Brain bee part 3

Draw out the pathway through the visual system.

add pic

How does interaction between parts of the visual system contribute to our perception of the world?

The sensory parts of the visual system are responsible for converting a photon of light into an electrical signal that the nervous system can use.

The optic nerves are then responsible for transporting this signal between the sensory areas towards the brain processing regions, which can then analyze these signals that the sensory cells have detected and converted to extract information.

Higher order areas of the brain can then integrate this processed visual information with other sensory inputs, memories, etc. This process allows us to perceive and interpret the visual world.

What is the difference between sensation and perception?

Sensation is the detection of stimuli, while perception relates to how those stimuli are interpreted.

For example u can sense music, other ppl talking, etc. at a party while talking to ur friend but can only perceive the person in front of u

Perception can also be shaped by past events-u can sense keys jingling but perceive that its ur parents that r home cause that's what has happened in the past

The eye

• Where visual sensation starts

• Captures photons

What is accommodation?

When the lens flattens as we focus on something far away and thickens as we focus on something close.

What muscles cause dilation and constriction of the pupils? What nervous divisions innervate them?

The pupillary dilator muscle causes dilation when activated by the sympathetic nervous system, while the pupillary sphincter causes constriction when activated by the parasympathetic nervous system.

What is the fovea?

The fovea is a small pit in the center of the retina where the light from within 2 degrees of the center of the field is focused.

It is where we have the clearest vision (highest aquity)

What are some key differences between the two types of photoreceptor cells?

Rod cells have high synaptic convergence, which allows for the amplification of small signals (eg low light conditions). However, this blurs together the activation of many rod cells, meaning that we are not able to see details in our peripheral vision.

Cone cells are used for highly detailed vision, and are concentrated at the fovea. Because they need to be highly specific, they have low convergence and are less effective in low light. There are also 3 different types of cone cells, each one having specific pigments to detect more wavelengths of light than rod cells.

What is the Purkinje shift?

This phenomenon is due to the fact that rod cells, which are most active in low light, are most sensitive to blue-green light wavelengths, which means that as it gets darker other colours will seem duller and things will seem tinted blue.

What is the duplicity theory of vision?

This theory suggests that rods and cones are used simultaneously.

It suggests that two systems work together; the photopic vision system uses cone photoreceptors of the retina to see details, while scotopic vision uses rod cells for low light conditions.

What is the optic chiasm?

The optic chiasm is where the optic nerves coming from both eyes merge.

At this point, axons cross over so that information coming from either the left or right visual fields ends up on the contralateral side of the brain.

What 3 signaling pathways does the optic nerve feed into?

1. To the thalamus for visual processing.

2. To the pretectal area for primitive visual functions such as smooth pursuit.

3. The retinohypothalamic tract to connect the retinal ganglion cells to the suprachiasmatic nucleus, which adapts circadian rhythms to changing day-night patterns.

Explain the retinotopic organization in the visual system.

This is the concept that a section of retinal inputs map onto neurons of a specific section of the primary visual cortex (V1).-neighboring areas of the retina correspond to neighboring areas in the brain-eg. visual info from the fovea only takes up 1% of the visual field but half of the neurons in V1 so tis gotta be smth else yk

What is the dual stream hypothesis?

The idea that after V2, visual information goes through 2 different processing streams; the dorsal stream determines where objects are located, and the ventral stream help identify objects.

The two streams are independently defined, however good communication between the two is essential.

What is akinetopsia?

This is a rare condition that causes the inability to see objects in motion.-see freeze frames instead

Usually a result of bran injury or strokes

What is prosopagnosia?

This is the inability to recognize faces-recognize they are looking at a face but can’t tell who it belongs to

More common than akinetopsia

What types of receptors do we use to detect changes (usually mechanical-like pressure or a stretch) at the skin? What are the 2 categories for these receptors?

Cutaneous (meaning found in skin) mechanoreceptors

• Detect these changes thru mechanically-gated ion channels-when pressure applied Na+ moves in and causes depol.

There are two categories:

1. Slow-adapting-change AC firing rate as long as stimulus is resent -only fires when stim gets there and when it leaves-so twice

   Sometimes called phasic receptors

2. Fast adapting.

   A) the slow-adapting ones

   • Merkel’s discs

     • Also called Tactile Epithelial cells

     • Located in superficial skin layers

     • Densely populated underneath fingertips

     • sense pressure and help us perceive edges, points, and corners.

     • Release serotonin a synapses

   • Ruffini endings

     • Also called bulbous corpuscles

     • Respond to stretching of the skin

     • Eg. object falling out of closed hand

   • etc.

     B) The fast adapting ones

   • Pacinian corpuscles

     • Also called Lamellar corpuscles

     • Wrapped in several layers of connective tissue

     • Respond to high frequency pressure and deep vibrations

     • Deepest of the cutaneous receptors

   • Meissner’s corpuscles

     • Also called Tactile corpuscles

     • Highly sensitive to light touch, skin movement, and low frequency vibration

     • Also found in superficial skin layers-concentrated easily at fingertips

   • Etc.

     Another class of cutaneous receptor is called a free nerve ending. Thermoreceptors and Nociceptors are a part of this class.

How are the auditory and vestibular systems similar? How are they different?

Both the auditory and vestibular systems link sensory input to electrical signals by causing movement in fluid to be detected by hair cells.

One of the main differences is in how they move this fluid; in the auditory system the fluid is moved by vibrations from sound waves, while in the vestibular system the fluid is moved by inertia of the head in a specific direction.

What are the three components of a sound wave?

The frequency, or how often the wave repeats

The amplitude, or the height of the waves

The timbre, or the complexity of the waveform.

What are the names of the middle ear bones (ossicles)?

Malleus, incus, and stapes.

What is the acoustic reflex?

This is when the tensor tympani and the stapedius muscles contract when exposed to loud noise to make the ossicles move less, dampening sound by about 15 decibels.

What organ contains the cells responsible for converting vibrations into electrical signals?

The Organ of Corti

• Made of hair cells, which detect vibrations of fluid inside the organ which are linked to neurotransmitter release.

• The Organ of Corti exists in the cochlea.

What is the difference between conductive and sensorineural hearing loss?

Conductive hearing loss

• When there is changes to the auditory pathway up to the oval window (the membrane on the inner side of the ossicles)

• This Creates a physical barrier to the vibrations associated with sound.

Sensorineural hearing loss

• Damage in the auditory pathway relating to the conversion of vibrations into an electrical signal, the propagtion of that electrical signal, or the processing of the signal.

CPP

What brain structure is responsible for determining what side of our head a sound comes from?

The superior olive.

What is tinnitus?

A symptom characterized by the perception of ringing/whistling/clicking/buzzing sound without an actual stimulus.

What are the otolith organs?

The utricle and the saccule which are responsible for detecting inertial changes.

Saccule is more sensitive to verticle movements while utricle is more sensitive to horizontal ones

Contain otolith hair cells

What are the semicircular canals?

A group of 3 membranous tubes that are able detect the direction of movement of the head.

What is the righting reflex?

This is a postural reflex that uses vestibular inputs to correct the body position if it ends up in an abnormal orientation.

What is the function of the vestibulo-ocular reflex?

This reflex allows the eyes to stay focused on an object while the head is moving.

What is the labelled line principle?

This is when sources of different types of information are carried in separate, but parallel paths.

What is the sensory homunculus?

This is a representation of a person where the body parts are scaled to the size of how large the areas of S1 are that represent those body parts.

What type of neuron are the cutaneous mechanoreceptors?

They are pseudounipolar neurons-neurons that starts as bipolar neurons but then fuse into one

What type of sensory cell detects temperature?

Thermoreceptors

What type of sensory cell detects painful stimuli?

Nociceptors

What is allodynia?

Allodynia is a condition where tactile stimuli that is not dangerous causes the sensation of pain.-so like increased pain sensitivity ig

What is hyperalgesia?

Hyperalgesia is an abnormally high perception of pain.

What gene mutation causes congenital insensitivity to pain (CIP)?

This condition is associated with mutations in the SCN9A gene, which expresses an important component of nociceptors, so, the mutation prevents proper pain signaling.

What is referred pain?

Referred pain occurs when the nervous system is unclear on how to process signals of trauma to an internal organ, so the brain interprets those signals as bodily pain.

What is proprioception?

This is the ability of your nervous system to sense where parts of your body are in space

It is important for movement coordination and rapid postural adjustments.

What two neural systems contribute to proprioception?

Muscle spindles are used to detect muscle length, while Golgi tendon organs detect the amount of tension on a muscle.

There are 5 basic tastes: salty, sour, sweet, bitter, and umami. Discuss which tastes are ionotropic taste receptors and which are metabotropic.

Ionotropic taste receptors are for both salty and sour taste.

metabotropic taste receptors.: Sweet, bitter, and umami

What is the olfaction and why is it useful?

The ability to sense and perceive volatile chemicals that are in the air.

The chemicals in the air serve as survival cues and the odorants can affect our behaviours unconsciously.

What are olfactory receptor neurons?

Bipolar neurons that begin to process smell.

The long dendrites project into the epithelium where they contact the air (only neuron directly exposed to the outside world).

Where are olfactory receptors located?

On the dendrites of the olfactory receptor neurons.

How do the olfactory receptors pass information to the brain?

There are a series of holes at the cribriform plate for the olfactory receptor neurons to pass through.

This then connects to the olfactory bulb, which is the beginning of the olfactory nerve (CN I).

What makes up the olfactory cortex?

These 4 structures: piriform cortex, cortical amygdala, entorhinal cortex, and orbitofrontal cortex.

PCEO

Why is smell and memory so strongly linked?

Because of the strong neural connections between the olfactory nerve and cortical amygdala.

The amygdala is a part of the brain that helps mediate complex emotional states. It receives strong inputs from the olfactory nerve.

What is hyposmia and anosmia? Which one is one of the main symptoms of COVID-19?

Hyposmia is reduced ability to smell, anosmia is a complete loss of smell.-anosmia is covid

What is the gustatory system and why is it useful?

The perception of taste-guides us to eating healthier foods.

Looking at the tongue, what gives the characteristic rough surface?-add more

Lingual papillae, each one of these contains up to 100 taste buds.

What is the appetite stimulating hormone?

Ghrelin.

What is the chemosensory trigger zone?

Part of the brain stem that is dense with neurons to sense the presence of chemicals.

The prefrontal cortex (PFC) plays a crucial role in motor control. Explain the purpose of the prefrontal cortex in planning movement.

The prefrontal cortex is responsible for deciding which motor pattern is appropriate in response to the stimulus.

PFC weighs the consequences of motor actions and makes changes for future motor actions.

The posterior parietal cortex (PPC) is a major cortex contributing to motor function. Explain how the PPC uses somatosensory and visual information to allow someone to stand up from a chair and walk across the room.

It takes the somatosensory proprioceptive info of where your body is positioned in the environment and the visual info of the objects in the environment to determine how you should move your body to walk around.

What does the motor system consist of? What are the key roles?

The motor system consists of the nerves that control body movements.

The key roles are to plan, control and execute voluntary and involuntary movements.

Name the three brain structures that contribute to the execution of movement.

Premotor area (PM), supplemental motor area (SMA), and primary motor cortex (M1).

What are mirror neurons?

Mirror neurons are argued to be involved in learning behaviors.

They are in the premotor area.

What is the supplemental motor area responsible for?

The proper communication between motor commands in both hemispheres.

The cerebellum is highly dense of neurons, 80% of the total number of neurons on the human brain. What is the purpose of the cerebellum?

To integrate sensory info to produce coordinated movement.

It refines motor-related outputs of motor tasks to execute functions.

What part of the cerebellum control eye movement? What happens if there’s a lesion there?

The lateral vestibulocerebellum.

If there’s a legion, then there is a deficit in smooth eye pursuit towards the side with the lesion.

The basal ganglia is involved with voluntary movement, habit learning, and selection of actions.

List some types of disease of the basal ganglia.

Parkinson’s, dystonia, Huntington’s, Tourette’s, and psychiatric disorders such as OCD.

Explain what reflexes are.

Involuntary motor responses that are performed automatically, without brain signals.

What are central pattern generators?

Produce intrinsic motor responses in the absence of sensory or brain inputs.

They are well rehearsed unconscious actions that the body does.

Eg. movement of the diaphragm, breathing, and alternating leg swing while walking.

What are the three types of muscles in humans?

Skeletal, cardiac, and smooth.

There are two types of skeletal muscles, what are they and what are the characteristics?

Fast-twitch muscles generate force quickly, but tire easily. These muscles are typically used in

Slow-twitch muscles generate less force but can work for a while. These muscles are used for endurance-based exercise.

How does neuropharmacology help us understand the underlying mechanisms of addiction and substance abuse?

Can you discuss specific neurotransmitter systems and brain regions that are involved in addiction and how drugs can manipulate these systems?

Neuropharmacology investigates the role of various neurotransmitter systems in addiction.

Some key neurotransmitters and their involvement in addiction are:

1. Dopamine:

2. GABA (Gamma-Aminobutyric Acid)

Brain Regions Involved in Addiction:

Neuropharmacology also delves into the specific brain regions implicated in addiction:

1. Nucleus Accumbens

2. Prefrontal Cortex

Manipulation of Neurotransmitter Systems:

Drugs can manipulate neurotransmitter systems in various ways:

1. Agonists and antagonists

2. Reuptake inhibitors

3. Enzyme inhibitors

Enzyme inhibitors

• Some drugs interfere with the enzymes that break down neurotransmitters.

• Eg. alcohol inhibits the breakdown of GABA, leading to increased GABAergic activity

Reuptake inhibitors

• Some drugs prevent the reuptake of neurotransmitters, leading to increased synaptic levels.

• For example, cocaine is a dopamine reuptake inhibitor.

Dopamine

• This neurotransmitter is strongly associated with the reward system in the brain.

• Drugs of abuse, such as cocaine and opioids, often lead to a surge in dopamine release in the nucleus accumbens, a region of the brain responsible for pleasure and reward.

• This reinforcement of pleasurable feelings can lead to drug-seeking behavior and addiction.

Prefrontal cortex

• Responsible for executive functions such as decision-making, impulse control, and judgment and personnality

• Substance abuse can impair the prefrontal cortex's function, contributing to impulsive drug-seeking behaviors.

• Pulse with injuries here perform worse on working memory tasks

Agonists and antagonists

• Some drugs act as agonists, mimicking the effects of natural neurotransmitters

• Others act as antagonists, blocking the receptors for these neurotransmitters.

GABA (Gamma-Aminobutyric Acid)

• The brain's primary inhibitory neurotransmitter

• Drugs like alcohol enhance GABA activity, leading to sedation and relaxation.

• Understanding the interactions between GABA and substances helps us comprehend the sedative effects of these substances and their potential for abuse.

Nucleus Accumbens

• This region is a central player in the brain's reward system

• Is heavily influenced by drugs that boost dopamine levels.

• Neuropharmacology research shows how drugs can manipulate dopamine pathways in the nucleus accumbens, leading to the pleasurable feelings associated with substance use.

How does the knowledge of neuropharmacology inform harm reduction strategies for substance users?

Can you discuss harm reduction programs, their effectiveness, and the ethical considerations surrounding these approaches in managing substance use and addiction?

Tailored Intervention:

• Understanding the neuropharmacological effects of different substances helps in designing tailored interventions.

• Eg. harm reduction strategies for opioid users often involve the use of medications like methadone or buprenorphine to reduce cravings and withdrawal symptoms.

• Knowledge of the brain's opioid receptor system informs the use of these medications.

Education and Outreach:

• Neuropharmacology provides the basis for educational campaigns that inform substance users about the specific risks and potential harms associated with different substances.

• This knowledge enables outreach programs to target their messages effectively.

Safe Consumption Spaces:

• Harm reduction programs often include supervised injection sites or safe consumption spaces.

• Understanding the neuropharmacological effects of drugs informs the design and operation of these spaces.

• Trained staff can provide immediate assistance in case of overdose and educate users about safer injection practices.

Naloxone Distribution:

• Naloxone, an opioid receptor antagonist, is a crucial tool in harm reduction.

• Understanding the neuropharmacology of opioids informs its use as an opioid overdose reversal agent.

• Harm reduction programs often distribute naloxone to both substance users and their communities.

NEST

What route of delivery is preferred for drugs that need to be present for long periods of time?

Oral

What are the two main classifications of routes of administra7on?

Enteral (absorbed by GI tract), parenteral (avoids GI tract)

What is the fastest route of drug delivery?

Intravenous (IV) injection

What compound in grapefruits can interact with many drugs?

Bergamottin

What is the difference between topical and transdermal drug administration?

Topical only affects local tissues, while transdermal allows diffusion of the drug into the bloodstream to affect the whole body.

What experiment is conducted in a Skinner box?

A skinner box is used when an organism has electrodes implanted in a certain part of the brain, and buttons contained in the box will stimulate these electrodes.

This allows us to determine if electrical stimulation of certain areas of the brain is desirable or not through the experimental paradigm of intercranial-self stimulation.

What two brain areas do the reward pathway connect?

The ventral tegmental area and the nucleus accumbens

What term is used to describe the randomness of a molecule’s movement (the location of a molecule has no influence on where it will go next)

Stochastic

What is the leading risk factor for premature death among males?

Alcohol use

What is the leading cause of preventable death in the United States?

Nicotine use

What is the action of cocaine at the synapse?

Cocaine acts as a reuptake inhibitor, preventing neurotransmitters from being re-absorbed and keeping them in the synapse to increase likelihood of signal transmission.

What term is used to describe a decrease in the ac7on of a drug due to repeated exposure?

Tolerance

What is conditional tolerance?

The result of the learning that occurs related to past drug exposure

If a cue is present to indicate that a drug will be introduced to the system, the body can start the opposite effect to counteract the expected drug.

As a result, the person may need to take more of the drug to counteract these changes due to anticipation.

What are two non-human model experiment conditions that are used to study drug use disorder?

Self administration and conditioned place.

1. Self admin:

   • Uses a Skinner box and implanted IV tube, which allows the organism to administer drugs intravenously whenever they choose.

     2. Conditioned place

        - Involves administering drugs to an animal in one room, and placebo in another, and then seeing what room they prefer to spend time in.

What is the hedonia hypothesis?

This is a theory of addiction that suggests that anything that increases dopamine will be desirable, based on the assumption that dopamine is the pleasure neurotransmitter.

What is the incentive sensitization model?

This is a theory of addiction that suggests that after chronic exposure to a drug, the person becomes fixated on acquiring the drug rather than the feeling they get in response to the drug.

What is the Brain Disease Model of Addiction?

This is a theory of addiction that is based on the idea that like other diseases, addiction has a genetic component, and that addicts seek drugs because of underlying brain circuitry that makes quittng difficult.

Stochastic

Used to describe randomness of a molecule’s movement

Tolerance

The decrease in the action of a drug due to

repeated exposure

Oral

Preferred delivery for drugs that need to be

present for long periods of time

Alcohol use

The leading cause of premature death among

males

Nucleus accumbens

Region of the brain that is a central player in

the brain’s reward system and is heavily

influenced by drugs that boost dopamine

levels

Bergamottin

The compound found in grapefruits that can

interact with other drugs

Lateral hanebula

Part of the brain that inhibits the ventral

tegmental area’s dopamine production in the

aversion pathway

Enzyme inhibitors

Type of drug that interfere with the enzyme

that breaks down neurotransmitters

GABA

The brain’s primary inhibitory neurotransmitter