Biological Basis in Behaviour

Question 1

What is the premise of psychology? Does it agree with Rene Descartes?

Answer 1

• No, he believed that mind resides outside body
• Premise is that human mind and brain are 1
• The biology of the mind begins with the “atoms” of the mind called neurons

Question 2

What is a neuron? Explain its structure.

Answer 2

• Basic unit of the brain and nervous system responsible for sending and receiving messages throughout body
• Dendrites: receive and transmit information from other neurons
• Cell body: contains the nucleus and decides the activation to go along body, synthesizes proteins that allow neuron to function
• Axon: conducts nerve impulses, carries message to end of neuron
• Terminal button: communicate with next neuron with neurotransmitters

Question 3

How do neurons “fire” a charge? Define action potential.

Answer 3

• Action potential: a neural impulse that travels to terminal buttons by the axon and is generated by moving positive and negative charges (like a wave)
• All neurons have a negative charge (resting potential)
• Receive signals from other neutron
• Failed initiations, if stimuli works then threshold is reached, neuron depolarizes and open
• Law of all or nothing: always the same intensity, signal strength is frequency
• Refractory period

Question 4

How do neurons communicate with other neurons?

Answer 4

• Action potential causes vesicles of terminal button to release neurotransmitters in the synaptic gap to reach dendrites of other neurons
• Float across the synaptic gap until they bind with specific receptor sites on dendrites of other neurons
• Different neurotransmitters have different receptor sites, like keys and locks
• After sending signal, they get detached from binding site (released from receptor sites)
• Either get broken down and go through reuptake

Question 5

What is reuptake?

Answer 5

The process by which the axon terminal vesicles reabsorbs the neurotransmitters

Question 6

What is a neurotransmitter?

Answer 6

Chemicals used to send a signal across the synaptic gap

Question 7

List all the common neurotransmitters and some examples!

Answer 7

• Acetylcholine: enables muscle action, learning, and memory (Alzheimer’s disease is correlated with low acetylcholine)
• Dopamine: influences movement, learning, attention, and emotion (Overstimulated dopamine led to extreme case of Parkinson’s disease)
• Serotonin: affects mood, hunger, sleep, and arousal (Undersupply linked to symptoms of depression)
• Norepinephrine: helps control alertness and arousal (Undersupply can affect attention, linked to ADD)
• Glutamate: a major excitatory neurotransmitter, involved with learning and memory (Oversupply can cause migraine or seizures)
• Gamma-aminobutyric Acid (GABA): inhibitory neurotransmitter, involved also in learning, memory, sleep (Alcohol increases GABA activity, which explains the cognitive and motor impairments and depressed mood after drinking too much)

Question 8

How do you alter neurotransmitter behaviour and what are some examples?

Answer 8

• Agonist: molecule (medicines or drugs) that fills the receptor site and activates it, acting like the neurotransmitter (L-dopa for Parkinson’s disease will mimic dopamine, however you need to raise the dose for the same effect)
• Antagonist: molecule (medicines or drugs) that fills the lock so that the neurotransmitter cannot get in and activate the receptor site (Curare is a poison that blocks acetylcholine sites)

Question 9

What is synaptic pruning?

Answer 9

• Synaptic pruning: elimination and creation of new connections
• Slow decline throughout life of synapsis (peak at 25)
• Useful connections that are used will be kept by network

Question 10

What is neurogenesis? How does it work?

Answer 10

• Neurogenesis: production of new neurons from immature stem cells
• Stem cells: cell “virgin” can take any function in the body mature if the appropriate environment
• Can replace dead pathways with new ones using stem cells
• Can allow us to delay ageing

Question 11

How is the nervous system divided? What role do neurons play?

Answer 11

• Nerves consist of neural “cables” containing many axons
• Central nervous system: brain and spinal cord
• Peripheral nervous system
  o Automatic (operate without need of immediate control)
  ♣ Sympathetic: arousing, “fight or flight”
  ♣ Parasympathetic: calming, “rest and digest”
  o Somatic (you can control)

Question 12

How does the nervous system communicate with the brain? What are hormones?

Answer 12

• Neural communication
  o Peripheral nervous system: brain, neurons
• Hormonal communication
  o Endocrine system: set of glands that produce chemical messengers called hormones
  ♣ Hormones: substances synthesized by the endocrine glands and travel through the bloodstream (eg. epinephrine), maintains homeostasis by stimulating glands
  o Hypothalamus, to pituitary gland, bloodstream to organs
  o Works much slower and lasts longer than the peripheral nervous system

Question 13

What are the types of neurons?

Answer 13

• Sensory neurons: type of neuron that receives information from bodily senses and bring to brain
• Motor neurons: type of neuron which carries messages away from the brain and spinal cord and to muscles to control flexion

Question 14

What is a glial cell? What do they produce? What is the ratio to neurons?

Answer 14

• Specialized cells of nervous system that are involved in mounting immune responses in the brain, removing waste, and synchronizing the activity of the billions of neurons that constitute the nervous system
• Outnumber neurons in brain by ratio of 10:1
• Myelin: formed by glial cells, fatty sheath that insulates axons from one another, resulting in increased speed and efficiency of neural communication

Question 15

What is the resting potential? How does an electrical charge work?

Answer 15

• Resting potential: relatively stable state during which cell is not transmitting messages
• Higher cation concentration outside
• Ion channels open up in neuron’s cell membrane and cations flow into cell, charging it
• Wave-like action where when one part of axon becomes depolarized, it forces open ion channels
• Action potential moves down until reaches axon terminal to release neurotransmitters
• Cations flow out, more negative than usual so can’t function (refractory period)
• Presynaptic cell: releases chemical
• Postsynaptic cell: receives input

Question 16

What are the types of neurotransmitters?

Answer 16

• Excitatory: actions of neurotransmitter cause neuron’s membrane potential to become less negative, increased probability that action potential can occur
• Inhibitory: actions of neurotransmitter decrease probability that action potential can occur

Question 17

What are the older brain structures?

Answer 17

• Brain stem
• Thalamus
• Cerebellum
• Limbic system

Question 18

What are the components of the brain stem and what do they do?

Answer 18

1. Medulla (at the bottom)
   - Base of brainstem
   - Life-sustaining functions
2. Pons
   - Helps coordinate unconscious movements (eg. smile)
   - Sleep (stops you from acting out your dreams)
3. Midbrain (reticular formation)
   - Associated with movement, tracking o visual stimuli and reflexes triggered by sound
   - Reticular formation is a collection of numerous small neural networks spread throughout the brain stem
   - Most known for role in sleep and consciousness (arousal control)
   - Helps filter incoming sensory information (discriminate relevant vs irrelevant stimuli)

Question 19

What does the thalamus do?

Answer 19

• Relay centre for sensory (organs) and motor information to different parts of the cerebral cortex (except smell which is directly wired to brain)
• Also sends information from cortex to the medulla and cerebellum

Question 20

What does the cerebellum do? Where is it?

Answer 20

• Located at the back of brain stem
• Fundamental to coordination of voluntary movement and balance
• Other functions include learning new motor skills (eg. riding a bike) or storing information such as the smell of perfume that reminds you of a specific moment

Question 21

What does the limbic system do? Where is it?

Answer 21

• Located on both sides of the thalamus
• Processes information about our internal states (eg. heart rate, blood pressure)
• Plays a key role in emotional experiences and memory formation

Question 22

What are the components of the limbic system?

Answer 22

1. Hypothalamus
   - Associated with emotions and motivations
   - Help in the regulation of hunger and thirst
   - Involved in the experience of rewards (pleasure) including sexual motivation
   - Adjusts body temperature as a function of changing environment
   - Directs the endocrine system via messages in the pituitary gland
2. Amygdala
   - Consists of two lima bean-sized neural clusters
   - Associated with the experience of different emotions, particularly negative ones (eg. fear)
   - Key role for fear conditioning
3. Hippocampus
   - Processing conscious, episodic memories
   - Key to creating mental maps
   - Works with the amygdala to form emotionally charged memories
   - Eg. removal of part of hippocampus and amygdala meant no new long-term memories
   - Communicates with hypothalamus to form pleasurable memories

Question 23

What is the cerebral cortex? What does it do?

Answer 23

• Layer covering the brain (approximately 3mm thick)
• Folds called circonvolutions made more surface area for 20+ billion neurons
• Grey matter (cell bodies)
• White matter (axons)
• 180+ billion glial cells, which feed and protect neurons and assist neural transmission
• Processes information about external stimuli (as opposed to the limbic system)

Question 24

Why is the prefrontal cortex of humans do big?

Answer 24

• Executive function (eg. good vs bad, delay of gratification, impulse control)
• Activated when engaged in top-down directed behaviour (brain to body)
• According to Dunbar, the prefrontal cortex controls our behaviour and relationships (Dunbar’s number says 150 people on average is the number of connections we can maintain and track)

Question 25

What are the lobes of the cerebral cortex?

Answer 25

1. Occipital lobes: rear of brain, visual information from thalamus is processed, sent to temporal lobes or parietal lobes
2. Temporal lobes: sides of brain, auditory information, facial recognition
   - Auditory cortex: hearing
   - Cortical deafness: problems with hearing due to brain
   - Wernicke’s area: understanding language
3. Parietal lobes: sensory information, touch and body position, putting information together (eg. reading)
   - Have somatosensory cortex which are nerve cells to register touch sensations
4. Frontal lobes: language, emotion, speech, movement, judgement, problem-solving, morality
   - Primary motor cortex: thick band of neurons at rear involved with control of voluntary movement
   - Prefrontal cortex: performs functions such as decision making and controlling attention

Question 26

How do hemispheres work? Talk about motor and sensory cortexes.

Answer 26

• 4 lobes found in both hemispheres, deal with similar things
• Contralateral connections to the body’s system (visual, somatosensory, and body part movements)
• Motor cortex: left hemisphere section controls body’s right side
• Sensory cortex: right hemisphere section receives input from body’s right side
• Has both in both sides

Question 27

What is the corpus callosum? Talk about the optic chiasm.

Answer 27

• Hemispheres talk to each other through this structure
• Allows exchange of information
• Million axon
• Sometimes has to be severed surgically in split-brain patients as last resort treatment for seizures but optic chiasm remains intact
• Optic chiasm is where visual fields switch sides in the brain due to prevention of two fields talking to each other
• The halves of the brain and the halves of the visual field are no longer coordinated
• Eg. pencil in left visual field goes to visual area of right hemisphere but needs to shift to speech to left hemisphere so if left isn’t working then cannot say what the pencil is

Question 28

Talk about hemisphere specialization.

Answer 28

• Right hemisphere seems to play a more important role in visual and special tasks (eg. creativity, imagination, motor skills for artistic work)
• Left hemisphere seems to play a more important role in language and analytical thinking (eg. speaking, understanding spoken words, mathematics)
• Broca’s area and Wernicke’s area deals with grammar and putting together complex sentences

Question 29

What are the strategies used to study the brain?

Answer 29

1. Stimulation
   - Most recent
   - Eg. chemically numbing, magnetically deactivating, or electrically stimulating parts of the brain
2. Lesion based
   - Surgeries (eg. dissected corpus callosum)
   - Accidents (eg. Phineas Gage)
3. Animal models
   - Eg. rats raised in an environment enriched vs unenriched; enriched environment yielded 7% larger brains and 20% more synapses develop
   - Stimulation allows kids to develop (music, toys to touch) enhanced brains
4. Noninvasive

a) Electroencephalogram: electrodes placed on skull, pick up electrical activity
- Studying interaction between brains
- Inexpensive, poor spatial resolution, good temporal resolution

b) Imaging (scanner)
- CAT (x-rays), MRI (magnetic field that moves oxygen particles through body to pick up structures): shows you structures NOT activity
- PET (glucose with radioactive tracer, brain that consumes more glucose will have more concentration of the tracer), fMRI (same as MRI): tells you structures and activity, poor temporal resolution, good spatial resolution