The brain Flashcards
Nervous system
Collects and responds to information. Coordinates organs including the brain
Nervous system subdivisions
CNS and PNS
PNS = ANS + SNS
ANS = sympathetic and parasympathetic
CNS= Brain and spinal cord
Central nervous system (CNS)
Right hemisphere controls left side of body and vice versa
Brain = conscious awareness and decision making.
Brain stem = automatic functions, some reflex responses and consciousness.
Peripheral nervous system (PNS)
information from outside world to CNS
Information from CNS to muscles
Autonomic nervous system (ANS)
Automatic functions eg. breathing, heart rate, stress response
Somatic nervous system (SNS)
Voluntary movement of muscles and reflex responses. Sends messages to muscles and takes in information from sensory organs.
ANS in depth
Homeostasis, an automatic system, sympathetic nervous system, parasympathetic nervous system
Homeostasis
Maintains a balanced internal state by monitoring activity of the body organs
Autonomic system
No conscious control because functions are vital to life
Sympathetic nervous system
psychological arousal, triggered when stressed and leads to fight or flight response.
Parasympathetic nervous system
opposite to sympathetic
Produces rest and digest response to return body to resting state.
Fight or flight response
Brain detects threat, Release of adrenaline, the response, Once the threat has passed.
Brain detects threat
hypothalamus identifies a threatening event (a stressor)
triggers the sympathetic division of the ANS to act
Release of adrenaline
ANS changes from parasympathetic rest state to aroused sympathetic state
Stress hormone adrenaline released into bloodstream
Flight or fight response
Immediate and automatic
Psychological changes due to action of adrenaline, e.g. increased heart rate, decreased digestion.
Gets body ready to confront threat (fight) or energy to run (flight)
Once the threat has passed
the parasympathetic division of ANS takes over, ‘rest and digest’.
James-lange theory of emotion
event –> arousal –> interpretation –> emotion
JL theory - psychological arousal first
Hypothalamus arouses sympathetic division of ANS.
Adrenaline released leading to psychological arousal (fight or flight)
JL theory - emotion afterwards
Brain interprets psychological activity
Causes emotion, e.g. love, fear.
JL theory- an example
Meet bear in forest
Sympathetic arousal: muscles tense, heart rate increases
Interpret as fear
JL theory - no physical changes = no emotion
Speaking in front of class, no increase in heart rate means you don’t experience any sense of fear.
JL evaluation 1
There is evidence that emotions do come after arousal in the case of phobias
JL evaluation 2
Challenged by the Cannon-Bard theory which argues that we experience emotions at the same time as psychological arousal. e.g. we feel embarrassed at the same time as we blush
JL evaluation 3
The two-factor theory suggests emotion may be more complex (Schacter and Singer 1962). We need social cues to determine the emotion (For example, your heart racing can be interpreted as fear if in a dark alley or as excitement if you’re kissing someone you like.)
Types of neurons
sensory, relay, motor
Sensory neuron
Carry messages from PNS to CNS
Long dendrites, short axons
Relay neurons
Connect sensory to motor
Short dendrites, short axon
Motor neuron
From CNS to effector (usually muscles or glands)
Short dendrite, long axon
Structure of neuron
Cell body, dendrites, axon, myelin sheath, terminal buttons
Cell body (soma)
contains the nucleus which holds the genetic material (DNA) of each neuron
Dendrites
carry electrical signals from neighbouring neurons to the cell body
Axon
carries electrical signals away from the cell body. It is covered in a fatty layer called the myelin sheath.
Myelin sheath
protects the axon and also speeds up the signal. The sheath has gaps called Nodes of Ranvier which make the signal speed up as it ‘jumps’ across the gaps.
Terminal buttons
Communicate with the next neuron in the chain across a gap called the synaptic cleft
Electrical transmission
Resting state cell is negatively charged
Action potential = movement into neuron of positive ions creating electrical impulse
Synaptic transmission
the process by which neighbouring neurons communicate with each other by sending chemical messages across the synaptic cleft that separates them.
Neurotransmitter
A chemical that is released from synaptic vesicles. These send signals across the synaptic cleft from one neuron to another, can cause excitation or inhibition of the next neuron in the chain
The synapse
Where neurons communicate with each other: terminal button at presynaptic neuron + synaptic cleft + receptor sites on postsynaptic neuron
Release of neurotransmitters
Electrical signals cause vesicles (in presynaptic terminal button) to release neurotransmitter into synaptic cleft
Reuptake of neurotransmitters
Neurotransmitter in synaptic cleft attaches to postsynaptic receptor sites .
Chemical message turn into electrical impulse
Remaining neurotransmitter absorbed.
Excitation and inhibition
Excitatory neurotransmitter increases postsynaptic neuron’s charge, more likely to fire.
Inhibitory neurotransmitter increases negative charge, less likely to charge.
Summation
More excitatory than inhibitory signals means that neuron fires, creating an electrical impulse.
Hebbs’ theory of…
learning and neuronal growth
The brain is plastic
Synaptic connections become stronger the more they are used. Brain can change and develop (Hence the reason why its ‘plastic’)
The brain adapts
Brain changes in response to new experiences, at any age.
Learning produces an engram
Learning leaves a trace called an engram. This can be permanent if we rehearse learning
Cell assemblies and neuronal growth
Groups of neurons that fire together
Neuronal growth occurs as cell assemblies rewire.
Hebbs’ theory evaluation 1
Hebbs’ theory is scientific - Objective basis gives theory validity and credibility,
Hebbs’ theory evaluation 2
Real-world application to education - Stimulating school environment can increase neuronal growth
Hebbs’ theory evaluation 3
Reductionist theory - Reduces learning to a neuronal level. It ignores ‘higher’ levels. e.g. Piaget’s idea that accommodation is a key part of learning. It doesn’t look at the wider factors that create learning.
Structure and function of the brain
Brain is divided into two halves called hemispheres.
Top surface layer is called the cerebral cortex.
Four lobes
frontal, parietal, temporal, occipital
Frontal lobe
Located at the front of the brain,
Controls thinking, planning and it includes motor area,
Also contains Broca’s area.
Parietal lobe
Behind the frontal lobe
At the front of it is the somatosensory area, where sensations are processed.
Occipital lobe
At the back of the brain,
contains visual area,
controls vision
Temporal lobe
Behind frontal lobe and below parietal lobe
Auditory (sound) area, related to speech and learning
Contains part of language area (Wernicke’s area)
Cerebellum
Receives information from spinal cord and brain
Coordinates movement and balance; attention and language too.
(Contains half of the brains’ neurons)
Localisation of function
Specific brain areas do particular jobs
Motor area
Damage to the left hemisphere affects the right side of the body, and vice versa.
Somatosensory area
Most sensitive body parts take up most ‘space’
Damage means less ability to feel pain.
Visual area
Damage to left hemisphere affects right visual field of each eye and vice versa
Auditory area
Damage can lead to deafness
Language area
Usually in the left hemisphere only
Broca’s area and Wernicke’s area.
Broca’s area
Damage leads to difficulty remembering and forming words
Wernicke’s area
damage leads to difficulty understanding and producing meaningful speech
Penfield’s study of…
the interpretive cortex
Penfield’s aim
To investigate the function of the temporal lobe using the Montreal procedure
Penfield’s Method
Operated on patients with severe epilepsy.
Could stimulate areas of the brain in a conscious patient who reported their experiences
Penfield’s Results
visual area stimulation: colours and shadows
somatosensory stimulation: tingling sensation or a false sense of movement
Temporal lobe stimulation: experiences and feelings (hallucinations) associated with those experiences including deja vu.
Penfield’s conclusion
The area of the brain called the interpretive cortex stores the personal meaning of previous events.
Penfield’s evaluation 1
Precise method - He could stimulate the exact same area of the brain and have verbal reports from awake patients.
Penfield’s evaluation 2
Unusual sample - All participants had severe epilepsy so their behaviour may not reflect people with ‘normal’ brains
Penfield’s evaluation 3
Mixed results in later research - Interpretive cortex may not always respond as Penfield had concluded. In later studies, less than 10% of participants reported recalling past experiences vividly.
His conclusion lacks validity.
Cognitive neuroscience
Aims to create a detailed map of localised functions in the brain
Structure and function of the brain relates to behaviour
Frontal lobe and motor area: movement
Temporal lobe and amygdala: processes emotion and aggression
Structure and function of the brain relates to cognition
Different types of memory are in different areas of the brain
Cognitive neuroscience and mental illness
Low serotonin affects thinking (e.g. suicidal thoughts) and behaviour (low mood, depression).
Importance of localisation
Damage to specific areas of brain affect certain areas/ behaviours.
The effects of stroke
When brain is deprived of oxygen (lack of blood supply) areas of brain die leading to effects on behaviour, unless other areas take over localised functions
Effects of neurological damage on motor ability
Damage to motor area can lead to problems with fine and complex movements. Damage to the left hemisphere affects the right side of the body, and vice versa.
Effects of neurological damage on behaviour
Broca’s aphasia: problems producing speech.
Wernicke’s aphasia: problems understanding speech.
Scanning techniques
CT scans, PET scans, fMRI scans
CT scans
Large doughnut-shaped scanner that rotates. Takes lots of X-rays of brain which are combined to give a detailed picture
CT Scans Strength
Quality is higher than traditional X-ray
CT scans weakness
High levels of radiation and only produces still images
PET scans
Patient injected with radioactive glucose. Brain activity shown on computer screen.
PET scans strengths
Shows brain in action and localisation of function
PET scans weaknesses
Expensive and may be unethical because of radiation
fMRI scans
Measures changes in blood oxygen levels. Displayed as 3D computer image
fMRI scans strengths
Superior as produces clear images without use of radiaiton
fMRI scans weaknesses
Expensive and have to stay very still.
Tulving’s aim
To investigate if episodic memories produce different blood flow patterns to semantic ones
Tulving’s Method
Six participants injected with radioactive gold.
Repeated measures design used with four episodic and four semantic memory trials.
Monitored blood flow using PET scan
Tulving’s Results
Different blood flow in three out of six participants
Semantic memories in posterior cortex i.e. parietal and occipital lobed
Episodic memories in anterior cortex i.e. frontal and temporal lobes.
Tulving’s Conclusion
Episodic and semantic memories localised.
Memory has a biological basis.
Tulving’s evaluation 1
Objective evidence - Evidence from brain scans is difficult to fake, producing unbiased evidence
Tulving’s evaluation 2
Problems with the sample - The six participants included Tulving, and conclusion based on just three of the participants
Tulving’s evaluation 3
Different types of memory? - Episodic and semantic memories are hard to separate, which may explain inconclusive evidence.
