Midterm Lecture Notes 2017-04-14 11:44 PM
Synaptic Transmission & Neurotransmitters
Types of Synapses
• Electrical
• Mediated by connexions
• Involved direct transmission between cytosol of different molecules
• Fast transmission
• Synchronizes electrical activity among neurons
• Chemical/Synaptic
• Influx of calcium ions at the presynaptic neuron, causes vesicles to fuse
to the membrane of the neuron and release neurotransmitters into the
synaptic cleft to be uptaken by receptors in the post neuron
• Could be excitatory or inhibitory
• Mechanism – requires really close control
o Regulate
o Synthesize
o Package (transmitter)
o Release
o Degrade
Neurotransmitter Types
• Small molecule transmitter
• Enzymes needed are produced in the cell body, transported along the
axon via slow axonal transport
• Packaged at the end of the terminal
• Peptide transmitter
• Completely in the cell body and not just enzymes
• The entire preparation happens in the cell body
• There is an expiration process for the NT
• Uses fast axonal transport
Biogenic Amine Neurotransmitt ers
• Dopamine
• Norepinephrine (noadrenaline) – Catecholamines
• Epinephrine (adrenaline)
• Histamine
• Serotonin Dopamine
• Mostly found in the corpus striata – receives major input from substantia nigra
• Helps coordinate body movements (implicated in Parkinson’ s disease)
• Motivation, reward, reinforcement – explains addictive behaviours
• Abnormally high network of dopamine activity
• Too many messages all at once – could be one reason
• Dopamine involved in attention to schizophrenia individuals get a deficits of this
– ex: of when we move way from the balance of concentration or amount, there
are bad effects
• Implicated in sleep regulation as well
• Dopamine inhibits norepinephrine’s release and stimulation of the pineal
gland (to release melatonin)
Serotonin
• Depression – serotonin is a mood balancer; a deficit can lead to depression
Synaptic Plasticity
Facilitation vs Synaptic Depression
Habituation
Benefits and Detriments to Sensitization Long Term Plasticity
• Amygdala and hippo fail to habituate to faces in individuals with an inhibited
temperament (shyness)
• People who are shy are poor at habituation to new faces; overactivation in the
amygdala and hippo
• Hard to tell if innate or if socialization
Pain Sensation & Neural Circuitry
Pain Nerves:
• Different types of pain & different receptors for each type
• First pain is SHARP – controlled by alpha epsilon fibres
o Respond to most intense stimuli – goes away fast so that we can
respond to what caused the stimuli
o These receptors are myelinated
• Second pain is LONG LASTING – C fibres
o Respond to all kinds of stimuli – much more diverse in nature
o Unmyelinated – which is why they carry signal slower
• Ascending nociceptor pathways
• Descending pain control pathways
• Top down processing
• Gate control theory of pain
o At each main relay point, there are gates that can be closed
making it harder for nociceptors impulses to get through the
spinal cord and brain
Pain Through the Body
• The brain does not feel pain – only interprets signals and sends them back that
they are feeling/experiencing pain
• Visceral (internal) pain is hard to identify
• Visceral pain receptors are connected to both the spinal cord and
different other nerves in associated affected areas
o Examples: Heart has pain receptors around the chest but also the
arms and upper throat area
o Right Prostate: upper pelvis, down the upper thigh area, and
parts of the lower leg Neural Circuits and Neural Circuitry
Neural Circuits
• Affected by environment and genetics
• Intrinsic mechanisms are driven by genetics
• These don’t paint the whole picture though
• Examples in axonal growth, synapse establishment, topographical map
formation (layout within the brain dedicated to establishing things like
sense)
• These mechanisms are influenced by experiences which modify synaptic
connections
Neuronal Priming
• Neurons that fire together, wire together
• What’s important for priming? Not only that you are firing at the same thing
(towards the same connections) but also at the same frequency
• When you fire at similar frequencies you are better able to target the
target neuron therefore strengthening connection
• Synaptic pruning happens
• Examples: Playing the piano – people who never play the piano can
listen to someone playing and mimic what they do. 5 hours later, the
motor area of brain activated, when you listen to piano music
Evolutionary Significance
• Some basic behaviours are established intrinsically – no environmental input is
required here, it happens as the embryo d evelops; KIN RECOG
• Modifications for complex behaviours most likely during specific temporal
periods – usually right before puberty is the deadline for everything
• As you age as a baby, the more time that passes the harder it is to learn
– when you cross threshold of puberty then v difficult
• Critical periods are CRITICAL
• Parental imprinting by Hatchlings – few hours after birth there is a
window of time where their parent must feed them so that they can
recognize their moms. When this passes baby will not want food from
anyone, and die. • Learning songs – short periods of time where they need to get exposed
to and mimic bird songs – males who cannot sing, lose mates and drive
out competitors
• Critical periods for sensory motor skills in babies (these last a lot longer
then a few hours or days) like language acquisition
• Critical Period Properties
• Time where behaviour is especially susceptible to (REQUIRES) specific
environmental input
• Once a period passes, core features of behaviours are unaffected by
subsequent experience or exposure
Neural Cortices
Parietal Association Cortex
• Mediates attention
• When you have a unilateral parietal lobe lesion, you have problems with paying
attention to objects and events contralateral to the lesion site
• Stroke in left parietal has problems with language; right has problems with
visual acuity and detection
Prosopagnosia
• Failure to recognize and identify faces
• Superficial layer of the temporal lobe – fusiform face area
• Because of this there are people who cannot recognize people they should know
• Also a part of memory dysfunction – they could recognize sex, age and make
judgments but cannot know who they are by relationship
Frontal Association Cortex Mediates Planning and Decision Making
• Responsible for logical reasoning, planning, etc
• Cognitive tasks can evaluate frontal lobe functioni ng; like the Wisconsin Card
Sorting Task – makes comments about planning ability, the delayed response
task evaluates memories, and the NoGo task, which evaluates inhibition Speech and Language Production 2017-04-14 11:44 PM
Lecture Outline
1. Language Lateralization
2. Language areas in the brain and aphasias
3. Non Human language
Lateralization of Various Functions Previously Discussed
• Spatial representation – hemispatial neglect with right parietal damage
• Left side of their world is neglected
• Facial recognition – prospopagnosia with right temporal lobe damage
• People having a hard time recognizing faces
Language is Lateralization to Left Hemisphere
• Within the left hemisphere is Broca and Wernick’s areas: link speech and sounds
to their meanings
• Broca: motor commands that allow for physical production of language (i.e
moving toungue, larynx)
• Wernicke – actual meaning of sounds
• These two areas can only be found on the left (?)
• The right hemisphere is usually thought to be responsible for emotional content
– emotional valence of speech
• Language centres are involved in visual symbolic representation: language is
just a series of symbols the brain interprets
• The cortical areas devoted to sound language are the same as those for
heard language – therefore suggests a symbolic representation concept
• You can have the ability to move muscles of larynx, pharynx, mouth, and
tongue but still not be able to sense or understand language
• Just the symbolic stream of language comprehension would allow you to
understand –logically—but you wouldn’t be able to produce language
itself
• Aphasias
Broca’s and Wernicke’s Areas
• Language itself is lcoalized to the frontal left love
• Loss of physical ability to produce language when Broca’s area is damaged
• Spared ability to comprehend language
• “We speak with out left brain” • Speech is disjointed, struggle because they retain meaning
• Wernicke’s area disting uished between loss of language comprehension and
production
• Lesions of left temporal lobe resulted in comprehension failure
• Speech is fluent and structured but makes no sense
Split Brain as Evidence of Language Lateralization
• Corpus colloseum – if you sever this, the left and right hemispheres cannot
communicate
• In patients with lesions in this area, you present info to one side; in real life,
they can process and do things normally, because both parts of eye’s are being
used and therefore both hemisph eres; in lab you can manipulate this
• If you place an object on the left side of someone (so they are using their left
visual field) this gets processed and stops in the right hemisphere; because
language centres are in the left, they cannot name the object they are looking
at, and they cannot classify it; they an describe it though!
• This processes is normal in the right field – they can process and name +
classify without any problem
Neuroimaging to Show Language Localization
• Different parts are act ivated for passively viewing works, speaking works, and
generating word associations + listening to words
• There are other parts of the brain that light up when we do all of these things –
not just Broca and Wernicke
• Just the two parts are most important fo r lang
Language and Handedness
• Historically, 9/10 people are right handed; so why is this why language is found
in the left hemisphere?
• Left handed people are more right hemisphere dominant – Broca and
Wernicke’s are more dominant on the right hemisphere
• Exhibit more varied, unpredictable and diffuse cerebral activity than right
handed people
• Right handedness is more about wiring efficiency!!
The Right Hemisphere Plays A Role • Damage to the right hemisphere “Broca/Wernicke” interrupts prosody – rhythm,
stress and tonal variation
• Variation in tone changes semantic meaning in certain languages
• Left = comprehension and production
• Right = supplements to generate speech richness
Sign and Spoken Languages Have Similar Neural Substrates
• Deaf + Left Hemispher e Lesion = deficits in sign production and comprehension
• Deaf + Right Hemisphere Lesion = deficits in visuospatial processing, emotional
processing, emotional tone Sleep Dysfunction 2017-04-14 11:44 PM
Lecture Outline
• Why is sleep important for cognitive function
• Intervention program to improve sleep quality and cognition
Amount of Sleep Needed Varies Across a Lifespan
• Babies – 17hrs; going through a lot of development
• Teenagers – 9hrs; should be sleeping until 10 am
• You accumulate sleep debt when you don’t get enough of the required
sleep
• Adults – 7/8hrs
Sleep
• The brain uses sleep to cleanse and get rid of problem debris
• Alzheimer’s disease is linked to sleep depri vation
• Development of amyloid beta plaques
• Dangerous protein that accumulates across time with lack of sleep
• Interferes with signalling among neurons
• Leads to memory dysfunction
• Plaques are permanent as well – no pharmaceutical treatment and
lifestyle treatment that can reverse these plaques
• Different aspects of sleep quality may become impaired with age
• Sleep Latency: time it takes to initiate sleep (5 -15 minutes for healthy
people) – good indicator of how effective you are at sleeping
• Mid Sleep Disturbance: ability to maintain sleep
• Sleep Efficiency: time in bed actually sleeping
• Sleep quality decreases with age
• Wake after sleep onset is lower in younger people (means that you
usually spend less then a few minutes awake during your scheduled
sleep)
• As you age it increases – you can wake up and be up for longer periods
of time; mom and dad
• Sleep efficiency also decreases as you age
• Seniors can sleep to little or TOO MUCH both are detrimental
• Sleep quality between 30 -60 year olds predicts cognitive function 28 years later
Physical Activity Improves Sleep Quality • One bout of exercise can reduce sleep onset time and mid sleep disturbances
immediately the night after
• Long term physical lifestyle also increases sleep quality
• But not every kind of physical activity is beneficial; intensity is the marked type
of preferred exercise
• Does not affect quantity (duration)
• Moderate intensity exercise improves sleep quality (efficiency)
• High intensity exercise actually decreases sleep efficiency!
o Maybe too vigorous
o Higher cortical release
• Intensity does not improve cognition enough – but that might be
because the study did 3 months; maybe if longer there would be Sexual Dimorphism 2017-04-14 11:44 PM
• Sexual dimorphism
• When two sexes of the same species show very different characteristics beyond
their sex organs. Phenotypically and behaviorally.
• Mandrill-- one of the most
More
Less
