Midterm 1 Flashcards
Neuropsychology
study of brain disfunction
Parkinson’s disease: lack of motor ability and tremors
Cognitive neuroscience
cognitive psychology with brain imaging
Phineas Gage
managed people working on the railway
Job to dig up hole and but blasting cap on -> must tamp (press down) to flatten down blasting cap
One day, there were explosives but no blasting cap so when he was tamping down, the tamping iron shoots through his head
He never rendered unconscious and explained that his brain ha shot through
Had brain bits coming out and pulsing from his skull
Then he vomited and half a teacup of brain bits fell out of his brain
Phineas’s family and friends noticed:
Before: capable, efficient, sharp, energetic and persistent at executing his plans
Afer: fitful, indulgent, impatient of restraint or advice when when it conflicts with desires, arranging plans then abandoning
change in personality
Ability to speak and count were all in tact
Materialist: you are your brain; when your brain is dysfunctional/damage = you are dysfunctional as well
Good evidence that gage recovered -> gage got a responsible job (horse carriage driver)
Died of seizures; epilepsy was generated from the traumatic brain injury
Golgi’s stain
mixes together silver nitrate stain
Stained 10% of neurons -> can see neurons in totality (shape + connections + dendrites)
Golgi: reticular theory
Golgi: reticular theory (neurons look like mesh) -> all cells are continuously connected together (how thoughts and signals are flown around in a big net)
Ramon y Cajal’s (spain) drawings
neurons are quite distinct (discontinuous)
Looked like they had specialized functions
There is a space between neurons through which they communicate = synapse
Drugs change how the nervous system functions -> can only do that if there is a place like the synapse
Ramon y Caja: neuron doctrine - principles upon which all of the neuroscience was performed
Ramon y Cajal correct with neurotransmitters
neurogenesis development
neurons you have from about a year old onward are not replaced - never gonna have any more than that
But not entirely true, there is adult neurogenesis in one part of the hippocampus to a certain extent
Adult Neurogenesis
In utero (in development), developing lots of neurons
Clearly shown in animal models that adult neurogenesis happens
In rats, adult neurogenesis only happens in a subregion of the hippocampus
Adult neurogenesis tapers off rapidly around puberty
Weak evidence of adult neurogenesis in some people who died in a car accident at 12
Only in part of hippocampus
Neurons lost to brain injury or damage -> serious, neurons are gone
Could add new neurons in theory (stem cell therapy) but they would not hold the memories or information stored within the neuron
But there is potential for new learning
Brain of insect- LOCUST
collection of ganglia
Sensory organs at front of body with lots of nervous tissues close together
Insects have ganglia throughout their body -> brain is spread out across the body
Sensory motor integration is much faster -> faster reflexes
Fish brain- vertebrates are similar
Spinal cord -> medulla -> cerebellum -> optic lobe -> cerebrum
Fish cerebrum is much smaller than humans
Most of the activity in the midbrain + cerebellum + brain stem is not accessible to consciousness
Cerebrum is most connected to consciousness
Large behavioural repertoire and nonconsious nervous system components
Rat: brain
Cerebrum so large that it is covering the midbrain and larger than the cerebellum
Olfactory bulb at the front -> smell
Not convuluted
Spinal cord coming out back - same plane
Dog brain
spinal cord coming out of back Convoluted brain Front of brain is the olfactory bulb not frontal cortex Front of brain is relatively undeveloped Understand pointing - cognitive ability
Monkey brain
Spinal cord coming out of bottom
Bipedal
Convoluted but less than humans
differentiation of different lobes
Chimpanzee brain
Much more convolution - doesnt match human brain
Bigger cerebrum
Frontal lobe is larger in humans
Increasing cognitive sophistication
Dolphin brain
Very convoluted
Larger brain mass
Very smart -> but not as smart as humans
Exception to trends for brain size
Macaw brain (grey parrot)
Smartest nonhuman animal known
Not convoluted
Amazing sophisticated machinery
Can count to very high numbers, categorize items and subcategories
Trends for brain sophistication (does not tell us anything mechanistic) - these trends are not absolute
Bigger cerebrum -> more cognitive capabilities
Cerebellum and midbrain -> remains similar size
Brains get more convoluted the more sophisticated the animal
Frontal cortex grows more with sophistication
Disproportionately large brain -> indicates intelligence
Brain cell density
Brain with the greater number of neurons wins
Size and the number of neurons are different
Humans have the densist brain with the most amount of neurons in a cubic cm/ weight
Primates have disproportionately dense brain
Matter:
Grey matter: cell body of neurons, and whole unmyelinated neurons
White matter: represnets the long connections (axons) which are myelinated (fatty sheath)
Our brain regions -> usually referring to grey matter areas
Staining reveals “matter”
Nissl-stained (cresyl violet)
Fiber stain
Must take brain and slice up (post mortem)
E.g. Alzeimhers was never diagnosed until post mortem
Nissl-stained (cresyl violet) - reveals where the grey matter is located (purple area)
Fiber stain (many types) - stains white matter (darker area)
Distinction of location of white matter and grey matter is slightly arbitrary
Two basic cell types:
Neurons
Glia
Neurons
main communicating cell in the nervous system (all cells communicate and virtually all cells release chemicals that are received by other cells)
Neurons can send signals very quickly and be targeted to very large distances
Many types/shapes but similar design
Dendrite -> soma -> axon -> terminal
Input layer integrate and come together and goes to output where chemicals are released
Cell determines whether it will fire an Action potential at the axon from the integrated signals from the dendrite
AP travels down axon and chemicals (NT) are released at the terminal
Apical dendrites at the end; basal dendrites near the cell body
Every time there is a synapse -> opportunity to modify the signal
Neurons:
- Pyramidal
- Stellate
- Purkinje
Pyramidal- major feature of cerebral cortex, pyramid shape
Stellate- cell found in deeper brain areas (cortical areas), star shape
Purkinje (cerebellem) - many many branches that branch off the collateral
2 basic types of neurons:
Projection neurons
Interneurons
Projection neurons
long axons that project to other distant brain areas (pyramidal cells)
Projection neurons send their long projections to other brain area connecting to another projection neuron (like wires with stops at synapses where interneurons can alter signal)
Interneurons
neurons that have short axons that project locally (stellate cell), nonmyelinated axons
Function: modify or modulate travelling signals between projection neurons
To adjust timing (movement, perception- shift attention), to stop it (ignore senses during sleep)
Glia:
Important for structure and support
Influence way neurons fire (communication)
Microglia
Microglia
immune system in brain which is separated from external environment (blood brain barrier)
Brian is walled off from their immune system so they need a protector
Detects of foreign bodies or agents -> when detected, microglia enter a prime state (larger and more active) -> engulfs foreign body, and digests it
Oligodendrocyte + Schwann cell -> both are myelinating glia and produces myelin which wraps around axon and speeds up neuronal communication but they do it in different ways and places
Schwann cells
wrap themselves around one axon found in the peripheral nervous system (not in brain and spinal cord)
Oligodendrocytes
myelinate several axons in the CNS (brain + spinal cord)
Glial networks (astrocytes)
Keep nervous system healthy and function
Part of blood-brain barrier
They wrap around the capillary/blood vessel to make sure blood does not enter the brain
Blood is toxic to the brain, meaning neurons do not have access to oxygen, glucose
Astrocytes mediate all the nutritional transfer
scaffolding neuronal migration in development
Astrocytes are wrapping themselves around the neuron + especially around synapses
- can control
- can influence
Can control the environment (chemical composition of area) around neuron + synapse
Can influence how the neurons talk to each other: they have gliotransmitters and receptors that receive signals from the neurons
gliosis
If there is damage or scarring to the brain
- the astrocytes form those glial scars
Gap junctions
protein on astrocyte fits in with another protein on another astrocyte, creating a continuous hole between astrocytes
The reticular theory is kind of true for astrocytes
This is how they quickly buffer out an ion to control the concentration of ions depending on the environment
Signals can travel very fast through astrocytes due to continuous connection
Fast adaptation from states
The tripartite synapse
Conversion of three (presynaptic neuron, postsynaptic neuron, astrocyte
astrocyte is receiving signal from the presynaptic axon as well
sending own signals that can influence how the axon or dendrites respond
Can send signals that decrease how many neurotransmitters are released from the presynaptic axon
Can also affect the efficacy of the presynaptic axon signal on the dendrites - influence how neurons talk to each other
Glia play a key role in brain function
Glia not neurons most affected by the brain aging
Glial cells play a key role in regulating motivation for drug in heroin addiction
Glial cells are critical players in brain response to social stress
Glial cells shape nerve endings through previously unknown molecular pathway
Memory - change in structure and/or function of your nervous system not just synapse
Myelination is related to learning how
the thicker the myelin around the axon, the more effectively it will insulate the axon
Learning can be affected by myelination -> neurons must be sending signals to the oligodendrocytes
The central dogma of molecular biology:
DNA ->(transcribed)-> mRNA->(translated)-> protein
Our DNA interacts with environmental factors
If learning and memory is just a change in structure and/or function of the neurons
One way to change is by transcription or translation
Cell membrane
phospholipid bilayer
Barrier to things except - Steroids hormones can enter the cell
Cytoskeleton
- 3 types
- expand on Microtubules
neurofilaments
Microfilaments
Microtubules- primary (biggest) part of cytoskeleton
Travel down axon
Have proteins that transport vesicles down to axon terminal to carry essential things
Kinesins: anterograde transport
Dyneins: retrograde transport
Alzheimer’s disease, and chronic traumatic encephalopathy (repeated head injuries) related to
Remodeling and shaping cytoskeleton
Synapse
Every time there is a synapse -> opportunity to modify the signal site of neural communication Presynaptic: NT release Postsynaptic: receptors Axodendritic synapse Axoscretory Axoaxonic Axoextracellular Axosomatic Axosynaptic
Axodendritic synapse
presynaptic axon to postsynaptic dendrite
Synapse
Axoscretory
Axons that release their NT/hormones into the bloodstream
Synapse
Axoaxonic
Axon synapsing with axon
Synapse
Axoextracellular
Axon not synapsing to environment
Synapse
Axosomatic
Axon that is on cell body
Synapse
Axosynaptic
Axon synapse on another synapse
Dendrites
Receiving signals, input layer
Spiny or non spiny
Blobs that compartmentalize the synapse - dedicated area to modify instead of modifying all
Glutamatergic neurons are often spiny neurons
Many neurons are non spiny (e.g. gabaergic)
We are a product of our dendritic spines (quantitatively and qualitatively) = We are the synapses
Higher than average dendritic spine number is associated with
autism spectrum disorder
Decrease in dendritic spine number associated with
- early life
- late life
schizophrenia in teen years, whereas later on in life may be related to Alzheimer’s disease
The Vertebrate Nervous system Peripheral NS Somatic Nervous system (SNS) - Afferent fibers - Efferent fibers
Somatic Nervous system (SNS): connects to the external environment
external environment, (mostly) conscious excess to
Afferent fibers: from the body to the brain
Sensory signals; touch, sensation, stretch
Efferent fibers: out of brain to body
Motor control: controlling body
Muscles that the somatic NS controls- muscles attached to to skeleton (striated muscles)
Conscious control
The Vertebrate Nervous system Peripheral NS Autonomic NS (ANS) Afferent: efferents:
Autonomic NS (ANS): Internal environment, (mostly) non-conscious
Afferent: sensation signals from inside of body
efferents:
Digest faster or slower
Not always mutually exclusive to one another
No voluntary control of viscera
Sympathetic
Parasympathetic
Sympathetic:
mobilize energy (fight or flight) Getting ready to deal with unexpected and stressful event Heart rate speeds up, lungs dilate (more O2), digestion slows down
Parasympathetic:
conserve energy
Innervates all the same targets (efferent)
Complementary or opposite of SNS
Focused on conserving energy: slows down heart rate, constricts lungs, increase digestion
Rest and digest
Cell clusters
grey matter -> cortex + underneath cortex and white matter
nucleus/nuclei (CNS) vs. ganglion/ganglia (PNS)
Dorsal root ganglia - where cell bodies for somatosensory system
Touch receptor going up spinal cord
Basal ganglia are nuclei!
Bundle of axons
white matter- many myelinated axons
tract (CNS) vs. nerve (PNS) vs. fibres (all)
Emerging from eye -> optic nerve
When entering the brain (optic chiasm) when in brain (optic tract)
Anatomical dimensions
Top: superior/dorsal Bottom: inferior/ventral Down midline: medial Lateral: sides Left and right are from the perspective of the person who owns the brain Anterior: toward top of spinal cord Posterior: toward bottom of spinal cord Dorsal: back side of spine Ventral: front (Stomach) side of spine
Spinal Cord
- order
- dorsal side
- ventral side
- middle of spinal cord
Cervical -> thoracic -> lumbar -> sacral -> coccygeal
Dorsal side: white matter for sensory information (Afferent)
Ventral side: white matter for motor signals (efferent)
Middle of spinal cord: grey matter
why does the Spinal Cord narrows/tapers when from cervical to coccygeal
Ends in cauda equina (tapering frays)
All of afferent have not yet entered the CNS near the top; all of the efferent signals have not yet left the spinal cord -> thickest near the top where the most about of signals are traveling
limited amount of points where nerves can leave or enter the spinal cord -> Intermittent projections from the spinal cord
how does Information leaves or enters the spinal cord?
in nerves (bundles of white matter) -> spinal cord is inside bone
Spinal cord damage: loss of function related to segment damage
Damage at cervical region is most severe (most nerves affected) compared to lower down the spinal cord
3 Major divisions of the brain and when does it appear
Appears early in development around 18-21 day old embryo
- Forebrain: we have a disproportionately large forebrain
- Midbrain (Mesencephalon)
- Hindbrain
Forebrain:
- we have a disproportionately large forebrain
1. Telencephalon
2. Diencephalon
Telencephalon
Cerebral cortex Major fissures Major gyri Four lobes Limbic system Basal ganglia Cerebral commissures (corpus callosum)
Cerebral cortex
- Neocortex
- Hippocampus
Major fissures
- Central fissure
- Lateral fissure
- Longitudinal fissure
Major gyri
- Precentral gyrus
- Postcentral gyrus
- Superior temporal gyrus
- Cingulate gyrus
Four lobes
- Frontal lobe
- Temporal lobe
- Parietal lobe
- Occipital lobe
Limbic system
- Amygdala
- Hippocampus
- Fornix
- Cingulate cortex
- Septum
- Mammillary bodies
Basal ganglia
- Amygdala
- Striatum
- Caudate
- Putamen
- Globus pallidus
Diencephalon
Thalamus Hypothalamus - Mammillary bodies Optic chiasm Pituitary gland Immediately adjacent to midbrain small
Thalamus structures
Massa intermedia
Lateral geniculate nuclei
Medial geniculate nuclei
Ventral posterior nuclei
Midbrain (Mesencephalon)
Tectum - Superior colliculi - Inferior colliculi Tegmentum - Reticular formation - Cerebral aqueduct - Periaqueductal gray - Substantia nigra - Red nucleus
Hindbrain
Metencephalon - Reticular formation - Pons - cerebellum Myelencephalon - Reticular formation
Myelencephalon (aka the medulla oblongata)
Junction between the spinal cord and brain
Lots of tracts
Oldest part of brain
Involuntary control of life sustaining functions (maintains heart beating, and diaphragm moving)
Doctors reluctant to perform surgery here - slight damage could be fatal
Opioid overdose -> respiratory depression -> affects which brain region that could be fatal
medulla - could be fatal fatal (posterior)
The reticular formation
Aka the reticular activating system (not true system but a collection of nuclei)
~100 nuclei
Runs from myelencephalon to mesencephalon -> travels through hindbrain and midbrain
Critical for arousal, wakefulness, attention sleep -> maintaining consciousness
Damage to the reticular formation
Aka the reticular activating system (not true system but a collection of nuclei)
~100 nuclei
Runs from myelencephalon to mesencephalon -> travels through hindbrain and midbrain
Critical for arousal, wakefulness, attention sleep -> maintaining consciousness
Damage to this region causes major disruptions to life, and/or can be (posterior) fatal -> difficulty maintaining consciousness
Metencephalon
(more anterior hindbrain)
Lots of tracts
Comprised of multiple regions
Houses the reticular formation -> damage can cause disorders of consciousness and/or difficulty with sensation and movement
pons
+ damage
Metencephalon
The pons: (ventral) large white-matter bulge, continuing from spinal cord/medulla
Both afferent and efferent
Damage: affect sensation and ability to feel things
Loss of sensation
Interfere with ability to control muscles (paralysis, plegia)
cerebellum
+ damage
The cerebellum: (dorsal)
10% of brain volume (small)
>50% of neurons
Critical for motor coordination, corrects movement
Integration of sensory and motor information
Damage: problems with motor coordination, and movement
Mesencephalon
Tectum
Tectum: dorsal
Comprised of two pairs of bumps (collliculi)
Aka the boston pizza part of your brain - integrating sensory information to control movement outside of your conscious control
Superior colliculi
Inferior colliculi
Outside of conscious access and often automatic
Mesencephalon
Tegmentum
more ventral/floor
Contains the top of reticular formation- nuclei involved in life-sustaining features
More fibres- lots of efferent and afferent
Periaqueductal grey
Dopamine-producing regions - movement related to motivation
Substantia nigra
Ventral tegmental area (VTA)
Red nucleus
Superior colliculi
in Mesencephalon Tectum
vision with respect to eye movement out of conscious control
Draws attention towards attention-grabbing things
Inferior colliculi
in Mesencephalon Tectum
audition with respect to head/body orientation
Draws attention toward loud sounds
Automatic and outside conscious
Tectum Damage (damage to superior colliculi)
Parinaud syndrome- inability to move eyes especially upwards and orienting towards sight or sound
Mesencephalon
Tegmentum
Red nucleus + damage
plays key role in movement and motor control in animals with smaller forebrain but our motor cortex does most of the movement related tasks
Species specific behaviour
Side effects of using anti-psychotic medication from this region
Damage from using anti-psychotic medication: strange motor quirks
Mesencephalon
Tegmentum
Periaqueductal grey
main target of amygdala
Fear or emotional emotions are generated here
Internal analgesia (suppresses pain)
Substantia nigra
Damage
Dopamine-producing regions - movement related to motivation
Substantia nigra
Damage: parkinson’s disease
Diencephalon (forebrain)
Thalamus
Many nuclei: inputs from sensory systems, cerebellum, basal ganglia
relay center for sensory information
Many different nuclei receives almost as much from cortex (many which are from sensory systems) as it sends to cortex
Every sense except olfactory system goes through the thalamus
Everytime an axon stops and creates a synapse -> opportunity to modify or influence the signal
Receives almost as much information from the cortex as it sends out to the cortex -> creating a loop
Corticothalamic loops
Has many different functions related to sensation and movement and consciousness
Corticothalamic loops
suggested that the generation of consciousness is from these loops from thalamus and the cortex that resonate is the substrate for conscious awareness
Thalamus damage
Damage to this region: problems with attention, difficulty sustaining consciousness, sensation, and motor
Diencephalon (forebrain)
Hypothalamus
Collection of Many nuclei
Master control center for endocrine system (hormone release)
Sending lots of outputs to pituitary gland
Key intersection with endocrine system via the pituitary gland
Diverse functions: sex, aggression, feeding, sleep/wake, gender
Hypothalamus damage
Damage: narcolepsy (falling asleep randomly), sex, aggression, eating
Telencephalon
The largest division of the human brian
Not just the cortex, but also underlying structures (e.g. hippocampus + amygdala)
Damage here is wide-ranging in its symptoms
Cerebral cortex: aka cortex, neocortex (outer layer)
Cerebral cortex
aka cortex, neocortex (outer layer)
Largest and most prominent feature of the human brain
The cortex is convoluted: (maximize surface area)
gyrus/gyri - bump (outer fold)
Sulci (sometimes fissures esp when important or particularly deep) - folds inward
Not much functional difference between gyrus and sulci
Damage may show up in only one specifically for sulci
Hippocampus - another cortex that is older
Hemisphere
The cerebrum is divided into two hemispheres
Separating the hemispheres: the longitudinal fissure (big vertical division - sagittal)
Left and right hemispheres are only connected by a few tracts (commissures)
Corpus callosum: the largest commissure, prominent white matter area
Disconnecting the hemispheres
Split brain patients: 2 indepently working hemispheres
They may guess and try to explain why they responded in such a way instead of saying they just didn’t know
Callosotomy, a rare treatment for severe epilepsy
Contralateral organization: left half of world governed by right side of brain, vice versa
Left hemisphere damage
Left hemisphere dominance for language - damage causes profound damage to language
Will be able to report words in their right visual field
Put something in right hand, able to verbally identify the thing