BioPsych
Frontal Lobe
Parietal Lobe
People are staring. Quick, cover your parietal!
The parietal lobe is a multi-fuction region at the top-back of the head. It processes pain, temperature and pressure information. It processes visual information it receives from the occipital lobe (the dorsal stream). And it provides a 3-D view of your environment.
Visual information from the occipital lobe helps you know where things are and how to reach them. Data from occipiatal lobe is compared to data obtained directly from the optic chiasm and superior colliculus. You get fast response to moving objects and a clear, if slower, understanding of where everything is.
Temperature and pain information is routed to the parietal lobe but it is less clear how this information is organized and processed. Touch information is clearly mapped but pain isn’t. Pain also invloves the frontal lobe for determining context and significance.
NOTES
Parietal Lobe
- Mechanical Senses
- Vestibular sensations (inner ear)
- Tactile Sensations
- Itch, touch, pressure, pain
- 1. Vestibular sensations
- Measures
- Position-movement of head
- Pressure, bending
- Spatial orientation
- Balance
- Signals come from:
- Semicircular canals
- Neck muscle “stretch” receptors
- Utricle (gravity)
- Sends signals to
- control eye movement
- keep you upright
- Labyrinth of inner ear
- Two major components
- Semicircular canal system
- rotational movements
- Otoliths
- linear accelerations
- Semi-Circular Canals
- Responsive to acceleration
- Detects rotational movements
- Detect head rotation
- fluid pushes hair cells
- 3D Structure
- Orthogonal
- Lateral (horizontal) = pirouette
- Superior (anterior) = head-heel
- Inferior (posterior) = cartwheel
- Push-pull system
- Sense all directions of rotation
- Three pairs work together
- 3 on left side & 3 on right side
- push-pull fashion
- Otolith Organs
- Linear accelerations
- Two on each side
- Utricle
- Saccule
- Utricular signals = eye move
- Saccular signals = posture
- Contain otoconia crystal
- Heavier than its gel layer
- Displaced during linear acceleration
- Deflects ciliary bundles
- Vestibular system projects to cerebellum
- Cerebellum to eye muscles, etc
- Also to thalamus & eyes
- Projects to spinal cord
- reflex reactions of limbs and trunk
- regain balance
- Sensations
- Vertigo
- Dizziness
- Whirling or spinning
- Feeling of motion when stationary
- Nausea and vomiting
- Trouble walking
- Three sensations
- Objective = world moving
- Subjective = you’re moving
- Pseudovertigo = rotation
- Common complaints
- 20%-30% of population
- Patients of all ages
- More common as get older
- 1. Peripheral Vertigo
- Most common cause
- Cold or flu
- Chemicals
- Head trauma
- Motion sickness
- 2. Central Vertigo
- Central Nervous System
- Cervical spine injury-disease
- Parkinson’s disease
- Migraine headaches
- Multiple sclerosis
- Epilepsy
- Tumors
- Prognosis
- Slow improvement
- No improvement
- Measures
- Itch
- Result of tissue damage
- release of histamine
- Contact with certain plants
- Itch Process
- Single spinal pathway
- slower than other tactile senses
- activates neurons in spinal cord
- produce a chemical called gastin-releasing peptide
- Why Itch
- Alert to remove irritation
- Scratch irritant off skin
- Not type of pain
- Opiates less pain & increase itch
- Correlated
- Vigorous scratching causes pain
- Reduce pain, reduce itch
- Similar to pain but not
- Both use unmyelinated neurons
- Same nerve bundle
- Both originate in skin but two distinct systems
- Both use unmyelinated neurons
- Itch receptors
- Only on top two skin layers
- Epidermis
- Epidermal
- Itch on top, pain under skin?
- No itch in muscles or joints
- Sensitivity
- Evenly distributed across skin
- Similar density to that of pain
- Neuropathic
- Itch can originate at any point along afferent pathway
- Damaged nervous system
- Diseases or disorders
- CNS or PNS
- Causes
- Multiple sclerosis
- Opioid use
- Psychogenic
- Psychiatric Itch
- Hallucinations & delusions
- Obsessive-compulsive
- Neurotic scratching
- Pain can reduce itch
- Rubbing, scratching
- Electric shock
- Noxious heat
- Chemicals
- Pain & itch sensitivity
- Negatively correlated
- More sensitive to pain
- Less sensitive to itch
- Central sensitization
- Spinal cord input (noxious $)
- Allodynia = exaggerated pain
- Hyperalgesia = extra sensitivity
- Contagious Itch
- Want to scratch
- Talking about it
- See someone scratch
- Mirror neurons?
- Treating Itch
- Itch-scratch-itch cycle
- Self-contagion
- Result of tissue damage
- Touch
- Skin Mapping
- 4 findings:
- 1. Sensations not continuous across skin
- Localized in discrete points
- 2. Number of pain spots > number of pressure > number for temperature
- 3. Localization shifts over time
- 4. Specific sensations do not always directly correspond with the type of receptor found at that location in the skin
- Somato-sensation
- 3 types of tactile sensations
- 1. Temperature
- 2. Pressure
- 3. Pain
- Skin Mapping
- 1. Temperature
- Two independent systems
- Cold
- Warm
- Not Hot
- Hot is not the extreme of warm
- Both warm and cold spots respond to “hot” stimuli
- Physiological zero
- Current skin temperature
- things you touch are compared to your current skin temperature
- Current skin temperature
- Structure
- Free endings of touch neurons
- Non-specialized endings
- Not so much separate neuron
- warmth receptors are slow; unmyelinated C-fibers
- cold uses both
- C-fibers (unmyelinated)
- A delta fibers (thin myelinated)
- How it works
- Warm = increase firing rate
- Cooling = decrease warm rate
- Cold = both
- = increase cool firing rate
- = decrease warm firing rate
- Some cold receptors
- Brief pulse at high temp
- paradoxical response
- Paradoxical cold
- Can’t distinguish extreme hot from extreme cold
- Temperature receptor location
- Skin
- Bladder
- Cornea
- Pre-optic & hypothalamic regions
- Core temp
- Path
- Up spinal cord
- To thalamus
- Two independent systems
- 2. Touch
- Pressure
- Light & Deep
- Use internal organ feedback
- Use touch receptors
- Meissner’s corpuscles
- Unmyelinated nerve endings
- Slow vibrations; texture changes
- Lips, finger tips, palm, foreskin
- Close to surface
- Onset & offset
- Touched a coin
- Merkel’s discs
- Sustained touch and pressure
- Close to surface
- Fingertips
- Slow adapting
- Still holding coin
- Ruffini’s end organs
- Sustained pressure
- Slow adapting
- Deep in skin
- Skin stretch
- Where coin is
- Pacinian corpusles
- Fast vibrations; deep pressure
- Fast adapting (joint position)
- Sudden displacements
- Onset & onset
- Coin leaves hand
- Pressure on receptor
- opens sodium channels in axon
- action potential if enough NT
- Touch perception
- Cutaneous rabbit illusion
- Tapped very rapidly 6x on wrist and then 3x near elbow
- sensation of rabbit hopping from the wrist to elbow with extra illusory stop in between
- Damage to somatosensory cortex (Alzheimer’s)
- impaired body perception
- trouble putting clothes on
- Pressure
- Pain
- All tactile senses except pain adapt quickly
- Survival function of pain
- Independent systems
- Sharp and dull
- Treatment for one not usually effective for the other
- A. Sensing Pain
- Nociceptors
- Bipolar neurons
- Cells in dorsal root of spinal cord
- Send signals on to brain
- Signal skin damage
- Muscles, joints and organs
- Degree of pain depends on:
- Sensitivity of receptors
- Level of stimulation
- Several types of nociceptors
- 1. Thermal nociceptors (extreme)
- 2. Mechanical nociceptors
- Respond to intense pressure
- Not Pacinian corpuscles (touch only)
- 3. Silent nociceptors
- Respond to inflammation chem
- Once activated are sensitive to thermal and mechanical stresses too
- 4. Polymodal nociceptors
- Respond to everything
- Thermal
- Mechanical
- Chemical stresses
- Axons that carry pain info, vary in diameter
- Myelinated faster than unmyel.
- Thicker the faster
- A-alpha
- Largest
- Insulated
- Muscles sensations
- Proprioception
- A-beta
- 2nd largest
- Insulated
- Touch
- A-delta
- Smallest of alphas; nearly as small as Cs
- Thinly insulated
- Pain, heat, touch
- “Good pain” = do something and it will go away
- Put down hot frying pan
- C fibers
- Smallest
- Unmyelinated
- Slowest
- Heat & itch
- Diffuse, dull, chronic pain
- “Bad pain” = removing $ doesn’t remove pain
- Signals damaged tissue
- ********************
- Example
- Stub (hurt) your toe
- 1. moving your foot
- A-alpha propreioceptive info
- 2. sensation of hitting object
- A-beta nerve fibers
- 3. pain of tissue damage
- A-delta and C-nerve fibers
- Primary afferent axons
- Vary in diameter
- A-alpha largest myelinated
- A-beta 2nd largest myelinated.
- A-delta 3rd largest myelinated.
- C fibers smallest unmyelinated
- Vary in speed
- A-alpha 265 mph
- A-beta 165 mph
- A-delta 75 mph
- C fibers 2 mph
- Vary in diameter
- ***************
- Rare Condition: Congenital Insensitivity To Pain
- Born without sense of pain
- Continue activity after injury
- Not detect broken bones-gash
- Often get pressure sores & damaged joints
- B. Relieving pain
- Capsaicin
- disrupts steady $ of pain cells
- Steroids (cortisone injections)
- Relieve pain & joint inflame
- Released by adrenal gland
- Steroid hormone that suppresses immune system
- Which reduces inflammation but stops trying to heal you
- Non-steroidal anti-inflam. drugs
- Tissue damage causes inflame
- Releases prostaglandins that trigger pain
- Capsaicin
- ************
- Prostaglandins
- Proteins
- Synthesized by 3 major enzymes
- Cyclooxygenase 1 (Cox-1)
- Cyclooxygenase 2 (Cox-2)
- Cyclooxygenase 3 (Cox-3)
- All three are blocked by:
- aspirin
- ibuprofen (Advil, Motrin)
- naproxen (Aleve)
- Acetaminophen (Tylenol)
- Blocks Cox 3 only
- Doesn’t irritate stomach
- Not likely cause of Reye’s syndrome; aspirin, children with viral infections?
- ************
- Non-steroidal anti-inflam drugs (NSAIDs)
- Opioids (opiates)
- Good news: Effective
- Bad news: Addictive
- Hydrocodone
- Most used opioid treat of pain
- Morphine = cancer pain
- Opioids (opiates)
- Social Pain
- Romantic breakup
- similar to physical pain
- Emotional pain
- experienced in cingulate cortex
- can be relieved by Tylenol
- Romantic breakup
- Parietal lobes
- Named for overlying bone (parietal bone)
- Above occipital lobe
- Behind frontal lobe
- Integrates sensory information
- Spatial sense
- Navigation
- 1. Somatosensory Cortex
- Visual
- Auditory
- Olfactory
- Gustatory
- 2. Posterior Parietal Cortex
- Also called Somatosensory Assoc. Cortex
- Multimedia
- Dorsal stream of vision
- Where stream of spatial vision
- How stream of visual action
- Used by oculomotor system for targeting eye movements
- Spatial location
- Organized in gaze-centered coordinates
- ‘remapped’ when eyes move
- Input from multiple senses
- Encode location of a reach target
- Manipulation of hands
- Shape, size & orientation of objects to be grasped
- Damage to right hemisphere
- Problems with visualization
- Imagery
- Neglect of left-side space
- Neglect left side of the body
- Damage to left hemisphere
- Problems in mathematics
- Reading
- Writing
- Understanding symbols
Parietal lobes
Named for overlying bone (parietal bone)
Above occipital lobe
Behind frontal lobe
Integrates sensory informationSpatial sense
Navigation
1. Somatosensory CortexVisual
Auditory
Olfactory
Gustatory
2. Posterior Parietal CortexAlso called Somatosensory Assoc. Cortex
Multimedia
Dorsal stream of visionWhere stream of spatial vision
How stream of visual action
Used by oculomotor system for targeting eye movements
Spatial locationOrganized in gaze-centered coordinates
‘remapped’ when eyes move
Input from multiple senses
Encode location of a reach target
Manipulation of hands
Shape, size & orientation of objects to be grasped
Damage to right hemisphereProblems with visualization
Imagery
Neglect of left-side space
Neglect left side of the body
Damage to left hemisphereProblems in mathematics
Reading
Writing
Understanding symbols
TACTILE SENSATIONS
Ascending pathways
1. Lemniscal System
Pressure information
Small receptive fields
Rapid transmission in long axons
Travels up the back of the spinal chord
Travels to somatosensory I in the Parietal lobe
(front part of parietal lobe)
SSI is organized into the sensory humunculus
the greater the sensitivity of a body part the greater the area of the brain devoted to it
2. Spinothalamic System
(Extralemniscal)
Pain & temperature information
Large receptive fields (dermatomes)
Small axons and slower transmission
Travels up sides of spinal chord
Travels to somatosensory II in the parietal lobe
– (back part of parietal lobe)
SSII does not have a neat organization
Many overlapping representations
Temporal Lobe
Data is crawling across the side of your head.
The temporal lobe is critical for processing vision, memory and sound. We’ll look at all three. For vision, there are two streams of visual information come from the occipital lobe. First, we’ll look at the info sent to the temporal lobe.
Auditory information comes from the eyes, passes through the inferior colliculus, then the MGN, and finally reaches the superior region of the temporal lobe. As it passes through the temporal lobe, sound info is processed with increasing complexity, and shared with the parietal and frontal lobes. The auditory cortex is structured concentrically, with the primary cortex in the middle.
- Temporal Lobe
- Ventral = high level visual process
- Medial = memory
- Superior = cochlea
- Posterior = audio-motor proces
- Temporal-parietal = Wernicke
- I. Ventral area of temporal lobe
- ventral = toward the tummy; under part of temporal lobe
- Ventral Stream
- Occipital to temporal
- Under part of temporal lobe
- Main input from LGN
- Parvocellular cells of V4
- As info moves thru temporal lobe
- Processes larger receptive fields
- Takes longer to process
- Analyses more complex
- Representation of entire visual field
- Uses cues to judge significance
- Attention
- Stimulus salience
- Working memory
- High-level visual processing
- Complex stimuli
- Faces (fusiform gyrus)
- Scenes (parahippocampal)
- Surrounds hippocampus
- Inferior temporal gyrus
- Visual processing
- Complex object features
- global shape
- face perception?
- Fusiform gyrus = faces
- Parahippocampal = scenes
- Lingual gyrus
- Word recognition
- Dreaming
- II. Medial Temporal Lobe
- Medial = toward median; toward middle
- Declarative memory
- Facts you know – L hemisphere
- Events you’ve experienced – R
- Interacts with frontal lobes
- Create long-term memories
- Maintain long-term memories
- Long-term memory
- Becomes independent of encoding process
- Hippocampus & adjacent areas work together
- No simple dichotomies
- associative vs. nonassociative
- episodic vs. semantic memory
- recollection vs. familiarity
- Transfer from STM to LTM
- Control spatial memory
- Damage causes
- anterograde amnesia
- Declarative (explicit) memory
- Semantic memory
- Left hemisphere
- Facts
- Episodic memory
- Right hemisphere
- What I did on my vacation
- Semantic memory
- Medial = toward median; toward middle
- III. Superior Temporal Lobe
- superior = upper
- Cochlea to auditory cortex
- A. Primary auditory cortex = sound
- Anatomy of the Ear
- 1. Outer Ear
- 2. Middle Ear
- 3. Inner Ear
- 1. Outer Ear = pinna
- Pinna (pinnae) – visible ear
- funnels sound to ear drum
- helps in sound localization
- Tympanic membrane
- Connects pinna to ear drum
- Vibrates to sound wave
- Eustachian tube = equalizes pressure
- Pinna (pinnae) – visible ear
- 2. Middle Ear
- Ossicular Chain
- Pre-amplifier
- amplifies vibrations 20x
- 3 small bones
- Malleus
- Incus
- Stapes
- Pre-amplifier
- Attenuation reflex
- brain senses loud sound
- tenses up muscles
- To prevent damage
- Bones don’t move
- Greater for low frequencies
- (higher freq. easier to discern)
- Ossicular Chain
- 3. Inner Ear
- A fluid-filled structure
- fluid is called endolymph
- similar to intracellular fluid
- high in potassium
- low in sodium
- Composed of
- Bony labyrinth
- Membranous labyrinth
- suspended within bony labyrinth
- delicate continuous membrane
- Space between membranous & bony labyrinths
- Filled with perilymph, similar to cerebral spinal fluid
- A fluid-filled structure
- 2 outlets to air-filled middle ear
- Oval window
- Filled by plate of stapes
- Fluid pressure
- Round window
- Pressure valve
- Oval window
- Cochlea
- Spiral-shaped tube
- Has 2 connected canals
- Upper vestibular canal
- Lower tympanic canal
- Separate at large end
- continuous at the apex
- Fluid filled (perilymph)
- Has a middle canal
- Cochlear duct
- Filled with endolymph
- Contains the Organ of Corti
- Organ of Corti
- “spiral organ”
- Contains hair cells for hearing (cilia)
- Basilar membrane with hair cells rest on it
- The basilar membrane separates the cochlear duct from the tympanic canal
- The tectorial membrane lies above the hair cells
- Stereocilia
- Connected by extracellular links
- Graded in height
- Arranged in bundles
- Pseudo-hexagonal symmetry
- How cochlea works
- Contains fluid
- Moving fluid $ hair cells, signals sent to brain, perceived as sound
- Arranged from high to low notes
- low notes travel farther
- Hearing Loss
- Bad bone conduction
- Hearing aids
- Bad cochlea
- Implant
- Dead cilia
- ?
- Bad bone conduction
- Most common causes
- Age (presbycusis)
- Gradual, steady loss
- Noise
- Motorcycles, lawn mower
- Music in headphones
- Gun shots
- db
- 0 barely audible
- 20 leaves ruffling
- 40 quiet suburbia
- 60 speaking voice
- 100 subway train
- 140 jet taking off
- Obstructions
- Earwax
- Objects
- Chemicals
- Some antibiotics
- Arsenic, mercury, tin, lead
- Head injury
- Structural damage
- Infections
- Middle ear (otitis media)
- Swimmer’s ear (otitis externa
- Fluid (cold or flu)
- Age (presbycusis)
- Preventing Loss
- Good genes
- Cover your ears
- Lawn movers
- Guns
- Don’t smoke
- Correlation, cause unknown
- Oxygen
- Neurotransmitters
- Developing brain
- No loud music
- Processing Sound
- Vestibulocochlear nerve
- Cochlea but stops at cochlear nuclei
- Neural Path
- Cochlei
- Cochlear nuclei
- Superior olivary complex
- Inferior colliculus
- Thalamus (medial geniculate nuclie)
- Primary auditory cortex
- Cochlear nucleus
- 1st processing
- Dorsal cochlear nucleus
- Ventral cochlear nucleus
- Superior olivary complex
- In the pons
- Input: ventral cochlear nucleus
- Lateral superior olive (LSO)
- Detecting ineraural level
- Medial superior olive (MSO)
- Interaural time difference
- Lateral superior olive (LSO)
- Inferior colliculi
- Just below superior colliculi
- Visual processing centers
- Integrates sound source info
- Medial geniculate nucleus
- Thalamic relay system
- The LGN of sound
- Auditory Cortex
- Highly organized into 3 parts
- Concentrically with primary in the middle
- Primary auditory cortex
- Secondary auditory cortex
- Tertiary auditory cortex
- 1. Primary Auditory
- Direct input from MGN
- Tonotopically organized
- Identifies loudness, pitch, rhythm
- Neurons are organized:
- Frequencies respond best to
- Low frequencies at one end
- Complete “frequency map”
- Tonotopic map
- Maps for vision & hearing
- Reina to cortex
- Cochlea to cortex
- Maps for vision & hearing
- 2. Secondary Auditory
- Surrounds primary cortex
- Interconnect
- Further processing
- Process patterns of
- Harmony
- Melody
- Rhythm
- 3. Tertiary Auditory Cortex
- Integrates musical experience
- What it all does
- Analyses
- Identifying auditory objects
- Segmenting streams
- Identifying location of a sound
- How it all works
- Unclear
- Inputs
- Multiple sounds
- Occur simultaneously
- Tasks
- Which components go together
- location of sounds
- groupings based on
- Harmony
- Timing
- Pitch
- Connects to Frontal & Parietal lobes too
- Why each note played by different instrument in orchestra sounds different
- Same pitch
- Gamma waves
- Ss exposed to three or four cycles of 40 hertz click
- Spike in EEG
- Hallucination 12-30 Hz
- Left auditory cortex of schiz.
- When remember song in mind
- Don’t perceive sound
- Experience melody, rhythm & overall experience
- B. Wernicke’s Area
- Where temporal & parietal lobes meet
- Understanding of written
- Understanding speech
- Auditory word recognition
- Mimicking words
- Dominant Side
- Usually left hemisphere
- Resolve associative meanings
- Bank———teller
- Non-Dominant Side
- Usually right hemisphere
- Resolve subordinate meanings
- Ambiguous word meaning
- River bank
- Money bank
- Damage to Wernicke’s Area
- Receptive aphasia
- Also called
- Fluent aphasia
- Jargon aphasia
- Impairs language comprehend
- Natural-sounding rhythm
- Normal syntax
- Gibberish
- Nonverbal sound problems
- Animal noises
- Machine sounds
Occipital Lobe
There are eyes in the back of your head.
Well, okay, not actual eyes. But at least there are vsion processors for the information that comes from the eyes. The occipital lobe is at the back of the head, just above the neck. This is the primary projection area for vision.
Sensory information comes from the eyes, passes through the LGN, reaches the occipital lobe, is processed and then routed to both the parietal and temporal lobes. The cortex here is striated into 6 layers. Each has its own speciality.
The processed visual information is distributed to both the parietal and temporal lobes. The dorsal path goes from the occipital lobe up to the parietal lobe to help give you a 3D view of the world. The ventral path goes along the side of the head to the temporal lobe where you keep your mental encyclopedia.
Neurotransmitters
-
This is your brain on drugs, naturally.
“Just Say No” doesn’t apply to these drugs. Neurotransmitters are built-in drugs. You have to have them to make interconnections between neurons.
If the activity within a neuron is primarily electrical (though battery driven), the connections between neurons are typically chemical. Once a neuron’s depolarization reaches the terminal buttons, calcium channels are activated to release neurotransmitters into the synapse.
300+ types
- Most Common In Brain
- Glutamate 90%
- GABA 9%
- Other 1%
- Monoamines
- Dopamine
- Norepinephrine
- Epineprine
- Serotonin
- Acetylcholine
- Monoamines
- Most Common In Brain
- Monoamines
- 1. Catecholamines
- Most abundant catecholamines
- Epinephrine (adrenaline)
- Norepinephrine (noradrenaline)
- Dopamine
- Molecules with a catechol nucleus
- Benzene ring
- 2 hydorxal side groups
- Intermediate ethyl chain
- 1 side-chain amine
- Catechol
- Dopamine
- Derived from tyrosine
- Dopamine
- Nor-epinephrine
- Epinephrine (adrenaline)
- Tyrosine eaten or synthesized
- Sent to catecholamine-secreting neurons
- Water-soluble
- 50% bound to plasma proteins
- circulate in bloodstream
- In blood, half-life of a few minutes
- Degraded either by COMT
-
- (catechol-O-methyltransferases)
- Or degraded by MAO
- (monoamine oxidases)
- Amphetamines and MAOIs bind MAO
- Inhibit its action
- Stops or slows breaking down
- Why amphetamines have longer lifespan than cocaine
-
- 5 types of receptors (D1….D5)
- Also acts as a hormone
- Released by hypothalamus
- Inhibits release of prolactin from pituitary
- Main source
- Dopaminergic neurons
- in midbrain
- Dopamine level modulated by two mechanisms
- tonic and phasic transmission
- Tonic release
- Small amounts are released
- Independent of neurons
- Regulates other neurons and neurotransmitter reuptake
- Regulates intensity of phasic dopamine response
- Sets background level
- Sustained release
- Phasic release
- Neurons firing
- Short-term activation
- single spikes, and rapid bursts
- 2-6 spikes in quick succession
- Impacts
- Cognition and learning
- Motivation and voluntary movement
- Sleep, mood, reward, punishment
- If it’s addictive, it’s dopamine!
- Controls flow of info
- Frontal lobe to other areas of brain
- Metacognition (memory, problem solving)
- Maybe
- Teaching signal?
- Reward-anticipation?
- Low Levels
- Parkinson’s
- Can’t give dopamine
- (blood-brain barrier)
- Give L-Dopa (levodopa);
- Hope it’s turned into dopamine
- Can’t give dopamine
- Parkinson’s
- High Levels
- Euphoria
- Orgasm
- Reward
- Drugs
- Nicotine
- increases dopamine in mesolimbic reward pathway
- Addicts have altered pathways?
- Cocaine
- Blocks re-uptake
- Takes very little stimulation to activate post-synaptic neuron
- Cocaine blocks dopamine transporter
- Cocaine also blocks norepinephrine transporter
- (increase of up to 150 percent)
- Blocks re-uptake
- Cocaine vs. Meth
- Both inhibit reuptake
- Use different methods
- Amphetamines
- Structure similar to dopamine
- Fool system
- Get reuptaken instead
- Force dopamine out of terminal buttons
- Transporters work in reverse
- Pump dopamine out
- Schizophrenics
- Reduced tonic dopamine release
- Over time, causes subsequent phasic dopamine release
- Abnormally large responses
- Antipsychotic Drugs
- Reduce dopamine
- Reduce concentration, motivation, pleasure
- Increase weight gain, fatigue, stroke, sexual dysfunction
- Structure similar to dopamine
- Derived from tyrosine
- Norepinephrine (NE)
- Also called noradrenaline
- Synthesized from dopamine
- Both hormone and neurotransmitter
- Stress Hormone
- Released from adrenals into blood
- Fight or flight response
- Increasing heart rate
- Increasing glucose
- Increasing blood flow to muscles
- Increases muscle tension
- Increases vascular tone
- Triggers compensatory reflex that drops heart rate
- Reduce brain inflammation
- In Brain
- Stored in synaptic vesicles
- Binds to adrenergic receptors
- Impacts top-down perceptual processing
- Signal termination by
- Degradation
- Reuptake by norepinephrine transporter
- NT for sympathetic neurons
- Regulates the heart
- Increase in NE, increases contraction rate
- Impact
- Top-down perceptual processing
- Attention
- Low levels in ADHD
- ********************
- To Increase dopamine levels
- Ritalin/Concerta
- Dexedrine
- Adderall
- SNRI (selective norepinephrine reuptake Inhibitor)
- Strattera (for ADHD)
- Doesn’t also impact dopamine
- Antidepressants
- Increase NE and Serotonin
- Effexor
- Cymbalta
- Increase NE and Serotonin
- NE transporter might also reuptake some dopamine
- *************************
- Epinephrine
- Hormone & Neurotransmitter
- Also called adrenaline
- As hormone
- Associated with fear
- Arouse body
- increases heart rate, constricts blood vessels, dilates air passages
- Given to treat
- Cardiac arrest
- Anaphylaxis
- Superficial bleeding
- Has been used for
- Bronchospasm
- Hypoglycemia
- Now use
- Salbutamol (synthetic epinephrine)
- Dextrose
- Local anesthetic injections
- Add epinephrine to retard absorption
- Bupivacaine
- Lidocaine
- Easily binds to most adrenergic receptors
- Inhibits insulin secretion
- Stimulate liver and muscles
- Stimulates pancreas to release glucose
- Stimulates pancreas to release ACTH
- Regulates cortisol
- Epinephrine Path
- Tyrosine
- L-DOPA
- Dopamine
- Norepinephrine
- Epinephrine
- Physiologic triggers
- Noise & bright lights
- Physical threat
- Excitement
- Hot rooms
- “Adrenaline junkie”
- Getting “high” on life
- Dangerous activities
- Always overwhelmed
- Need for emergency
- Endorphins released too
- Most abundant catecholamines
- 2. Indolamine
- Tryptamine – also called indolamine
- Serotonin
- Serotonin (5-HT)
- Regulates pain and stress
- Opiate-like
- Tryptophan
- helps body produce niacin (B3)
- Needed to produce serotonin
- Serotonin is converted into melatonin
- Stored in intestines
- Released by liver into blood
- Binds to platelets
- When platelets bind to a clot, give off serotonin
- Vasoconstrictor
- Regulates clotting
- Wound healing
- In Brain
- 5-HT released from varicosities
- Not terminal buttons
- Varicosities
- Axon can have long chains of swellings
- Near terminal branches
- Receptors
- At least 9 types
- 5-HT3 is ion gate
- All others are G-protein regulated
- Impact
- Regulate release of insulin
- Mating behavior of males
- Regulate growth
- Regulate intestinal movements
- Regulate mood, sleep, appetite
- Serotonin regulates intensity of mood
- Not change mood itself
- Change perception of depression
- Change perception of phobia
- Too Much
- In peripheral areas
- Sudden increase is painful
- Venom of wasps and scorpions
- In Brain
- LSD
- Visual hallucinations
- Psychedelic drugs increase serotonin
- Psilocin-Psilocybin, DMT, Mescaline, LDS
- MDNA (ecstasy), Mephedrome release serotonin
- In peripheral areas
- Low Levels
- Depression
- Prozac increases serotonin
- Inhibits reuptake of 5-HT
- Sudden Infant Death Syndrome (SIDS)
- Defective serotonin signaling?
- Not enough serotonin in brain stem, drop in heart rate?
- To Increase
- Stop from breaking down
- Inhibit MAO wth MAOI
- Stop reuptake
- Inhibit reuptake with SSRI
- Tricyclic antidepressants
- Inhibit reuptake
- Serotonin
- Norepinephrine
- Inhibit reuptake
- Stop from breaking down
- Problems?
- Chronic use of SSRI
- Might lover baseline levels
- Even if increase serotonin
- Worse than when started
- Switched meds usually resets it
- Serotonin Syndrome
- Extremely high levels
- toxic and potentially fatal effects
- To avoid too much of one:
- SSRI & MAOI taken together
- Extremely high levels
- Tryptamine – also called indolamine
- Acetylcholine (Ach)
- First neurotransmitter identified
- small molecule substances
- similar to amino acids but structurally different
- Activates muscles
- Impacts
- Peripheral nervous system (PNS)
- Central nervous system (CNS)
- Major neurotransmitter in autonomic nervous system (ANS)
- Inhibitory neurotransmitter
- Slows heart rate
- Excitatory neurotransmitter
- Neuromuscular synapses
- Activates Muscles
- Binds to receptors
- Opens sodium channels
- Sodium ions enter muscle cell
- Starts sequence that produces muscle contraction
- Inhibits Heart Muscle
- Different receptor
- muscaninic
- In CNS
- Neuromodulator
- Impact plasticity, arousal, reward
- Enhances senses when wake up
- Help us pay attention
- Promotes REM sleep
- Impacts short term memory
- Increases response to sensory $
- Facilitates transmission from thalamus to cortex
- Reporting expected uncertainty?
- Low Levels
- Alzheimer’s disease
- Two main receptor types
- 1. Nicotinic Acetylcholine Receptors (AChR)
- Ionotrophic
- Sodium, potassium and chloride
- Muscle and neuron types
- Curare blocks muscle type
- Stops quick effects
- Myasthenia gravis
- Muscle weakness and fatigue
- Body produces antibodies against acetylcholine nicotinic receptor
- Inhibits acetylcholine signal transmission
- Destroys motor end plate
- Curare blocks muscle type
- 2. Muscaninic Acetylcholine Receptors (mAChR)
- Metabotrophic
- In heart, lungs, sweat glands
- Blocked by atropine
- Deadly Nightshade
- Poison-tipped arrows
- Increases pupil size
- For attractiveness in past
- Deadly Nightshade
- Sometimes used in cataract surgery
- Causes pupil constriction
- Miochol-E (CIBA Vision)
- First neurotransmitter identified
- 1. Catecholamines
