the brain and behavior (neurotransmission)

Question 1

the main work in the brain is done by:

Answer 1

glutamate, gamma-amino-butyric acid (GABA), glycine

Question 2

Which of these does our brain have more of? -Glial? -neurons?

Answer 2

glial. they are not directly involved in conveying electrical impulses.

Question 3

how many neurons does the brain have?

Answer 3

billions of neurons.

Question 4

what is the size of neurons?

Answer 4

They differ in size. Some are almost a meter in length, while most are shorter than a millimeter.

Question 5

three main parts of a neuron?

Answer 5

a body (soma), dendrites, and an axon that could be branched.

Question 6

what is the direction of neurons?

Answer 6

from dendrites through the body and along the axon.

Question 7

what is a myelin sheath?

Answer 7

it is a fatty sheat–> info goes much faster when you have myelin. myelin is located around the axons

Question 8

what happens when the neuron is at rest?

Answer 8

there is a resting potential of -70 millivolts between the inside of the neuron and the outside due to concentrations of ions.

Question 9

what does excitatory mean?

Answer 9

the neuron is made more likely to react

Question 10

what does inhibitory mean?

Answer 10

the neuron is made less likely to react.

Question 11

what are the two important things that neurons do?

Answer 11

1) they generate electricity

2) they release chemicals that allow them to communicate with other neurons and with muscles and glands

Question 12

how do neurons communicate with each other?

Answer 12

• the neurons convert the electrical signal to a chemical signal in order to pass the information to another neuron.
• the target neuron then converts the message back to an electrical impulse to continue the process

Question 13

3 basic steps of the electrical activity of neurons

Answer 13

1) resting potential (neuron at rest)
2) action potential (nerve impulse)
3) resting potential (neuron at rest)

Question 14

extracellular fluid and cytosol

Answer 14

extracellular fluid: outside the neuron

cytosol: inside the neuron

Question 15

what would happen if the potential reaches approx -50 millivolts? (action potential)?

Answer 15

the membrane of the neuron becomes permeable and sodium and chloride ions enter the neuron and potassium ions exit the neuron. this exchange of ions leads to a sudden change in the potential to +40 millivolts. this change travels along the neuron from dendrite to end-terminal of axon and this makes up the signal inside the neuron.
when the impulse reaches the end-terminal vesicles open up and release the content, a neurotransmitter, into the synaptic gap. the molecules of a neurotransmitter can travel across the gap and bind to receptors on the dendrites or body of the next neuron.

Question 16

what are the drugs that bind to receptors for endorphins (a group of neurotransmitters)?

Answer 16

morphine and opiates

Question 17

why do anesthetics work?

Answer 17

because they hinder ions to pass through the membrane of the neurons.

Question 18

drugs that hinder or facilitate reuptake?

Answer 18

cocaine inhibits the reuptake of dopamine, serotonin, and nor-adrenaline.

Question 19

reasons why serotonin levels are low? and treatments of this?

Answer 19

major depression is caused by decreased levels of serotonin, a neurotransmitter that seems to regulate mood.

• levels of MAO (monoamine oxidase), an enzyme that breaks down serotonin could be high, or reuptake could be too effective.
  treatments:
• MAOI (MAO-inhibitor), is one kind of drug that inhibits MAO, an enzyme, from breaking down serotonin.
• SSRI, selective serotonin reuptake inhibitor, is another kind of anti-depressant that decreases the reuptake of serotonin. (Prozac is a kind of SSRI)

Question 20

limitations of serotonin?

Answer 20

• not possible to measure amount of serotonin in a living brain.
• we don’t know whether a decreased level of serotonin is a cause or an effect of depression

Question 21

what are GABA (gamma-aminobutyric acid), glutamate, and glycine?

Answer 21

GABA:
-the major inhibitory neurotransmitter in the brain.
Glutamate:
-the most common excitatory neurotransmitter in the brain.
Glycine:
-a neurotransmitter used mainly by neurons in the spinal cord. it probably always acts as an inhibitory neurotransmitter.

Question 22

what is serotonin’s name? where in the brain? amount in the brain? function? inhibitory or excitatory?

Answer 22

name: 5-hydoxytryptamine (5-HT). synthesized from the amino acid L-tryptophan. At least 15 types of 5-HT receptors have been described.
where in the brain?
-midline of the brainstem
amount in the brain?
-200 000 of the 100 billion neurons in the human brain are serotonergic.
function?
-influence sleep cycle, sex drive, eating, body temperature, cardiovascular activity, respiration. Also, mood, aggression, anxiety, antisocial behavior, addictions, autism, eating disorders. romantic love.
inhibitory or excitatory?
-can be both. there are 14 types of receptors.

Question 23

what is dopamine’s name? where in the brain? amount in the brain? function? inhibitory or excitatory?

Answer 23

name: DA.
where in the brain?
-released in the brain’s reward system (part of the limbic system). natural rewards, including food, liquids and sex as well as electrical brain stimulation increase extracellular dopamine levels.
amount in the brain?
-1 million brain cells in the human brain contain dopamine.
function?
-involved in goal-directed behavior (motivation) such as pleasure-seeking, control of movement, emotional response, and addictive behavior.
inhibitory or excitatory?
-can be both

Question 24

what is VAT?

Answer 24

ventral tegmental area: drugs like alcohol, heroin, nicotine excite dopamine-energic neurons in VTA (produce more action potentials)

Question 25

study 1

Answer 25

Meyer et al (2006) Elevated Monoamine Oxidase-A levels in the brain.

aim: to investigate whether MAO-A levels (an enzyme that breaks down the neurotransmitters in the synapse) are elevated during untreated depression.
pps: 17 healthy and 17 depressed with major depressive disorder. depressed pps had been medication-free for at least 5 months.
procedure: PET to measure amount of MAO-A. pps is injected with a harmless dose of radioactive glucose. the scans produce a colored map of brain activity.
results: MAO-A was highly significantly elevated in every brain region assessed. The MAO-A was elevated on average by 34% (2 SDs) throughout the brain during major depression.

Question 26

study 2

Answer 26

Fisher et al (2005), reward, motivation, and emotion systems associated with early-stage intense romantic love.

aim: to investigate neurophysiological correlates of early-stage romantic love.
pps: 10 women and 7 men.
procedure: word of mouth. all pps reported being in the early stage of romantic love (range 1-17 months). they were interviewed abt their love(duration,intensity, range of feeling). also 2 questionnaires(one abt intensity of passion, one on general emotional intensity. pps were provided a photo of the beloved (positive stimulus) and a similar photo of a familiar(neutral stimulus). fMRI for four tasks(for 30s, pps viewed the positive stimulus; for the following 40s, pps performed countback from 700 in steps of 7; for the following 30s, pps viewed the neutral stimulus, and for the following 20s pps performed the countback.) it repeated for 6 times for a total of 12 min.
results: there was increased activity in the VTA and caudate nucleus when pps watched the faces of their partners. this activity correlated positively with pps’self-reported levels of passion and degree of attractiveness of partner.