Neuro Final

Task distribution: We met up and went through the powerpoints as a group. We’d collectively agree on what content was important with each person writing and explaining an equal amount of the content. Then we went through and added information some of us remembered from the lectures.

Signed by: Lauren Gracie, Madi Quayle, Zoe North, 

Introduction to Neuroscience and Behavior

• Behaviors are Motor responses to stimuli

• All organisms: acquire energy and nutrients (foraging), find an appropriate environment (taxis), avoid danger, time reproduction 

• Some organisms have sex, are social and parent offspring

Tinbergen’s 4 questions

Proximate 

-Ontogeny: How did this trait develop or change with age?

-Mechanism: how does this trait work?

Ultimate

-Adaptation: What is the function of this trait?

-Phylogeny: How is this trait distributed among closely (and distantly) related species 

• How do we study behavior?

• Field observations, semi-natural experiments, field experiments, colored tags, RFID tags, tiny QR codes, or Radio GPS collars

Things to consider when studying behavior

• Replacement of live subjects, Reduction of subjects , and refinement ( minimize aggression or predation of subjects)  of Ethics

Swimming Neuron 

• Gravitaxis-gravity

• Phototaxis-light 

• Chemotaxis-chemical

• Phonotaxis-sound

• Magnetotaxis-magnetic field

• Rheotaxis-water currents

• Galvanotaxis-electricity

• Anemotaxis-wind

• Thermotaxis-temp

• Thigmotaxis-touch

• Taxis-movement towards

• Kinesis-non-oriented movement like changing speed

Fluid mosaic

• Phospholipids, cholesterol, integral proteins, peripheral proteins, glycoproteins

• Anchored by extracellular matrix and cytoskeleton

• Diffusion-down the electrochemical gradient, passive just crossing membrane or facilitated using channels 

• Active transport-uses ATP, against electrochemical gradient using ion channels and pumps 

• Two types

  • equilibrium ion potential-the electrical potential difference across a cell membrane that balances the concentration gradient for an ion.

  • Membrane resting potential-voltage across the membrane at rest

  • Membrane potential results from: electrochemical grandiants, permeability to important ions, action of pumps/active transport

• Types of gated channels:ligant, stretch, voltage, phosphorylation

• Transduce-changing one type of signal to another 

• Ionotropic transidction-ligand gated ion channel, ligand is a molecule that binds to a receptor

• Metabotropic transduction=g protein coupled receptors/enzyme linked 

• Motor proteins use ATP to produce motion=change the shape of the protein 

• Used a second messenger to allow ATP to bind because we dont want to do it all the time

Nervous System Organization

• The nervous system

  • The network of nerve tissue in an organism

• Development of organizational systems

  • • Endoderm: develops into organs

    • Mesoderm: develops into muscles and bones

    • Ectoderm: develops into nervous system and skin

• Cell fate determination

  • • Cell fate determination

      • Neurogenesis

        • Neurons being formed in the brain

1. Cells specialize into ectoderm vs. neuroectoderm of the neural plate

2. Neurons differentiate from precursor cell

3. Newly migrated neurons migrate to their final position

   1. Along glial cells

4. Axon growth and pathfinding

• Cnidaria

  • Nerve net 

  • Centralization

    • Condensed neurons in specific sections of the body

• Nematoda

• Arthropoda

• Annelida

• Vertebrate

Olfaction and Gustation 

Learning Goals

1. Understand and explain why chemoreception is one of the most ancient and diverse forms of sensory reception 

   1. There are many gene families for chemoreception

   2. One of the most flexible sensory domains

2. Explain the organization of olfactory and gustatory cells in animal bodies. 

   1. Olfactory receptor cells located in the olfactory epithelium, which is found in the nasal cavity of invertebrates. 

   2. Taste receptor cells located in the taste buds

      1. Taste buds found on tongue, soft palate, pharynx, and epiglottis

      2. Taste buds grouped within structures called papillae

3. Explain how metabotropic transduction of olfactory stimuli (odorants) lead to an electrical change in olfactory neurons 

   1. Odorant molecules bind to specific GPCRs on the cilia of olfactory receptor neurons. Each neuron expresses a single type of GPCR but each receptor can recognize multiple odorants

4. Explain how ionotropic and metabotropic transduction of gustatory stimuli (tastants) lead to electrical changes in taste receptor cells.

   1. See other sections for explanation of ionotropic and metabotropic transduction 

Terms: 

1. Chemoreception 

2. Olfaction

   1. Transduction of volatile molecules into an intracellular signal

3. Metabotropic transduction

   1. What human olfactory neurons

4. Depolarization 

5. Labeled line coding

   1. Neurons of similar types are organized into discrete sensory units in the olfactory bulb (glomeruli and tracts).

6. Gustation

   1. Transduction of water-soluble molecules in solution into an intracellular signal

Olfactory neurons in humans:

1. The dendrites of these neurons extend directly into the environment. They have receptor molecules that are activated by different kinds of chemicals in the environment. Their axons cross through the skull and lead into the olfactory bulb. 

2. In the dendrites of these neurons are G-protein-coupled-receptors. There are many different versions of these molecules.

3. There are many different versions that have ligand-binding sites specific for different kinds of odorant molecules.

4. Odorants may bind to more than one receptor AND receptors may be activated by more than one odorant. 

5. When there are no olfactory stimuli in the environment the neuron is at rest

Human taste cells use both ionotropic and metabotropic transduction

1. Ionotropic

   1. Salty 

      1. Na+ enters through open sodium channels

      2. Na+ depolarizes the membrane.

         1. This change in voltage opens voltage gated ion channels.

      3. Ca++ ions entering the cell triggers the release of neurotransmitters. These chemicals will tell the next cell in line what to do

   2. Sour

2. Metabotropic

   1. Bitter

   2. Sweet

   3. Umami 

Most of our coding of tastes occurs via labeled line coding

1. A small proportion occurs through population coding

Almost all vertebrates have taste receptors

Cells At Rest

• Learning Targets

  • Describe how cells create and store charges.

    • Create and store while the cell is at rest

    • To determine direction of ions 

      • Need to know equilibrium potential of the ion

      • How it compares to the membrane potential

    • E_ion

      • The charge where 2 unequal concentrations are at equilibrium. (in mV)

  • Ohm's law

    • voltage=currents*resistance

  • At rest

    • Membrane potential is dominated by K⁺ because of leak channels, also some Cl^- 

    • If Na⁺ opens, potential will move towards the potential of Na because the membrane will be more permeable. 

Animal Physiology

• Evolutionary and history of major cell types

  • Behavior needs ability to detect and respond to stimuli, not the brain or neurons

• One big cell is not efficient or possible, multiple cells tho? YES

  • Too much surface area bad

• More surface area = more volume

• Colonial living = competitive advantage, but no specialization

  • Can't perform tasks (sensory reception, info transfer, etc) all at once

• Multicellular organism = obligate of cells w/ specialization

  • Spatial segregation of functions

• Cells in sensory, nervous, and motor system

  • Motile cells: cells for movement (ie. crawling)

    • Motor proteins

    • Muscle cells (ie. Striated muscles)

  • Sensory cells

    • Mechanoreceptors: transcues info about mechanical stimuli

    • Stiff elements: anchored to surrounding tissue or membrane

    • Photoreceptors: metabotropic transduction of light into cellular signals

      • Photosensitive pigments

    • Chemoreceptors: transduce external signals into cellular signals

      • G- protein receptors

• Structures

  • Cytoskeletal

    • Microtubules (cilia and flagella)

    • Microfilaments (actin-dependant mechanisms)

• Dendrites: receive information, filled with receptor proteins and ligand gated channels

• Cell body:

• Axons: transmits info for long distances, filled with membrane voltage gated ion channels, has myelin

• Axon Hillock: where the soma and the axon meet

• Nodes of ranvier: spaces between myelin

• Myelin: insulates and speeds up signal

• Direct connections between two cells

• Chemical synapse: pre synaptic neuron releases neurotransmitters to the post synapse

• Astrocytes: blood brain barrier

• Oligodendrocytes: myelinates multiple the axons, CNS

• Schwann cells: myelinates an axon, PNS

• Microglia: cleans shit up and repairs

Synapses and neurotransmitters

Describe how voltage changes at the axon terminal result in the release of packets (quanta) of neurotransmitters 

• Explain the relative costs and benefits of electrical synapses, and the two types of chemical synapses (ionotropic and metabotropic). •

 Describe the ionic basis of EPSPs and IPSPs and how these potentials influence the probability of an action potential occurring in the postsynaptic cell. and the ionic basis of each • 

Describe the major classes of neurotransmitters and their receptors.

Synapse

• Electrical synapses lead directly to the depolarization of the postsynaptic cell cause it uses gap junctions, like a channel 

• Bidirectional according to the electrochemical gradient

• Postsynaptic cell depolarization is at the same time as the pre cell but with a lower amplitude

• Use case-crayfish escape responses, giant neurons

• Chemical synapse

• What you think of as a normal neuron

• Synaptic cleft

• Action potential-a brief change in the electrical potential across the membrane

• Depolarized-positively charged

• Down axon to terminal to release neurotransmitter

• 3 pools of neurotransmitters

  • Readily releasable-used first

  • Recycling pool- 1st back up

  • Reserve pool- 2nd back up 

• Axon terminals have voltage gated calcium channels

• Voltage change from action potential opens the channels 

• Calcium changes the shape of synaptic protein, allowing vesicles to dock to the membrane

• Once its docked it fuses with the cell membrane and the neurotransmitter diffuse into the synaptic cleft

Criterias for neurotransmitters

• Made and stored in presynaptic neuron

• Released at axon terminal 

• Has the same effect on pre and postsynaptic neuron

• Amino acid NTs-glutamate, GABA, glycine , for ionotropic synapses

• Generate EPSP-Excitatory postsynaptic potential-by opening ligand gated sodium channels

• Side of EPSP-proportional to NT release

• agonists=activate

• antagonists=inhibit

• AMPA receptors respond to glutamate first, then NDMA is activated by voltage gated channels

• IPSP-inhibitory=ligand gated chloride channels=GABA and glycine=chloride ion channel, chloride entering the cell

Metabotropic reception

• Receptor at rest-receptor binds to NT-recruits g protein complex-g protein breaks apart-subunits activate ion channels or enzymes

• Second messengers like cAMP amplify signal

• cAMP/phosphorylation opens ion channels

Cell Physiology: Transmission of Information

-Describe how spatial and temporal summation trigger the start of the action potential

-Explain the phases of an action potential and the ionic basis of each phase

-Explain how scientists determined which ions contributed to the action potential

-Explain how action potentials allow signals to travel long distances rapidly and the modification of cells that increase the speed of conductance

• Amount of depolarization is not  proportional to the current change in action potentials

• The rate of firing of an AP reflects the magnitude of the depolarizing current; cells maximum rate of firing is determined by the refractory period

• Voltage clamp can be used to measure ionic currents

• If the cells are held at a negative voltage, there is little current to add

• If the cell is held at a more positive membrane voltage, you must apply negative current to continue to hold it at the same voltage, however after a short while positive current must be applied to hold the membrane at the same voltage. 

• Outward rather than inward flow of Na in freshwater experiment. This told experimenters that sodium is responsible for normal inward flow. When K channels are blocked, there is no overshoot. K this might be responsible for normal outward flow.

• At rest- the positively charged parts of the voltage gated sodium channel are attracted to the negative charged cell interior 

• If the inside of the cell becomes sufficiently depolarized, the positive parts of the protein will be repelled and the channel will open. This allows more na into the cell.

• At rest, potassium leak channels are open, and permeability to K is high so it dominates the membrane potential.

Action Potential Conduction

• The direction of action potential conduction is determined by the inactivation of sodium channels after their opening via polarization of the membrane.

• Saltatory conduction: The action potential is regenerated at nodes of Ranvier, which contain voltage gated sodium channels. The depolarization spreads passively down the portions of the axonal  membrane that is myelinated. The action potential spreads from node to node (saltatory conduction). Conduction speed can increase by having a large axonal diameter Not all axons are myelinated.

Passive Potentials

• How membrane potentials change

  • Change in concentrations of ions

  • Changing membrane permeability to ions

• Membrane time constant: how long it takes for the membrane to respond to the changes in current

• Membrane length constant: how far the change will spread down the membrane

• Increase in resistance (Rm) = increase in length constant

• Increasing neurite diameter (d) = increase in length constant

• Graded potentials won't work in longer cells, so action potentials are used

Neuromuscular Junctions and Motor Output

• Metabotropic synapses

  • cAMP can open ion channels, also can be opened through phosphorylation

  • Cellular proteins can also be turned on/off, as well as transcription initiation via phosphorylation

• Synapse types

  • Additional information:

    • Vertebrates:

      • One motor neuron can innervate (supply nerves to) multiple muscle fibers but each muscle cell can only be innervated by one motor neuron. 

      • Both together is called a motor unit

      • Muscle is many motor units (motor pool)

    • Invertebrates:

      • One motor neuron can innervate many muscle fibers, each muscle fiber can also be innervated by multiple neurons. 

    • Acetylcholine(ACh)

    • Gamma-aminobutyric acid(GABA)

    • Glutamate(Glu)

    • Muscles are bundled

    • Simple Circuits

      • Golgi Tendon Signaling

      • Monitoring Stretch

      • Withdrawal Reflex

      • Crossed-Extensor Reflex

Somatosensation

• Four major types of somatosensation

  • Touch: reception and processing of mechanical stimuli

    • Merkal’s disc: precise mechanoreceptors

    • Pacinin’s corpuscles: vibrations

    • Meissiner’s corpuscles: skin motion/movement

    • Ruffini’s endings: stretching of skin

All of the touch things:

• Itch

• Pain:

  • Mechanical

  • Thermal

  • Chemical

• Temperature

  • Hot and Cold

• Role of size and structure

  • Bigger size = faster connection

    • A -beta = faster (mechanoreceptors)

    • A-delta = middle (first pain/temp)

    • C = slowest (second pain/temp/itch)

  • Bipolar allows it to form synapses and projections in the brain

• Distribution

  • Broadly distributed

  • Larger receptive fields = more sensitive to change

  • Smaller receptive fields = precise spatial differences

  • Lumbar spinal cord -> cervical spinal cord -> caudal medulla -> ventral posterior lateral nucleus of the thalamus -> somatosensory cortex

Introduction to audition 

Learning goals:

1. Describe the basic properties of sound (frequency, amplitude, cycles, period, etc.) 

2. Explain how sound is transduced into electrical activity in vertebrate hair cells.

3. Explain how information about frequency and amplitude are encoded in the auditory periphery and central auditory pathways. 

4. Explain the principles of tonotopic organization. 

5. Explain how auditory filters produce trade-offs between frequency and temporal resolution. 

Terms:

1. Period

   1. Time between two successive peaks of a cycle

2. Frequency

   1. Inverse of the period

   2. Number of cycles per unit of time

3. Waveform

   1. Depict changes in pressure over time (or over distances)

4. Amplitude

   1. Distance from the negative pressure trough to the positive pressure peak of a sound

   2. Typically measured in micropascals

   3. Animals tend to interpret amplitude on a logarithmic scale

      1. Thus we often express the amplitude of sound in decibels of sound pressure (dB SPL)

5. Power spectrum

   1. Depicts the relative amplitude of a sound at different frequencies 

6. Outer hair cells

   1.  Receive only efferent innervation

   2. Important in setting up the tuning properties of the mammalian cochlea

   3. Contain an electrically motile protein called prestin 

      1. When they are depolarized the bounce up and down, but do not release neurotransmitters or transmit information

7. Mechanical tuning

   1. Hair cells respond to certain frequencies based on their location on the basilar membrane. A hair cell in a petri dish will respond to any frequency.

   2. Mechanical tuning is due to the stiffness of the membrane and the motion of outer hair cells

8. Inner hair cells

   1. Transduce sound into electrical signals

   2. Both afferent and efferent innervation

9. Place theory 

   1. The idea that frequency is encoded based on the part of the cochlea (called a cochlear partition) that responds to a particular frequency. This “place” is preserved in subsequent neurons. This is very important for high frequency hearing in birds and mammals. Some animals, like many fishes, do not have an obvious tonotopy of the inner ear, suggesting the place principle won’t work for all species. 

10. Temporal theory

    1. The idea that the receptor potential in hair cells and the firing rate of auditory neurons encode frequency

11. Phase locking

    1. A way neuron’s firing rate can encode frequency

    2. Phase locking is an incredibly important way in which we can encode information about the time of the stimulus that is independent of frequency. This will be very important for sound localization

12. Tonotopy 

    1. Maintained as you ascend through the central auditory pathway

Inner hair cells are depolarized in response to mechanical stimulation (stretch-gated ion channels). This depolarization will open voltage-gated calcium channels and trigger

neurotransmitter release. 

Hair cells have receptor potentials (not action potential). The amount of neurotransmitter release will be proportional to the depolarization of the cell.

Sounds with more cycles per second (hertz/Hz) are higher in frequency

1. We perceive these different frequencies as different pitches

For terrestrial mammals the middle ear helps navigate the impedance mismatch between the acoustic media (gas) and the inner ear (liquid)

Ear:

1. Pinna

2. External auditory meatus (ear canal)

3. Tympanic membrane

4. Ossicles

   1. Malleus, incus, stapes

5. Oval window (attached to cochlea)

6. Cochlea 

7. Auditory nerve 

8. Round window

Audition/Sound Localization

Learning goals:

1. Describe how having two ears separated in space can produce differences in time of arrival (ITDs), intensity (IIDs), phase (IPD), and spectral (ISD) differences between the two ears.

   1. ITDs occur because sound waves reach one ear before the other when the source isn’t directly in front of or behind the listener

   2. IIDs happen because our head blocks some of the sound from reaching the ear on the far side of the source. The ear closer to the source experiences a higher intensity

   3. IPDs occur when the phase of a sound wave is different between the two ears

   4. ISDs arise because the shape of the pinna affects how sound waves are filtered before entering the ear canal. Helps provide information about the vertical location of a sound source

2. Explain how interaural cues are used to calculate spatial locations of sound sources

3. Describe the pathways for intensity and time information in avian and mammalian brains.

   1. Mammalian

      1. Time (ITD)

         1. Cochlear nuclei → medial superior olive (coincidence detector)

      2. Intensity (IID)

         1. Lateral superior olive and medial nucleus of the trapezoid body

   2. Avian

      1. Time (ITD)

         1. Nucleus laminaris 

         2. Functions like mammalian medial superior olive (uses delay lines and coincidence detectors) 

      2. Intensity (IID)

         1. Nucleus angularis, similar to lateral superior olive

4. Describe how delay lines and coincidence detectors contribute to sound localization (ITDs). Describe how excitation and inhibition contribute to sound localization (IIDs).

Terms:

1. Interaural Time Differences (ITDs)

   1. Frequency independent 

   2. Sometimes represented as interaural phase differences

2. Interaural Intensity Differences (IIDs)

   1. Low or none below ~1750 Hz

   2. The smaller the animal the higher the frequency needed to create a sound shadow

      1. Present at higher frequencies for smaller animals and lower frequencies for bigger animals

3. Interaural Spectral Differences (ISDs)

4. Sound shadow

5. Spectral shapes

6. Constructive and destructive interference 

7. Spectral cues

   1. Most effective for broadband sounds

8. Azimuth 

   1. Horizontal direction

9. Elevation 

10. Phase 

11. Ipsilateral and contralateral sound presentations 

Frequency and Wavelength - inversely related

Wavelength = 343 m / # cycles

Human auditory pathway:

1. Cochlea

2. Cochlear nerve

   1. Axon = delay lines

3. Medulla

   1. Cochlear nuclei

4. Pons

   1. Superior olivary complex

      1. Binaural processing

      2. First place that sound localization can happen

      3. Soma = coincidence detectors

   2. Nucleus of lateral lemniscus

5. Midbrain

   1. Inferior colliculus

   2. Medial geniculate nucleus

   3. Where sensorimotor integration happens

6. Primary auditory cortex

   1. A1

   2. Interfaces with other sensory areas to refine information about sound sources

In general sound is split into a frequency and intensity stream

Vision:

• Learning Goals

  • Describe the basic properties of light and how it interacts with the environment.

    • Measured in wavelengths, shown in a spectrum based on frequency/wavelength 

    • Monochromatic light:

      • Light that has the same wavelength/phase

    • Complex light:

      • Multiple wavelengths and varying amplitudes

    • Environments with differing intensities of light influences the evolution of processing light.

    • Light can be reflected, refracted, absorbed

    • ARTS: leads to color perception 

      • Ambient light

      • Reflectance

      • Transmittance

      • Sensitivity

  • Explain the differences between photoreception and vision.

    • Photoreception:

      • The ability for an organism to detect and respond to light

    • Vision: 

      • The ability to form an image using photoreceptor cells

    • Opsins:

      • Proteins

      • Absorb photon

      • Many animals have, but not all animals have vision

  • Describe the two main types of eyes that have evolved in animals.

    • To have vision, photoreceptor cells are crucial

      • Packed with opsins and ion channels

      • Rods:

        • Low Light

      • Cones:

        • High Light

    • Single-Chambered Eye:

      • Only one lens

    • Compound Eye:

      • Multiple lenses

    • 5 main cell types in the retina

    • Cones are highly concentrated in fovea, rods are found in the periphery.

      • Rods good for movement detection but not for color or spatial acuity

  • Explain how photoreceptors can transduce electromagnetic radiation into electrical signals in a cell.

    • In the dark

    • In the light

  • Explain how edges are encoded by the visual system. 

    • The surrounding of the receptive field moves from dark to light as the horizontal cells communicate to decrease firing. (On center off surround sound)

  • Trace visual information through the three main central pathways.

    • Central Visual Processing:

      • Non-Thalamic

        • Visual info carried to superior colliculus via retinotectal pathway, also carried to hypothalamus.

      • Thalamic

        • Visual information carried via optic tract to the LGN then passed to the primary visual cortex via optic radiations.

  • Additional Information:

    • Acuity:

      • How able one is to determine where something is coming from

    • Sensitivity:

      • The ability to detect something (typically a signal)

Learning and Memory:

• Define

  • Learning:  the process by which organisms acquire information

    • Benefits: optimal decision making based on past info/exp, rapidly adjust behavior to changing environments, improved fitness

  • Memory: the process by which organisms process, store, and retrieve info

  • Memory consolidation: the process of converting short term memory into long term memory

• Types:

  • Non-associative learning: change in response to a single stimulus

    • Habituation: decreased response to repeat stimuli

    • Sensitization: increased response to repeat stimuli

  • Associative learning: behavior is altered by associating it with events, requires 2+ stimuli

    • Classical conditioning: unconditioned response to an unconditioned stimulus is associated with a conditioned stimulus and becomes a conditioned response

    • Operant conditioning: Reinforcement of behavior by reward/punishment

  • Working Memory: temporary storage, recalled for a few seconds, easily lost

  • Short-term memory: recalled for a few seconds to a few minutes, still able to be disrupted

  • Long-term memory: recalled for days to years

  • Declarative/Explicit memory: facts and events

  • Semantic memory: facts

  • Episodic memory: events

  • Non declarative/implicit memory: skills, habits, emotions, motor things

    • Used in habituation and sensitization

• Anatomical Substrates of Memory

• Physical modification of the brain due to incoming sensory information, which modifies the transmission between neurons

• Neural Network Model: distributed model of memory

  • Pattern of activation is representative of a memory

• Working memory stored in the prefrontal cortex

• Declarative memory stored in the medial temporal lobe, hippocampus, entorhinal, perirhinal cortex, and parahippocampal cortex

• Spatial memory, long term memory, and consolidation stored in the hippocampus

  • Place cells: fire when an animal is in a specific place

  • Grid cells: fire when an animal is at multiple locations

• How are memories acquired, consolidated, and retrieved

  • Hebb’s Cell Assembly: Activation of cell -> continued activation of cell without the stimuli -> activation modifies the cell and strengthens connections -> partial activation in the future leads to reactivation and retrieval of memory (when reactivated the connections can be altered or updated)

• Bat things: they have cells that fire to plan movement, they have cells that fire when watching friends, they have cells that fire at food

Sex and Reproduction

-Define Sex and be able to identify different types of sex determination

-Describe the two major classes of sex hormones and the way they are produced

-Explain organizational vs activational effects of hormones

-Describe when and how sex differences in brain anatomy and function may arise.

-Describe different reproductive systems and how the brain might be involved in modulating these behaviors.

• Sexual Reproduction: When two animals fuse gametes together in order to produce an offspring

• One gamete has evolved to be large while the other is small in some organisms

• Most individuals can only produce one gamete at a time; large=female, small=male

• Female:XX, Male: XY; SRY gene is heavily involved in making males male by developing testes and related hormones

• Sex is determined through genetics, haplodiploidy (haploid males in bees), polygenetics (more dosage of a gene means male), temperature, age/size, or social factors (ie nest availability or mate death)

Neuroendocrine pathways

• HPG axis (hypothalamus pituitary gonad)

• Hypothalamus is sensitive to light information and provides information about the time of year based on this. It then either produces reproductive hormones or regulates the reproductive cycle accordingly.

• Hypothalamus releases GnRH —> anterior pituitary, which releases LH and FSH into bloodstreams

• Males have androgens (made in testes), while females have estrogens (made in ovaries). BOTH ARE STEROIDS AND MADE FROM CHOLESTEROL. Can travel into cell and act as transcription factors.

• Aromatase: T -> E

• Also membrane bound receptors that mediate fast action of steroids.

• Testosterone is converted to estradiol locally. This masculinizes animals.

• Estradiol receptors concentrated in hypothalamus, pituitary, and preoptic area

Sex differences in the brain

• Can occur at the circuit, synapse, cell, or molecular level

• Typically are constrained to particular structures or tasks 

• They arise when there are differences in fitness benefits across the sexes associated with behaviors regulated by those brain areas

• Male and female brain are more similar than different

• Spatial Learning-  Learning related to the spatial elements of an animal’s environment 

• Some animals develop a cognitive map

• Organizational effects of hormones: development and anatomy; they tend to be permanent

• Activational effects: behaviors, tend to be temporary 

•  More testosterone leads to response of fetus to maternal hormones

• Gynandromorph: having both male and female tissues; differential gene expression

• Steroid modulate functions of enzymes

• Estradiol increases hippocampal neural dendritic 

Mating patterns

• Promiscuous

• Polygynous and polyandrous

• Monogamous, social vs genetic 

•  Oxytocin and vasopressin increase pair bonding and parental behavior

Communication: Define language and communication

Be able to argue for and against animals using language using evidence from the primary literature 

Describe anatomical substrates of acoustic communication 

Describe the complex systems involves in the production of acoustic communication 

Describe vocal learning in birds and humans

Identify the differences in brain connections for animals that do and do not learn how to vocalize

• Language=a system for representing and communicating information using words combined according to grammatical rules. It can be expressed in a variety of ways, including gestures, writing and speech 

• For: animals vocalize and use gestures, with communication systems that are different from what humans use, but the definition of language often excludes those systems.

• Against: animals do not meet the standard for human language, flexibility and grammatical rules.

Mechanisms of sound production

• larynx=human vocal organ

• All muscles controlled by motor cortex

• Vocal folds in larynx

• Sounds produced by vibrations of tightened vocal folds

• Mammals inhale by moving the diaphragm to lower the air pressure in the chest cavity and pull air into the lungs, exhaling increases pressure and pushes air out

• Birds: Birds have a different lung shape, air sacs that store and pump air through stationary lungs. Air flows in one direction through birds lungs which allows birds to take in oxygen even in exhalation, allows birds to breathe at much higher elevations

• Uses muscles to control tympanic membranes, length and volume of vocal tract, air flow and beak movements

•  syrinx not larynx which branches into two sides, which is why birds can sing two sounds at once 

• Song birds have many more complex pathways to do with sound production than non song birds

• Female birds do not not have the same brain volume to do with singing as males do, sex difference

• You can make female song birds songs sound more like male songs by giving them hormones

Language acquisition in humans

• Recognize sounds early, innate

• Learn through practicing what they hear

• Motor practice with auditory feedback

• Songbirds have innate ability to sing, if they don't hear other songs they sing an incomplete song

• They can learn other dialects but they will only incorporate other birds songs if it fits in with their natural songs

• Learning periods in birds

  • Sensory phase-hear

  • Sensorimotor phase-practice

  • Crystallization-internalize

Brain areas for language

• Broca's area-frontal lobe, articulate speech sounds

• Wernicke's, temporal lobe, making it make sense

• Brain pathways are similar in birds and mammals 

• Pre-motor planning, motor execution

• Motor information passed to vocal organs