Lecture 4: Neurobiology Flashcards
Componential levels of organization
Animals are composed of:
Systems —> Organs —> Structures —> cells eg. neurons —> subcellular structures —> molecules
Whats in level 1 of the componential levels of organization? Name some examples!
Molecules! Eg. Neurotransmitters, neuromodulators, and hormones
Neurotransmitters (3) characteristics
- Molecules used for synaptic transmission by binding to ion channel receptors in postsynaptic cells
- Affect one cell
- Are fast acting
Neoromodulators are molecules used to _____ ____ _____
Modulate neural excitation
How do neuromodulators module neural excitation? (3-step process)
- They bind to G-protein receptors
- G-protein receptors activate secondary messengers within the neurons
- Controls production and release of neurotransmitters
What do neuromodulators affect?
Cell ensembles (collections of cells)
Are neuromodulators slower/faster acting?
SLOWER!
Are neurmodulators longer/shorter lasting than neurotransmitters
LONGER!
Hormones
Molecules used for long range cellular communication carried in the blood stream
What is Serotonin? Neurotransmitter/Neuromodulator/Hormone
Neurotransmitter and neuromodulators!
Where is serotonin produced primarily?
In the raphe nuclei in the brain
Serotonergic neurons project to?
Nearly every region in the brain!
What does serotonin regulate?(3)
It regulates:
1. Mood
2. Sleep
3. Sexual interest
How are serotonin levels partially mediated?
Through social rank! Eg. High ranking members in animals have more serotonin and vice versa
High ranking members of groups have higher/lower serotonin levels
HIGHER!
Low ranking members of groups have higher/lower levels of serotonin?
LOWER!
What do high levels of serotonin do? (2)
- Decrease inhibition
- Increase goal-directed behavior
What do low levels of serotonin do? )2_
- Increase inhibition
- Decrease goal-directed behavior
What do the Differences in serotonin levels between higher and lower ranking members of social groups reduce?
Likelihood of harm/death during within group conflicts
What’s the primary pharmacological treatment for depression
SSRI - Selective serotonin reuptake inhibitors
What do SSRI’s do?
They inhibit the reuptake of the serotonin in the presynaptic neurons, thereby increasing serotonergic transmission
What is dopamine between a Neurotransmitter/neuromodulators/hormone
ALL OF THEM! It’s a neurotransmitter, neuromodulators, and a hormone
Where is dopamine primarily produced?
In the nucleus accumbens in the basal ganglia and the ventral regimental area in the midbrain in the brainstem
What are the functions of dopamine? (3)
It regulates:
1. Motivation
2. Reward
3. Movement
In depression is the mesolimbic dopamine pathway under/overactive in depression?
UNDERACTIVE!
What are agonists?
Agonists are molecules that bind to a receptor and produce action potentials
What do dopamine agonists do? What mental health problem do they treat sometimes?
Dopamine molecules that bind to a receptor and produce action potentials and are sometimes used to treat DEPRESSION
Is the mesolimbic dopamine pathway under/overactive in Schizophrenia and bipolar disorder?
OVERACTIVE!
What are antagonists?
Molecules that bind to receptors and prevent action potentials
What does a dopamine antagonist do? What are they used to treat?
Dopamine molecules that bind to a receptor and prevent action potentials and are often used to treat Schizophrenia and Bipolar disorder
Are Norepinepherine and Epinephine neurotransmitters, neuromodulators, or hormones?
ALL OF THEM! They are neurotransmitters, neuromodulators AND hormones
Where is Norepinepherine produced?
In the locus ceruleus in the pons in the brainstem and also in the adrenal glands
Where is epinephrine produced?
In the adrenal glands
How is Norepinephine released? (Continuous or in chunks vs Small or large amounts)
Continuously in small amounts
When is epinephrine released?
During stress (adrenaline)
What are the functions of Norepinephrine and Epinephrine? (3)
They regulate:
1. Arousal, alertness
2. Physiological regulation eg. Heart rate, blood pressure, glucose release, blood flow to muscles
3. Fight/Flight/Freeze response
Neurons that use epinephrine and norepinephrine are usually under or overactive in anxiety disorders and PTSD?
OVERACTIVE!
What happens when epinephrine and norepinephrine are overactive in people? (3)
They make people
1. Hypervigilant
2. Reactive to stressors
3. Sympathetically activated
Other than SSRI’s what are are sometimes used to treat depression?
Selective norepinephrine reuptake inhibitors (SNRIs)
Is Glutamate a neurotransmitter/neuromodulator or hormone?
A neurotransmitter!
Specifically what kind of neurotransmitter is Glutamate?
EXCITATORY ONE!
Acute stress can lead to?
Excessive glutamate and excitotoxity
What does excessive glutamate and excitotoxity do to the prefrontal cortex, hippocampus, and amygdala? (2)
- Causes atrophy (decreases size) to the prefrontal cortex and hippocampus
- Causes hypertrophy (increases size) to the Amygdala
Is GABA a neurotransmitter/neuromodulator or hormone?
It’s a NEUROTRANSMITTER!
Specifically what kind of neurotransmitter is GABA?
an INHIBITORY neurotransmitter
Where are usually decreased or increased levels of GABA in people with schizophrenia and bipolar disorder?
DECREASED!
What is in level 2 of the componential levels of organization?
Neurons and Glial Cells!
What do Neurons consist of? (3 main things)
- Cell body (soma)
- Dendrites (inputs)
- Axons (outputs)
Sensory neurons what type of neuron are they and what do they do?
Afferent (conducting/conducted inward/towards something) neurons that carry information from sense organs to brain
Motor neurons what type of neuron are they and what do they do?
efferent (conducted/conducting outward/ away from something) neurons that carry information from brain to body
Interneurons
Neurons in between sensory and motor neurons
Action potential what is it?
the “firing” of a neuron caused by sodium ions entering the neuron through ion channels
How are action potentials caused?
When neurotransmitters from the presynaptic cell bind to receptors in the postsynaptic cell in sufficient quantities
What effects can action potentials have?
Excitatory or inhibitory effect on downstream neurons
What are the functions of Glial cells? (5)
- Provide structure surrounding neurons
- Supply nutrients and oxygen to neurons
- Electrical insulation between neurons
- Destroy pathogens and remove dead neurons
- Computation
What does level 3 of the componential levels of organization consist of?
Cellular ensembles, neural networks and neural circuits
Neural network
A collection of neurons that form a structural/functinoal unit
How is a structural unity identified?
By cellular architecture (what’s connected to what)
How is functional unity identified?
By task analysis (what’s connected the network does )
Neural networks in the brain process information by?
Distributed computation
Distributed computation
Computation (representation transformation) that’s distributed across multiple computational components
In the brain what are the computational components?
NEURONS!
Thought
Patterns of activation in neural networks
Synaptic connection
A presynaptic neuron’s Axonal connection to a postsynaptic neuron’s dendrite
Synaptic connection weight
how “strong” the synaptic connection between two neurons
How do we determine the “Strength” of a synaptic connection? (3)
- Number of connections between presynaptic neurons axon and postsynaptic neurons dendrites
- Quantity of neurotransmitter release into synaptic cleft
- Myelin action of presynaptic neuron
What does myelination of presynaptic neuron promote?
Signal conduction
Learning
Changes in synaptic connections/connection weights
Memory
Constellations of synaptic connections weights
Memory loss
In neurodegenerative disorders it is partly the loss of synaptic connections
Neural circuit
A collection of nuclei and projections with one or more common functions
The mesolimbic dopamine pathway is a neural circuit that connects the ____ to the ____ _____ and the _____ ____
Connects Ventral Tegmental Area (VTA) to Nucleus Accumbens and Prefrontal cortex
What does the mesolimbic dopamine pathway mediate? (2)
Mediates motivation and rewards
The mesolimbic dopamine pathway is smaller/larger and under/overactive in people with depression?
SMALLER AND UNDERACTIVE
Nuclei and example?
Collections of cell bodies eg. The Ralph nuclei in the brain stem
Projection
A collection of axons that bundle together from a common source to a common target
Afferent projection
Projection to a nucleus
Efferent projection
Projection from a nucleus
What is an example of a mental disorder mediated by overactivation of excitatory circuits
Mania in bipolar disorder
What is an example of a mental disorder mediated by overactivation of inhibitory circuits?
Anxiety disorders
What is an example of a mental disorder mediated by under activation of excitatory circuits?
Depression
What is an example of a mental disorder mediated by under activation of inhibitory circuits?
Attention deficit/hyperactivity disorder (ADHD)
Chronic Stress, Trauma, and mood disorders and other aversive experiences can have a ________ effect on neurons
excitotoxic effect
What happens when there’s an excitotixic effect on neurons?
IT KILLS THEM —> Reduces altering brain volume and impairs function —> functional impairments
What is level 4 of the componential levels of organization?
The hemispheres and lobes!
Hemispheres
The right and left “halves” of the brain
Most brain structures have a right and left counter part but there is an exception:
The pineal gland!
What do the hemispheres do?
Some lateralization of function eg. Language is disproportionately processed in the left hemisphere
Cerebral cortex
The outermost part of the brain, divided into lobes
Lobes
Major bilateral structural divisions of the cortex
Main lobes of the brain (4)
- Occipital
- Parietal
- Temporal
- Frontal
What does the occipital lobe function in?
Vision
What does the parietal lobe function in?
Sensory processing
What does the temporal lobe function in? (2)
- Auditory processing
- Language comprehension
What does the Frontal lobe function in? (3)
- Language production
- Motor processing
- executive functioning
What is level 5 of the componential levels of organization?
The systems! Specifically the central/peripheral nervous systems
Central nervous system consists of?
- Brain
- Spinal cord
Peripheral nervous system mainly consists of (2) and where are they located?
- Nerves (axon bundles)
- Neuronal cell bodies (ganglia)
They are located outside the brain and spinal cord
Autonomic nervous system
Part of the peripheral nervous system that innervates organs, glands, and smooth muscle
What functions does the autonomic nervous system regulate? (5)
- Heart rate
- Respiratory rate
- Pupillary response
- Digestion
- Immune function
What are the 2 subsystems of the autonomic nervous system?
- Sympathetic nervous system
- Parasympathetic nervous system
What does the sympathetic nervous system meditate?
Arousal (Fight/flight)
What does the parasympathetic nervous system mediate?
Rest (rest and digest)
Anxiety disorders and PTSD often involve the chronic activation of the ____ ____ ______
Sympathetic nervous system
