PSY251 V3

Question 1

Excitatory postsynaptic potential (EPSP) (4)

Answer 1

Normally found on the dendritic tree or spine

Opening transmitter gated ions channels ( Na+) in postsynaptic membrane

Both an electrical and a concentration gradient driving Na+ into the cell;

The postsynaptic membrane will become depolarized (EPSP)

Question 2

Inhibitory postsynaptic potential (IPSP)

Answer 2

Normally found on the cell body (If you think about it, the reason for this is because if you wanted to stop the action potential with IPSP, then you would need to stop it further down the chain reaction, so the cell body makes sense)

A impulse arriving in the presynaptic terminal causes the release of neurotransmitter; The molecular bind and active receptors on the postsynaptic membrane open CI- or, sometimes K+ channels; More CI- enters, K+ outer the cell, producing a hyperpolarization in the postsynaptic membrane.

It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold.

Question 3

Role of sodium-potassium pump

Answer 3

Pump sodium out of the cell, 3 sodium ions exported and two potassium ions are imported. Cost one ATP molecule.

Question 4

Measure of voltage across cell membrane

Answer 4

Known as membrane potential.

Outside of the cell is considered 0, so whatever the difference in charge between outside and inside is what the membrane potential is.

Usually sits at -70mV at resting potential.

Question 5

Sequence of chemical events at the synapse. (6)

Answer 5

Precursor transport

The neurotransmitter is synthesized somewhere inside the neuron.

It is packaged and stored within vesicles at the axon terminal.

It is transported to the presynaptic membrane and released into the cleft in response to an action potential in a process of exocytosis.

It binds to and activates receptors on the postsynaptic membrane.

It is degraded or removed, so it will not continue to interact with a receptor and work indefinitely.

Question 6

Two types of summation and how they work.

Answer 6

Summation is the concept of the occurrence of multiple stimulation coming from the same place (spatial summation) and at the same time (temporal summation). When more stimulus occurs together in time and space it creates a bigger wave and will bring the membrane potential closer to threshold, the more stimulus occurring together, the more likely threshold will be met.

Question 7

Drug antagonist

Answer 7

Drug that opposes or inhibits effects of particular neurotransmitter on postsynaptic cell

Block receptors

Block release from vesicle

Question 8

Drug agonist
Explanation and 5 responses.

Answer 8

Drug that facilitates effects of particular neurotransmitter on postsynaptic cell

Can increase production of neurotransmitter.

Promotion of release from vesicle.

Stimulation of the receptor.

Reduction in the enzyme that breaks down neurotransmitter.

Reuptake transporter blocked

Question 9

Sensitisation to drugs:

Answer 9

Opposite to tolerance, an increased responsiveness to successive equal doses.

Does not work in a familiar environment, before becoming addicted or dependent on a drug need to be sensitised by numerous experiences with the drug away from home environment.

Life experience can work in the same way and prime the nervous system for addiction.

Question 10

Withdrawal:

Answer 10

Physical and psychological behaviour displayed by a user when drug use ends.

Question 11

Tolerance: explanation and three things that can cause it.

Answer 11

Decrease in response to drug over time,in that the effective dose will need to go up over time as tolerance builds.

Can be learned tolerance – learn to cope with being drunk

Metabolic tolerance – produce more enzymes to break down the alcohol.

Cellular tolerance – Brain cells adjust to minimise effects of alcohol

Question 12

Mesolimbic (Dopaminergic) pathways:

Answer 12

Reward system

Starts ventral tegmental area (VTA), through to nucleus accumbens, hippocampus, basal ganglia, and frontal cortex. Also flow to cerebellum.

Thought to be the reward system

Most affected by addictive drugs and behavioural addictions.

Increased DA may be related to schizophrenia

Decrease in DA associated with attention deficits.

Question 13

The Incentive-Sensitization Theory:

Answer 13

Dopamine release is the neural correlate of wanting and the repetition of behaviour.

Cues trigger a wanting.

Cue itself pulls attention.

Pavlovian (classical conditioning) where paired stimulus increases wanting.

Different states can increase cue power. Withdrawal is one.

Question 14

Electroencephalograph (EEG)

Answer 14

Summed graded potentials.

An EEG recorded from the cortex displays an array of patterns, some rhythmical. Alpha rhythms
An EEG recorded from the cortex displays an array of patterns, some rhythmical.

Records electrical information of the brain, used to record sleep stages and excessive neuronal activity associated with seizures.

It is possible to record from outside the skull.

PYRAMIDAL cells span layers of the cortex and have parallel cell bodies. Their combined extracellular field is small but measurable at the scalp.

Question 15

MEG (Magnetoencephalography) x4

Answer 15

Records the magnetic field created by the electrical currents created by neurons.

More precise than EEG.

High cost in comparison to EEG and ERP

Can locate the source of an epileptic discharge

Question 16

TMS (Transcranial magnetic stimulation)

Answer 16

Magnet that can depolarise neurons.

Magnetic field that can depolarises neurons propagating action potentials.

Used to induce behaviour or to disrupt ongoing behaviour.

Question 17

Single-cell recording

Answer 17

Intracellular recordings are is therefore confined to neurons grown in a dish or, for short periods (hours), to neurons in living brain slices.

Problem is intracellular recordings can kill the cell from inserting electrode into it.

Need to insert microelectrode into the cell.

Question 18

Event-related potentials (ERPs)

Answer 18

Complex EEG waveform related in time to a specific event eg. Something happens, EEG spikes, this is the ERP.

Can be used with many electrodes, sometimes 200, to identify brain areas that respond to different stimuli.

Can be used to map the order in which different regions of the brain participate in a stimulus.

Cannot penetrate the cortex.

Question 19

fMRI Functional magnetic resonance

Answer 19

Measures blood flow to the areas of the brain.

Question 20

Primary motor cortex

Answer 20

Produces skilled movements such as those with the hands arms and mouth. Executes movements

Question 21

Premotor cortex

Answer 21

Receives instructions from the prefrontal and then organises movement sequences. Coordinates different movements together eg. Two hands coordinating to achieve the same task. Does not execute the movements, just plans them out. Motor sequences – movement sequences pre-programmed into the brain and produced as a whole unit.

Question 22

Spinal cord and its involvement in movements (e.g., voluntary vs involuntary movements, spinal reflex, etc)

Answer 22

Spinal column produces movement for people even when they have their spinal column severed. Can be seen in patients automatic leg movement when stimulated from walking when they do not have to hold up their own weight. Seen mostly from the medial interneurons.

Spinal reflexes
Somatosensory neurons send out collaterals to motor neurons, directly or through interneurons, to mediate spinal reflexes.

Question 23

Unilateral damage to spinal column (In regard to somatosensory)

Answer 23

Loss of fine touch and pressure sensation of same side of cut. This is below damage.

Loss of nociception on opposite side of cut. This is below damage.

Question 24

Motor pathways (e.g., corticospinal tract)

Answer 24

Axons from the corticospinal tract originate mainly in the motor cortex, but some also come from the pre-motor cortex and the sensory cortex. They travel through the brainstem where they send out collaterals to other nuclei and emerge on brainstem ventral surface on bumps called pyramids. Finger hand and arm movement cross to the opposite side, while trunk and shoulder movement continue on. Motor neurons carry all information to the muscles. Interneurons coordinate complex movements through their connection to other motor neurons.

Lateral corticospinal tract is crossed. Connects to motor neurons directly or through interneurons to control muscles of limbs and digits. Motor neurons carry all information to the muscles. Connects to the lateral interneurons and motor neurons.

Ventral (anterior) corticospinal tract is uncrossed. Connects with motor neurons directly or through interneurons to innervate the trunk (Midline of body) Motor neurons carry all information to the muscles. Connect to medial (middle) interneurons and motor neurons.

Question 25

Movement disorders (e.g., Parkinson’s disease)

Answer 25

Parkinson’s is caused by the loss of dopamine neurons in the substantia nigra, especially in the neural pathway to the basal ganglia. When these cells die there is not enough dopamine to transmit messages.

Parkinson’s disease has four major symptoms (although they aren’t necessarily all observed): tremors (generally of arms and hands), cog-wheel rigidity (a stiff, mechanical type of movement), akinesia (lack of movement) or bradykinesia (slowness of movement), and disturbances of posture.

Some back and forth here as too much dopamine is thought to cause schizophrenia, and too little Parkinson’s.

Question 26

Treatment for Parkinsons

Answer 26

Normally L-dopa or some drug that works as an agonist on dopamine.
Deep brain stimulation (subthalamic brain stim)
Combination of drugs and DBS
Transcranial direct current (research sketchy)
Levodopa/carbidopa/entacapone

Question 27

Three components of emotion

Answer 27

Physiological/Autonomic response (e.g., increased heart rate)
Hypothalamus and associated structures as well as ENS

Subjective feelings (e.g., fear)
Amygdala and parts of frontal lobes

Cognitions (e.g., thoughts about the experience)
Cerebral cortex

Question 28

Neural control of emotion 3 theories.

Answer 28

Constructivist theories argue that the brain produces a cognitive response to autonomic states.

Appraisal theories define emotional episodes as processes rather than states. Emotions result from an evaluation of context, including somatic components, which lead to a subjective feeling.

Neuropsychological theories emphasize asymmetrical cerebral control of emotions. Eg. Right hemisphere plays a large part in emotion, like left does for language.

Question 29

Where in the brain do emotions generate from

Answer 29

Emotions are not found in a single place in the brain but rather are distributed in limbic and frontal lobe structures, especially the amygdala and prefrontal cortex. Emotional disorders, such as depression and anxiety, are believed to result from dysfunction in these structures.

Limbic system (amygdala and hippocampus)

Hypothalamus

Prefrontal cortex

Cingulate cortex

Question 30

Where in the brain does motivated behaviour generate from

Answer 30

Motivated behaviours are inferences to why an animal engages in particular behaviours.

Motivated behaviours can be regulatory and no regulatory.

Many brain structures are involved in motivated behaviours but primarily the hypothalamus is involved.