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Behavioral Neuroscience > Review Slides > Flashcards

Review Slides Flashcards

Review Slides for Final Exam

1
Q

What is electron microscopy?

A

Using Electrons to provide HIGH spatial resolution, but LOW temporal resolution.

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2
Q

What is light microscopy?

A

Used to identify individual cells or groups of cells.

- Stains can be applied to highlight different types of cells.

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3
Q

What is genetic engineering?

A
  1. Gene knockout techniques: Breaking a gene to observe what sort of behaviors are lost.
  2. Gene replacement techniques: Transgenic organsims (add a gene and see how it changes the behavior of an organism = knock IN)
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4
Q

What is optogenetics?

A
  • Control events in living tissues with millisecond resolution.
  • Light-activated ion channels allow gain or loss of function in neurons.
  • Light-activated GPCRs (gene protein coupled receptors) allow manipulation of metabotropic events.
  • Provide insight to autism, schizophrenia, depression and drug addiction.
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5
Q

What is an intracellular unit recording?

A

An intracellular microelectrode records the membrane potential from ONE neuron as it fires. mV/mS

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6
Q

What is a multiple-unit recording?

A

A small electrode records the action potentials of MANY nearby neurons.
- These are added up and plotted.

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7
Q

What is an extracellular unit recording?

A

An extracellular microelectrode records the electrical disturbance that is created each time an adjacent neuron fires.

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8
Q

What is an invasive EEG recording?

A

A large implanted electrode picks up general changes in electrical brain activity. The EEG signal is not related to neural firing in any obvious way.

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9
Q

What is EEG?

A

Electroencephalography measures the average electrical activity of brain and can be combined with other techniques.

  • Noninvasive
  • Deep sleep = HIGH amplitude and LOW frequency waves.
  • Aroused = LOW amplitudes and HIGH frequency waves.
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10
Q

What is an ERP?

A

Event Related Potentials are EEG time-linked to sensory stimulus.

  • A stimulus is repeated many times and recorded responses are averaged.
  • The averaging cancels out irregular or unrelated electrical activity; leaves on those potentials that were generated by stimulus.
  • Looking for mismatch negativity ie. novelties from a pattern. beep beep beep BOOP beep beep beep
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11
Q

What types of lesion studies are there?

A
  • Stroke or Tumor Damage: Can’t control where damage occurs, but observe behaviors.
  • Stereotactic Surgery: Big metal framework, screw into skull. Lesion a particular region and see how that affects behavior (surgical).
  • Chemical Lesions: Neural tissue is destroyed by the infusion of a neurotoxin.
  • Reversible Lesions: TMS (Transcranial Magnetic Stimulation) used to stimulate or inhibit function and is non invasive.
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12
Q

What types of brain imaging are there?

A

CAT(CT) and MRI = Structural

fMRI, PET, and MEG = Functional

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13
Q

What is a CT scan?

A

Computed Axial Tomography or CT uses many x-rays at different angles.
- Image reconstructed by computer to create 3D representation of brain structure.
~ 1 mm resolution
- Not functional

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14
Q

What is a PET scan?

A

Positron Emission Tomography (PET)

  • Inject or inhale isotope that emits positrons.
  • O15 or F18-deoxyglucose most common
  • Isotope carried by blood to most metabolically active area. (Used a lot in cancer patients because tumors use a lot of energy).
  • Isotopes decay giving off gamma rays.
  • Can also identify location of different receptors.
  • Spatial resolution ~ 3mm
  • Build synthetic neurotransmitters and determine where the receptors are in the body.
  • Functional
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15
Q

What is an MRI?

A

Magnetic Resonance Imaging

  • Strong magnetic fields align and disturb protons in brain.
  • Excellent spatial resolution&raquo_space; 1mm
  • Data often combined with fMRI to show structure and function.
  • Structural: detects change in energy from the alignment of protons.
  • Field strength: ~ 3-4 teslas
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16
Q

What is an fMRI?

A

Functional MRI

  • Identity changes in blood oxygenation that result from metabolic activity in brain.
  • Increased activity brains more oxygenated blood.
  • Increased Hb-O/Hb increases MRI signal
  • Localizes function indirectly
  • Spatial resolution ~ 2mm
  • Deoxygenated hemoglobins are detected, determine what parts of the brain are active by measuring the blood flow changes.
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17
Q

What is a MEG?

A

Magnetoencephalography

  • Electrical activity of neurons generates VERY small magnetic fields
  • Directly detects neuronal activity perpendicular to scalp
  • Detectors have 100 - 200 channels allowing sub -mm and second resolution
  • HIGH resolution and detects brain activity directly.
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18
Q

Describe the Cerebral cortex.

A

Four lobes

  • Subcortical areas: Limbic system, Basal Ganglia, and Hippocampus
  • Protection: Meninges (Fibers and connective tissues), Cerebrospinal fluid (CSF), and Blood Brain barrier.
  • Outer most portion of brain
  • Six layers
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19
Q

What is the subcortical nuclei?

A

A collection of cells (gray matter cells not at the level of the cortex).

  • Limbic System: Motivational behaviors
  • Basal Ganglia: Motor control
  • Hippocampus: Memory and navigation
  • Nuclei not homogeneous: clusters of gray matter.
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20
Q

Describe the Limbic System.

A

The motivational system: Emotional and behavioral drives.

  • Amygdaloid body: Associated with emotions mainly with fear.
  • Cingulate gyrus: Important for decision making, planning
  • Parahippocampal gyrus: Associated with memory function, communicates with the hippocampus. Damage here leads to memory impairment.
  • Hippocampus: Memory consolidation and navigation.
  • Fornix: Connects hippocampus to rest of brain.
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21
Q

Describe the Basal Ganglia.

A

Controls muscle tone and coordinates learned movement patterns

  • Globus pallidus: output of the basal ganglia
  • Caudate and Putamen: input to basal ganglia (take signals from brain and send the information to globes pallidus).
  • Substantia nigra: projects upwards to the basal ganglia
  • Subthalamic nucleus: input
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22
Q

Describe the Hippocampus.

A

Between the thalamus and cerebral cortex

  • Critical for storing certain types of memory.
  • Navigation
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23
Q

Describe the meninges.

A 
Fibrous layers surround and protect CNS
- Dura mater: tough outer membrane
- Arachnoid membrane: weblike
- Pia mater: adheres to CNS surface
Continuous with meninges of spinal cord
- Protection from both chemical and physical things.
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24
Q

Describe the purpose of CSF.

A

Cerebrospinal Fluid

  • Cushions delicate neural structures
  • Supports brain
  • Transports nutrients, chemical messengers and waste products
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25
Q

What is the pathway of CSF?

A
  1. Produced at choroid plexus.
  2. Travels through lateral and medial apertures to subarachnoid space.
  3. Diffuses across arachnoid granulations into superior sagittal sinus.
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26
Q

Describe the blood brain barrier.

A
  • Endothelial cells of blood vessels tightly packed in CNS to isolate brain from general circulation.
  • Astrocytes regulate permeability of cerebral blood vessels (secrete chemicals).
  • Molecules actively transported across barrier.
  • Incomplete in parts of hypothalamus, pituitary gland, pineal gland and choroid plexus. (These areas need instant access to blood levels for proper regulation.)
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27
Q

What parts arise from the diencephalon?

A
  • Thalamus
  • Hypothalamus
  • Pineal body
  • Third ventricle
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28
Q

Describe the thalamus.

A

Sensory information enters thalamus

  • Thalamus processes and “relays” information to cortex
  • Subdivided into 50 _ nuclei, each with different functions.
  • Somatotopic organization maintained.
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29
Q

Describe the Thalamic Projections.

A

Almost all nuclei receive reciprocal connections from the cortical areas they project to.
Anterior Nuclei
- Input: Hypothalamus, Hippocampus
- Function: Emotion, memory
Medial Nuclei
- Input: Basal Ganglia, Amygdala, Midbrain
- Function: Memory
Ventrolateral Nuclei
- Motor and somatosensory relay
Posterior Nuclei
- Special senses relay
Nonspecific or Modulatory Nuclei
- Mediate cortical arousal and integrate sensory modalities
- Reticular nucleus uses GABA to inhibit thalamic output based on thalamic activity

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30
Q

Describe the hypothalamus.

A

Coordinates activities of endocrine and nervous systems

  • Controls autonomic function
  • Produces emotions and behavioral drives
  • Regulates body temperature
  • Circadian rhythm
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31
Q

What parts arise from the midbrain?

A
  • Tectum
  • Tegmentum
  • Cerebral aqueduct
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32
Q

Describe the tectum.

A

Midbrain - Dorsal surface

  • Inferior colliculi - audition
  • Superior colliculi - Vision
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33
Q

Describe the tegmentum.

A

Midbrain - Ventral

  • Periaqueductal gray - analgesia (pain neurotransmission)
  • Substantia nigra - sensorimotor (PD): part of the basal ganglia loop
  • Red nucleus - sensorimotor: voluntary motor control
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34
Q

What parts arise from the hindbrain?

A

Cerebellum, pons, medulla, fourth ventricle

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35
Q

Describe the cerebellum.

A

Derived from Rhombencephalon

  • Located in hindbrain
  • Has many deep folds to allow ~ 70 billion neurons
  • Helps regulate motor movement, balance and coordination (real time error correction)
  • Important for shifting attention
  • More recently found to be important in cognition
  • Size increases with physical speed and dexterity of species.
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36
Q

Describe the Pons

A

Superior to medulla

  • Reticular formation
  • Increases arousal and readiness.
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37
Q

Describe the medulla.

A

Just above the spinal cord

  • Breathing, heart rate, vomiting, salivation, coughing, sneezing.
  • Several cranial nerves
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38
Q

What are the anatomical planes and directions?

A

Refer to image.

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39
Q

What are the four segments of the spinal cord?

A

Cervical (8 nerves)
- Cervical enlargement (gray matter gets a little wider to help provide innervation to the arms)
Thoracic (12 nerves)
Lumbar (5 nerves)
- Lumbar enlargement (innervation to legs)
Sacral (5 nerves)

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40
Q

What do Cranial Nerves do?

A

Refer to image

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41
Q

Describe the sensation in the spinal cord.

A

Somatosensory neurons have cell bodies in dorsal root ganglia.

  • Input from periphery
  • Central projections to dorsal horn.
    • Can terminate in horn
    • Can project up to medulla
  • Somatotopic organization in horn and in tracts
    • Caudal regions represented medially in dorsal white matter
    • Rostral regions represented laterally.
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42
Q

Spinal cord tracts (ascending)

A

Gracile and Cuneate Fasciculus
- Fine Sensation
Anterior and lateral spinothalamic tracts
- Coarse touch, pain
Most other tracts are for reflex activity.

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43
Q

Spinal cord tracts (descending)

A

Corticospinal and rubrospinal tracts
- Fine motor control of periphery (voluntary movement: typing, writing, etc)
Remaining tracts
- Motor control of trunk, postural control
- Tectospinal and vestibulospinal tracts
Proprioceptive information carried by tracts surrounding gray matter (how extended or how flexed is a muscle)

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44
Q

Sensory pathways in the spinal cord to brain.

A

Dorsal Column: fine touch, decussates at medulla.
Anterolateral: pain, temperature, deep pressure, decussates at entry to spinal cord.
Decussate: cross each other by form of an “X”

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45
Q

Describe the sympathetic nervous system.

A
  1. Thoracolumbar
  2. Fight or flight
  3. Second stage neurons far from target neuron
  4. Neck to back
  5. Ganglia located close to CNS (short first branch allows faster reactions)
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46
Q

Describe the parasympathetic nervous system.

A
  1. Craniosacral
  2. Rest and restore
  3. Second stage neurons near target organ.
  4. Cranial nerves to sacral
  5. Ganglia located close or in targets. (Long first branch, short second)
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47
Q

What is a microglia responsible for?

A

Immune system function.

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48
Q

What kinds of macroglia are there?

A

Astrocytes (do a little bit of everything)

  • Schwann Cells
  • Radial Glia
  • Oligodendrcytes
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49
Q

What are glia responsible for?

A
  • Act as glue
  • Exchange signals with neurons
  • Help establish synapses
  • Remove neurotransmitters after release
  • Release “gliotransmitters” to regulate activity of neurons.
  • make proteins and pass it on to the neurons.
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50
Q

What are some examples of different types of neurons?

A

Sensory neurons: bring information to the central nervous system.
Inter-nuerons: associate sensory and motor activity in the cns.
Motor neurons: Send signals from the brain and spinal cord to muscles.

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51
Q

Describe the pathway of a neuron.

A
  1. Dendrites
  2. Cell body
  3. Axon hillock
  4. Axon
  5. Presynaptic Terminal
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52
Q

What do reflexes do?

A

pass information to brain.

  • Used to study behavior
  • Automatic
  • Include inhibition and excitation
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53
Q

What are convergence and divergence reflex pathways?

A
  • Convergence (many signals come to one) and divergence (one signal splits to many) pathways.
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54
Q

What occurs at the axon hillock?

A

Integration of information.

  • Rich in voltage-sensitive channels
  • EPSPs and IPSPs integrated
  • Action potentials initiated here
  • Depolarize membrane at axon hillock to threshold.
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55
Q

What is a labeled-line?

A

Each neuron is prewired to carry information from a certain point to the appropriate part of the brain.

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56
Q

Describe ion-channels.

A

Membrane-spanning proteins.

  • regulate ion passage based on size and chemical identity.
  • Gated: voltage, chemically, physically.
  • Studied using patch clamps
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57
Q

What are the factors for ion movement?

A

Concentration gradient and Electrical charge.

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58
Q

How do channels open and close?

A

By changing conformation due to ligands, signals, etc.

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59
Q

Do K+ and Cl- pass readily?

A

Yes

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60
Q

What are leak channels?

A

Ion channels that are always open and NOT gated.

- EG. K+ leak channel or Na+ leak channel

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61
Q

What is Nernst (equilibrium) potential?

A

E(x) = 57mv/z log [Xout]/[Xin]

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62
Q

What do graded potentials do?

A

Disrupt RMP

  • small voltage fluctuation in cell membrane
  • decay over time and space
  • depolarizing (EPSP) or hyperpolarizing (IPSP)
  • Combined through spatial or temporal summation.
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63
Q

What are the differences between Graded and action potentials?

A

AP: all or none, slower, passive AND active
Graded: decremental, fast, passive

64
Q

Describe spatial summation.

A

The larger the slower the curve falls off.

- Membrane length constant

65
Q

Describe temporal summation.

A

Larger = drops off slowly

- membrane time constant

66
Q

Describe the steps of an action potential.

A
  1. Depolarization to threshold.
  2. Activation of sodium channels and rapid depolarization (influx of Na+)
  3. Inactivation of sodium channels and activation of potassium channels (efflux of K+) repolarization
  4. Return to normal permeability after hyperpolarization
67
Q

What is an absolute refractory period?

A

Action potentials can’t generate during this time.

  • Prevent backwards movement
  • Limit rate of firing
  • Na+ channels inactive
  • Occurs during depolarization
68
Q

What is the relative refractory period?

A

K+ channels still active

  • Requires stronger than usual stimulus to trigger an action potential.
  • Occurs during repolarization phase.
69
Q

What are chemical synapses?

A

APs open Ca2+ channels

  • Forces vesicles to fuse with membrane
  • chemical released and diffuses across synaptic cleft (20-40 nm)
  • neurotransmitter bins to receptors and causes change in postsynaptic cell
  • slower than electrical synapses (0.3 ms)
  • allows variability and signal amplification
70
Q

What is an ionotropic transmembrane protein?

A

Ion movement through ion channels.

71
Q

What are metabotropic transmembrane proteins?

A

Alter metabolism by changing shapes and effecting interactions inside.

  • Activates second messenger via G protein
  • Hydrolysis of membrane phospholipids (IP3, DAG, arachidonic acid (inflammation))
  • Soluble gases (NO, CO)
  • cAMP
  • 7 domains.
72
Q

What is an example of indirect gating?

A

G-protein coupled receptors

73
Q

What is an example of direct gating?

A

Ion channels

74
Q

Describe ACh-Gated Ion channels.

A

Requires 2 ACh to open

  • Permeable to both Na+ and K+
  • Rapid switching between on and off states.
  • Allows 17 million ions to pass/sec
  • Average open time 1 ms
  • Normal stimulation opens ~200,000 channels
75
Q

Describe a type 1 synapse (slide 69)

A

Excitatory

  • typically coated on dendrites
  • large active zone
  • wide cleft
  • round vesicles
  • dense material on membranes (a lot)
76
Q

Describe a type 2 synapse (slide 69)

A

Inhibitory

  • typically located on cell body
  • small active zone
  • narrow cleft
  • flat vesicles
  • Sparse material on membranes (little)
77
Q

Basic pathway of metabotropic receptor.

A
  1. External signal (first messenger)
  2. Receptor (extracellular side)
  3. Transducer
  4. Primary effector
  5. Second messenger
  6. Secondary effector
78
Q

What are some first messenger signals?

A

Norepinephrine, ACh, Histamine

79
Q

What are some receptors?

A

Beta-adrenergic receptor, muscarinic ACh, Histamine receptor

80
Q

What are some primary effectors?

A

Adenylyl cyclase, PLC, PLA2

81
Q

What are some second messengers?

A

cAMP, IP3, DAG, Arachidonic acid

82
Q

What are some transducers?

A

G subunits

83
Q

What are some secondary effectors?

A

cAMP-dependent protein kinase, Ca2+ release, PKC, lipoxygenase

84
Q

What are the criteria for neurotransmitters?

A
  1. Synthesized in neuron
  2. Present in synaptic terminal and released to cause effect
  3. Exogenous administration mimics endogenous effects.
  4. Removal mechanism exists
85
Q

Describe small-molecule transmitters.

A
  1. Quick-acting neurotransmitters
  2. Synthesized in axon terminal and pumped into vesicles.
    EG: ACh, Amines (DA,NE, Histamine), Amino acids, ATP
86
Q

Describe neuropeptide transmitters.

A
  1. Multifunctional chain of amino acids that act as neurotransmitter
  2. Synthesized from mRNA; often many different made from single mRNA
  3. Do not bind to ion channels
  4. Cause inhibition, excitation or both
87
Q

What are the similarities and differences between small-molecule and peptide neurotransmitters?

A

Similarities: Send signals, used in most neurons, can coexist in vesicles for peptides
Differences: SM = synthesized locally, vesicles produced at presynaptic terminal and recycled, released by Ca2+ influx at active zones.
Peptides = synthesized in cell body, vesicles derived from golgi and are not recycled, released by non-specific mechanism anywhere in the cell, and requires higher Ca2+ concentration to cause exocytosis (repeated stimulation)

88
Q

What are the three mechanisms for removal of neurotransmitters?

A
  1. Enzymatic degradation: ACh esterase
  2. Diffusion: Large molecules (transmitters, polypeptides)
  3. Reuptake: Repackaged and reused (DA, NE, Serotonin)
89
Q

What is modality?

A

An attribute of stimulus.

- Type of energy transduced

90
Q

What is location (stimulus attribute)?

A

Which receptors active (topography) and helps define size of object.

91
Q

What is intensity (stimulus attribute)?

A

Size of response of each sensor.

92
Q

What is timing (stimulus attribute)?

A

When receptor starts and stops signaling.

93
Q

What is sensory transduction?

A
  1. Sensory receptor transduces stimulus energy into electrical signal, the receptor potential.
  2. Intensity and timing of stimulus related to amplitude and duration of receptor potential.
94
Q

What is the idea of Labeled Lines?

A
  1. “Law of Specific Sense Energies”
  2. Each sensory receptor maximally sensitive to one type of energy and wired to specific area of brain.
  3. Modality perceived depends on which sensory pathway was activated.
  4. Action potentials only encode stimulus intensity and duration.
95
Q

What are 4 categories of receptors?

A
  1. Mechanical: inner ear
  2. Chemical: Pain, itch, taste, smell
  3. Thermal: Temp
  4. Electromagnetic: Vision
96
Q

Explain the neuronal tuning curve.

A

In terms of auditory, a neuron is able to elicit a response for certain frequencies depending on the intensity of the sound. EG. At lower sound frequencies (.5 kHz), the sound intensity must be high (100dB) in order for the neuron to respond and register the sound. At 2 kHz, the same neuron can respond at sound intensities lower than 25 dB etc.

97
Q

What is retinotopic organization?

A

Information from the receptive field is mapped accordingly in the brain.

98
Q

How are activated receptors organized and what do they do?

A
  1. Receptors arrayed topographically. EG. A hand has many receptors that send specific information.
  2. Information about size and location in space (visual system, somatosensory system)
  3. Information about pitch (auditory), taste (gustation) or smell (olfaction).
99
Q

Describe receptive fields.

A
  1. Neuron only responds to stimulation within receptive field.
  2. Receptor density varies in different regions.
  3. Receptor density affects level of detail of information received.
100
Q

What types of cells have receptive fields?

A

Ganglion cells, LGN cells, simple cells, complex cells

101
Q

Transduction in the visual system.

A
  1. Sensory cells: rod and cone cells in retina convert light into electrical impulses that travel to brain.
  2. Light causes conformational change in rhodopsin.
  3. Reduction of electrochemical gradient of photoreceptor.
102
Q

Transduction in the auditory system.

A
  1. Mechanical strain to inner hair cells in organ of Corti transduced into electrical potentials.
  2. Neurotransmitter release encodes intensity, timing, and frequency.
103
Q

Transduction in olfactory system.

A
  1. Odorant molecules in mucus bind to G-protein receptors on olfactory cells.
  2. G-protein activates downstream signaling cascade that increases levels of cAMP.
  3. cAMP triggers neurotransmitter release.
104
Q

Transduction in gustatory system.

A
  1. Sweet, salty, sour, bitter, umami activates transduction pathways.
  2. Taste receptors cells -> G-proteins.
  3. Ion channels -> effector enzymes
105
Q

Pathway of light entering eye.

A
  1. Cornea
  2. Pupil
  3. Lens
  4. Fovea
106
Q

Organization of retina (Inner to outer)

A
  1. Ganglion cells
  2. Amacrine cells
  3. Bipolar cells
  4. Horizontal cells
  5. Cones
  6. Rods
  7. Pigmented part of retina
107
Q

Describe rods

A
  1. Low acuity (low detail vision)
  2. Color insensitive
  3. Threshold: single photon (more sensitive to light)
  4. Low temporal resolution (little timing detail)
  5. High convergence (Many rods converging to one point. Consequence: specificity is vague)
108
Q

Describe cones

A
  1. High acuity (HD)
  2. Color vision (3 cones for wavelength of color)
  3. Threshold: 100s photons (needed before response)
  4. High temporal resolution
  5. Low convergence (1 to 1) (Very specific for location of signal)
109
Q

Describe Color Perception

A
  1. One aspect of vision
  2. Considered in context of brightness, background, lighting (how you see something affects the color)
  3. Visual system detects light reflected from surface (wavelengths of visible light are either absorbed or reflected)
110
Q

How do cones help with color perception?

A
  1. Three cones (S,M,L) maximally sensitive to different wavelengths of light.
  2. Cones do no transmit about wavelength of light detected.
  3. Relative activity of all three cones interpreted as color. (combined output)
111
Q

Short wavelength cone responds best to _____.

A

Blue

112
Q

Medium wavelength cone responds best to _____.

A

Green, less to yellow

113
Q

Long wavelength cone responds well to _____.

A

Red or yellow

114
Q

Describe blobs and color perception.

A
  1. Blobs -> V2 thin stripes -> V4

2. Color-sensitive cells seem clustered in blobs

115
Q

What is binocular disparity?

A

When you fixate on an object causing objects further or closer than fixation point to be represented at different locations on retina.
- Cells in V1, V2, V3, MT sensitive to disparity

116
Q

When are monocular cues used and what are they?

A

When judging distance of objects more than 100 feet away.

  1. Familiar size
  2. Occlusion (one object behind another)
  3. Linear perspective (parallel lines converge)
  4. Size perspective
  5. Distribution of shadows and illumination
  6. Motion parallax (close things move in opposite direction, things that are far seem to be moving along with you)
117
Q

Motion detection pathway

A

M cells -> V1 layer 4B -> MT/V5

118
Q

MST detects what?

A

Global motion in visual field (Starship going light speed)

119
Q

P cells project to ______ and ______.

A
  1. V1 layers 4Cbeta and 4A
  2. Most of these cells are color insensitive
  3. Some sensitive to opponent colors.
120
Q

Structure of the external ear.

A
  1. Auricle

2. Ear canal

121
Q

Structure of the middle ear.

A
  1. Tympanic membrane
  2. Malleus, incus, stapes
  3. Oval window
    Bones act as a damper or amplifier for force/energy of volumes
122
Q

Structure of the inner ear.

A

Cochlea (looks like snail shell, sense organs reside here)

123
Q

Describe the Organ of Corti.

A
  1. Contains ~16,000 hair cells/ear (inner and outer hair cells)
  2. Movement of basilar membrane distorts hair cells, causing depolarization or hyper polarization of receptors.
  3. Each hair cell maximally sensitive to particular frequency
124
Q

Describe the capture of sound.

A
  1. Pressure fluctuations in air move tympanum.
  2. Movement of tympanum moves auditory ossicles.
  3. Movement of stapes moves oval window
  4. Movement of oval window generates “waves” in the fluid filled scala vestibuli
  5. Motion distorts basilar membrane
125
Q

How does the cochlea amplify signal?

A
  1. Most sound energy goes to moving fluid, not deforming hair cells.
  2. Cochlea much more sensitive at LOW intensity sound than high intensity (volume selective switch).
126
Q

Describe the spiral ganglion.

A
  1. Curves around the core of cochlea.
  2. Majority (90%) of input from inner hair cells
  3. Encodes stimulus intensity and frequency
  4. Linear relationship between sound intensity and firing rate: as volume increases, firing rate increases
  5. Frequency encoded by place and neurons fire in-phase with sound.
127
Q

What is the auditory pathway?

A

Spiral ganglion -> CN 8 -> cochlear nuclear complex at medulla-pons junction

128
Q

How is sound localized?

A
  1. Anteroventral cochlear nucleus projects to medial olive where the olive receives bilateral input to be able to do sound localization.
  2. Localization based on inter aural timing differences
  3. Lateral superior olive uses inter aural intensity differences to localize.
129
Q

How does the vestibular system work?

A

Movement or acceleration of head causes deflection of hair cells.

130
Q

Describe the two types of linear acceleration.

A

Utricle: horizontal motion
Saccule: vertical motion

131
Q

Describe angular acceleration (semicircular canals).

A

3 canals responsible for different angles of acceleration: Front flips, cart wheels, spinning around in circles.

132
Q

Describe the hair cells in linear acceleration.

A
  1. Localized in macula (utricle+saccule)
  2. Top attached to otolithic membrane (rock in ear that acts like a level and bubble in liquid)
  3. During motion, membrane moves after skull causing deflection of hair cells.
  4. Different hair cells oriented to be sensitive to acceleration in different directions.
  5. Degree of acceleration signaled by graded response
133
Q

What is the endolymph for and where?

A
  1. Found in the semicircular canal (angular acceleration) and moves in the opposite direction of the head.
  2. Movement of endolymph pushes on cupula, distorting hair cells.
134
Q

What does the horizontal semicircular canal help with?

A

Helps subtract movement of your head (uses ion channels for fast detection/response) and helps eyes remain focused on the same spot.

135
Q

What are the functions of vestibular reflexes?

A
  1. Monitors body movement and position
  2. Stabilize eyes when head moves (signals speed and direction of movement)
  3. Quick response time helps maintain posture
136
Q

What is the vestibular pathway?

A
  1. Vestibular nerve projects to vestibular nuclei in medulla and pons.
  2. Integrated with information from spinal cord, cerebellum and visual system.
  3. Projects to oculomotor nuclei, skeletal movement nuclei, cerebellum, thalamus.
137
Q

How is olfaction thought to work?

A
  1. Odorant molecules have characteristic shapes.

2. Dissolves in mucus and binds to olfactory receptor neurons in olfactory epithelium.

138
Q

Smells project through what?

A
  1. The cribiform plate of ethmoid bone (has many axons in the area that help detect smell)
139
Q

What type of receptors are olfactory receptors?

A

G-proteins using secondary messengers

140
Q

Explain how receptors are differently sensitive.

A

Experiment with 3 smells and 3 receptors (A,B,C). EG. Isoamyl acetate (banana smell): A didn’t respond, B responded a little, and C responded greatly.

141
Q

What are the steps for olfactory transduction?

A
  1. Odorant binds to G-protein coupled receptor
  2. Binding increases adenylyl cyclase activity
  3. cAMP opens cation channel
  4. Action potential generated
  5. IP3, cGMP, and CO also implicated in olfactory signaling.
142
Q

What is olfactory pathway?

A

Glomeruli -> Lateral Olfactory Tract -> Cortex

143
Q

What does the Olfactory cortex consist of?

A
  1. Anterior Olfactory Nucleus
  2. Piriform Cortex
  3. Amygdala
  4. Olfactory Tubercle
  5. Entorhinal Cortex
144
Q

What are the two theories of odor?

A
  1. Shape of odorant = smell

2. Molecular vibrations

145
Q

What are pheromones?

A
  1. Chemical messages emitted to influence other members of same species.
  2. Influences reproductive and social behaviors (EG. Ants release pheromones to describe where food is)
146
Q

How are pheromones detected?

A

By olfactory system and vomeronasal system

147
Q

Do humans have vomeronasal systems? Animals?

A

No, it is where most animals stick their pheromone receptors.

148
Q

What is the vomeronasal system pathway?

A

Vomeronasal organ -> vomeronasal nerve -> accessory olfactory bulb

  1. Projects to amygdala, hypothalamus
  2. Not consciously perceived (never goes through thalamus)
  3. Influences reproductive physiology
149
Q

Describe taste buds: how many receptors, where its found, how many types, what taste pores do.

A
  1. Each contains 50-100 taste receptor cells
  2. Taste pore allows tastants access to receptors
  3. Found on tongue, esophagus, palate
  4. Three forms found on different parts of tongue
150
Q

How do we get “taste?”

A

Gustation combined with olfaction and somatosensory information = taste.

151
Q

Taste buds are innervated by which CNs?

A

VII, IX, X

152
Q

What are the 3 forms of taste buds?

A
  1. Circumvallate (back of tongue)
  2. Foliate (back lateral sides of tongue)
  3. Fungiform (a lot towards tip of tongue)
153
Q

Taste receptors for salty and sour use what type of signaling?

A

Ion channels

154
Q

Taste receptors for bitter, sweet, and umami are what type of signaling?

A

GPCRs

155
Q

Describe the labeled line model for encoding of taste qualities in the periphery.

A
  1. Receptor cells are tuned to respond to single taste modalities - sweet, bitter, sour, salty, or umami - and are innervated by individually tuned nerve fibers.
  2. Each taste quality is specified by the activity of non-overlapping cells and fibres
    (supported by recent studies: activation of a single type of TRC is sufficient to encode taste quality)
156
Q

What is the gustatory pathway?

A
  1. Neurotransmitter (possibly ATP) released from taste receptor cells to sensory fiber.
  2. Converted to action potentials and travel over cranial nerves VII, IX, X, XII to solitary tract nucleus in medulla.
  3. Project to thalamus
  4. Project to ipsilateral insula and operculum

Behavioral Neuroscience (9 decks)

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