The Brain and The Nervous System Flashcards
1
Q
List the approaches over time to understanding the role of the brain
A
Brain versus heart debate
Mind-body Problem
Phrenology
2
Q
Brain versus Heart Debate
A
Is our brain or our heart the source of all our thoughts, feelings and behaviours?
3
Q
Brain Hypothesis
A
Thoughts and feelings are rooted in the brain
Alcmaeon = first person to locate brain as the source of mental processes (experiments on animals and location of optic nerve)
Galen = treated head injuries of gladiators = determined that the brain was at the centre of mental processes
4
Q
Heart Hypothesis
A
Thoughts and feelings are rooted in the heart
Egyptians = believed that the heart held the mind and the brain had no relevance (heart remained in body and brain was removed and discarded)
Empedocles = blood was the means in which we all think and feel. Heart pumps blood around body therefore the centre of mental processes
5
Q
Mind-body Problem
A
concerns the question of whether our mind and body are distinct and separate entities or whether they are the same thing
relates to whether or not the mind (soul or non physical entity) is linked to the body or if it is separate
6
Q
List the two sides of the Mind-Body Problem debate
A
Dualism
Monism
7
Q
Dualism
A
Suggests the mind (non physical) and body (physical) are two distinct and distinguishable entities but interact to produce sensations, thoughts, emotions and other conscious experiences
8
Q
Monism
A
Suggests that the mind and body are one and the same
9
Q
Cartesian/Descartes’ Dualism
A
Suggests that we are composed of two separate substances: the physical and the mental (which includes the mind and the soul)
10
Q
Phrenology
A
Gall’s phrenology explored the relationship between the skull’s surface features and an individual’s personality characteristics
based on anecdotal evidence = pseudoscience
legacy = localising particular functions to certain parts of the brain
11
Q
Brain Ablation Experiments
A
Brain Ablation involves disabling, destroying or removed selected brain tissue, followed by an assessment of subsequent changes in behaviour
For obvious reasons, experiments using brain ablation are considered unethical on humans (causes irreversible brain damage)
12
Q
Key Figures in Brain Ablation Experiments
A
Pierre Flourens
Karl Lashley
Moniz
13
Q
Brain Ablation - Pierre Flourens
A
Developed techniques of damaging or removing small areas of brain tissue to observe the effects on behaviour
Found evidence for neural plasticity
Limitations = imprecise surgical procedure, not detailed report of findings
14
Q
Brain Ablation - Karl Lashley
A
Used brain ablation on rats, monkeys and chimpanzees to find the location of learning and memory in the brain
Failed to produce amnesia of recently learned tasks
15
Q
What were the two proposed conclusions of Lashley’s research
A
Mass Action - large areas of the brain function as a whole for complex functions (if part of the brain is destroyed, loss of function will depend on amount of destroyed cortex)
Equipotentiality - healthy part of the cortex can take over the function of an injured part (plasticity)
16
Q
Moniz
A
Developed lobotomies - form of psychosurgery to treat mental illnesses
Involves scraping away (via the eyes) most of the connections in the prefrontal cortex
17
Q
Consequences of Moniz surgeries
A
Reduction in cognitive processes and behaviour
Lack of emotional expression
Reduction in interest and energy
Personalities appeared dull and lifeless
18
Q
Electrical Stimulation of the Brain
A
Electrodu\es on or inside a person’s head send an electrical signal to specific part of brain and stimulate the activity of neurons in that area, which causes behaviour to be made
Inferences made about what different areas of the brain do based on how they respond to stimulation
Assumption = if electrical stimulation of a particular brain region triggers a response, that region is involved in that function
19
Q
Key Figures involved in EBS
A
Fritsch and Hitzig (discovered contralateral control of limb movement)
Wilder Penfield
20
Q
Penfield - Mapping the Brain
A
When the cerebral cortex was exposed, Penfield was able to stimulate different areas of the brain using an electrode and asking his patients to report their experiences
Penfield used tiny numbered tags to mark the areas of the cortex that he electrically stimulated as he developed his brain map. Then he recorded the responses of his awake and alert patients.
21
Q
Split Brain Experiments
A
Split Brain Surgery involves cutting the band of nerve tissues (corpus callosum) connecting the two hemispheres
Disconnecting the two hemispheres reduces the severity of seizures
22
Q
Testing a Split Brain
A
Participants were asked to focus on the dot and images were flashed to the left or the right
Visual info in the left visual field is sent to the right hemisphere and vice versa
Split brain patients could recognise and name images projected in the right visual field but could not when the image was presented in the left visual field
Participants were able to locate the pencil with their left hand despite not being able to verbalise what they saw
23
Q
Sperry and Gazzangiga Results
A
The left hemisphere is responsible for the organisation of language expression and comprehension and when images are not processed in this hemisphere, they cannot be verbally stated
This is bc info processed in the right hemisphere could not be transferred to the left hemisphere via the corpus collosum
The right hemisphere is involved in language comprehension and the left hemisphere is dominant in language expression
24
Q
What does CT stand for
A
Computerised Tomography
25
What does a CT do
Neuroimaging technique that produces a computer enhanced image of a cross section from x-rays taken at different angles
Used to locate structural brain abnormalities
26
What is contrast
A dye that may be used to make some tissues show up more clearly. These dyes are harmlessly removed from the blood by the kidney and passed out in the urine
27
Advantages of a CT scan
- provides clear and accurate images
- allows for comparison between 'normal' and 'abnormal' brains
- relatively non invasive (only contrast injection)
28
Limitations of a CT scan
- only shows brain structure not function
- pregnant women advised not to as radiation can cause some damage to unborn child
- rarely, it is possible to have an allergic reaction to the contrast injection
29
What does PET stand for
Positron Emission Tomography
30
What does a PET scan do
- provides info regarding the function and activity of brain during tasks
- tracks blood flow by measuring the use of glucose by neurons in the active area of hte brain
- flurodeoxyglucose is injected into blood stream, travels to brain and emits radioactive signals that are detected and processed
- different colours are used to indicate different levels of brain activity (easy to interpret)
- least to most activity colours :violet, blue, green, yellow, red
31
Advantages of a PET scan
- displays detailed, colour coded images of a functioning brain
- allows researcher to see how different areas of the brain function together for certain tasks
- colours make interpretation simple
32
Limitations of a PET scan
- requires injection (radioactive glucose)
- use of radio activity means that longitudinal studies are difficult and dangerous
- PET scans need 40sec rest between each 30sec scan so can miss rapid changes in brain function
33
What does a MRI stand for
Magnetic Resonance Imaging
34
What does an MRI do
Uses magnetic fields and radio waves to vibrate the brains neurons and produce an image
Primarily used for identifying structural abnormalities
35
Advantages of a MRI scan
- clearer and more detailed images than a CT scan
- non-invasive
- no x-rays or radio activity involved
36
Limitations of a MRI scan
- only shows structure and anatomy, not function
| - cannot be used on people with internal metallic devices
37
What does a fMRI stand for
Functional Magnetic Resonance Imaging
38
What does a fMRI scan do
Detects changes in oxygen levels and blood to show brain function
Technique is like a standard MRI but blood and oxygen flow are recorded to show level of functioning of neurons
Colour changes indicate activity levels whilst performing a task
Applied in hemispheric specialisation studies
39
Advantages of a fMRI scan
- no exposure to radiation
- detailed images of brain functioning
- combination of structure and function
- detect changes in function in rapid succession
40
Limitations of a fMRI scan
- expensive and limited access
| - cannot be used on people with internal metallic devices
41
What does an EEG stand for
Electroencephalograph
42
What does an EEG scan do
Detects, amplifies and records general patterns of electrical activity within the brain
Electrodes placed along the scalp
43
Advantages of an EEG scan
- provides overall info about brain without being invasive
- used to study patterns of activity over a long length of time (eg. while sleeping)
- it shows different brain waves for different activity and useful for studying hemispheric specialisation
44
Limitations of an EEG scan
- doesnt provide detailed info regarding structures of the brain
- difficult to pin point specific areas of activity
- unable to distinguish a response from 'background noise' neural activity
- only provides a summary of neural activity
45
The Nervous System
The human nervous system is a hierarchical structure that reacts to changes both outside and inside the body. It receives and processes sensory information form the environment and transmits motor information around the body, that, in turn, determines our reaction to environmental stimuli
46
Draw the diagram of the Divisions of the Nervous System
Refer to notes when correcting
47
The Central Nervous System
Is composed of the brain and spinal cord. It processes sensory information to activate appropriate actions
The spinal cord connects the brain to the rest of the body
48
State the 2 functions the spinal cord serves
It sends information from sensory neurons in various parts of the body to the brain
It relays motor commands (actions/change) back to muscles and organs via motor neurons
This process occurs extremely rapidly and continuously
49
The Peripheral Nervous System
Is connected to the spinal cord and consists of all the nerves outside the CNS (brain and spinal cord)
It carries sensory info from the body to the CNS and motor info from the CNS to the body
Consists of the Somatic NS and the Autonomic NS
50
The Somatic Nervous System
Transmits sensory info to the CNS and carries out its motor commands
The Somatic NS is involved in voluntary muscle movements so it is often called the 'voluntary nervous system'
Two components: Sensory information (Afferent), Voluntary Skeletal Muscles (Efferent)
51
The Autonomic Nervous System
Is responsible for Automatic responses (life-giving responses) (breathing is the exception)
It carries info to internal bodily structures (eg. heart, lungs, glands) that carry out basic life functions
Divided into two main systems: Sympathetic NS (Fight/flight response) and Parasympathetic NS (Homeostasis)
52
The Sympathetic Nervous System
Readies the body for the fight or flight response when its exposed to threats
Sympathetic is speedy - fast reaction, instantaneous, short term
53
List four examples of the Sympathetic Nervous System
Dilates pupils
Increases heart rate
Relaxes bronchi
Slows digestion
54
The Parasympathetic Nervous System
Supports more routine activities that maintain the body's store of energy
When a threat has passed, the parasympathetic NS resumes control from the Sympathetic NS
55
List four examples of the Parasympathetic Nervous System
Heart rate decreases
Pupils constrict
Digestion increases
Blood pressure lowers
56
Neurons
Carry info/ messages in the form of an electrical impulse to the appropriate part of the nervous system. They also assist the brain in interpreting messages that they have received to enable a motor response
57
List the components of a neuron
```
Dendrites
Cell Body/Soma
Axon
Myelin Sheath
Terminal Buttons/ Synaptic Knobs
Synapse
Axon Terminals
```
58
Dendrites
Receive input from other neurons
59
Cell Body/Soma
Includes a nucleus which controls the neuron
60
Axon
Transmits information to other neurons
61
Myelin Sheath
'fatty covering' that insulates the axon from chemical and physical stimuli that might interfere with the transmission of neural impulses and increase the speed of transmission
62
Terminal Buttons/Synaptic Knobs
Send signals from a neuron to adjacent cells (release neurotransmitters)
63
Synapse
The space between neurons where transmission occurs
| Includes pre-synaptic terminal buttons, synaptic gap, post-synaptic dendritic spines/receptor sites
64
Axon Terminals
Branch-like extensions from the axon that carries message to terminal button
65
Neural Messages
Within neurons = electrical impulse
| Between neurons = chemical messages (neurotransmitters)
66
Draw a neuron
Correct using workbook
67
List the types of neurons
Sensory/Afferent Neurons - PNS
Interneurons - CNS
Motor/Efferent Neurons - PNS
68
Sensory/ Afferent Neurons
Transmit info from sensory cells in the body (called receptors) to the brain (either directly or by the way of the spinal cord)
Main role = sense the external world and monitor changes within our bodies
There are different types of sensory neurons, specialised to respond to a particular stimulation
69
Motor/ Efferent Neurons
Also called effectors
Carry messages from the CNS to the cells in the skeletal muscles, organs and glands to stimulate activity
Enable muscles to move so that we can walk, talk and carry out all other forms of behaviour
Located in the lower brainstem and spinal cord. All outgoing neural info must pass through them to reach the muscles
70
Interneurons
Also called connecting or associated neurons
Act as a link between sensory and motor neurons, relaying info from one neuron to another (sensory and motor neurons rarely connect directly)
Enable simple reflexes in the spinal cord as well as complicated functions in the brain
71
Glial Cells
Provide the structural framework that enable a network of neurons to remain connected
also:
- supply nutrients and oxygen to neurons so they can function
- destroy and remove dead neurons
- soak up excess neurotransmitters at the synapse that can clog communication between neurons
- block the entrance of toxic barriers to the brain
72
List the types of Glial Cells
```
Astrocytes (CNS)
Microglia (CNS)
Oligodendroglia (CNS)
Schwann Cells (PNS)
Satellite Cells (PNS)
```
73
Astrocytes
Provide the physical and nutritional support for CNS system
74
Microglia
Are the immune cells of the CNS - they fight infection and respond to injury
75
Oligodendroglia
Produce myelin sheath of neurons in the CNS
76
Schwann Cells
Produce myelin sheath of neurons in the PNS. Essential to the maintenance, function and development of peripheral nerves
77
Satellite Cells
Surrounds and covers the cell bodies/ soma. Maintain the cell body and keeps the neuron functional by supplying nutrients to the soma.
78
The Hindbrain contains the
cerebellum, medulla, pons
79
The Midbrain includes the
Reticular Activating System
80
The Forebrain includes the
Hypothalamus, Thalamus, Cerebrum
81
The Hindbrain
- found at the base of the brain
| - contains lower-level brain structures (cerebellum, pons, medulla)
82
Medulla
- found at the top of the spinal cord
- often referred to as the medualla oblongata due to its shape
- controls reflexive functions vital for survival eg. swallowing, breathing, heart pumping, blood pressure
83
Damage to the Medulla can cause
respiratory failure, paralysis, loss of sensation
84
Pons
- connects the top of the spinal cord to the brain
- involved in sleep, dreaming and arousal
- has a relay/ bridge function from cerebrum to cerebellum (eg. passes messages from the cortex about voluntary movement to the cerebellum)
85
Damage to the Pons can cause
locked-in syndrome
86
Cerebellum
- found at base of brain towards back
- coordination of fine muscle movement (ensures movement is smooth and precise)
- regulates posture and balance
- plays a role in speech - damage linked to stuttering
87
Damage to the Cerebellum can cause
loss of coordination, problems with speech and motor movement
88
Midbrain
- located deep within the brain
- collection of structures involved with movement, processing of sensory info, sleep and arousal
- contains Reticular Formation (includes the Reticular Activating System)
89
Reticular Formation
- filters incoming sensory info so the brain is not overloaded
- maintains consciousness, regulates arousal and muscle tension
90
Damage to the Reticular Formation can cause
an irreversible coma
91
Reticular Activating System
- extends in various directions to the brain and spinal cord
- involved in arousal
- involved in attention especially selective attention
- it initiates the attention response by rapidly alerting cortical areas of the brain to significant changes in the environment
92
Damage to the RAS can cause
issues with wakefulness, sleep and consciousness
93
Forebrain
- controls and regulates higher-order functions (eg. personality, cognitive functions, learning, perception)
94
Hypothalamus
- maintains the body's internal environment (homeostasis) ie. body temperature, hunger (not overeating or undereating), thirst, sexual functioning
95
Damage to the Hypothalamus
When sections of the hypothalamus are stimulated or damaged, eating problems can occur ie. not feeling full, not eating
96
Thalamus
- filters and transfers all sensory info (except smell) to relevant parts of the brain for processing
- transfers neural info (concerning alertness and attention) from the Reticular Formation to the cerebral cortex
- minimises sensory pathways during sleep
- direct link to RF (involved in arousal and alertness)
97
Damage to the thalamus can cause
- loss of any sense (except smell)
- attention difficulties as there is no 'filter' - the brain does not know what to ignore and what to attend to
- lower arousal from lethargy to coma
98
The Cerebral Cortex
- top layer of the cerebrum
- divided into two hemispheres
involved in receiving and processing sensory info and initiating motor responses
99
Hemispheric Specialisation
The cerebral hemispheres are two almost symmetrical areas of the brain running from its front to its back that are connected by the corpus callosum
Describes the unique functions of one hemisphere that is not shared with the other
100
Contralateral functioning
Meaning that each hemisphere controls the opposite side of the body
the RH receives sensory info from and controls the movement of the LHS of the body
the LH receives sensory info from and controls the movement of the RHS of the body
- each hemisphere has its own specialised functions
101
Left Hemisphere functions
verbal and analytical functions including
- reading
- writing
- the production and interpretation of speech
- aspects of sequential processes of analysis
102
Right Hemisphere functions
non-verbal functions including being active in
- visual awareness, including recognition of places, objects and faces
- spatial awareness
103
List the lobes of the brain
Frontal
Parietal
Occipital
Temporal
104
List the specialised areas of the brain
```
Primary Motor Cortex
Broca's Area
Primary Somatosensory cortex
Primary Visual Cortex
Primary Auditory Cortex
Wernicke's Area
```
105
Frontal Lobe
Concerned with higher-order functions such as decision making, reasoning, planning and emotions
Includes the primary motor cortex which stores info about how to carry out different movements
- has contralateral organisation
106
Frontal Lobes are important for
- expressive language and managing higher level executive functions - collection of cognitive skills including the capacity to:
plan
organise
self monitor
- considered our behaviour and emotional control centre and home to our personality
107
Damage to the Frontal Lobe can result in
- inability to express language (Broca's Aphasia)
- inability to focus on a task and filter out distractions (Attention)
- mood fluctuations
- changes in personality
108
Parietal Lobe
- Concerned with processing sensory info (including temperature and touch), orientation and types of recognition and memory)
- They are important for processing and interpreting somatosensory input (eg inform on objects in external environment through touch)
- Responsible for integrating sensory input and construction of a spatial coordinate system to represent the world around us
109
Somatosensory Cortex
- Receives sensory info from the skin and body enabling perception of bodily sensations
- Lips, tongue and hands are the most sensitive (take up more cortical space on the somatosensory cortex)
- sense of position of our body in space, visual attention, spatial reasoning, locating objects
- contralaterally organised
110
Damage to the Parietal lobe can result in
- difficulty with drawing objects
- difficulty in distinguishing left from right
- spatial disorientation
- inability to focus visual attention
111
Occipital Lobe
Contains the primary visual cortex. It is concerned with processing info from the eyes including vision, colour, shape and perspective
112
Damage to the occipital lobe can include
- difficulty with locating objects in the environment
- difficulty with identifying colours
- production of hallucinations
- difficulties with reading and writing
113
Temporal Lobe
- Concerned with processing auditory info (ie. hearing, sound, recognition of speech)
- Also involved in memory, encoding faces and expression
- Contains the Primary Auditory Cortex
- Plays an important role in processing emotions and certain aspects of visual perception
114
Dominant and non-dominant temporal lobes
The dominant temporal, in LH in most people, is involved in understanding language, learning and remembering verbal info
The non-dominant lobe, in RH in most people, is involved in learning and remembering non-verbal info (eg. visuo-spatial material and music)
115
Damage to the temporal lobes can result in
- difficulty in understanding spoken words
- difficulty learning and retaining new info
- impairing factual and long-term memory
- difficulty in recognising faces
116
Broca's area
- Located in the Frontal Lobe
- Responsible for the production of clear and articulate speech
- Coordinates muscles responsible for clear speech (eg. tongue, mouth, vocal chords)
117
Broca's Aphasia
- characterised by non-fluent speech
- by large, speech perception is not affected and language comprehension is normal
- Broca's aphasics have a halted speech pattern and have difficulty speaking sentences
118
Aphasia
An impairment in language production or comprehension brought about by neurological damage
119
Wernicke's Area
- Located in the temporal lobe
| - involved in the comprehension of speech (ie making sense of verbal communication)
120
Wernicke's Aphasia
- deficits in the comprehension of language
- speech is, by and large, fluent, but it may appear to not make sense to listeners as the patients themselves cannot understand what they are saying - this meaningless speech is sometimes called jargon aphasia
- unlike Broca's aphasia, people with Wernicke's Aphasia may seem unaware of their disorder
121
Primary Auditory Cortex
- located in the temporal lobe
- responsible for receiving and processing auditory info
- the left PAC is primarily involved in receiving and processing verbal auditory info
- the right PAC is primarily involved in receiving and processing non verbal auditory info
122
A Neuron
An individual nerve cell that is specialised to receive, process or transmit info
Neurons communicate with each other, muscles and glands
- Within neurons = electrical/ neural impulse/ action potential
- Between neurons = chemical messages/ neurotransmitters
123
List the Key Stages of Neural Communication
1. Resting Potential
2. Threshold
3. Depolarisation (Action Potential)
4. Repolarisation
124
Resting Potential
- the natural state for a nerve cell
- the neuron is not sending an electrical signal
- the inside of a neuron is negative (relative to the outside) = polarised
- there are more Na+ ions outside the cell and more K+ ions inside the cell
- more positve ions outside the cell than inside
- voltage inside the cell is -70mV
- sodium outside, potassium inside, positive outside, negative inside (SOAPI PONI)
125
Threshold
- 55mV
- an event/ stimulus causes the resting potential to move toward 0mV
- the neurotransmitters (chemicals) bind with receptors at dendrites and cause sodium channels to open
- when threshold is reached, an action potential will always fire
- if critical threshold level is not reached, no action potential will fire
126
Steps in neural impulse between neuron
1. Neural impulse arrives at terminal button
2. Chemical messenger (neurotransmitter) is released into synapse
3. Neurotransmitter diffuses across the synapse
4. Neurotransmitter binds with a receptor on the membrane of the post-synaptic neuron
5. Binding of neurotransmitter to receptor stimulates impulse in post-synaptic neuron (if threshold is met)
127
Depolarisation/ Action Potential
- between +30-40 mV
- after the threshold is reached, the inside of the neuron becomes more positive
- the action potential causes Na+ channels to open with Na+ to flood into the cell
- sodium has a positive charge, so the neuron becomes more positive and becomes depolarised
128
Repolarisation
- potassium channels open, potassium rushes out of the cell, reversing the depolarisation
- this starts to make the cell more negative, so that it returns to resting potential in that part of the cell
- the neural impulse (action potential) continues to travel along the axon until it reaches the terminal buttons
129
Spinal Reflex
An unconscious, involuntary and automatically occurring response to certain stimuli without any involvement of the brain
The spinal cord can initiate some simple responses on its own independently of the brain
- sometimes known as the reflex arc
- spinal reflex demonstrates a response to sensory stimulus can have both a conscious and unconscious component
- eg of a polysynaptic reflex
- involves activation of more than one synapse, including an interneuron making a connection between sensory and motor neuron, causing extreme sensation
130
Steps involved in the withdrawal response
1. Sensory neurons carry message along sensory pathway to the spinal cord
2. Interneurons in the spinal cord relay the message to motor neurons
3. Motor neurons carry the message along the motor pathway to the hand muscles causing a withdrawal reflex
4. The spinal reflex occurs at the same time that sensory neurons carry the message further up the SC to brain
5. The message is received in the area of the brain that processes that particular type of sensory info and interprets the pain (in the hand)
131
'Patella' Knee Joint
eg of a monosynaptic reflex
- involves one synapse and the interaction between sensory neuron and a motor neuron
- patella nerves are directly connected to the SC, so reflex is result of info travelling along a sensory neuron to a motor neuron in the SC and therefore activating only one synapse between these two neurons, so rapid
132
Reward System
The striatum is regulated by the pre-frontal cortex to release dopamine (reward chemical)
Higher brain activation and release of dopamine in teenagers than kids and adults, hence sharp increase in sensitivity and excitement to info, leading to decreased calculated behaviour
133
Neural Plasticity
Refers to the manner in which the brain changes in response to stimulation from the environment
134
List the types of Neural Plasticity
Developmental Plasticity
| Adaptive Plasticity
135
Developmental Plasticity
Changes in the brain's neural structure during its growth and development (maturation)
significantly linked to genetics
136
List the Key Processes in Developmental Plasticity
```
Proliferation
Migration
Synaptogenesis
Synaptic Pruning
Myelination
```
137
Proliferation
Unborn baby's neurons divide and multiply at a rapid rate
138
Migration
New neurons in the foetus and newborn move to their location in Nervous System
139
Synaptogenesis/ Circuit Formation
Creation of multiple connections between neurons
Existing synapses are strengthened, molded or changed, or new ones are formed
During learning, glutamate is released by pre-synaptic neuron
Leaning new info causes new neural connections
This enables new info to be transferred faster
140
Synaptic Pruning
The removal of connections that have not formed strong pathways and are no longer needed
141
Myelination
Development of thick myelin sheaths which speeds up neural transmission (ie makes messages more efficient). This process continues through to very late adolescence
142
Infancy and Adolescence (Developmental Plasticity)
Neuroscientists have identified infancy and adolescence as two periods of significant change due to developmental plasticity
In infancy, the number of synapses greatly increases through synaptogenesis - our synaptic density is greatest from the end of infancy to early childhood (6/7 years old)
From late childhood and into adolescence, our synapses are refined and reduce greatly in number
The adult brain has 40% less synapses than a 3 year old
143
Frontal Lobe Development
- Long term maturation of the frontal lobe, including its growth in size and the development of its neuronal pathways
- The last area of our brain to mature and undergo myelination and synaptic pruning (up to 25y/o)
- Pre frontal cortex = last to develop in frontal lobe - responsible for higher-order decision making and reasoning
144
Sensitive Period
The period of time when an organism is more responsive to certain stimulation
- lack of stimulation over this period can lead to long term deficits
eg. closed eyes from birth to late childhood leads to blindness even when eyes open
145
Genie Case Study
0-12years = sensitive period for vocabulary/ basics of language
- critical period for comprehension, language and grammar
146
Critical Periods
The narrow period of time where development in an animal is preprogrammed for learning to occur
eg. birds have critical periods hours after birth where they will follow the first large moving object they see
147
Experience Expectant Development
Brain is primed (it expects) to make neural changes provided it gets the correct input ie. hearing language during the sensitive period
eg. learning a first language
148
Experience Dependent Development
Not related to sensitive periods and the brain is not primed to make neural changes. Refers to the creation and organisation of neuron connections that occur as a result of a person's life experiences
- differing life experiences and circumstances influence how certain areas of the brain develop and continue to grow
eg. learning to play an instrument - brain does not 'expect' to make these changes
149
Adaptive Plasticity
How synaptic connections are formed or synaptic connections are altered due to one or more of the following:
- a change in environmental conditions (adapting to environmental changes)
- learning new concepts
- re-learning something after brain injury
Allows us to learn new things across the lifespan
150
List the two key processes that underline rehabilitation
Rerouting
| Sprouting
151
Rerouting
Neurons near damaged area seek new active connections with healthy neurons
152
Sprouting
New dendrites grow to enable new connections between neurons, allowing a shifting of function from damaged area to healthy area
- relearning tasks (eg. walking, eating) helps these new connections form - aim of rehabilitation
153
The Nature of the Brain
Everything that makes you who you are comes from the way your brain cells interact and connect. It is the source of your consciousness - your awareness of who you are, your state of being and your external environment
154
Parkinson's Disease
A neurodegenerative disease in which neurons at the base of the brain (substantia nigra) degenerate and gradually cease to function normally
- impairs the sufferer's motor skills (movement and balance) and speech
155
Causes of Parkinson's disease
- degeneration of dopamine - producing neurons (60-70%) in substantia nigra (midbrain), lack of dopamine results in tremors and difficulty initiating movement
156
Basal Ganglia
- regulates movement
- depends on a certain amount of dopamine to function at peak efficiency
- has strong neural links to the substantia nigra
157
Dopamine
Carries messages between neurons to ensure effective planning, initiation and maintenance of motor movements
When there is a deficiency of dopamine in the brain, movements may become delayed and uncoordinated and the brain will receive fewer or irregular messages on how to control movements in the body
158
Motor symptoms of Parkinson's disease
- muscle rigidity
- reduced motor control and precision of movement
- tremors
- difficulty balancing
159
Non-motor symptoms of Parkinson's disease
- fatigue
- mental health problems (depression)
- increased sensitivity to temperature
- REM sleep behaviour disorder
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Treatment and research of Parkinson's disease
- no known cure for disease, so treated with medication that can be converted into dopamine by body (can cause nausea and hallucinations)
- animals = similar dopamine producing areas so can be induced with PD
- levodopa = chemical converted to dopamine by neurons, alleviates symptoms in early stages
- Deep brain stimulation - neurosurgery to electrically stimulate the basal ganglia
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Glutamate
- An excitatory neurotransmitter and major neurotransmitter in the brain
- Found in hippocampus and outer layers of cerebral cortex
Receptor sites associated with glutamate are: NMDA, AMPA, Kainate
When glutamate binds with these receptor sites it makes it more likely for the post synaptic neuron to fire
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Glutamate is associated with
Cognition, memory, learning, behaviour, movement, sensations
| When combined with the receptor site NMDA, glutamate is associated with Long Term Potentiation
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Too much Glutamate in the brain has been associated with
Abnormal neural development (innappropriate neural connections forming)
Neurodegenerative diseases eg MND
Attention disorders (over excitation)
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GABA (Gamma amino butyric acid)
An inhibitory neurotransmitter
It slows neural transmission and reverses the effects of excitatory neurotransmitters eg. reduces the stress response
- low levels are associated with high levels of anxiety and GABA is used to treat anxiety disorders
- alcohol can increase GABA activity
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Inhibitory
Makes the post synaptic neuron less likely to fire
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Lock and Key Process
Receptor sites are specially designed to only bind with certain neurotransmitters
The distinct molecular structure of the neurotransmitter being matched by the receptor site means that the receptor site will only respond to specific neurotransmitters and ignore others
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Agonists
Substances that increase the release of neurotransmitters or imitate their functioning making their effects on the post-synaptic neuron more likely to occur eg. morphine, benzodiozophine
Agonist mimics neurotransmitter
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Antagonists
A substance that inhibits the release of neurotransmitters or blocks receptor sites, making it less likely that the post synaptic neuron will respond to a neurotransmitter eg. snake venom
Antagonist blocks neurotransmitter
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Hebbian Learning
Leaning results from the creation of cell assemblies ie. interconnected groups of neurons that form pathways
Repeatedly sending and receiving pre and post synaptic info at the same time changes the chemistry of the cell leading to stronger connections
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Long Term Potentiation
A persistent increase in synaptic strength following high-frequency stimulation of the synapse
The long lasting strengthening of synaptic connections resulting in enhanced or more effective neurotransmission across the synapse making the post synaptic neuron more likely to fire
- neurons that are stimulated will have a greater potential to fire again if stimulated
- the more the neural pathway is activated the more it is strengthened
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Long Term Depression
A long lasting decrease in the strength of synaptic transmission
Process of long term weakening of synaptic connections
- post synaptic neuron becomes less responsive to neurotransmitter released by the pre synaptic neurotransmitter
Allows for the pruning of unwanted and unneeded neural connections
This allows for the strengthening of important neural connections
