Synaptic Transmission and Behaviour

Question 1

Action Potential

Answer 1

Synaptic inputs causes neuron to depolarise or hyperpolarise
Triggered when depolarisation surpasses threshold (-50mV)
Neural membrane opens to allow positively charged ions to move inside the cells, negatively charges ions to move out
- Na moves in, K moves out
Causes a rapid increase in positive charge, rapidly decreases
Charge reaches +40mV - electrical impulse is propogated down nerve fibre

Question 2

Failed initiation

Answer 2

Depolarisation doesn’t surpass threshold

Question 3

Refractory period

Answer 3

Protection method - stops the nerves from continually firing

Question 4

Sensory receptors

Answer 4

converts sensory energy into neural activitiy; only responds to a narrow band of energy

Question 5

Neurotransmitters

Answer 5

Influences transmembrane flow; either increase (excitatory) or decrease (inhibitory) probability of post-synaptic AP

Question 6

Neurotransmitter production

Answer 6

1. Synthesis
2. Release
3. Receptor action
4. Inactivation

Question 7

Excitatory messages

Answer 7

increases probability (type 1)

Question 8

Inhibitory messages

Answer 8

decreases probablity (type 2)

Question 9

Neurotransmitter Traits

Answer 9

1. chemical must be synthesised/be present in a neuron
2. must produce a response in a target cell
3. same response must occur when chemical is experimentally placed on the target
4. must be a mechanism for removing the chemical

Question 10

Classes of neurotransmitters

Answer 10

Small molecules - derived from food, quickly replaced following release
Peptide neurotransmitters - slow production, made on ribosomes, packed in membrane

Question 11

Small molecule neurotransmitter examples

Answer 11

Acetylcholine and serotonin

Question 12

Acetylcholine

Answer 12

function in PNS and CNS as neuromodulator
Plasticity, arousal and reward
Used in learning, decision making and attention

Question 13

Serotonin

Answer 13

Excitatory; found in raphe region of pons, upper brainstem
Regulates sleep and wakefulness, mood and aggression, appetite and arousal, perception of pain
Anxiety, depression, cognitive symptoms of schizophrenia,

Question 14

Peptide neurotransmitters

Answer 14

Slow production, act slowly, not easily replaces

Question 15

Brain opiod peptide systems

Answer 15

motivation, emotion, attachement behaviour, response to stress and pain, control of food intake

Question 16

Transmitter gases

Answer 16

small gasous molecules freely permeable to membranes
Synthesised as needed
Nitric oxide - aids digestion dilates blood vessels in active brain regions

Question 17

Ionotropic receptors

Answer 17

form ion channel pore, permits movement of Na, K, Ca

Rapid changes in membrane voltage - excitatory

Question 18

Metabotropic receptors

Answer 18

receptor of eukaryotic cells, acts through a secondary messenger
May be located at surface of cells, in vesicles

Question 19

Neurotransmission in SNS

Answer 19

Acetylcholine as main neurotransmitter (cholinergic system)

Question 20

Neurotransmission in ANS

Answer 20

CNS acetylcholine synapses with sympathetic neurons
Sympathetic neurons contain norepinephrine (NE)
Ach transmits NE neruons to prepare for fight-or-flight

Question 21

Four activating CNS systems

Answer 21

Cholinergic
Dopaminergic
Noradrenergic
Serotonergic

Question 22

Cholinergic system

Answer 22

Impacts higher order processes - starts in brain stem, extends into frontal lobe
Input in basal forebrain -sustained attention
Activation - attentional processing of threatening stimuli
Projections to medial prefrontal cortex influences anxious responses to contextual stimuli
Impacts working memory and attentional processes for error detection
Decreased cholinergic tone = impaired cognitive performance; memory, attention, executive functioning

Question 23

Dopaminergic systems

Answer 23

4 major pathways;

• Mesolimbic
• Mesocortical
• Nigrostriatal
• Tuberoinfundibular

Question 24

Nigrostriatal Pathway

Answer 24

Projects from substantia nigra to striatum - primary input to basal ganglia
Parkinson’s - loss of innervation to the striatum

Question 25

Mesolimbic pathway

Answer 25

"reward pathway" Begins in ventral tegmental area of midbrain, connects to nucleus accumbens, amygdala, hippocampus and prefrontal cortex Role in neurobiology of addition, schizophrenia, depression Role in motivation, pleasure, reward and reinforcement learning

Question 26

Noradrenergic System

Answer 26

Areas producing/affected by norepinephrine Neurons originate in the locus coeruleus and lateral tegmental field Concerns emotion, contributes to depression and mania

Question 27

Serotonergic System

Answer 27

Originates in dorsal raphe and median raphe (midbrain) Axons form a system reaching almost every part of CNS Maintain EEG in forebrain and plays a role in wakefulness Implicated in OCD, depression and schizophrenia