Midterm 2

Question 1

Describe all the major divisions of the nervous system, including their functions. (PERIPHERAL NERVOUS SYSTEM)

Answer 1

PNS: The rest of your nervous system (not brain and spinal cord); Connected to limbs and organs to relay information to and from CNS.

Splits off into two different systems, the Somatic nervous system (SNS) and Autonomic nervous system (ANS).
SNS is related to the external environment (mostly conscious), while ANS is related to internal environment (mostly unconscious). The SNS and ANS both consist of Efferent (motor; from the brain to the body) and Afferent (sensory) pathways.

The ANS’ Efferent pathway consists of the Sympathetic nervous system and Parasympathetic nervous system. Sympathetic mobilizes energy (“fight or flight”) and prepares you for action in stressful situations. The Parasympathetic conserves energy (“rest and digest”) and stimulates digestion and recovery.

Question 2

Describe all the major divisions of the nervous system, including their functions. (DEFINITION OF NERVOUS SYSTEM + CENTRAL NERVOUS SYSTEM)

Answer 2

The nervous system is a network of neurons that conveys electrochemical information throughout the body. Comprised of both the Central nervous system (CNS) and Peripheral nervous system (PNS).

CNS: it is the brain and spinal cord; The control center of the body for processing and responding to information.

Question 3

Describe the sensation of smell and how we perceive it

Answer 3

Olfactory information (sense of smell) enters frontal lobe, amygdala, hippocampus, etc. rather than connecting to the thalamus first, resulting in close relationship between smell, emotional/social behaviour, and memory

Olfactory epithelium (mucous membrane situated on top of nasal cavity) contains olfactory receptor neurons (ORN) that transduce odourant molecules into neural impulses

ORN sends axons from epithelium into bulb to process axons that form olfactory nerve

Smell is determined by bottom-up influences

Question 4

What is a perceptual set?

Answer 4

Predisposition to perceiving one thing and not another (top-down processing) and is determined by schemas (ways that humans organize/categorize ambiguous information)

Schemas appear as:
- context effects (culture/pre-existing knowledge)
- motives can influence perception
- emotions (positive emotions alter our perceptions of how other people present themselves)

Question 5

What is the physical stimulus that becomes the mental phenomenon of sound? How does this physical stimulus get transformed into sound?

Answer 5

Sound waves are physical stimulus that becomes sound. Sound waves compress and expand air molecules, creating areas of high and low density that ears detect as brief pressure changes

Sound waves from environment enter outer ear and travel along ear canal to eardrum (membrane that vibrates in response to different air densities) –> vibrations from eardrum pass to ossicles (bones connected to eardrum: hammer, anvil, and stirrup) that amplify sound vibrations and transfer to oval window –> oval window and cochlea (fluid-filled structure that stimulates hair cells, vibrations transduced into electrical signals) connected to brain

Question 6

Differentiate the terms sensation and perception.

Answer 6

Sensation is how a physical stimulus is represented by the nervous system and sensory receptors - it is the registration of light, sound, pressure, odour or taste

Perception is how we organize, identify, and interpret sensory signals to form a mental representation

Question 7

How do we perceive pain?

Answer 7

Tissue damage is transduced by free nerve endings that sense painful stimuli –> neural signals for pain travel to two distinct areas in the brain

• one sends to somatosensory cortex, identifying where pain is occurring and its intensity
• other sends signals to motivational and emotional centres of brain (hypothalamus, amygdala, and frontal lobe) –> aspect of pain that motivates us to escape or relieve pain

Referred pain: pain that originates internally but can be felt on the surface of the body (when sensory information from internal and external areas converge on the same nerve cells in spinal cord)

Question 8

What is perceptual constancy? What are some notable examples?

Answer 8

Perceptual Constancy is the ability to perceive an object as the same regardless of the context (perceived as unchanging)

• Colour constancy: familiar objects will have consistent colour even if illumination changes around it (ex. banana is yellow under variety of lighting)
• Size constancy: recognizing that things remain the same size even though they take up more space in our retina
• Relative luminance: taking visual cues and building mental image of lightness and darkness based on context

Question 9

How do we study selective attention? What does it tell us about unattended stimuli? What does it tell us about the value of attention?

Answer 9

We can conduct dichotic listening tasks where two different audio stimuli are present, one in each ear, and participants are told to attend to one ear, resulting in their ability to “shadow” the audio that is in the focused ear but filter out the audio in the other ear.

Another way to study selective attention is to use a cueing paradigm, which allows the participant to have enhanced detection to stimuli in the directed area but decreased ability to detect stimuli when pointed to a wrong spot.

These examples show that attention is a very limited resource and fixed by its capacity. As such, attention is important in order to filter out unimportant information so that our brains are storing only the critical details in our short-term and long-term memories.

Question 10

Describe the organs and brain areas related to sound.

Answer 10

Electrical signals from the hair cells transmitted through auditory nerve, carrying sound information from cochlea to the brain.

Auditory signals pass through several processing centers (including brainstem and midbrain) where brain interprets information about sound location and timing

Auditory signals reach primary auditory cortex in temporal lobe to interpret and recognize sounds

Question 11

What is priming? How is it related to the idea of subliminal messaging? Does subliminal
messaging work?

Answer 11

Subliminal Threshold: stimulus (that we experience less than half of the time) that reaches the brain but not the consciousness, could affect behaviour without our awareness

Priming is when we see things in our environment but were focused on other things, so it only has a weak activation in our brain (unconscious activation in mind)

Subliminal messaging does work but effects are very brief and weak and not enough to have an enduring influence on behaviour

Question 12

Have a fundamental understanding of how visual information reaches the brain.

Answer 12

Cornea –> pupil –> iris –> lens –> retina –> bipolar/retinal ganglion cells (optic nerve)

• Cornea bends the light wave, reversing it and turning it upside down
• Pupil is where the light travels
• Iris controls the size of the pupil and amount of light that can enter the eye
• Lens stretches and relaxes muscles to bring things in and out of focus (process is called accommodation)
• Light information travels through fluid and blood vessels (inefficient machinery blurs image)
• Retina is where photoreceptors (rods and cones) are located and then travels to optic nerve to thalami before being sorted and reconstructed in the occipital lobe (primary visual cortex)

Question 13

Describe all the major divisions of the brain, including the functions we discussed. (FOREBRAIN)

Answer 13

Forebrain: Consists of the Telencephalon and Diencephalon.

The Telencephalon (cerebral hemispheres) is the largest division of the human brain with the cerebral cortex and other underlying structures.
The cortex is the most prominent feature of the brain, having lots of convolutions as it is important for human behaviour and cognitions.

The Diencephalon is comprised of two structures, the thalamus and hypothalamus:

The thalamus includes inputs from sensory systems, motor systems, cerebellum, and basal ganglia. This region is called the “relay station/centre” for sensory information as most info stops and the thalamus before entering the cortex (all senses except smell).

The hypothalamus is a key intersection with the endocrine system via the pituitary gland (the master gland). The endocrine system is a junction of systems with organs and glands to produce hormones. It has diverse functions related to sex, sociality, aggresion, feeding, sleeping/waking, circadian rhythm, etc.

Question 14

Describe the Limbic “System” and Basal Galglia

Answer 14

It is not a real system. The word “limbic” simply means on the edge/border between the cortex and deeper brain structure.

The Limbic “System” contains the amygdala, hippocampus, cingulate cortex, hypothalamus, mammillary body, fornix, septum, and olfactory bulb. The amygdala is related to emotions, learning, and decision-making, while the hippocampus is important for memory formation and spatial awareness. The cingulate cortex is critical for decision-making, pain, and autobiographical thoughts.

The Basal Ganglia is other structures (made of striatum and globus pallidus) in your brain nearby the Limbic “System” which are responsible for muscle memory, movement, skills, habits, motivation, and addiction.

Question 15

Describe ten key features of consciousness.

Answer 15

Subjectivity: personally felt from experience and not immediately accessible to others

Intentionality: thoughts/experiences are always regarding something (can’t be empty)

Unity: cannot bring multiple information into awareness, resistant to division

Selectivity: brain fills in gaps in world and filters things out (attentional mechanism)

Transience: consciousness shifts and moves between states (can switch from topic to topic)

Body Awareness: tendency to know where your body begins and ends (note not all beings can recognize their body parts

Agency: recognizing that you have an influence over the world and have control over yourself (schizophrenia may cause people to act outside of their control)

Theory of Mind: recognize mind, knowledge, and more are separate from someone else’s

Self-awareness: carrying our own identity/idea of “I”

Metacognition: cognition about cognition

Question 16

What is psychophysics? What major discoveries has it revealed?

Answer 16

Psychophysics looks at our relation between the physical experience and the psychological experience (literal amounts vs. perceived amounts)

Psychophysics established methods for quantifying how sensory experiences relate to physical stimuli via thresholds (absolute and difference)

Question 17

Describe signal detection theory and the different thresholds

Answer 17

Signal Detection Theory: how we determine if and when an individual perceives anything at all based on response to a stimulus (depends on person’s sensitivity and decision criterion)

Absolute Threshold: smallest amount of stimulus that can be detected (50% may go undetected) - can be altered by alertness

Difference Threshold (JND): minimum difference that can be perceived between two stimuli (acuity is how well we can distinguish that)
Weber’s law: two stimuli must differ from some constant minimum percentage, not a constant amount, in order to be able to perceive

Question 18

How is attention related to memory?

Answer 18

Attention controls the information that reaches our short-term (working memory) and strongly influences what is stored in the long-term memory.

Question 19

Describe the sensation of taste and how we perceive flavour

Answer 19

Taste system contains 5 taste receptors (salt, sour, bitter, sweet, umami) and tongue is covered with papillae, which contain taste buds (organs of taste transduction)

Food molecules dissolved in saliva evoke specific, combined patterns of activity in receptor types - smell and taste (primary gustatory cortex) are connected and taste information is passed to primary olfactory cortex

Question 20

Describe the mechanisms that support the brain’s healthy functioning (blood, meninges, cerebrospinal fluid). Why is damage to these support mechanisms so devastating?

Answer 20

The brain has four main arteries which are vertebral arteries and internal carotids.

There is also the two-step system with the blood-brain barrier that protects the brain from any viruses and bacteria.

Half of it is from the capillaries that have tight junctions to prevent harm from coming onto the brain, and the other half is from the feet of astrocytes that wrap around the arteries.

Chronic stress, aging, and diseases can weaken or loosen the blood-brain barrier.

The brain is concealed in 3 layers of protection: The Dura Mater (“tough mother”), Arachnoid Mater, and Pia Mater (“little mother”). These layers protect the brain alongside the skull and cerebrospinal fluid (CSF; layer of fluid with ventricles (pockets of fluid) converging together at an aqueduct. Without the CSF, traumatic brain injuries would be significantly more severe.

Question 21

Describe monocular cues

Answer 21

Depth cues available to either eye (can be perceived with only one eye so information sent to brain still has depth information)

• Light and shadow
• Relative motion
• Relative size
• Linear perspective/Linearity
• Parallelism/parallelity
• Interposition
• Relative height
• Motion perception: humans are imperfect at motion perception, only get certain amount of information per second from photoreceptors, results in limited movement information about the world
  Perception of movement as a result of alternating signals appearing in rapid succession in different locations = apparent motion
  Biological motion perception = ability to perceive biological motion critical for identifying individuals and various socially relevant features, such as emotional state, personality characteristics, whether they are vulnerable to attack, or are engaging in deceptive actions
  Region in back of temporal lobe strongly linked to this
  § Ie. Helicopter blades look like a blur

Beta movement/phi phenomenon makes us “see” things moving even though it’s just a lot of discrete images because of our limited frame rate of vision
§ Used in movies and video games

Question 22

Describe all the major divisions of the brain, including the functions we discussed. (MIDBRAIN)

Answer 22

Midbrain: Consists of the Mesencephalon.

The Mesencephalon is comprised of a roof (tectum) and a floor (tegmentum).

The tectum receives visual information and generates eye and head movements. Has “automatic” orientation to stimuli and outside of conscious access (“Boston Pizza part of the brain” - part that always monitors environment for flashy and salient things; Ex. flashy TVs at B.P.). Also reacts to auditory stimuli too.

The tegmentum is important for movement related to emotions, motivation, and species-specific behaviours (ex. dog howling or a primate hooting). Dopamine neurons are found here.

Question 23

What is attention? Why do we only attend part of the environment and not all?

Answer 23

Attention is the process of selectively focusing on certain pieces of information in our environment while ignoring other stimuli.

We only attend to parts of the environment and not all because we have limited capacity and the brain chooses to attend to the most important things while filtering out the least important information.

Question 24

What is split brain and what are its implications on consciousness?

Answer 24

severing hemispheres by cutting the corpus callosum –> results in hemispheres operating independently on some tasks and intermanual conflict that suggests two different brains acting in the same body

left hemisphere controls speech and therefore only the right side of the world is communicated

patients cannot identify items in left visual field, but information is consciously available to the brain but not the part of brain responsible for speech

Question 25

What is the relationship between the brain and consciousness? Are all parts of the brain part of our conscious experience?

Answer 25

Consciousness is a product/result of some activity in the brain. However, not all brain activity is directly correlated to our conscious experience.

Question 26

What might happen if the myelencephalon were damaged? How about the metencephalon/mesencephalon/diencephalon/telencephalon?

Answer 26

Damage to…

Myelencephalon: Often fatal, as it controls many life-sustaining functions and vital reflexes.

Metencephalon:
The pons: Can cause issues with your sleep states.
Cerebellum: Can cause issues with motor coordination (unsteady movements, weird way of walking or grabbing, etc.)

Mesencephalon:
Tectum: Can cause issues such as Parinaud’s syndrome, where someone has great trouble automatically detecting and reacting to stimuli.
Tegmentum: Can cause issues like Parkinson’s disease, having difficulty with your ability to move through the world.

Diencephalon:
Thalamus: Can disrupt sensation and perception. Can lose consciousness as a result.
Hypothalamus: Can cause issues like narcolepsy, maintaining consciousness throughout the day.

Telencephalon: Can cause a diverse range of symptoms. Physical abilities, cognition, sensory perception, and/or emotional responses can be impacted from damage here.

Question 27

What is consciousness? Why is it difficult to define? Why is it difficult to study?

Answer 27

Consciousness is difficult to DEFINE because it is subjective and we often assume that other people are like us, but still represents the awareness and experience of our mental states (thoughts, memories, actions, perceptions)

Consciousness is difficult to STUDY because difficult to access and only internally accessible

Question 28

Do we need a brain in order to react to sensory information, i.e. to move? Support your answer with evidence.

Answer 28

No, we do not necessarily need a brain in order to react to sensory information. For instance, simple reflexes such as flinching from touching a hot stove is an automatic motion that uses only 3 neurons (sensory neuron, synapses on an interneuron, and then to a motor neuron)

Question 29

Describe a number of conditions where aspects of consciousness can be selectively damaged. What do these studies tell us about consciousness?

Answer 29

Anterograde amnesia: inability to produce new memories

Blindsight (dual processing): information simultaneously processed on separate conscious (explicit) and unconscious (implicit) tracks

Blindsight (awareness): ability to respond to a visual stimulus without consciously experiencing it (suggest conscious pathway through cortex, but other visual pathways like tectum drive movement)

Visual Agnosia: can see basic features of something but cannot form perceptual whole

Neglect (left): brain is incapable of shifting attention to left side of the world

Anosognosia: unawareness of one’s own disorders

Question 30

Describe how pitch (e.g. high versus low) is discriminated.

Answer 30

Place Theory: along the cochlea, some areas will shift in response to different pitches
- apex (innermost part) of cochlea responds to low-pitched frequencies, while base responds more to high-pitched frequencies
- helps brain recognize higher pitches accurately

Frequency Theory: rate at which hair cells in cochlea fires action potentials that match the frequency of the sound wave, producing low-pitched sounds (between 20hz and 500hz)

Combination of Theories: for pitches in intermediate range, place and frequency theories help us accurately discriminate pitch

Question 31

What is an example of a top-down process? What is an example of a bottom-up process?

Answer 31

Bottom-up processing: detect specific features of stimulus –> combine features into complex forms –> recognize stimulus (using data to understand stimuli w/o preconceived ideas)

Ex. reading gibberish writing and being unable to decipher it

Top-down processing: formulate perceptual hypothesis about the nature of the stimulus –> select and examine features to check hypothesis –> recognize stimulus (using existing knowledge and expectations to interpret stimuli)

Ex. someone tells you what writing means and you can suddenly recognize and read it (Darius’s writing)

Question 32

Explain gate-control theory and how pain is suppressed

Answer 32

Interneurons in spinal cord can prevent the arrival of signals from pain receptors via skin/brain feedback

PAG (periaqueductal grey): where brain’s feedback to spinal cord comes from - is a region in midbrain
- under extreme conditions like stress, naturally occuring endorphins send inhibitory signals to neurons in spinal cord to suppress pain signals

Question 33

Explain our sense of bodily position and how we maintain balance

Answer 33

Proprioception: sense of bodily position - sensory receptors provide feedback about desired movements and resistance from objects (weight)

Maintaining balance depends on vestibular system (3 fluid-filled semicircular canals and adjacent organs located next to cochlea in each inner ear)

Question 34

Describe the sensation of touch

Answer 34

Use sensory receptors in muscles, tendons, and joints - responds to stimulation and long axons enter the brain via spinal or cranial nerves

Each receptor under skin has a tactile receptive field, which is a small patch of skin that relates information about pain, pressure, texture, pattern or vibration
Thermoreceptors are nerve fibres that sense cold and warmth and respond when skin temperature changes

Question 35

Describe the various ways to map the cortex (i.e. folds, lobes and hemispheres, layers, areas)

Answer 35

Folds/Convolutions: Gyrus/gyri and Sulcus/sulci. Sulci is sometimes called fissures. Not really functionally meaningful.

Hemispheres + Lobes: The cerebrum is split into two hemispheres, which are connected by white matter called commisures (largest commisure is called the corpus callosum).
The brain consists of four lobes: Frontal, parietal, temporal, occipital (named after nearby bones). Central fissure separates the frontal and parietal lobes, while the lateral fissure separates the temporal and occipital lobes.

Layers: The neocortex has 6 layers. Output layers send signals out to the spinal cord for motor functions. Each layering structure is for different functions.

Areas: The brain is contralaterally organized, therefore the right side of your brain controls the left side of your body, while the left side of the brain controls the right side of your body.

Question 36

What are the different states of consciousness?

Answer 36

Spontaneous: daydreaming, drowsiness, dreaming

Physiologically induced: hallucinations, orgasm, food/oxygen starvation

Psychologically induced: sensory deprivation, hypnosis, meditation

Question 37

What does “neuroplasticity” mean? How does it relate to healthy human cognition and behaviour, as well as to our response to brain damage?

Answer 37

“Neuroplasticity” simply refers to how our brains are “plastic”, meaning flexible and changing (often mistakenly known as creating new neurons). Young brains are extremely plastic, but less so as we age. Learning and memory are neuroplasticity. They cause a change in the structure and function of our synapses.

Responses to brain damage: Severed or dead brain and spinal cord neurons are not regenerated. Some neural tissues are capable of reorganizing and taking on roles that the dead neurons used to occupy. Neighbouring brain areas can share/adjust neurons to injured areas with damaged neurons in order to recover some of the important functions at the cost of the less relevant functions that they used to control.

Question 38

Describe sensory and emotional adaptation

Answer 38

Sensory: diminished sensitivity as a consequence of constant stimulation (filters out information that can rapidly return)
Ex. body adapts to blood vessels in eyes and also you aren’t always thinking about the clothes on your body

Emotional: adaptation in peripheral nervous systems and in the brain that requires greater context to influence our understanding of emotions
Ex. staring at someone’s face for a long time makes it difficult to differentiate emotion

Question 39

Have a fundamental understanding of how the brain interprets this visual information,
including colour, depth, and motion.

Answer 39

Colour: processed and detected by cones - 3 types in our eyes that see red, green, and blue from light wavelengths- and then mixed to form various shades in world (note: colour blindness is due to having damaged cones in one colour and such)

Depth: Binocular cues, light information that reaches both eyes (not the same in both, and having both improves our perception of depth)

Motion: when something moves, light patterns change quickly on retinas and brain tracks change to see motion

Question 40

Describe all the major divisions of the brain, including the functions we discussed. (HINDBRAIN)

Answer 40

Hindbrain: Consists of the Metencephalon and Myelencephalon. This region coordinates information coming to and from the spinal cord.

The Metencephalon is comprised of multiple parts: The pons and the cerebellum.
The pons is a large white-matter bulge, continuing from spinal cord/medulla and relays information from the cerebellum to the rest of the brain.
The cerebellum is 10% of the brain’s volume but is comprised of over half of a human’s neurons. It is critical for motor coordination (compares what we meant to do vs what we actually did, and corrects it).

The Myelencephalon (medulla) consists of a lot of afferent and efferent axons. Neurons here are for involuntary control of life-sustaining functions. It keeps the diaphragm functioning and allows you to swallow.