Biopsychology Flashcards
1
Q
What is the central nervous systems main functions?
A
To collect, process and respond to information in the environment and to co-ordinate the working of different organs and cells in the body.
2
Q
What is the human nervous system?
A
Our primary internal communication system.
3
Q
What are the two main components of the nervous system?
A
The Central Nervous System
The Peripheral Nervous System
4
Q
What does the CNS consist of?
A
Spinal cord and brain
5
Q
What does the PNS consist of?
A
The Somatic and Autonomic nervous system.
6
Q
What does the Autonomic nervous system consist of?
A
The Sympathetic and Parasympathetic nervous system.
7
Q
What is the function of the CNS?
A
Control behaviour and regulate the body’s physiological processes.
8
Q
What does the brain do?
A
Provides concious awareness and is involved in all psychological processes. It consists of many regions which are responsible for different functions.
9
Q
What are the brains 4 main lobes and their function?
A
Occipital lobe-processes visual information
Temporal lobe-processes auditory information
Parietal lobe-intergrates info from the different senses and is important in spatial navigation
Frontal lobe-higher order functions eg. planning and logic
10
Q
What is the cerebellum responsible for?
A
Balance and co-ordination.
11
Q
What is the brain stem responsible for?
A
Connects brain and spinal cord and controls involuntary processes eg. heart-rate
12
Q
What is the role of the spinal cord?
A
Transfer messages to and from the brain and the rest of the body. Simple reflex actions that do not involve the brain through reflex archs.
13
Q
How does a reflex arch work?
A
Information travels by the sensory input to a sensory neuron and then to the relay neurons in the spinal cord motor which immediately instruct the neurons of a muscle to contract.
14
Q
What is the role of the Peripheral Nervous System?
A
Relay messages from the CNS to the rest of the body.
15
Q
What does the somatic nervous system do?
A
Facilitates communication between the CNS and outside world.
16
Q
What is the somatic nervous system made up of?
A
Sensory receptors that carry information to the spinal cord and brain and motor pathways allow the brain to control voluntarymovement.
17
Q
What is the role of the somatic nervous system?
A
Carry sensory information from the outside world to the brain and provide muscle responses via the motor pathways.
18
Q
What does the autonomic nervous system do?
A
Auto means self-regulating so workings are unconscious. Important role in homeostatis which maintains intenal processes like body temp, heart rate and blood pressure. Transmits info to and from internal organs.
19
Q
What is the autonomic nervous system made up of?
A
Only consists of motor pathways and has two components-the sympathetic and parasympathetic nervous system.
20
Q
What is the sympathetic nervous system responsible for?
A
Responses that prepare the body for fight or flight. ‘Fight or flight’
21
Q
How does the sympathetic nervous system work?
A
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.
22
Q
What is the parasympathetic nervous system responsible for?
A
Relax the body and return us to our resting state. ‘Rest and digest’
23
Q
How does the parasympathetic nervous sytem work?
A
Slows down our heart rate and breathing rate and reduces our blood pressure. Any functions previously slowed are now started again.
24
Q
What can the SNS and PNS not be?
A
Active at the same time as they have opposing effects on the same organs.
25
Similarites between the brain and spinal cord?
Both control involuntary processes.
26
Differences between the brain and spinal cord?
Brain provides conscious awareness and allows for higher order thinking.
Brain consists of multiple regions responsible for different functions.
27
Similarites between the somatic/autonomic nervous systems and symapthetic/parasympathetic?
Sympathetic and somatic nervous systems respond to external stimuli. Sympathetic responds by preparing the body via fight or flight and somatic responds by carrying info to the brain and spine.
28
Differences between somatic/autonomic and sympathetic/parasympathetic nervous systems?
Autonomic has 2 sub-systems whereas somatic has only 1.
Somatic has sensory and motor pathways whereas autonomic only has motor pathways.
29
Examples of what the sympathetic nervous system does?
Dilates pupils
Increases heartbeat
Decreases saliva production
Inhibits digestion
Inhibits bladder
30
Examples of what the parasympathetic nervous system does?
Constricts pupils
Slows heartbeat
Stimulates saliva production
Stimulates digestion
Contracts bladder
31
Why do neurons have different functions?
Depending on its location in the body and its role within the nervous system.
32
What are the features of a sensory neuron?
Long dendrites
Short axon
Pseudounipolar (one axon split into two branches)
33
Where are sensory neurons found?
Receptors in the eyes, ears, tongue and skin and carry nerve impulses to the spinal cord and brain, when at the brain they are turned into sensations. However not all reach the brain those which stop at the spine allow for quick reflex actions.
34
What are the features of a relay neuron?
Many short dendrites
Short or long axon
Multipolar (have one axon and several dendrites)
No myelin sheath
35
Where are relay neurons found?
Between the sensory input and motor output/response. Found in the brain and spinal cord and allow sensory and motor neurons to communicate.
36
What are the features of a motor neuron?
Short dendrites
Long axon
Cell body in CNS but long axons form part of the PNS
Multipolar (have one axon but several dendrites)
37
Where are motor neurons found?
In the Central Nervous System and controls muscle movement. When motot neurons are stimulated they release neurotransmitters that bind to receptors on muscles to trigger a response, which lead to movement.
38
What do dendrites do?
Recieve signals from other neurons or from the sensory receptor cells. They are typically connected to the cell body.
39
What is an axon?
Long slender fibre that carries nerve impulses in the form of electrical signals known as action potential, away from the cell body towards the axon terminals where the beuron ends.
40
What is a myelin sheath?
Surronds an axon and insulates it so the electrical impulses travel quicker down the axon.
41
What is an axon terminal?
Connects the neuron to other neurons using a process called synaptic transmission.
42
What is synaptic transmission: When is a neuron in a resting state?
When the inside of the cell is negatively charged compared to the outside.
43
What is synaptic transmission: What happens when a neuron is activated?
When a neuron is activated by a stimulus the inside of the cell becomes positively charged for a split second causing an action potential to occur. This creates an electrical impulse that travels down the axon towards the end of the neuron.
44
What is synaptic transmission: What happens when the electrical impulse reach the presynaptic terminals?
It triggers the release of neurotransmitters from vesicles across the synapse.
45
What is synaptic transmission: What do neurotransmitters combine with?
Receptors on the post synaptic membrane (dendrites) of the next neuron.
46
What is synaptic transmission: Stimulation of postsynaptic receptors by neurotransmitters results in what?
Either excitation or inhibition of the postsynaptic membrane.
47
What is synaptic transmission: What is done with the excitatory and inhibitory influences?
The influences are summed and if the net effect on the post synaptic neuron is inhibitory, the neuron will not fire whereas if the net effect is excitatory the neuron will fire.
48
What is synaptic transmission: What happens when the post synaptic neuron fires?
The chemical message is converted back into an electrical impulse and the process of transmission begins again in this other neuron.
49
What is synaptic transmission: What does each neurotransmitter do?
Binds to a specific receptors and has specific functions. Eg. acetylcholine is found at each point where a motor neuron meets a muscle and upon its release it will cause muscles to contract.
50
What is synaptic transmission: What mechanicisms prevent neurotransmitters remaining active in the synapse?
There are re-uptake and enzymatic degradation.
51
What is synaptic transmission?
When a neuron is in a resting state inside the cell it is negatively charged compared to its surrondings. When a neuron is activated by a stimulus the inside of the cell becomes positevly charged for a spilt second, causing an action potential to occur. This creates an electrical impulse that travels down the axon towards the end of a neuron. When the electrical impulse reaches the synaptic terminals, it triggers the release of neurotransmitters from vesicles across the synapse. The neurotransmitters combine with receptors on the postsynaptic membrane. Stimulation of postsynaptic receptors by the neurotransmitters results in either excitation or inhibition of the postsynaptic membrane. The excitatory or inhibitory influences of binding neurotransmitters are summed and if the net effect on the postsynaptic neuron is inhibitory, the neuron will not fire whereas if the net effect is excitatory the neuron will fire. When the postsynaptic neuron fires the chemical message is converted back into an electrical impulse and the process of transmission begins again in the other neuron. Each neurotransmitter only binds to specific receptors and each have a specialist function. Eg. acetylcholine is found at each pointwhere a motor neuron meets a muscle and upon its release it will cause muscles to contract. Two mechanisms prevent neurotransmitters remaining in the synpase. These are re-uptake and enzymatic degradation.
52
What can neurotransmitters be?
Excitatory or inhibitory
53
What are neurons when they are at rest?
Negatively charged compared to their surrondings.
54
What must a neuron be to fire?
Momentarily become positively charged.
55
How does a neuron become depolarised?
The excitatory effects of the neurotransmitters binding to the receptors of the post synaptic neuron must reach a threshold (after the excitatory and inhibitory influences of the binding neurotransmitters have been summed through a process of summation.)
56
What effect does excitatory neurotransmitters have?
Depolarising effect on the postsynaptic neurons receptive membrane.
57
What are depolarising effects known as?
EPSPs because they increase the likelihood that the postsynaptic neuron will fire.
58
What effect does inhibitory neurotransmitters have?
Hyperpolarising effect on the postsynaptic neurons receptive membrane.
59
What are hyperpolarising effects known as?
IPSPs because they decrease the likelihood that the postsynaptic neuron will fire.
60
What happens if the net effect of the binding neurotransmitter on the post synaptic neuron is inhibitory?
If the threshold is not met then the post synaptic neuron will not fire.
61
What happens if the net effect of the binding neurotransmitter on the post synaptic neuron is excitatory?
If the threshold is met then the post synaptic neuron will fire.
62
What is an action potential?
An electrical potential
63
What is the cell body?
Control centre of the neuron.
64
What are the nodes of ranvier?
Gaps in the myelin sheath that speed up the electrical impulse.
65
Why can neurons only transmit information in one direction at the synapse?
The synaptic vesicles containg the neurotransmitters are only present on the presynaptic neuron and the receptors are only on the postsynaptic neuron. It's the binding of the neurotransmitter to the receptor that enable the info to be transmitted to the next neuron. Diffusion of the neurotransmitters mean theycan only go from high to low concentration so can only travel from the presynaptic neuron to the post synaptic neuron.
66
What does the endocrine system work alongside?
Nervous system
67
What is the endocrine system?
A network of glands across the body that secrete chemical messages called hormones.
68
How does the endocrine system transmit information?
This system uses blood vessels.
69
What do different hormones do?
Produce different effects.
70
What does each gland produce?
Different hormones
71
What is a hormone?
Chemical signals which are secreted from the glands into the blood stream to a specific target organ where they influence behaviour and mood.
72
What is the hypothalamus connected to?
Pituitary gland
73
What is the hypothalamus responsibe for?
Stimulating or controlling the release of hormones from the pituitary gland. It is the control system which regulates the endocrine system.
74
What is the pituitary gland responsible for?
The hormones released by the pituitary gland control and stimulate the release of hormones from other glands in the endocrine system.
75
What is the pituitary gland divided into?
The anterior and posterior lobes which release different hormones.
76
What does the posterior lobe release?
Oxytocin which is responsible for uterus contractions during childbirth.
77
What does the anterior lobe release?
Adrenocortial trophic hormone (ACTH) which stimulates the adrenal cortex and the release of cortisol, during the stress response.
78
What is the pineal gland responsible for?
Releasing melatonin which is important for biological rhythms such as the sleep-wake cycle.
79
What is the thyroid gland responsible for?
Releasing thyroxine which is responsible fore regulating metabolism.
80
What is the adrenal gland divided into?
The adrenal medulla and the adrenal cortex.
81
What is the adrenal medulla responsible for?
Releasing adrenaline and noradrenaline, which is key in the fight or flight response.
82
What is the adrenal cortex responsible for?
Releasing cortisol which stimulates the release of glucose to provide the body with energy while suppressing the immune system.
83
What are the testes responsible for?
Releasing androgens including testosterone which is responsible for the development of the male sex characteristics and promotes muscle growth.
84
What are the ovaries responsible for?
Releasing oestrogen which controls the regulation of the female reproductive system including the menstrual cycle and pregnancy.
85
What effect does the endocrine system have in comparison to the nervous system?
A longer lasting effect but it is a slower response.
86
When someone enters a potentially stressful situation what is activated?
Amygdala
87
What does the amygdala respond to?
Sensory input and connects sensory input with emotions associated with the fight or flight response.
88
What does the amygdala do in a stressful situation?
Sends a distress signal to the hypothalamus.
89
How does the hypothalamus communicate with the body?
Via the sympathetic nervous system.
90
If a situation requires a short term response what is activated?
The sympathomedullary pathway (SAM pathway) is triggered activating the fight or flight response.
91
What happens when a person enters a dangerous/stressful situation?
The amygdala is activated which sends a distress signal to the hypothalamus.
92
What happens after the amygdala is activated which sends a distress signal to the hypothalamus?
The hypothalamus activates the SAM pathway which runs to the adrenal medulla and the sympathetic nervous system.
93
What happens after the hypothalamus activates the SAM pathway which runs to the adrenal medulla and the sympathetic nervous system.
The sympathetic nervous system stimulates the adrenal medulla, part of the adrenal galnd.
94
What happens after the sympathetic nervous system stimulates the adrenal medulla?
The adrenal medulla secrets the hormones adrenaline and noradrendaline into the bloodstream.
95
What happens after the adrenal medulla secrets the hormones adrenaline and noradrendaline into the bloodstream?
Adrenaline cause a number of physiological changes to prepare the body for fight or flight.
96
What physiological changes are cause by the sympathetic nervous system in preperation for the fight or flight response?
Increased heart rate, increased breathing rate, pupil dilation, sweat production and reduction of non-essential functions.
97
Why does our heart rate increase during fight or flight?
To increase blood flow to organs and increase the movement of adrenaline around the body.
98
Why does our breathing rate increase during fight or flight?
To increase oxygen intake.
99
Why do our pupils dilate during fight or flight?
To increase light entry into the eye and enhance vision.
100
Why does sweat production increase during fight or flight?
To regulate temperature.
101
Why is there a reduction of non-essential functions during fight or flight?
To increase energy for other essential functions.
102
What happens after the fight or flight response?
The parasympathetic nervous system is activated to return the body back to its normal resting state. Our heart rate and breathing rate are slowed and blood pressure is reduced. Any functions previously slowed are started again.
103
Weaknesses of the flight or flight response?
Gray 1988 suggests the first response is freeze.
The flight or fight is typically a male response and females tend to adopt a tend and befriend approach.
104
What does localisation of function mean?
Specific functions have specific locations within the brain.
105
Who founded the theory of localisation of function?
Franz Gall's theory of phrenology was influential but quickly discredited.Pierre Flourens demonstrated the main divisions of the brain and what they were responsible for via animal experimentation. Since then techniques have grown far more sophisticated.
106
What are the 4 lobes of the brain?
Frontal
Parietal
Occipital
Temporal
and Cerebellum (not technically a lobe)
107
What is the frontal lobes function?
Motor area at the back of the frontal lobe is responsible for motor processes. Movements on the right hand side of the body are controlled by the left hemisphere and vice versa.
Frontal lobe is also involved in higher thought processes.
108
What was the result of lobotomies?
Apathy
Loss of planning and initiative
Memory disorders
Blunted emotions
Loss of facial expressions
109
What is the parietal lobe's function?
The somatosensory area processes sensations from the skin and muscles of the body. They respond to heat, cold, touch, pain and sense of body movement.
110
What is the amount of somatosensory area associated with?
Particular part of the body related to its use and sensitivity.
111
What is the temporal lobe's function?
Mainly involved in processing auditory information, sometimes called the auditory cortex.
112
Where is Wernicke's area found?
Left temporal lobe
113
What is Wernicke's area function?
Understanding speech
114
What is the occipital lobe's function?
Responsible for processing visual information, soemtimes called the visual cortex. Predominately nerve fibres from the inner half of the retina cross at the optic chiasm and travels to the opposite side of the brain. Nerve fibres from the outer edge do not cross.
115
What does damage to the left optic nerve result in?
Affect the left eye
116
What are the 4 main cortexes?
Motor
Somatosensory
Visual
Auditory
117
What is the function of the motor cortex?
Generation of voluntary motor movement. Located in the front lobe, both hemispheres of the brain with the motor cortex on one side controlling the muscles on the opposite side of the body. The regions are arranged logically and damage to this area may result in the loss of control over fine movements.
118
What is the function of the Somatosensory cortex?
Detects sensory events arrising from different regions of the body, located in the parietal lobes along the postcentral gyrus. Which is dedicated to the processing of sensory information relating to touch. It produces sensations of touch, pressure, pain and temperature then localises it to specific body regions. Both hemispheres have one with the amount of somatosensory area devoted to a particular body part denotes its sensitivity.
119
What is the function of the visual centres?
Primary visual centre is located in the visual cortex in the occipital lobe. But visual processing begins the retina, nerve impulses are transmitted via the optic nerve. It spans both hemispheres with the right hemisphere receiving input from the left visual field.
120
What is the function of the auditory centres?
Concerned with hearing and lies within the temporal lobes (auditory cortex.) Pathways begin in the cochlea where sound waves are converted to nerve impulses. It first goes to the brain stem where basic decoding occurs then the thalamus where further processing occurs and finally the auditory cortex where the impulse/sound is recognised.
121
What are the language centres?
Broca's area
Wernicke's area
122
What is Broca's area?
Named after Paul Broca and his patient 'Tan' who could only say one syllable. Tan was able to understand spoken language but couldn't produce it. Broca studied 8 other patients, with similar langauge deficits. He then identified the langauge centre in the posterior portion of the frontal lobe in the left hemisphere.
123
What is damage to Broca's area?
Broca's aphasia which is slow, labourious and speech lacking in fluency.
124
Other functions of Broca's area?
Neuroscienists have found evidence of activitybof Broca's area for cognitive tasks. Fedorenko discovered two regions of Broca's area, one for language and one for demanding cognitive tasks.
125
What is Wernicke's area?
Another area of the brian involved in understanding language. It's found in the posterior portion of the left temporal lobe.
126
What does damage to Wernicke's area result in?
Patients could speak but were unable to understand language (Wernicke's aphasia) which is the production of nonsense words as fluent but meaningless speech.
127
What did Wernicke propose?
Language involves seperate motor and sensory regions located in different cortical regions. The motor regions in Broca's area are close to the area which controls the mouth,tongue etc. Wernicke's area is close to the areas which are near to auditory and visual input. There is a neural loop running between Broca's and Wernicke's area.
128
What is Broca's area responsible for?
Production of language
129
What is Wernicke's area responsible for?
Processing of spoken language
130
Strengths of localisation of function theory?
Evidence for the areas functions comes from the different results/aphasia which occurs. Expreesive/Broca's aphasia is an impaired ability to produce language and in most cases is caused by damage to Broca's area. Receptive/Wernicke's aphasia is an impaired ability to understand language and is usually the result of damage to Wernicke's area.
Supporting evidence from case studies eg. Phineas Gage 1848 a tamping iron went through his brain. He survived and after many months he wanted to go back to work but his behaviour had changed to being rude, blasphemous and quick tempered. This suggests that the ventromedial regions of the frontal lobes is responsible for regulating mood and making rational decisions.
131
Weaknesses of localisation of function theory?
Dronkers et al 2007 re-examined the preserved brains of two of Broca's patients to identify the extent of their legions by using high tech MRI scans. The findings revealed other areas could of contributed to the patienst reduced speech abilities. This is significant because although legions to Broca's area alone can cause temporary speech disruption they don't usually result in the severe disruption of spoken language suggesting language is more complicated than once thought and aren't localised to one area.
It isn't possible to generalise results from one case study and conclusions may be based on subjective assumptions of the researcher. Reports of Gage's changes in behaviour may be inaccurate as psychologists in 1848 didn't have access to specialised equipement and Damasio's recent study of Gage's skull has allowed for more advanced/detailed study. Reports of Gage's changes in behaviour may also be inaccurate, unrealible and cannot be checked.
132
What is laterisation?
The two hemispheres of the brain are not entirely alike and each hemisphere has functional specialisations.
133
What is the left hemisphere dominant in?
Language and speech
134
What is the right hemisphere dominant in?
Visual motor tasks
135
Is vision lateralised?
Complicated as it is contralateral and ipsilateral (opposite and same sided). Each eye recieves light from the left visual field and the right visual field. The LVF of both eyes is connected to the right hemisphere and RVF of both eyes is connected to the left hemisphere.
136
What are the two hemispheres connected by?
Corpus callosum which is a thick band of nerve fibres. It means info recieved in one hemisphere can be sent ot the other.
137
What is the corpus callosm severed for?
Treatment for epilepsy as a way to prevent violent electrical activity crossing across the hemispheres.
138
Who researched split brain patients?
Sperry and Gazzaniga 1967
139
Sperry and Gazzaniga: aim?
Examine the extent to which the two hemispheres are specialised for certain functions.
140
Sperry and Gazzaniga: Method
An image/word is projected to the patient's left visual field or right visual field. When info is presented to one hemisphere (in a split brain patient) the info is not transferred to the other hemisphere. The patients completed different tasks either tactile or drawing or say what you see.
141
Sperry and Gazzaniga: What was the tactile tests?
Object placed in patient's left or right hand and they had to either describe it or select a similar object from a list of alternative objects.
142
Sperry and Gazzaniga: What was the drawing tasks?
Presented with a picture to either left or right visual field and they had to simply draw what they saw.
143
Sperry and Gazzaniga: What was the say what you see tasks?
A picture was presented to either the left or right visual field and the participants had to describe what they saw.
144
Sperry and Gazzaniga: Findings of the say what you see tasks?
Picture shown to right visual field/left hemisphere:
Patient could describe what they saw, showing how left hemisphere is responsible for langauge production.
Picture shown to left visual field/right hemisphere:
Patient could not describe what was shown and often reported nothing was present.
145
Sperry and Gazzaniga: Findings of the tactile tests?
Objects placed in the right hand/processed by left hemisphere:
Could verbally describe what they felt or identify object in right hand by selecting a similar object from a series of alternative objects.
Objects placed in the left hand/processed by right hemipshere:
Could not describe what they felt. But the left hand could identify a test onject resented in the left hand by selecting a similar object from a series of alternative objects.
146
Sperry and Gazzaniga: Findings of the drawing tasks?
Picture shown to right visual field/left hemisphere:
Right hand would attempt to draw a picture but it was never as clear as the left hand demonstrating the superiority of the right hemisphere for visual motor tasks.
Picture shown to left visual field/right hemisphere:
Left hand would consistently draw better pictures even though participants were left handed. Demonstrating the superiority of the right hemisphere for visual motor tasks.
147
Sperry and Gazzaniga: Conclusions?
Highlights a number of key differences between the two hemispheres. The left hemisphere is dominant in terms of speech and langauge and the right hemisphere is dominant in terms of visual motor tasks.
148
What is the difference between the localisation and lateralisation of function?
Localisation of function refers to the principle that specific functions have specific locations within the brain whereas lateralisation of function refers to the fact the two hemispheres of the brain aren't entirely alike.
149
Strengths of hemispheric lateralisation theory?
The case of Karen Byrne at age 27 she had her corpus callosum severed. After surgery her left hand functioned seperately and she was diagnosed with alien hand syndrome. This case onviously demonstrates how movement on each side of the body is lateralised into the two hemispheres.
Experiments investigating split brain patients have used highly specialised and standardised procedures ensuring control. In terms of ethics split brain operations weren't performed for Sperry's study so Sperry's particiapnts weren't deliberately harmed. In addition procedures were fully explained so informed consent was given.
150
Weaknesses of hemispheric lateralisation theory?
Andrewes 2001 points out many split brain studies have very few participants. Andrewes also claims in some cases conclusions have been drawn from individuals who either haave confounding physical disorders or less compotent sectionning of the two hemispheres than originally believed. (Lacks population validity and generalisability.)
Sperrys research had major methadological flaws. The disconnection between hemispheres was greater in some patients than others and some had even experienced drug therapy. Therefore differences between participants were causing effects rather than being split brain patients. The data was artifically produced as in real life a severed corpus callosum can be compensated by the unrestricted use of two eyes. (Lacks mundane realism)
151
Strengths of split brain research?
Case studies provide supporting evidence for example patient JW developed the capacity to speak out of his right hemipshere and JW can now speak about info presented to he left or right brain Turk et al. Meaning langauge is not lateralised.
Support from the case of Karen Byrne who had alien hand syndrome after her corpus callosum was cut. Her right hemisphere refused to be dominated by the left hemisphere after surgery so her left hand started to act independently.
Lateralisation appears to change over time, lateralised patterns in children turn to bilateral patterns in healthy older adults. Szaflarski found language became more lateralised with increasing age but after age 25 it decreased.
Experiments used highly specialised equipment and standardised procedures ensuring control. Ethically investigations are sound as the split brain operations weren't performed for the study.
152
Weaknesses of split brain research?
Gazzaniga suggests early discoveries have been disconfirmed by more recent discoveries. Eg. split brain research has suggested the right hemisphere is unable to handle even rudimentary language.
However in research such as Sperry and Gazzaniga the disconnection between hemipheres was greater in some patients so their wasn't an indentical response. Some patients had undergone drug therapies which may of caused differences rather than being split brain patients.
Split brain research is rarely carried out these days, so there are insufficient numbers to be useful for research. FIndings may not represent all of those with split brains so findings can't be generalised.
153
What is plasticity?
Brain plasticity refers to the brains abiliy to change and adapt as a result of experience.
154
What is functional recovery?
The brain's ability to move functions from a damaged area of the brain to other undamaged areas.
155
What did researchers believe about the changing brain?
Only occured during infancy.
156
What do reseachers now believe about the changing brain?
Brain continues to create new neuronal pathways and alter existing ones to adapt to new experiences or traumas.
157
How is plasticity formed as a result of new experiences?
As people gain new experiences, nerve pathways that are frequently used develop stronger connections whereas neurons which are rarely or never used eventually die. By developimg new connections and pruning weak ones, the brain is constantly adapting to a changing environment.
158
Evidence of plasticity: Boyke et al?
Found evidence of brain plasticity in 60 year olds who were taught a new skill-juggling. They found an increase in grey matter in the visual cortex but when practising stopped these changes reversed.
159
Evidence of plasticity: Maguire?
Studied London taxi drivers and found more volume of grey matter in the posterior hippocampus than in a matched control group. This part of the brain is associated with spatial and navigational skills. There was a positive correlation between time spent as a taxi driver and the amount of structural differences.
160
How is plasticity formed as a result of playing video games?
Playing video games makes many different complex cognitive and motor demands. Kuhn et al compared a control group with a training group who trained for 2 months at least 30 mins a day. They found a significant increase in grey matter in various regions of the brain including the cortex, hippocampus and cerebellum in the training group. They concluded playing video games had resulted in new synaptic connections in skills essential to playing the game well.
161
How is plasticity formed as a result of meditation?
Research into Tibetan monks demonstarted that meditation can change the inner workings of the brain. Davidson et al compared 8 Tibetan meditating practiioners with 10 volunteers. Both were fitted with electrical sensors and asked to meditate. There was a greater amount of gamma rays in the monks. Researchers concluded meditation changes the workings of the brain but may also produce permenant changes.
162
What does brain trauma include?
Physical damage
Cerebal haemorrhage
Cerebal ischaemia
Viral/bacterial infection whcih destroys brain tissue.
163
What did researchers in the 1960s find from studying stroke victimes who regained functions?
When brain cells were damaged or destroyed the brain rewires itself over time so some level of function was regained. Other parts of the brain can take over functions. Neurons next to damaged areas can form new circuits which resume some of the lot function. Neuroscientists suggest the process of recovery can occur quickly after trauma but slows down after a few weeks.
164
What are mechanisms for recovery?
Regenerative developments in brain function arise from the brain's plasticity , its ability to change structurally and functionally following trauma. Two ways to do this is neuronal unmasking and stem cells.
165
What is neuronal unmasking?
Wall first identified what he called dormant synapses in the brain. However increasing the rate of input to these synapses as would occur when the surronding brain area becomes damaged they can open/unmask these dormant synapses.
166
What is a dormant synapse?
They are synaptic connections that exist anatomically but their function is blocked. Under normal conditions these synapses can be ineffective because the rate of neural input is too low for them to be activated.
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What is the effect of unmasking dormant synapses?
Opens connections to regions of the brain that are not normally activated, creating a lateral spread of activation which gives way to the development of new structures so in effect the brain rewires and organises itself by forming new synaptic connections.
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How are new synaptic connections formed?
Axonal sprouting
Denervation sensitivity
Recruitment of homologous areas on the opposite side of the brain
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What is axonal sprouting?
Growth of new nerve endings which connect with undamaged nerve cells to form new pathways.
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What is denervation sensitivity?
When axons do similar jobs become aroused to a higher level to compensate for those that are lost.
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What is recruitment of homologous areas on the opposite side of the brain?
When similar areas on the opposite side of the brain take up the function.
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What are stem cells?
Unspecialised cells which have the potential to differentiate into different cell types that carry out different functions, including taking on the characteristics of nerve cells.
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What are the different views on how nerve cells should be used?
1) Stem cells implanted into the brain would directly replace dead or dying cells.
2) Transplanted stem cells secrete growth factors which rescue injured cells.
3) Transplanted cells from a neural network which links uninjured brain sites where new stem cells are made with the damaged region of the brain.
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Strengths of plasticity and functional recovery theory?
Tajiri provided evidence for the role of stem cells in recovery from brain injury. They randomly assigned rats with traumatic brain injury to one of two group. G1 recieved stem cells transplanted into region of injury and G2 received a solution containing no stem cells. 3 months later those who recieved stem cellsshowed clear development of neuron like cells.
Research suggests that women recover quicker from brain injury then men as their functions aren't as lateralised as men's. Ratcliffe examined 325 brain trauma patients at a rehabilitation centre, when assessed a year later women significantly outperformed men on attention/working memory and language skills.
Danelli studied patient EB (2.5 years old) who had an operation to remove his left hemisphere. After linguistic rehabilitation his abilities returned and his right hemisphere was compensating for the loss of the left hemisphere.
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Weaknesses of plasticity and functional recovery theory?
Given the significant differences in the structure and functionning of human and non-human animal brains, we must be careful when generalising findings of animal studies to humans.
Elbert concluded the capacity for neural reorganization is much greater in children than adults, thus recovering from trauma is more likely when the person is young and the brain is still maturing.
Evidence from unique casestudies cannot be generalised from one individual to many others.
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What is a post-mortem?
Investigations into the damaged brain after the person has died. They allow the identification of abnormalities and damage found can be related to symptoms and previous behaviours. It involves comparison with a neurotypical brainto ascertain the extent of the difference.
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Strengths of a post mortem?
Detailed examination of brain in comparison to non-invasive procedures.
Study brain on individual cellular level and examine deeper regions.
Person has usually died naturally so the living brain isn't being deliberately damaged.
Significantly contributed to our understanding of localisation of function/psychological disorders.
Eg. Broca's post mortem of Tan helped him to identify Brocas Area in the left temporal lobe.
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Weaknesses of a post mortem?
Damage hasn't been controlled in any way so it's not possible to compare how the person behaved before damage so you can't establish a cause and effect relationship.
Difficulty in obtaining human brains especially if the known deficits are rare.
Findings may lack validity due to small sample sizes and neuronal changes during and after death.
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What are fMRI's?
Measuring changes in brain activity while a person performs a task. Measures change in blood flow in particular areas of the brain, indicating increased neural activity, (more activity = higher demand for oxygen. Brain responds by increasing blood flow of oxygen in red blood cells.) This can produce a 3D map showing which areas of the brain are involved in a particular mental activity.
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Strengths of fMRI's?
Non-invasive and don't use radiation so risk free.
Produces images with good spatial resolution so make a clear picture.
Provides a moving picture so patterns can be compared not just physiology of brain.
Cognitive neuroscience is heavily reliant on fMRI and virtually every cognitive process has been studied this way.
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Weaknesses of fMRI's?
Poor temporal resolution as there is a 5 second lag behind the image on screen and inital firing of neural activity.
fMRI's measure changes in blood flow so do not offer an exact measure of neural activity.
Attempts to focus on localised activity whereas many critics would argue that communication among different regions is the most critical to mental functionning.
fMRI research is expensive and requires trained operators, leading to reduced sample sizes which negatively impact validity.
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What is an EEG?
Electrodes are placed on the scalp and detect neural activity directly below where they were placed. It's a recording of general brain activity usually linked to states such as sleep. When the electrical signals from the different electrodes are graphed over a long period of time the resulting representation is an EEG. Their primary function is to indicate whether brain activity is rhythmic or not. Arrhythmic patterns may indicate neurological disorders.
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Strengths of an EEG?
Safe way as there is no surgery or invasive procedure
Provides a recording in real time and has high temporaql resolution and can detect brain activity in a single millisecond.
Invaluable in diagnosis of conditions such as epilepsy
Relatively cheap so can be widely used.
Has contributed to our understanding of stages involved in sleep and sleep disorders.
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Weaknesses of an EEG?
Poor spatial resolution-it lacks precision in pinpointing the exact source of neural activity. So researchers cannot distiguish between activities originating in different but closely adjacent areas.
Only detect activity in superficial regions of the brain so cannot reveal what is going on in deeper regions.
Output from equipment needs to be interpreted so there is a level of expertise required.
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What is an ERP?
Uses the same apparatus as an EEG but measures very small voltage changes in the brain triggered by specific events or activities.
They are difficult to pick out from other electrical activities being generated within the brain so to establish a specific response to the target stimulus it requires many presentations of the stimulus. Any extraneous neural activity will not occur consistently whereas activity linked to the stimulus will. So effectively it cancels out background neural noise so the specific response stands out more clearly.
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What are the two categories of an ERP?
Waves occuring within the first 100 milliseconds are termed sensory as they reflect the inital response to the physical characteristics of the stimulus.
After 100 milliseconds reflect the subject evaluating the stimulus are termed cognitive as they demonstrate information processing.
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Strengths of an ERP?
Non invasive and don't use radiation (risk free)
Good temporal resolution
Offer a direct measure of neural activity.
As they provide a continous measurement of processing it's possible to determine how processing is affected by a specific experimental manipulation.
Relatively cheap so are widely used in research.
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Weaknesses of an ERP?
Poor spatial resolution-it lacks precision in pinpointing the exact source of neural activity. So researchers cannot distiguish between activities originating in different but closely adjacent areas.
In order to establish pure data, background noise and extraneous material must be completely eliminated which can be difficult to achieve.
Outputs need to be interpreted so there is a level of expertise required.
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Temporal resolution
Ability to see the brain responding in real time and without delay
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Spatial resolution
Ability to investigate specific and isolated parts of the brain
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Invasiveness
Whether the technique causes harm or discomfort to the patient
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Implications
Whether the technique has been used to help us understand or treat human conditions.
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What are biological rhythms?
Cyclical changes in the way that biological systems behave.
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How have biological rhythms evolved?
The environment in which organisms live ha cyclic changes, day/night, summer/winter and so on.
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What is a circadian rhythm?
A cycle that lasts about 24 hours
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What do circadian rhythms do?
Optimize an organism's physiology and behaviour to best meet the varying demands of the day/night cycle.
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How are circadian rhythms determined?
Driven by our body clocks found in cells and synchronised by the master circadian pacemaker, the suprachiasmatic nuclei (SCN) in the hypothalamus.
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What must our pacemaker constantly do?
Reset itself so our bodies are in synchrony with the outside world.
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What is light in relation to circadian rhythms?
Primary input and sets the body clock to the right time. In mammals, light sensitive cells within the eye act as a brightness detectors.
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What are examples of circadian rythms?
Sleep-wake cycle
Core body temperature
Hormone production cycle
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What is the sleep-wake cycle?
Circadian rhythm indicates when we should be both asleep and awake. Light and darkness are the exogenous zeitgebers and our endogenous pacemakers include hormones. The circadian rhythms peaks and dips during the day and the sleepiness we feel is less intense if we have had sufficient sleep.
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What are sleep and wakefulness dtermined by?
Circadian rhythm and are also under homeostatic control.
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How is homeostatis involved in the sleep wake cycle?
When we have been awake for long periods, homeostatis tells us the need for sleep is increasing as our energy is being used up. This homeostatic drive for sleep gradually increases until its peak typically at late evening. The homeostatic system makes us sleepier as the day goes on.
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How does the circadian rhythm keep us awake?
As long as there is daylight it will keep us awake then prompts us to sleep as it becomes dark.
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How is the internal circadian clock described?
Free running as it will maintain a cycle of about 24-25 hours even in the absence of external cues. It is intolerant of any major alterations as this causes the biological clock to become out of balance.
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What is core body temperature a good indicator of?
Circadian rhythms.
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When is core body temperature at its lowest?
36 degrees celcius at 4.30 am
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When is core body temperature at its highest?
38 degrees celcius at 6 pm
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How is sleep and core body temperature connected?
Sleep occurs when core body temperature begins to drop and body temp rises during the last hours of sleep to promote a feeling of alertness in the mornings. A small drop in body temp. occurs between 2pm and 4pm explaining tiredness in the afternoon.
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How does hormone production follow a circadian rhythm?
The production and release of melatonin from the pineal gland follows this rhytm with peak hours occuring in darkness. By activating receptors in the brain with melatonin encouraging feelings of sleepiness. When its dark more melatonin is produced and when its light melatonin production decreases.
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What is an exogenous zeitgeber factor?
External factor eg. light
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What is an endogenous pacemaker factor?
Internal factor eg. hormones
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Support for exogenous factors affecting circadian rhythms?: Michel Siffre case study
Provided evidence for a free running circadian rhythm, on multiple occasions he subjected himself to long periods of living underground with no external cues. First time he left the cave believing it to be August 20th when it was the 17th of September. On the second occasion he spent 6 months in a cave in Texas. His natural circadian rhythm settled down to 24.5 hours. On his final underground stay in 1999 he investigated the effects of aging on his circadian rhythm and found it was slower and stretched up to 48 hours.
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Conclusions from Siffre's case study
Some say yes light is important as his sleep wake cycle was longer than 24 hours.
Others argue no as it only increased to slightly above the normal 24 hour cycle so it's largely biologically driven.
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Counter support for exogenous factors affecting circadian rhythms?: Czeisler
Early research studies of circadian rhythms suffered from an important flaw when estimating 'free running' cycles. Ppts are isolated from variables that may affect rhythms. However, they weren't isolated from variables such as artificial dim light as it was believed they wouldn't effect circadian rhythms. But research suggests this may not be true. Czeisler altered ppts circadian rhythms down to 22 hours and up to 28 hours by dim lighting.
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Support for exogenous factors affecting circadian rhythms?: Aschoff and Weber
Studies ppts living in a bunker who had an electric light they could control. Eventually their body clock settled into a cycle of 25-27 hours. It suggests that we use our natural pacemakers with the environment and the 24 hour clock is not inline with our natural bodily rhythms.
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Counter support for exogenous factors affecting circadian rhythms?: Folkhard
Folkhard studied 12 ppts who lived in a cave for 3 weeks. They went to bed at 11.45 and woke up at 7.45. Researchers gradually sped up the clock and only 1/12 participants was able to adjust. Suggesting a strong existence of free running circadian rhythm that cannot be overriden by exogenous zeitgebers.
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Support for exogenous factors affecting circadian rhythms?: Hughes
Hughes tested the circadian hormone release in participants in scientists in the Antartic. In February at the end of summer, cortisol levels followed the similar patterns with highest levels when ppts wke up. However after 3 months of continous darkness the peak levels of cortisol was at noon. Suggesting that the extremes of daylight in polar regions may be responsible for variations in circadian hormone release.
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Counter support for exogenous factors affecting circadian rhythms?
However other research from scientific communities in the Artic who would be subject to similar prolonged winter darkness found no such disruption to cortisol levels.
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Evaluating exogenous factors: individual differences?
2 types:
Cycle length-it can vary 13 to 65 hours
Cycle onset-everyone is inately different in when their circadian rhythms peak.
This indicates biological rhythms aren't simply due to exogenous zeitgebers or endogenous pacemakers, the relationship between these factors is more complicated.
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Evaluating exogenous factors: research methodolgy?
Studies of the sleep/wake cycle tend to involve small groups or individual cases so may not be representative of the wider population so limits extent to which findings can be generalised.
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Evaluating exogenous factors: temperature may be more important?
SCN responds to light but Buhr et al believed its temp which actually controls the body clock, although light may be the trigger the SCN transforms this info into neural messages that set the bodys temperature. Body temp fluctuates on a 24 hour circadian rhythm and small changes can have big effects. Buhr said these fluctuations set the timing of cells in the body therefore causing tissues and organs to become active or inactive.
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Application of exogenous cues: chronotherapeutics
Led to the study of how timing affects drug treatments. The specific time a patient takes their medication is important and has significant impact on treatment success. It's essential the right concentration is released to the target organ at the right time. Therefore chronotherpaeutic medications have developed with a novel drug delivery system. Medication can be administered before bed but the actual drug isn;t released until the vunerable period of 6am to noon. (Heart attacks most likely in morning.)
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Application of exogenous cues: understanding the consequences of shift work
When people work night shifts their endogenous pacemakers try to force inbuilt rhythms of sleep but these oppose the zeitgeber of light.
A lack of concentration is associated with shift work.
Also a suggested relationship between shift work and poor health including anxiety, 3x more likely to develop heart disease due to stress of poor quality sleep and disrupted sleep/wake cycle.
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Weaknesses of the application of exogenous cues: understanding the consequences of shift work
Studies tend to be correlational so it is difficult to establish whether desynchronization of the sleep/wake cycle is actually a cause of negative effects of shift work.
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What are the three biological rhythms?
Circadian
Ultradian
Infradian
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How long do ultradian rhythms last?
Less than 24 hours
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How long do infradian rhythms last?
Longer than 24 hours
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Example of an ultradian rhythm?
Sleep cycle
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Example of an infradian rhythm?
Menstrual cycle
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Describe the ultradian rhythm-sleep cycle?
A pattern of alternating REM (5) and non REM (1-4)sleep stages. The cycle repeats every 90 mins and each stage has a different duration.
Our knowlegde comes from EEGs as a person enters deep sleep their brain waves slow and their breathing and heart arte decreases. During REM sleep EEG resembles an awake person and the most dreaming occurs here.
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What is the basic rest activity cycle (BRAC)?
Kleitman calls the 90min sleep cycle BRAC but he also suggests this ultradian 90min cycle continues during the day.
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What does Kleitman say the difference between the 90min ultradian cycle at day and night is?
During the day we move through a state of alertnessw into a state of physiological fatigue every 90 mins.
Research suggests the human mind can focus for 90mins and by the body runs out of resources resulting in loss of concentration, fatigue and hunger.
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What is the operation of BRAC during wakefullness?
Not as obvious but everyday observations provide evidence eg. 10.30 coffee break and cat naps more likely mid afternoon.
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Supporting evidence for ultradian rhythms: sleep stages Dement and Kleitman?
Monitered sleep of ppts in a sleep lab recording their brainwave activity on EEG. REM sleep was highly correlated with the experience of dreaming. Replications of this study have found similar results.
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Counter evidence for ultradian rhythms: individual differences in sleep stages Tucker?
Differences in sleep patterns are usualy attributed to differences in non-biological factors eg. room temp. However Tucker suggests differences may be biologically determined and have a genetic origin. Ppts were studied for 11 days in a lab environment. Researchers assessed sleep duration, time taken to fall asleep and amout of time in each sleep stage. They found large individual differences consistently across the 8 nights.
For deep sleep (stages 3+4) individual differences were particulary significant meaning differences are somewhat determined biologically.
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Supporting evidence for ultradian rhythms: lab experiments?
Lab studies take place in a lab meaning there is control over extraneous variables. Meaning no other variables which may affect sleep eg. noise can be eliminated.
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Counter evidence for ultradian rhythms: lab experiments?
Participants are attached to apparatus which may affect sleep meaning findings don't represent everyday/real life sleep.
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Supporting evidence for ultradian rhythms: age related changes?
Slow wave sleep reduces with age and this stage is when growth hormone is produced meaning it becomes deficient in older people. Eve van Cauter suggests this explains impairments in old age such as reduced alertness and has led to practical applications.
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Supporting evidence for ultradian rhythms: supporting evidence for BRAC?
Studies of elite performers Ericsson studied a group of elite violinists and found practice sessions were limited to 90mins and practises distributed into 90min segements. Ericssons analysis indicated violinists frequently napped to recover and the best napped more. Also patterns among other musicians, athletes, chess playuers and writers.
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Counter evidence for ultradian rhythms: criticismsof research support for BRAC?
Elite performers aren't representative of all people. Studies have contained small samples which supports criticisms that findings may not be representative.
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The average length of a sleep cycle is ...?
90 minutes
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REM stands for...?
Rapid eye movement
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Whcih stages of the sleep cycle have delta waves?
3 and 4
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Which stages of the sleep cycle have alpha waves?
1
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In whats tage of the sleep cycle does dreaming occur?
REM
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Which stage of the sleep cycle has brain waves like the waking state?
REM
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At which stage of the sleep cycle does deep sleep begin?
3
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The deepest sleep stage is?
4
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IN which stage of the sleep cycle is the body mainly paralysed?
REM
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Explain the infradian rhythm of the menstrual cycle?
It on avergae lasts 28 days but there can be considerable variations eg. 23-36 days. The menstrual cycle is regulated by hormones which either promote ovulation or stimulate the uterus for fertilisation. The cycle starts when the womb lining is shed then ovulation occurs halfway through the cycle when oestrogen levels peak (16-32 hours.) After the ovulatory phase progesterone levels rise. If pregnancy doesn't occur then the egg is absorbed into the body and the womb lining is shed.
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Explain infradian rhythms: annual rhythms?
In most animals annual rhythms are related to the seasons but in humans the calendar year influences behaviour regardless of changes to temperature. Research suggests seasonal variation in mood especially in women eg. SAD-seasonal affective disorder.
