Psychobiology Flashcards
What is neuropsychology?
a method of exploring the brain - shows the consequences of damage to specific areas.
What is PET imaging?
Position emission tomography - detects radiation and brain activity (glucose levels).
What is MRI imaging?
Magnetic resonance imaging - measures blood oxygenation changes - measure of neuronal activity
What is the CNS?
Nerves that make up the spinal cord and brain.
What is the PNS?
What is left over from the CNS - responsible for providing us with inputs/outputs.
What is the PNS made up of?
The autonomic nervous system and the somatic nervous system.
What is the ANS made up of?
Two branches: the sympathetic and parasympathetic.
What are sympathetic nerves responsible for?
Fight or flight - e.g. speeding up heart rate - bring the body to an aroused state.
What are parasympathetic nerves responsible for?
Rest and digest - e.g. lower heart rate - return the body to its resting state.
What is the somatic nervous system responsible for?
Handles inputs from the external world by functioning via the spinal cord. Inputs come from the dorsal root and leave to affect muscles via the ventral root.
What do the ventricles contain?
Cerebrospinal fluid (CSF)
What is CSF?
A liquid produced from ependymal cells which bathes the brain, protecting it from injury - circulates between membranes, along large blood vessels and through the ventricles.
What are neurones?
Information transmitting cells which transmit and process information using electrical signals
What are neurones made up of?
Dendrites, which receive info
Soma, which integrate inputs
Axons - axon hillock, myelin sheath and axon terminal
What the types of glia?
Astrocytes, oligodendrocytes and microglia
What is the role of astrocytes?
Wrap processes around and communicate with neurones and contact blood vessels.
What is the role of oligodendrocytes?
Wrap myelin sheath around axons.
What is the role of microglia?
The brains resident immune system - remove damage and infection.
What is Ohm’s law?
current = (potential x conductance)
or
(potential / resistance)
What creates the concentration gradient?
Ion channels in the membrane allow potassium ions to flow outside of the cell, making the inside more negative which then attracts more potassium ions inside the cell - equilibrium maintained by a Na+ / K+ pump.
What is an action potential?
A wave of transient depolarisation that travels down the axon.
What are the steps of an action potential?
1) When neurotransmitters bind to receptors they depolarise the neurone (+)
2) A threshold of -55mV has to be reached for an AP to go ahead
3) Depolarisation occurs due to Na+ channels opening and the shutting of K+ channels (+)
4) Then the neurone is repolarised due to the Na+ channels closing and the K+ channels opening (-)
5) The neurone is then hyper-polarised as K+ continues to leave the cell, causing the inside to become very negative.
6) Then the neurone returns to its resting state of -70mV.
What is an absolute refractory period?
When all sodium channels are inactivated, enforcing one way transmission. The neurone is unable to respond to another stimulus.
What is a relative refractory period?
When some sodium channels are inactivated and only a very strong stimulus can reopen them to produce an action potential.
What is saltatory conduction?
When the action potential travels through gaps in the myelin sheath (Nodes of Ranvier).
What happens at the presynaptic cell?
An AP arrives, depolarising the terminal. this releases calcium which activates the release of neurotransmitters into the synapse. Then the neurotransmitter binds to receptors on the postsynaptic membrane, producing either an excitatory or inhibitory response.
What happens to produce an excitatory response?
Depolarisation of dendrites due to ions flowing through glutamate receptors generates an excitatory post synaptic response (EPSP) which increases the likelihood of an AP occurring.
What is temporal summation?
Lots of EPSP’s are needed to reach the threshold for an AP.
What is spatial summation?
The activation of lots of synapses produces enough EPSP’s at the same time to summate and reach the threshold for an AP.
What produces an inhibitory response?
GABA, an inhibitory neurotransmitter, opens chloride channels which allows negative charge into the cell, generating an inhibitory post synaptic potential (IPSP), hyper-polarising the membrane.
What is tolerance?
When you take a drug in repeated, identical doses the effects diminish.
What is sensitisation?
Repeated exposure to a drug makes the effects stronger.
What is addiction?
Compulsive use: which leads to a loss of control over a form of behaviour pleasurable to most people - suggests a separation between wanting and liking.
What are the effects of cocaine?
It blocks dopamine transporters, increasing the levels of dopamine at the synapse.
What are the effects of amphetamine?
Amphetamine is transported into the presynaptic terminal and displaces dopamine from its vesicles, releasing it into the synapse, and then reduces its reuptake.
What does cannabis do?
It mimics the effects of endocannabinoids.
What is a full agonist?
Produces maximal stimulation at higher doses - high efficacy and affinity.
What is a partial agonist?
Produces a small effect than a full agonist but can reduce its effects. High affinity and a lower efficacy.
What is an antagonist?
Reduces the effects of agonists. Has high affinity and low efficacy.
What is anxiety?
A feeling or fear or dread, usually in situations where there is no reasonable external cause. Or clinical anxiety which interferes with other activities.
What are rods and cones?
Specialised cells that hyper-polarise when light falls on them, depolarising retinal ganglion cells, producing an action potential.
How is information projected in the eyes?
Information from the nasal side of the retina is sent to the opposite side of the brain - projected contra-laterally.
Information from the temporal side of the retina remains on the same side of the brain - projected ipsilaterally.
How do muscle contractions occur?
Acetylcholine released at muscle end plate and binds to nicotinic receptors, opening sodium channels. This depolarises the muscle membrane which releases calcium ions, triggering the muscle fibres to contract.
What are individual differences in response to stress?
People have one of two gene variants of an enzyme important in degrading dopamine - either Met (which leads to higher dopamine levels due to lower COMT activity) or Val. Individuals with Met may be more prone to greater stress and worry whereas those with Val are at a greater vulnerability to psychosis.