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comparative approaches > Nerve Cells & Behaviour > Flashcards

Nerve Cells & Behaviour Flashcards

1
Q

542-520 MYA

CAMBRIAN EXPLOSION

A
  • rise in organism diversity
  • rapid appearance of many animal body plans aka. trilobite fossils
  • vertebrate origins
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2
Q

key questions

BIOLOGICAL PSYCHOLOGY

A
  • how/why do brains/beh change?
  • does it always have to be complex?
  • are there brain/beh features conserved across taxa/over evolutionary times?
  • what do brains/beh of animals reveal about ours/vice versa?
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3
Q

THE BRAIN: NAKED EYE

A
  • 15cm front to back (adult)
  • even the largest nerve cells are miniscule and need to be stained to be seen
  • cortex = 3mm thick
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4
Q

THE BRAIN: LIGHT MICROSCOPE

A
  • large nerve cell bodies = 100um (0.1mm) in diameter (x100 magnification)
  • large axons/dendrites are about 10um (.01mm) in diameter (x1000 magnification)
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5
Q

THE BRAIN: ELECTRON MICROSCOPE

A
  • synaptic ending = 1um in diameter (x10^4 magnification)
  • synaptic cleft between neurons = 20nm across (x10^5 mag)
  • neuronal membrance = 5nm (x10^6 mag)
  • ion channel diameter = .5nm (x10^7 mag)
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6
Q

BEHAVIOUR MODEL

A
  • beh can be observed/measured to directly/indirectly identify underlying mechanisms
  • evidence = either causal/of correlational nature
  • brain/neurons/muscles + evolution -> genetic/epigenetic inheritance + ecology = behaviour
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7
Q

TINBERGEN (1963)

A
  • showed why we should care about neuro/physiological mechanisms when studying beh via 4 explanatory lvls:
    1. PROXIMATE - description of mechanisms underlying beh in individual/group
    2. ONTOGENY - development of beh within individual lifespan
    3. PHYLOGENY - development of beh over generations/in dif populations
    4. ULTIMATE/FUNCTIONAL - adaptive sig/utility of beh for organism
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8
Q

MACHANISMS & ADAPTIVE FUNCTIONS OF BEHAVIOUR

A

PROXIMATE CAUSATION
ULTIMATE CAUSATION

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9
Q

PROXIMATE CAUSATION

A
  • during animal’s life-time
  • how is beh produced?
  • how does beh develop?
  • how is beh inherited?
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10
Q

ULTIMATE CAUSATION

A
  • over several generations
  • why has a beh developed?
  • what selective advantage does it provide?
  • what is the evolutionary history?
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11
Q

COMPARATIVE APPROACHES ROOTS

A
  • roots of comparative approaches/methods in beh/neuroscience research
  • focus on systematic comparisons by middle of 20th century
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12
Q

ETHOLOGY

A
  • “bio study of beh” (Tinbergen (1963))
  • “comparative study of beh which applies to beh of animals/humans” (Lorenz (1981))
  • ethological approach = animals observed in natural habitats/under ecologically relevant conditions; research focused on beh w/low interindividual variability ie:
    1. LOCOMOTION (walking/swimming/flying)
    2. SEQUENCES (courtship/copulation/fights)
    3. FAST RESPONSES (escape/collision avoidance/capture)
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13
Q

BEH = MOTOR OUTPUT

A
  • movement of dif parts of body (dif muscle groups/appendages/limbs/vocal cords/syrinx)
  • decision-making in neuronal mechanisms to switch between movements/actions
  • variable/stereotyped elements of motor patterns
  • rapid responses/oscillatory activity
  • coordination/sequences of motor patterns
  • aka. SEE W1 VIDEO NOTES
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14
Q

CLASSICAL ETHOLOGICAL STUDIES

A
  • fixed (elementary) actions/fixed action patterns (beh action sequences) = highly stereotyped beh responses (ie. greylag geese egg rolling)
  • vacuum activity = responses in absence of stimuli
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15
Q

TINBERGEN (1952): STICKLEBACKS

A
  • some beh patterns = stereotyped (fixed acts/action patterns); can be triggered by specific stimuli
  • sign stimulus (releaser) & releasing values
  • testing retrieval beh w/egg pairs; shape/size = critical cues
  • see W1 VIDEO NOTES
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16
Q

UNDERLYING MECHANISMS

A
  • releaser stimuli can trigger beh output
  • ie. herring gull chicks begging response; beak colour preferences
17
Q

ADVOCATING COMPARATIVE APPROACHES: HOPKINS

A
  • neuroethogists believe we can learn gen principles about nervous systems by specialised studying systems
  • they learn from animals that experience dif sensory world from our own
  • such qs derive introductory survey of neuroethology incl. exotic senses/motor progams/surprising integration
18
Q

ADVOCATING COMPARATIVE APPROACHES: PAPANIKOLOPOULOU

A
  • dorsophilia offer facile/economical whole animal system w/many homologous organs to humans/high functional conservation/established methods of generating/validating human disease models BUT…
  • remains relatively underused as drug discovery tool as its relevance to mammalian systems = questionable
  • recent exciting success stories using validation strongly suggest fly models should figure prominantly in drug discover pipeline
19
Q

ROOTS OF NEUROETHOLOGICAL RESEARCH

A
  • sign stimuli -> sensory pathway -> innate releasing mechanims (+ biorhythms + arousal inhibition) -> motor pathway -> muscles aka. fixed action pattern
  • early ethological concepts of mechanisms underlying beh patterns
  • neurobiology unravelling substrates for beh/plasticity
20
Q

BEH PHYSIOLOGY

A
  • study of localisation/release of stereotypes/elementary forms of beh in CNS (ie. von Holst (1939))
  • J. Segaar (1961) studies effect of brain lesions on fixed motor beh in 3-spined stickleback
21
Q

BEHAVIOURISM IN SCHOOLS OF EXPERIMENTAL PSYCHOLOGY

A
  • experimental psychology emphasised role of learning/individial experience that influences beh expression (ie. Skinner/Pavlov) BUT…
  • focus on input-output relations & discarding role of genetic/epigenetic factors/inheritance
22
Q

QUANTIFYING BEH W/COMPUTATIONAL TOOLS

A
  • machine vision algorithms allow to track fly & monitor posture of body/wings
  • high-throughout behavioural screening facilities study of role of genes in social beh in fruitflies (aggression/courtship)
23
Q

SYNAPTIC PROCESS

A
  • at synapses, neuronal signals are transmitted between neurons OR to target tissue/organ under neural control
24
Q

HODGKIN-HUXLEY MODEL (1952)

A
  • model of action potential
  • studies on giant axons of squids revealed basic properties of neural signals
25
Q

KANDEL (2000)

A
  • simple neuronal model of aplysia californica includes (20k neurons):
    1. buccal/cerebral/pleural/pedal/abdominal ganglion
    2. siphon
    3. mantle shelf
    4. parapodium
    5. gill
26
Q

ESCAPE BEHAVIOUR

A
  • stimuli -> afferent neurons -> interneurons/ganglia/brain -> efferent neurons = beh (aka. signal transmission)
  • reflex responses = very fast
  • may not require communication w/brain
  • synapse -> terminal ganglion -> abdominal segments -> nerve cord -> methathoracic ganglion
27
Q

HILL, WYSE & ANDERSON (2008)

A
  • centralisation/cephalisation in evolution of nervous system
  • neuronal interactions = very similar across animal kingdom; what differs = number of cells, connectivity complexity & nervous system structure
28
Q

WHY ARE BRAINS DIVERSE?

A
  1. COMPARATIVE NEUROANATOMY
  2. BEHAVIOURAL PHYSIOLOGY/NEUROETHOLOGY
  3. NEUROGENETICS
29
Q

COMPARATIVE NEUROANATOMY

A
  • study brain structures/neuronal connectivity in dif species of selected groups (taxon) within phylogenetic lineage
30
Q

BEHAVIOURAL PHYSIOLOGY/NEUROETHOLOGY

A
  • measure neural activity; link to beh responses w/consideration of dif tasks & species-specific adaptations
31
Q

NEUROGENETICS

A
  • identify neurons & brain areas from dif patterns of gene activity & link to dif tasks & beh responses
32
Q

NORTHCUTT (2002)

A
  • brain-body relations; larger bodies can grow/carry/sustain larger brains
  • concentrated brain evolution = size-associated variations/allometric effects within phylogenetic lineage (ie. enlargement of whole brain)
33
Q

HALLEY & KRUBITZER (2019)

A
  • mosaic brain evolution = selective size changes in some brain components
  • human/primate brains have very large neocortexs w/more areas/unique connectivities > other mammals
  • associated w/larger number of non-primary cortical areas
  • other areas ie. subcortical (dorsal thalamus) don’t change much in size
  • frontal brain enlargement including thalamus has occurred independently in various vertebrate groups
  • only largest rodent (capybara) has similar thalamus-to-neocortex as smallest primate
  • aka. dif evolutionary selection factors can affect only some brain systems and/or whole brain
34
Q

MEASURING NEURAL ACTIVITY

A
  • aka. intracellular recordings
  • can measure neuronal signals as dif in potential on each side of membrane (units/Volt) by creating electrical circuit w/wired electrodes:
    1. inserted inside (intracellular fluid) & outside (extracellular fluid) aka. the neuron
    2. placed close outside neuron (extracellular fluid) relative to other tissues elsewhere (extracellular fluid)
35
Q

ELECTROPHYSIOLOGICAL METHODS OF MEASURING NEURAL SIGNALS

A
  • placing electrodes in tissues/dissociated cells – intracellular/extracellular recordings of membrane potentials (single/multi-unit recordings aka. EMG)
  • placing electrodes on skin/scalp – extracellular recordings of membrane potentials (EEG; EMG)
  • optical methods to measure neural activity ie. optical imaging (Ca^2+imaging; fMRI; MRI; PET) measuring activation of processes correlated w/changes in membrane potential in neurons
36
Q

CAREW (2000)

A
  • dif ways to measure signals from motoneurons to a muscle at neuro-musclar junction:
    1. extracellular recording of multiple units
    2. intracellular recording from single motoneuron
    3. extracellular recording of multiple units from nerve tract (bundle of axons) w/hook electrodes
    4. intracellular recordings from muscle fibre
    5. EMG
37
Q

BONTONOU & THOMAS (2014)

A
  • sexual communication in drosophilia genus
  • Fru^m = responsible for orchestrating whole sequence of male’s courtship beh
  • Fru^m = allele of Fru expressed in males
  • Fru^f = allele of Fru expressed in females
38
Q

DROSOPHILIA: MANIPULATIONS OF NEURAL CIRCUITS UNDERLYING COURSHIP BEH

A
  • knock-out/inhibition of genes in neurons
  • knock-down/reversibly silence neurons in normally-beh transgenic flies (ie. change in ambient temperature illuminating w/UV-light)
  • generating/testing gynandromorphs (ie. fly w/mixtures of male/female brain tissues)
39
Q

MANOLI & BAKER (2004)

A
  • median bundle neurons coordinate beh during drosophilia male courtship
  • fru (fruitless) gene = only expressed in neurons; codes 4 proteins aka. regulatory genes (which control other genes)
  • GFP = green fluorescent protein; excited by blue/UV light; gene found in jellyfish & other cnidarians (corals/sea anemones); copepods (crustaceans); amphioxus (early vertebrates)

comparative approaches (10 decks)

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