 are ‘deep sleep’ stages; brainwave patterns here are slower, delta waves. A complete sleep cycle goes through the four stages of NREM sleep before entering REM (Stage 5) and then repeating, usually lasting 90 minutes. Another ultradian rhythm is appetite or meal patterns in humans. Most humans eat three meals a day and appetite rises and falls because of food consumption. These meals are external, social cues which can affect the ultradian rhythm.

Question 29

Brain plasticity - AO1?

Answer 29

The brain is not a static organ, and the functions and processes of the brain can change as a result of experience and injury.

Brain plasticity refers to the brain’s ability to change and adapt because of experience. The brain continues to create new neural pathways and alter existing ones in response to changing experiences (see evidence below).

The brain also appears to show evidence of functional recovery: the transfer of functions from a damaged area of the brain after trauma to other undamaged areas. It
can do this through a process termed neuronal unmasking where ‘dormant’ synapses (which have not received enough input to be active) open connections to compensate for a nearby damaged area of the brain.

This allows new connections in the brain to be activated, thus recovering any damage occurring in specific regions.

Question 30

Fight Or Flight AO3?

Answer 30

Early research into the fight or flight response was conducted on males (androcentrism). This highlights a beta bias in the original research into fight or flight because psychologists generalised the results to females. More recent research criticises this early research into fight or flight. Taylor et al suggests that the fight or flight response is a male response to danger and suggests that females adopt a ‘tend and befriend’ response in a stressful/dangerous situation. Taylor et al suggests that women are more likely to protect their offspring (tend) and form alliances with other women (befriend), rather than fight or flee as running away (flight) may be seen as a sign of weakness which would put their offspring in danger. This research further suggests the original research into the fight or flight response shows a beta bias as the theory suggests women respond in the same way as men, which recent research suggests they do not.

The fight or flight response is criticised for being too simplistic. Gray suggests that the first response to danger is to avoid confrontation, which is demonstrated by a freeze response. During the freeze response, animals and humans are hyper-vigilant; they assess the situation to decide the best course of action for that particular threat. This theory suggests that the fight or flight response is too limited and that the freeze response is incorporated into fight or flight.

The fight or flight response is also further criticised for being maladaptive. While the fight or flight response may have been useful to our ancestors who faced life-threatening situations (e.g. from predators), modern day life rarely requires the intensity of a fight or flight response. Research shows that repeated activation of the fight or flight response due to daily stressors in modern day life can lead to damage in blood vessels and heart diseases. This suggests that the fight or flight response is a maladaptive response to modern, every-day life.

Question 31

Latency of ERP’s?

Answer 31

ERPs have a short latency (the time between the presentation of the stimulus and the response).

Sensory ERPs show a response to a stimulus within 100 milliseconds and cognitive ERPs show a response to a stimulus after 100 milliseconds.

Question 32

“Describe and evaluate scanning techniques as a way of investigating the brain?” - AO3?

Answer 32

Strength of using the fMRIs:
- Good spatial resolution (the ability to discriminate between different brain regions with greater accuracy). fMRI scans have a spatial resolution of approximately 1-2 mm. Consequently, psychologists can determine the activity of different brain regions with greater accuracy when using fMRI, in comparison to when using EEG and/or ERP which have poor spatial resolution. EEGs and ERPs can only detect the activity in regions on the surface of the brain. This is a weakness to using EEGs and ERPs as they are unable to provide information on what is happening in the deeper regions of the brain (such as the hypothalamus), making this technique limited in comparison to the fMRI, which has a spatial resolution of 1-2mm.

Weakness of using fMRI scans:
- They have a temporal resolution (how quickly the scanner can detect changes in brain activity) of 1-4 seconds which is worse than the temporal resolution of EEG/ERP techniques at 1-10 milliseconds. This means EEG and ERP scans can record the brain’s activity in real time as opposed to looking at a passive brain, leading to accurate measurements of electrical activity when performing a task. Consequently, psychologists are unable to predict with a high degree of accuracy the onset of brain activity in fMRI scans compared to when using EEG/ERP techniques.

Strengths to using the fMRI, EEG and ERP:
-They are all techniques that do not use radiation or involve inserting instruments directly into the brain, and are therefore virtually risk-free. The non-invasive nature of these techniques should allow more patients/participants to undertake fMRI scans, which allows for more studies to be conducted and a greater understanding of brain activity. While post-mortem exams are invasive, this is not an issue because the patient is no longer alive.

Weakness of EEG and ERP techniques:
- They are criticised for being uncomfortable for the patient due to the electrodes attached to the scalp. This discomfort (which is not apparent in fMRI scans) results in unrepresentative readings as the patient’s discomfort may affect cognitive responses to situations.
This may allow fMRI to have more accurate readings in comparison to EEG/ERP techniques.

Strength of Post-mortem examinations:
- They can access areas of the hypothalamus and hippocampus which is not possible when using any of the other brain-scanning methods. This provides researchers with an insight into the deeper brain regions, which allows further and more thorough research. Iverson examined the brains of deceased schizophrenic patients and discovered a positive correlation between higher concentrations of dopamine in the limbic system (deep within the cerebrum) and schizophrenia development compared to non-sufferers of schizophrenia. This association would not have been discovered with the use of ERP/EEG/fMRI.

Criticism of the post-morten exam:
- Ethical issues in relation to the technique. The patient is unable to give informed consent unless the patient provides this consent before his/her death. In addition to this, patients with severe psychological deficits (e.g. patient HM who suffered severe amnesia) would be unable to give fully informed consent. Despite this, a post-mortem examination has been conducted on his brain, fading severe ethical questions surrounding the nature of these examinations.

Question 33

“Discuss research into circadian rhythms. Refer to evidence in your answer?” - AO3?

Answer 33

Research has been conducted to investigate circadian rhythms and the effect of external cues like light on this system. A study conducted by Siffre found that the absence of external cues significantly altered his circadian rhythm. When he returned from an underground stay with no clocks or light, he believed the date to be a month earlier than it was. This suggests that his 24-hour sleep-wake cycle was increased by the lack of external cues, making him believe one day was longer than it was, and leading him to think that fewer days had passed. This research suggests that external cues are essential in providing an accurate 24 hour, sleep-wake cycle. However, Siffre’s case study has been criticised. Siffre was both the sole participant and researcher which raises several issues with generalisability; the results of the study cannot be generalised to other people due to individual differences. Duffy et al found that ‘morning people’ prefer to rise and go to bed early (about 6 am and 10 pm) whereas ‘evening people’ prefer to wake and go to bed later (about 10 am and 1 am). This demonstrates that there may be innate individual differences in circadian rhythms, which suggests that researchers should focus on these differences during investigations to enable accurate research into sleep-wake cycles. Although Siffre’s study is criticised for the inability to generalise the results due to individual differences, further research by Aschoff and
Weber provides additional support for Siffre’s findings. Aschoff and Weber studied participants living in a bunker with no windows and only artificial light, which the participants were free to turn on and off as they pleased. Aschoff and Weber found that the participants settled into a longer sleep/wake cycle of between 25-27 hours. These results, along with Siffre’s findings, suggest that humans use natural light (exogenous zeitgebers) to regulate a 24-hour circadian sleep-wake cycle, demonstrating the importance of light for this circadian rhythm.

It has also been suggested that temperature may be more important than light in determining circadian rhythms. Buhr et al found that fluctuations in temperature set the timing of cells in the body and cause tissues and organs to become active or inactive. Buhr claimed that information about light levels is transformed into neural messages that set the body’s temperature. Body temperature fluctuates on a 24-hour circadian rhythm and even small changes in it can send a powerful signal to our body clocks. This shows that circadian rhythms are controlled and affected by several different factors, and suggests that a more holistic approach to research might be preferable.

(Biologically deterministic? Beta bias because Siffre’s study was on man?)

Question 35

Research using what brain scanning technique has allowed us to understand infradian rhythms?

Answer 35

Research using EEG has highlighted distinct brain waves patterns during the different stages of sleep.

Question 36

“Discuss research into infradian and/or ultradian rhythms?” - AO3?

Answer 36

Strength:
- Research suggests that the menstrual cycle is, to some extent, governed by exogenous zeitgebers (external factors). Reinberg examined a woman who spent three months in a cave with only a small lamp to provide light. Reinberg noted that her menstrual cycle shortened from the usual 28 days to 25.7 days. This result suggests that the lack of light (an exogenous zeitgeber) in the cave affected her menstrual cycle. This demonstrates the effect of external factors on infradian rhythms.

Weakness:
- There is further evidence to suggest that exogenous zeitgebers can affect infradian rhythms. Russell et al found that female menstrual cycles became synchronised with other females through odour exposure. In one study, sweat gland samples from one group of women were rubbed onto the upper lip of another group of women. Despite the fact that the two groups were separate, their menstrual cycles synchronized. This suggests that the synchronisation of menstrual cycles can be affected by pheromones, which have an effect on people nearby rather than on the person producing them. These findings indicate that external factors (exogenous zeitgebers) must be taken into consideration when investigating infradian rhythms and that perhaps a more holistic approach should be taken, as opposed to a reductionist approach that considers only endogenous influences. Further support for the effects of exogenous zeitgebers affecting infradian rhythms comes from evolutionary psychologists. They claim that the synchronised menstrual cycle provides an evolutionary advantage for groups of women, as the synchronisation of pregnancies means that childcare can be shared among multiple mothers who have children at the same time. This research provides a reason for the synchronisation of menstrual cycles.

Strength:
- Research is due to it being carried out in a controlled lab setting, which meant that the differences in the sleep patterns could not be attributed to situational factors, but only to biological differences between participants. The results from this study provide convincing support for the role of innate biological factors in ultradian rhythms. However, this research is also criticised as the study took place in a lab setting, where participants were attached to monitors. These factors make the ecological validity of the study low and this could lead to false conclusions of the sleep cycle.

Weakness:
- However, this evidence is ocunterargued by research studying ultradian rhythms. Tucker et al. found significant differences between participants in terms of the duration of each stage, particularly stages 3 and 4 (just before REM sleep). This demonstrates that there may be innate individual differences in ultradian rhythms, which means that it is worth focusing on these differences during investigations into sleep cycles.

Question 37

“Discuss the effects of endogenous pacemakers and exogenous pacemakers on the sleep/wake cycle?” - AO1?

Answer 37

Endogenous pacemakers control biological circadian rhythms but are altered by exogenous zeitgebers (external cues). For example, the suprachiasmatic nucleus (SCN) which lies in the hypothalamus. The SCN receives information about light levels (an exogenous zeitgeber) from the optic nerve and sends signals to the pineal gland, which leads to an increase in the production of melatonin at night, helping to induce sleep and synchronize the body with the outside work; the sleep-wake cycle.

Exogenous zeitgebers are environmental events that are responsible for resetting the biological clock of an organism, such as light or social cues like mean times.
Melanopsin, which is a protein in the eye, is sensitive to light and carries signals of light information to the SCN. The SNC contains receptors that are sensitive to light which allows the SNC to send signals to the body to secrete melatonin or not.

Question 37

Localisation of brain function - AO3?

Answer 37

Strength:
- There are supporting case studies. E.g. Phineas Gage experienced a metal pole being unintentionally forced through his left cheek, damaging his left frontal lobe. Gage experienced a personality change; going from a calm to an angry person. This supports localisation theory as it suggested the part of his brain damaged was in control of mood regulation.

Weakness:
- However there is contradictory research into cases previously seen as a strength for this theory, namely tan. Dronker did an MRI on Tan’s brain and found lesions on Broca’s area but also in surrounding areas, suggesting damage to other areas contributed to the aphasia and not just Broca’s area alone. Therefore, the reliability of the study is low.

Weakness:
- Furthermore there is the issue of individual differences in case studies. It is possible that specific peoples brains are structurally different. Herasty’s study can be brought into this as they found women have a proportionally larger Broca and Wernicke area, which would explain a noticed ease of language in women. However it is arguable that this study in fact implies to beta bias and not individual differences. It is undeniable that the difference between men and women is minimised in this theory.

Weakness:
- This theory may also be seen as being too reductionist as it tries to reduce complex human behaviour and processes to specific religions of the brain. It is suggested that an overall thorough understanding is better suited as an explanation. An example of a study which may be classified as reductionist or on the other hand support the idea that the brain should, in fact, be looked at as a whole is the work of Karl lashley who worked with rats. This may be seen as reductionist as it is suggesting there is no difference between humans and rats. This also questions whether it should be generalised to humans at all.

Weakness:
- However it may also be seen as supporting the holistic approach. In this study he removed areas of the cortex in rats which were learning to route a maze. It was found that no area of the brain was found to be more important than others, suggesting a holistic approach may be more suited in comparison to the localisation approach. Opposingly there is other case studies done on humans which supports localisation theory and conflicts with the holistic approach.

Question 38

“Discuss the effects of endogenous pacemakers and exogenous pacemakers on the sleep/wake cycle?” - AO3?

Answer 38

Strength:
- Research supports the SCN as being responsible for maintaining biological rhythms. Morgan bred hamsters so that they had circadian rhythms of 20 hours rather than 24. SCN neurons from these abnormal hamsters were transplanted into the brains of normal hamsters, which changed the circadian rhythm of the normal hamsters to 20 hours. The transplanted SCN had imposed the abnormal 20 hour patten onto the hamsters. This research supports the SCN as being an important endogenous pacemaker for biological circadian rhythms.

Weakness (of above):
- However, this research is criticised because of its use of hamsters. Humans would respond very differently to manipulations of their biological rhythms, not only because we are different biologically, but also because of the vast differences between environmental contexts. This research can therefore not be generalised to the biological rhythms of humans.

Strength:
- There is research to support the role of melanopsin. Skene and Arendt claimed that the majority of blind people who still have some light perception have normal circadian rhythms whilst those without light perception show abnormal circadian rhythms. This shows the importance of exogenous zeitgebers as being a cue for biological circadian rhythms. There is further research support for the role of exogenous zeitgebers.

Strength:
- A study conducted by Siffre found that the absence of external cues significantly altered his circadian rhythm. When he returned from an underground stay with no clocks or light, he believed the date to be a month earlier than it was. This suggests that his 24-hour sleep-wake cycle was increased by the lack of external cues, making him believe one day was longer than it was, and leading him to think that fewer days had passed. This research suggests that external cues are essential in providing an accurate 24 hour, sleep-wake cycle.

Weakness:
- However, despite all the research support for the role of endogenous pacemakers and exogenous zeitgebers, the argument could still be considered biologically reductionist. For example, the behaviourist approach would suggest that bodily rhythms are influenced by other people and social norms, i.e. sleep occurs when it is dark because that is the social norm and it wouldn’t be socially acceptable for a person to conduct their daily routines during the night. The research discussed here could be criticised for being reductionist as it only considers a singular biological mechanism and does not consider other factors and mechanisms.

Question 39

Split-brain research in investigating hemispheric lateralisation - AO1?

Answer 39

Lateralisation is the idea that the two halves of the brain have functional specialisations.

The corpus callosum facilitates communication between the two hemispheres. Sperry and Gazzaniga investigated hemispheric lateralisation with the use of split-brain patients (individuals who had their corpus callosum cut).

In the describe what you see task, a picture was presented to either the left or right visual field. The patients could only describe the picture if it was presented in the right visual field (showing the superiority of the left hemisphere in language production).

In the tactile tests, an object was placed in the patients left or right hand. The patients could only describe verbally what they felt when the object was placed in the right hand (showing the superiority of the left hemisphere in language production).

In the drawing task, participants were presented with a picture in either their left or right visual field. The left-hand would consistently draw clearer and better pictures than the right hand. This demonstrates the superiority of the right hemisphere in visual-motor tasks.

This concluded that the left hemisphere is dominant in terms of speech and language and the right hemisphere is dominant in terms of visual-motor tasks.

Question 40

Split-brain research in investigating hemispheric lateralisation - AO3?

Answer 40

Strength:
- There is research to support why brain lateralisation would occur. Brain lateralisation increases the ability to perform multiple tasks simultaneously. Rogers et al found that in a domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks
simultaneously (finding food and being vigilant for predators). Using only one hemisphere to engage in a task leaves the other hemisphere free to engage in
other functions. This provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in cognitive tasks.

Weakness (of above):
- However, because this research was carried out on animals, it is impossible to conclude the same of humans. Such studies often include very few participants, and often the research takes an idiographic approach. Therefore, any conclusions drawn are representative only of those individuals who had a confounding physical
disorder that made the procedure necessary. This is problematic as such results cannot be generalised to the wider population.

Weakness:
- It could be argued that language may not be restricted to the left hemisphere. Turk et al discovered a patient who suffered damage to the left hemisphere but developed the capacity to speak in the right hemisphere,
eventually leading to the ability to speak about the information presented to either side of the brain. This suggests that perhaps lateralisationis not fixed and that the brain can adapt to damages.

Question 41

Brain plasticity - AO3?

Answer 41

Strength:
- Kuhn et al. found a significant increase in grey matter in various regions of the brain after participants played video games for 30 minutes a day over a two-month period. Similarly, Davidson et al. demonstrated the permanent change in the brain generated by prolonged meditation: Buddhist monks who meditated frequently
had a much greater activation of gamma waves (which coordinate neural activity) than did students with no experience of meditation. These two studies highlight
the idea of plasticity and the brain’s ability to adapt as a result of new experience, whether it’s video games or mediation.

Strength:
- There is further research to support the notion of brain plasticity. Maguire et al. found that the posterior hippocampal volume of London taxi drivers’ brains was
positively correlated with their time as a taxi driver and that there were significant differences between the taxi drivers’ brains and those of controls. This shows that
the brain can permanently change in response to frequent exposure to a particular task.

Weakness:
- However, some psychologists suggest that research investigating the plasticity of the brain is limited. For example, Maguire’s research is biologically reductionist and only examines a single biological factor (the size of the hippocampus) in relation to spatial memory. This approach is limited and fails to take into account all of the different biological/cognitive processes involved in spatial navigation which may limit our understanding. Other psychologists suggest that a holistic approach to understanding complex human behaviour may be more
appropriate.

Strength:
- There is research to support the claim for functional recovery. Taijiri et al found that stem cells provided to rats after brain trauma showed a clear development of neuron-like cells in the area of injury. This demonstrates the ability of the brain to create new connections using neurons manufactured by stem cells.

Weakness:
-While there is evidence for functional recovery, it is possible that this ability can deteriorate with age. Elbert et al concluded that the capacity for neural
reorganisation is much greater in children than in adults, meaning that neural regeneration is less effective in older brains. This may explain why adults find change more demanding than do young people. Therefore, we must consider individual differences when assessing the likelihood of functional recovery of the brain after trauma.

Question 42

The Hypothalamus?

Answer 42

Stimulates and controls the release of hormones from the pituitary gland.

The pituitary gland releases:
- ACTH (adrenocortical trophic hormone) from anterior.
This Stimulates the adrenal cortex and the release of cortisol during the stress response.

-Oxytocin from posterior.
Responsible for uterus contractions during childbirth.