UNIT 3 & 4 PSYCHOLOGY
U3AOS1
Neuron → nerve cell that receives and transmits neural information.
1. Sensory Neurons → travels on Afferent pathways
2. Motor Neurons → travels on Efferent pathways
3. Interneurons → found in the Brain & Spinal cord → transferring neural messages between sensory & motor neurons
Central NS → receives & transmits sensory info from the body’s internal & external environments, then creates a response.
• Brain →
- Receives & processes sensory stimuli from the body
- Coordinates responses including voluntary movement, emotion & conscious thought
- Regulates functions that do not require conscious thoughts like breathing, temperature regulation & hunger
• Spinal Cord →
- Carries incoming sensory info from the body (peripheral) towards the brain for processing
- Carries incoming motor info from the brain toward the body (peripheral)
- Connects the brain to the peripheral NS via afferent and efferent pathways
Peripheral NS → network of nerves outside the CNS that carries sensory info to the CNS & motor info from the CNS to the
body’s muscles, organs & glands.
• Somatic NS →
- Carries afferent info from the five senses (sight, smell, hearing, taste, touch) to the CNS
- Carries efferent info from the CNS to the body involving motor neurons responsible for voluntary movement
• Autonomic NS →
- Controls the body’s internal environment in an involuntary/autonomous & self-regulating manner
- Directly connects CNS with organs, glands & visceral muscles (smooth, involuntary) like heart, lungs, stomach &
digestive tract
Sympathetic NS → when under threat; pupils dilate, ↑BP, ↑HR, ↑ RR, ↑sugar & fat in blood
Parasympathetic NS → once threat passed; pupils constrict, salivation, ↓HR, intestines digest
Enteric NS → important in the Gut-Brain Axis
, UNIT 3 & 4 PSYCHOLOGY
Unconscious Responses →
• Fight-Flight-Freeze Response → involuntary reaction to danger that is powered by adrenaline.
- Sympathetic NS is dominant
- Freezing is the pause to decide whether to fight or flight (reactive immobility/attentive immobility)
- Sympathetic is before the threat, autonomic (rest & digest) is after the threat it gone
• Spinal Reflex → unconscious response without participation of the brain
1. Harmful sensory stimulus comes into contact with sensory receptors
2. Sensory neural info travels along an afferent pathway to the spinal cord
3. Interneurons in the spinal cord relay the sensory signal to the motor neurons as a neural signal
4. Initiates an automatic & unconscious motor response
5. Motor message are then carried along efferent pathways to the skeletal muscles which response (usually
retracting a part of the body to protect it)
6. Sensory info continues to travel to the brain via afferent pathways
7. Brain independently registers the sensation that triggered the spinal reflex (usually pain) but only after the
response occurred.
Conscious Response → carried out by the Somatic NS
1. Sensory stimulus meets sensory receptors
2. Sensory neural info travels along afferent pathways to the interneurons in the spinal cord & to the brain
3. Brain processes sensory info & then coordinates & initiates the conscious motor response
4. Motor neural messages are transmitted to interneurons in spinal cord, motor neurons pass motor messages along
efferent pathways to skeletal muscles.
5. Movement then occurs
Neurotransmitters in Neural Transmission →
• Whenever a thought it formed or memory recalled, neurons communicate with each other → Neural Transmission.
• Neuron activates/fires an electrical impulse (action potential) down Axon, away from Soma, in direction of Axon
Terminals.
• Electrical charge/action potential reaches axon terminal, triggering release of neurotransmitters, bonding to
corresponding receptor sites.
• Synaptic vesicles holding neurotransmitters/chemicals move to membrane of presynaptic terminal & emerge with it,
releasing chemicals into synaptic gap.
• Neurotransmitters travel across synaptic gap to ward receptor sites on the dendrites of the postsynaptic neuron.
• Then bind to receptor sites, specialized to receive specific neurotransmitters & make postsynaptic neuron more or
less likely to ‘fire’.
• Whether a postsynaptic neuron fires or not depends on the type of neurotransmitter & its effect.
Glutamate →
• Main excitatory neurotransmitter
• Postsynaptic neurons are more likely to fire
• Activates/stimulates neural activity in the brain
• Involved in neural plasticity & process of learning & storing memory
, UNIT 3 & 4 PSYCHOLOGY
GABA →
• Main inhibitory neurotransmitter
• Postsynaptic neuron less likely to fire
• Suppresses/slows down neural activity in the brain
• Low levels are associated with conditions like anxiety & specific phobia
Neuromodulators → influence effects of other neurotransmitters
• Neuromodulation is a process that changes synaptic efficacy, originating in presynaptic via
alteration in number of neurotransmitter molecules released or originating in postsynaptic
neuron via altering receptor sensitivity
• Both pre & postsynaptic mechanisms can work together & result in altered synaptic efficacy
between two or more neurons
• Release chemical messages into the synaptic gap (broader are), affecting large numbers of
neurons at once → entire neural tissue, brain area, pathway or multiple pathways may be
influenced by
• Work slower than neurotransmitter, effects take longer to establish & last longer
• Convey global control of brain states that underlie different behaviours like sleep & wakefulness
Neurotransmitters Neuromodulators
Description Chemical released by presynaptic neuron Chemical released by neurons to alter
to send signals to postsynaptic neuron effectiveness of neural transmission
Role Transmit chemical signals to adjacent Alter neural transmission of neurons by
neurons (excitatory or inhibitory) controlling production & release of
neurotransmitters
Site of Release Into synaptic gap (between two neurons) Outside synaptic gap (vast regions with many
neurons affected at once)
Target Single postsynaptic neuron Groups of neurons
Speed Fast Slow
Time of Effectiveness Short-acting Lasts for longer periods of time
Dopamine → both excitatory & inhibitory effects that reinforces neural activity in regions of the brain associated, involved
in CNS functions including feelings of pleasure, movement, attention, mood, cognition & motivation.
• Reward Pathway → group of structure in the brain that activate when experiencing rewarding or reinforcing stimulus.
- Pathway controls responses to natural rewards like food, sex & social interactions → determinant of motivation
- More dopamine released within Reward Pathway → more motivated to repeat the behaviour
- Brain has many dopamine producing areas & neural pathways
Serotonin → inhibitory neurotransmitter & neuromodulator.
• More than 90% of body’s serotonin is found in the gastrointestinal tract.
• Modulate behaviour processes like mood, perception, reward, anger, aggression, appetite, memory, sexuality &
attention
• Produce in the brain stem & travels to the cerebrum (including cerebral cortex), modulating brain activity in these areas
- ↑serotonin levels → ↑mood
- ↓serotonin levels → ↓mood
- ↓serotonin levels → disrupted circadian rhythm → sleep-wake cycle → release of melatonin
- ↓serotonin levels → ↓waiting for reward →↑impulsive behaviours
- ↑serotonin levels → ↑waiting for reward → ↓impulsive behaviours
- ↓serotonin levels → ↓communication between limbic system (amygdala & frontal lobes of cerebral cortex) →
↓control of emotions → ↑aggressive behaviours
- Tryptophan is raw material produced in the gut → ↓serotonin levels if no food consumed
, UNIT 3 & 4 PSYCHOLOGY
Synaptic Plasticity → relatively permanent strengthening of synaptic connections due to repeated activation of neural
pathways.
• When learning something new & storing the memory of it, a relatively permanent connection between neurons is
formed
• Strengthening of neural connection is made between pre & postsynaptic neurons, involving axon terminals,
neurotransmitters being released & receptors of dendrites of postsynaptic neuron
- Long-Term Potentiation → relatively permanent strengthening of synaptic connections due to repeated activation
of neural pathway.
Neural pathway is activated during the process of learning, the excitatory neurotransmitter glutamate is
released
Repeated activation of the pathway (repeated stimulation & release of glutamate) neural connection
strengthen → memory/learning becomes stronger & more permanent
- Long-Term Depression → neural pathway is not activated any longer, strong neural connections were once
formed become weaker.
Relatively permanent weaking of synaptic connections due to repeatedly lower levels of activity in a neural
pathway
Helpful as it allows the brain to reduce or ‘prune’ neural connections that are no longer useful
Modifications due to LTP & LTD →
• Sprouting (LTP) → growth of axon or dendrite fibres at the synapse, changing the physical structure of neurons.
- Growth of dendritic spines on postsynaptic neuron
- Growth of axon branches called ‘Filigree Appendages’ on axon terminal of the presynaptic neuron
- Formation of additional synapses where these dendritic spines & filigree appendages meet, Synaptogenesis
• Rerouting (LTP) → formation of new connections between neurons to establish alternative neural pathways.
- Damaged areas of the brain where neural connections have been lost due to accident or disease
- New connections (rerouted connections) making brain more efficient, usually after learning new ways of doing
things
• Pruning (LTD) → removal of excess neurons & synaptic connections to increase efficiency of neural transmission.
- Allows brain to fine-tune neural networks, making brain & neural connections more efficient
Stress → state of mental, emotional & physiological tension resulting from a stressor.
U3AOS1
Neuron → nerve cell that receives and transmits neural information.
1. Sensory Neurons → travels on Afferent pathways
2. Motor Neurons → travels on Efferent pathways
3. Interneurons → found in the Brain & Spinal cord → transferring neural messages between sensory & motor neurons
Central NS → receives & transmits sensory info from the body’s internal & external environments, then creates a response.
• Brain →
- Receives & processes sensory stimuli from the body
- Coordinates responses including voluntary movement, emotion & conscious thought
- Regulates functions that do not require conscious thoughts like breathing, temperature regulation & hunger
• Spinal Cord →
- Carries incoming sensory info from the body (peripheral) towards the brain for processing
- Carries incoming motor info from the brain toward the body (peripheral)
- Connects the brain to the peripheral NS via afferent and efferent pathways
Peripheral NS → network of nerves outside the CNS that carries sensory info to the CNS & motor info from the CNS to the
body’s muscles, organs & glands.
• Somatic NS →
- Carries afferent info from the five senses (sight, smell, hearing, taste, touch) to the CNS
- Carries efferent info from the CNS to the body involving motor neurons responsible for voluntary movement
• Autonomic NS →
- Controls the body’s internal environment in an involuntary/autonomous & self-regulating manner
- Directly connects CNS with organs, glands & visceral muscles (smooth, involuntary) like heart, lungs, stomach &
digestive tract
Sympathetic NS → when under threat; pupils dilate, ↑BP, ↑HR, ↑ RR, ↑sugar & fat in blood
Parasympathetic NS → once threat passed; pupils constrict, salivation, ↓HR, intestines digest
Enteric NS → important in the Gut-Brain Axis
, UNIT 3 & 4 PSYCHOLOGY
Unconscious Responses →
• Fight-Flight-Freeze Response → involuntary reaction to danger that is powered by adrenaline.
- Sympathetic NS is dominant
- Freezing is the pause to decide whether to fight or flight (reactive immobility/attentive immobility)
- Sympathetic is before the threat, autonomic (rest & digest) is after the threat it gone
• Spinal Reflex → unconscious response without participation of the brain
1. Harmful sensory stimulus comes into contact with sensory receptors
2. Sensory neural info travels along an afferent pathway to the spinal cord
3. Interneurons in the spinal cord relay the sensory signal to the motor neurons as a neural signal
4. Initiates an automatic & unconscious motor response
5. Motor message are then carried along efferent pathways to the skeletal muscles which response (usually
retracting a part of the body to protect it)
6. Sensory info continues to travel to the brain via afferent pathways
7. Brain independently registers the sensation that triggered the spinal reflex (usually pain) but only after the
response occurred.
Conscious Response → carried out by the Somatic NS
1. Sensory stimulus meets sensory receptors
2. Sensory neural info travels along afferent pathways to the interneurons in the spinal cord & to the brain
3. Brain processes sensory info & then coordinates & initiates the conscious motor response
4. Motor neural messages are transmitted to interneurons in spinal cord, motor neurons pass motor messages along
efferent pathways to skeletal muscles.
5. Movement then occurs
Neurotransmitters in Neural Transmission →
• Whenever a thought it formed or memory recalled, neurons communicate with each other → Neural Transmission.
• Neuron activates/fires an electrical impulse (action potential) down Axon, away from Soma, in direction of Axon
Terminals.
• Electrical charge/action potential reaches axon terminal, triggering release of neurotransmitters, bonding to
corresponding receptor sites.
• Synaptic vesicles holding neurotransmitters/chemicals move to membrane of presynaptic terminal & emerge with it,
releasing chemicals into synaptic gap.
• Neurotransmitters travel across synaptic gap to ward receptor sites on the dendrites of the postsynaptic neuron.
• Then bind to receptor sites, specialized to receive specific neurotransmitters & make postsynaptic neuron more or
less likely to ‘fire’.
• Whether a postsynaptic neuron fires or not depends on the type of neurotransmitter & its effect.
Glutamate →
• Main excitatory neurotransmitter
• Postsynaptic neurons are more likely to fire
• Activates/stimulates neural activity in the brain
• Involved in neural plasticity & process of learning & storing memory
, UNIT 3 & 4 PSYCHOLOGY
GABA →
• Main inhibitory neurotransmitter
• Postsynaptic neuron less likely to fire
• Suppresses/slows down neural activity in the brain
• Low levels are associated with conditions like anxiety & specific phobia
Neuromodulators → influence effects of other neurotransmitters
• Neuromodulation is a process that changes synaptic efficacy, originating in presynaptic via
alteration in number of neurotransmitter molecules released or originating in postsynaptic
neuron via altering receptor sensitivity
• Both pre & postsynaptic mechanisms can work together & result in altered synaptic efficacy
between two or more neurons
• Release chemical messages into the synaptic gap (broader are), affecting large numbers of
neurons at once → entire neural tissue, brain area, pathway or multiple pathways may be
influenced by
• Work slower than neurotransmitter, effects take longer to establish & last longer
• Convey global control of brain states that underlie different behaviours like sleep & wakefulness
Neurotransmitters Neuromodulators
Description Chemical released by presynaptic neuron Chemical released by neurons to alter
to send signals to postsynaptic neuron effectiveness of neural transmission
Role Transmit chemical signals to adjacent Alter neural transmission of neurons by
neurons (excitatory or inhibitory) controlling production & release of
neurotransmitters
Site of Release Into synaptic gap (between two neurons) Outside synaptic gap (vast regions with many
neurons affected at once)
Target Single postsynaptic neuron Groups of neurons
Speed Fast Slow
Time of Effectiveness Short-acting Lasts for longer periods of time
Dopamine → both excitatory & inhibitory effects that reinforces neural activity in regions of the brain associated, involved
in CNS functions including feelings of pleasure, movement, attention, mood, cognition & motivation.
• Reward Pathway → group of structure in the brain that activate when experiencing rewarding or reinforcing stimulus.
- Pathway controls responses to natural rewards like food, sex & social interactions → determinant of motivation
- More dopamine released within Reward Pathway → more motivated to repeat the behaviour
- Brain has many dopamine producing areas & neural pathways
Serotonin → inhibitory neurotransmitter & neuromodulator.
• More than 90% of body’s serotonin is found in the gastrointestinal tract.
• Modulate behaviour processes like mood, perception, reward, anger, aggression, appetite, memory, sexuality &
attention
• Produce in the brain stem & travels to the cerebrum (including cerebral cortex), modulating brain activity in these areas
- ↑serotonin levels → ↑mood
- ↓serotonin levels → ↓mood
- ↓serotonin levels → disrupted circadian rhythm → sleep-wake cycle → release of melatonin
- ↓serotonin levels → ↓waiting for reward →↑impulsive behaviours
- ↑serotonin levels → ↑waiting for reward → ↓impulsive behaviours
- ↓serotonin levels → ↓communication between limbic system (amygdala & frontal lobes of cerebral cortex) →
↓control of emotions → ↑aggressive behaviours
- Tryptophan is raw material produced in the gut → ↓serotonin levels if no food consumed
, UNIT 3 & 4 PSYCHOLOGY
Synaptic Plasticity → relatively permanent strengthening of synaptic connections due to repeated activation of neural
pathways.
• When learning something new & storing the memory of it, a relatively permanent connection between neurons is
formed
• Strengthening of neural connection is made between pre & postsynaptic neurons, involving axon terminals,
neurotransmitters being released & receptors of dendrites of postsynaptic neuron
- Long-Term Potentiation → relatively permanent strengthening of synaptic connections due to repeated activation
of neural pathway.
Neural pathway is activated during the process of learning, the excitatory neurotransmitter glutamate is
released
Repeated activation of the pathway (repeated stimulation & release of glutamate) neural connection
strengthen → memory/learning becomes stronger & more permanent
- Long-Term Depression → neural pathway is not activated any longer, strong neural connections were once
formed become weaker.
Relatively permanent weaking of synaptic connections due to repeatedly lower levels of activity in a neural
pathway
Helpful as it allows the brain to reduce or ‘prune’ neural connections that are no longer useful
Modifications due to LTP & LTD →
• Sprouting (LTP) → growth of axon or dendrite fibres at the synapse, changing the physical structure of neurons.
- Growth of dendritic spines on postsynaptic neuron
- Growth of axon branches called ‘Filigree Appendages’ on axon terminal of the presynaptic neuron
- Formation of additional synapses where these dendritic spines & filigree appendages meet, Synaptogenesis
• Rerouting (LTP) → formation of new connections between neurons to establish alternative neural pathways.
- Damaged areas of the brain where neural connections have been lost due to accident or disease
- New connections (rerouted connections) making brain more efficient, usually after learning new ways of doing
things
• Pruning (LTD) → removal of excess neurons & synaptic connections to increase efficiency of neural transmission.
- Allows brain to fine-tune neural networks, making brain & neural connections more efficient
Stress → state of mental, emotional & physiological tension resulting from a stressor.
