BIopsychology Flashcards
What is Charles Darwin’s theory of evolution? Give an example.
Organisms that are better suited (able to adapt and adjust to their environment) for their environment will survive and reproduce while those that are poorly suited for their environment will die off.
Example: species of birds: Each species has adapted to different environments, primarily through variations in their beak shapes and sizes - allowing them to better reach for their food source.
Give an example of human genetics supporting Darwin’s theory.
Example: Sickle cell anemia
- A genetic condition in which red blood cells take on a crescent-like shape affecting how they function.
- Causes many people to die at an early age but it is still common among people of African descent.
- Carriers of only one copy of the sickle cell gene are thought to be immune from malaria, a deadly disease which is common in Africa. HOWEVER, FULL BLOWN SICKLE-CELL ANEMIA, WITH TWO COPIED OF THE SICKE-CELL GENE, DOES NOT PROVIDE IMMUNITY.
- In this example, carrying the gene makes a person better suited for their environment. This is why certain genetic diseases that cause people to die not been removed from human genetics.
BOOK: 2 soeurs africaines, one carried the gene of sickle-cell disease ( HAS ONE COPY OF THE SICKLE-CELL DISEASE, BUT NOT THE FULL-BLOWN SICKLE-CELL ANEMIA, they still experience symptoms tho) and the other no. Both catch malaria. The one that had the gene is protected and the other dies two weeks later. This is a great example of how carrying a certain gene can make a person better suited for their environment. While does who are not adapted to their environment might just die off.
keep in mind: en afrique sa mutation is beneficial, aux us pas tant, she might pass it on to her descendants but it will not be beneficial in any way.
GENES (NATURE/BIOLOGY) AND THE ENVIRONMENT (NURTURE)
(va voir l’image diapo 5 if any doubt)
What is a gene?
Genes are segments of your DNA, which give you physical characteristics that make you unique (they are found in chromosomes)
GENES (NATURE/BIOLOGY) AND THE ENVIRONMENT (NURTURE)
What are chromosomes?
Chromosomes carry DNA in cells. DNA takes the form of a double-helix configuration.
GENES (NATURE/BIOLOGY) AND THE ENVIRONMENT (NURTURE)
What is DNA?
DNA is responsible for building and maintaining your human structure.
GENES (NATURE/BIOLOGY) AND THE ENVIRONMENT (NURTURE)
What is heritability? Give an example.
Measure of the variability of behavioural traits among individuals that can be accounted for by genetic factors.
À quel point un trait est héréditaire vs environnementale.
FOR EXAMPLE: if a trait like intelligence has high heritability, it means that a significant portion of the variation in intelligence levels among people is due to genetic differences rather than upbringing (how you were raised) or life experiences.
What is the degree of relatedness?
The probability that a gene in one individual is identical-by-descent (inherited by a common ancestor) to a gene in another individual
EXAMPLE: monozygotic (division d’un ovule fécondé par un spermatozoïde) versus dizygotic twins (Les premiers proviennent de deux ovules fécondés par deux spermatozoïdes différents -> faux jumeaux)
What is a genotype?
The term “genotype” refers to the genetic makeup of an organism; in other words, it describes an organism’s complete set of genes, so their unique sequence of DNA. It refers to how the alleles are paired.
EXAMPLE:
BB (blue eyes)
Bb (blue eyes)
bb (green eyes)
What is a phenotype?
It describes an individual’s observable characteristics, such as hair color, skin color, height, and build. In other words, it’s the description of the genetic makeup (so how it looks: blue/green eyes…).
What does a polygenic trait mean?
A trait that is controlled by more than just one gene. The majority of inheritable (traits passed down from parents) traits are polygenic.Polygenic traits typically show a range of variations, such as height or skin color, because they result from the combined effects of several different genes. This complexity can make these traits more variable and less predictable than traits controlled by a single gene.
what is the difference between a gene and an allele?
Le gène est une très petite portion de chromosome. Comme les chromosomes (one from mom, one from dad), chaque gène est présent en double dans nos cellules (together they code a trait). Ces deux copies d’un même gène s’appellent des allèles (c’est une forme du gene, comme un des constituant en gros). Alleles can be dominant or recessive.
What does it mean to possess a dominant allele
That it will always result in expression of that phenotype. The phenotype of a recessive allele will only be physically expressed if the person is homozygous for that allele, meaning they inherited a recessive allele from BOTH parents (aa).
Heterozygous vs homozygous
Heterozygous - consisting of two different alleles (Aa).
Homozygous - consisting of two identical alleles (AA/aa).
What are mutations?
sudden, permanent change in a gene.
Keep in mind: many mutations are harmful but some can also be beneficial (because, mutations created a genetic diversity -> mutation benefice can give an advantage to better adapts survive and reproduce : remember sickle-cells anemia example)
What is the tool used to predict how genes will interact in the production of offspring?
A punnett square: The capital B represents the dominant allele, and the lowercase b represents the recessive allele. In the example of the cleft chin ( an inherited trait), where B is cleft chin (dominant allele), wherever a pair contains the dominant allele, B, you can expect a cleft chin phenotype. You can expect a smooth chin phenotype only when there are two copies of the recessive allele, bb.
Mom has a dominant and recessive allele, while dad two recessive allele, which means there is a 50% chance for their kid to have a cleft chin.
GENE-ENVRIONMENT INTERACTION:
What is a range of reaction? Give an example.
Our genes create a limit of range for our potential in different traits, but where we actually end up within that range depends on our environment.
Example: a child who has a natural “connection/strength” with music, but has never nurtured that ability.
GENE-ENVRIONMENT INTERACTION:
What is genetic-environmental correlation?
Our genes can shape the kind of environment we experience, and in turn, that environment can also influence how are genes are expressed. It’s a loop. For example, someone who is naturally athletic (genes) mights be drawn to sports (environmental), reinforcing their athletic abilities even further.
GENE-ENVRIONMENT INTERACTION:
What are epigenetics?
It’s the study of gene-environment interactions such as how the same genotype leads to different phenotypes. Epigenetic changes are modifications to DNA that regulate whether genes are turned on or off.
A gene might be in our DNA, but not expressed, unless something triggers it (think schizophrenia. Also, something that was to be expressed can also be silenced.
What are some early reflex action theories (5) ?
- Nerves and muscles compared to pipes and levers
- Animal spirits
- External object can illicit an
involuntary response - Reflex action did not require the mind
- Precursor to stimulus- response (S-R) behaviorism
How did we get to these theories?
By experimenting on animals
What is galvanism?
What was Luigi Galvani’s experiment and what was his impact on the development of early reflex action theories?
Galvanism is the process of contracting muscles with the use of electrical current. He believed that that electricity was created within the animal itself, he called it “animal electricity”
His experiment:
Dead frog -> a static electrical charge carried through a scapel through the frog -> shocked the frog’s legs, making it move as if it was still alive (so he moved with no need of the brain).
He also tried another way:
Two metals (the hook and the iron wire ). The iron wire connects to the frog’s exposed nerve , stimulating the muscles and causing them to contract.
Conclusions:
* Nerve impulses were electrical in nature
*Galvanic skin conductance
What was the work of Giovanni Aldini (Galvani’s nephew).
*He expanded on his uncle’s work, focusing on the effects of electrical currents on dead animals and humans.
*Public demonstration of the electro-stimulation technique of deceased limbs was performed on the executed criminal George Forster at Newgate in London in 1803:
He connected wires from a voltaic pile (the early version of a battery) to various parts of Foster’s body, including face and limbs (arms or legs). The electric shocks caused his jaw to quieter, face muscles contracted and one ey opened, Right hand was raised and clenched and the legs and tights were in motion.
Now, how does the electricity get through the body?
Neurons
What is the Golgi staining method?
It’s a technique to make the structure of neutrons visible under a microscope.
What did Santiago Ramón y Cajal discover?
- Santiago Ramón y Cajal
used a Golgi stain to highlight the appearance of neurons. - Each neuron composed of a body with many threads extending outward toward other neurons.
- Threads of each neuron do not actually touch other neurons (the synapse)
*** His observations led to understanding how neurone communicate with each other.
What are the origin of Behaviour?
Neurons.
What are the two main types of cells that make up the nervous system?
- Glial cells :
They play a supportive role to neurons. In fact, they provide scaffolding on which the nervous system is built, help neurons line up closely with each other to allow neuronal communication, provide insulation to neurons, transport nutrients and waste products and mediate immune responses. - Neurons:
They generate and propagate electrical and chemical signals.
What characterizes the neurone’s cell membrane.
It’s semi-permeable membrane. Which means by its small pores that act as channels, it allows small electrically charged ions to flow in and out of cells, while stopping larger or highly charged molecules.
What are the two stages referred to as electrochemical action?
- Conduction: internal flow of electrical signal(information) within a neutron.
- Transmission: The process of sending electrical signal (information) from one neutron to another across a synapse.
SO we can say that there is communication of information within and between neurons.
What is the role of the cell body?
Coordinates information-processing tasks (so processes and forms a cohesive understanding) and keeps the cell alive
What is the dendrite’s role?
Receives information from other neurons and relays it to the cell body
What is the axon’s role?
Transmits information to other neurons, muscles, or glands
What is the synapse?
- The space between the terminal button of one neuron and the dendrite of another neuron
- Notice that neurons do not actually touch one another: There is a small synaptic space between them across where information is transmitted.
ELECTRICAL SIGNALLING: CONDUCTION INFORMATION WITHIN A NEURON
Do neurons have a natural electrical charge which changes as information is passed?
Yes.
What is the resting potential?
Difference in electric charge between the inside and outside of a neuron’s cell membrane when the cell is in a non-excited state. It’s a state of readiness (being ready or prepared to fire the action potential, so to send a signal)
In the resting state, sodium (Na+) is at higher concentrations outside the cell since it is kept out (the channel is closed). On the other hand, K+ molecules flow freely across the cell membrane. So [Na+] is higher on the outside of the cell than on the inside. While [k+] is higher inside the cell rather Than outside. This creates a difference in electric charge between the inside and outside of a neuron’s cell membrane. This means that the inside of the cell is approximatively 70 millivolts less positive than the outside.
So resting potential: - 70 mv, this is the potential energy that will be used to generate the action potential.
What are ion channels?
They are channels for each ion (Na+, k+…). As ions move across the channels, they cause the membrane’s potential to move away from its resting potential.
What is the threshold of excitation?
It’s the start of depolarization stade (goes from -70 to 40, when the action potential is reached), which implies the change of the membrane’s potential from negative to positive.
This is how it happens: From this resting potential state, the neuron receives a signal and its state changes abruptly (Figure 3.11). When a neuron receives signals at the dendrites—due to neurotransmitters from an adjacent neuron binding to its receptors—small pores, or gates, open on the neuronal membrane, allowing Na+ ions, propelled by both charge and concentration differences, to move into the cell. With this influx of positive ions, the internal charge of the cell becomes more positive. If that charge reaches a certain level, called the threshold of excitation, the neuron becomes active and the action potential begins.
Why is the action potential and “all-or-none” phenomenon?
In simple terms, this means that an incoming signal from another neuron is either sufficient or insufficient to reach the threshold of excitation. There is no in-between, and there is no turning off an action potential once it starts.
Because it is all or none, the action potential is propagated at its full strength at every point along the axon. It does not fade away as it travels down the axon.
What is the action potential (influx nerveux) and how is it reached?
It’s the electric signal that is conducted along a neuron’s axon to a synapse (it’s the positive spike)
What is the repolarization state and how does it happen?
At the peak of the spike, the sodium gates close and the potassium gates open. As positively charged potassium ions leave, the cell quickly begins repolarization.
The depolarization state is like a reset button, preparing the neuron for the next signal.
What is the hyperpolarization state?
The cell membrane’s potential becomes slightly more negative than the resting potential, and then it levels off (thanks to an active chemical “pump”), returning to the resting potential.
The active chemical “pump”in the cell membrane, moves Na+ outside the axon and moves K+ inside the axon. This helps restore the original distribution of sodium and potassium. The neuron can now generate another action potential.
This drop, is also called a refractory period: this is when the neuron recovers. it’s very rested and stimulation should not happen. In other words, the refractory period is the time following an action potential during which a new action potential cannot be initiated.
What factor determinate if a signal will pass along or not.
The strength of the signal received by the dendrites. If the stimulation is strong enough it will be transmitted along the axon.
What role does myelin and nodes of Ranvier play?
Saltatory conduction:
Action potential happens at the nodes of Ranvier.
The electrical signal moves down the axon with the impulses jumping in a leapfrog fashion between the Nodes of Ranvier. The Nodes of Ranvier are natural gaps in the myelin sheath. At each point, some of the sodium ions that enter the cell diffuse to the next section of the axon, raising the charge past the threshold of excitation and triggering a new influx of sodium ions ( like charging stations, allowing the signal to be strong as It moves down the axon) .
CHEMICAL SIGNALLING: Transmission between neurons.
Where does it happen and how does it happen?
It happens at the synaptic gap:
(1) The action potential travels down the axon and (2) stimulates the release of neurotransmitters from vesicles.
(3) The neurotransmitters are released into the synapse, where they float to bind with receptor sites on a dendrite of a postsynaptic (lui qui attrape les neurotransmetteurs) neuron, initiating a new action potential.
The neurotransmitters are cleared out of the synapse by (4) reuptake into the sending neuron, (5) being broken down by enzymes in the synapse, or (6) binding to auto receptors on the sending neuron.
Good to know:
each vesicle contains about 10,000 neurotransmitter molecules.
What is a presynaptic neuron?
The neuron releasing the neurotransmitters.
What are autoreceptors?
Signal to Stop: The binding sends a signal to the neuron that there’s enough neurotransmitter in the area, which often leads the neuron to reduce or stop releasing more of that neurotransmitter.
Detect Levels: Autoreceptors are on the surface of nerve cells and check how much of a neurotransmitter (the chemical messenger) is around.
Regulate Release: If there’s too much neurotransmitter, the autoreceptors signal the neuron to stop or slow down releasing more.
Maintain Balance: If there’s not enough, they don’t send that signal, allowing the neuron to release more.
So, their main role is to help keep the right amount of neurotransmitter in the brain, making sure things don’t get too high or too low!
What happens to the neurotransmitters
in the synapse?
Each neurotransmitter will bind to the receptor of its type.
Example: dopamine with dopamine (different shapes for different molecules)
