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Neuroethlogy NROC34

• Prof. A. Mason• e-mail:

– amason@utsc.utoronto.ca– s_sen24@hotmail.com

– subject = NROC34• Office Hours: Friday, 1 – 4:00 pm, SW566• Weekly Readings: download from course webpage

www.utsc.utoronto.ca/amason/courses/coursepage/syllabus2012.html

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Course Goals

• What is neuroethology?– Role of basic biology– Model systems (mainly invertebrate)– Highly specialized organisms– Biomimetics

• Primary literature and the scientific process– No textbook– But if you really want one, there are a couple of suggestion on the

syllabus• Basic principles of integrative neural function

– More on this a bit later

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How?

• Case studies of several model systems– Different kinds of questions– Different kinds of research (techniques)– Sensory, motor, decision-making…

• Selected papers each week– Read before, discuss during: usually readings are

challenging and “discussion” means me explaining (so don’t be discouraged)

• Most topics include current work– Take you to the leading edge of research in selected

areas

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Evaluation

• Weekly readings 5%• Mid-term 35-45%• Final Exam 45-60%• Presentation (optional) 10%• Weekly reading marks: each week several

people will be selected at random to contribute 3 questions about the papers.

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Information

• Who are you people?• What do you expect to learn in this course?• What previous course have you taken in:

– neuroscience– Behaviour

• Is this a req’d course for you?

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Neuroethology

• The study of the neural mechanisms underlying behaviour that is biologically relevant to the animal performing it.

• This encompasses many basic mechanisms of the nervous system.

• Combines behavioural analysis and neurophysiology

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Neurobiology• What do I mean by “integrative neural function”?• What does the nervous system do?

– detect information in the environment– process the information to select appropriate behaviour– generate the appropriate behaviour

• How does the nervous system work?• Why does it work that way?

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Behavioural Science

• Ethology– biological behaviour– natural contexts– Lorenz, Tinbergen,

Von Frisch share Nobel Prize 1973

• Psychology– abstract concepts (e.g.

learning, memory)– controlled conditions

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Environment Organism

physiology

Sensory Stimuli Adaptive Behaviour

nervoussystem

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Senory input

Neural processing

Motor output

Information from the environment

Integrate & analyse multiple inputs

Activate muscles etc. to create actions

The flow of information through the nervous system is the connection between stimulus and response.

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HISTORYPsychology, Ethology & Neurobiology

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Behaviour• Early approaches

– subjective, anecdotal, antrhopomorphic• Darwin

– supplied a functional interpretation; did not have the immediate effect of stimulating more objective methods, but ultimately led in this direction.

– In the 20th century, application of objective methodology led to the development of scientific studies of animal behaviour in two major directions

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Behaviour

• Psychology– Concentrated on a reductionist analysis in

controlled (laboratory) conditions – Ivan Petrovich Pavlov and conditioned

reflexes– Burrhus Frederic Skinner and operant

conditioning

Behaviorist / comp. psych.13NROC34 2012:1

Pavlov’s dog

Skinner’s “Heir Conditioner”

Two main ideas:LearningStimulus‐response

Skinner Box

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Behaviour

• Ethology– Emphasized natural (or seminatural) condition

and behaviours– Konrad Lorenz– Niko Tinbergen– Concentrated on "innate" behaviours. Fixed

action patterns, innate releasing mechanisms, action-specific energy, etc.

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e.g. graylag goose egg-rolling

Any vaguely egg‐like object will do…Sign Stimulus (Innate Releasing Mechanism)

Innate Behaviour: nature/nurture debate

Entire sequence always completed once it starts…Fixed Action Pattern

EthologicalNROC34 2012:1

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e.g. digger wasp homing behaviour

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Behaviorism

• Habituation/dishabituation• Classical conditioning• Operant conditioning• Formation of new stimulus-response

connections (or modification of existing ones) -- Learning

Behaviorist / comp. psych.NROC34 2012:1

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Ethology

• Traditional ethology identifies “innate” or “natural” connections between stimuli and responses.

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These are old-fashioned concepts.

Behaviour is almost always much more complex.

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Back to the nervous system...• There are built-in mechanisms, activated by

external stimuli, that generate the resulting behaviour.

• Something changes as a result of experience that causes a modification of behaviour.

• Both indicate there is something that could be identified in the nervous system that represents the physical basis of the behavioural phenomenon.

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Neurobiology• Traditionally disconnected from behaviour.

– Anaesthetized animals (or pieces of them)– Properties of small elements of the nervous system

• But there were some early efforts at inferring broader functions. – Charles Sherrington's Integrative Function of the Nervous System – emphasized reflexes as a fundamental functional unit– nervous system acting to coordinate the action of many local

reflexes (ie stimulus/response relationships) to guide to result is overall goal-directedness of behaviour

– Higher mental functions and emotions beyond the reach of mechanistic analyses.

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Other influences• Jakob von Uexküll

– Umwelt– Interested in the animal’s

“point of view”– Origins of the integrative

view?

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Just as morphological adaptations evolve to match an organism to its environment...

Neuroethology

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…the structure and physiology of the nervous system have evolved to match behaviour and context.

http://www.artsci.uc.edu/collegedepts/biology/fac_staff/buschbeck/strepsiptera.aspx

Neuroethology

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Relating nerve cells to behaviour(the super-simplified view)

• Nervous system is composed of neuronsthat share certain basic features.

• Basic features of neurons are common across all animals.

• Electrical activity is the currency of the nervous system.

Neurophysiology Review

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Measuring and manipulating electrical activity in neurons

intracellular recording

electrodeamplifier Volts- +

time

mV

penetration

0-65

Neurophysiology Review

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Membrane potential

Semi-permeable membrane,

opposing electrical and chemical gradients,

potential difference across membrane (inside negative re. outside)

Neurophysiology Review

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Action potential

Electrical impulse that propogates along a neuron

Neurophysiology Review

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Synaptic transmission

Neurophysiology Review

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Excitatory = depolarizing; tending to make post-synaptic cell fire an action potential

Inhibitory = hyperpolarizing; tending to stop post-synaptic cell from firing an action potential

Neurophysiology Review

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Function of the nervous system depends on...

• Connectivity (interconnections between neurons)

• Intrinsic properties of neurons

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Connectivity

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Connectivity

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Connectivity

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Connectivity

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Intrinsic Properties

Tonic

Phasic

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Modulation & Plasticity

(Aplysia…)

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Behaviour + Neurophysiology

• “Natural” behaviour- What the nervous system is “designed” to

produce

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Identifying the neural basis of behaviour

• Correlation– what neural activity is reliably associated with

particular stimuli and/or responses?• Necessity

– if neural activity is suppressed, is behaviour also suppressed?

• Sufficiency– if neural activity is generated artificially, does it

result in behaviour?

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Correlation

Necessity

Sufficiency

e.g. crayfish tailflip

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Crayfish tail-flip circuitry

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Senory input

Neural processing

Motor output

Information from the environment

Integrate & analyse multiple inputs

Activate muscles etc. to create actions

The flow of information through the nervous system is the connection between stimulus and response.

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Senory input

Motor output

Information from the environment

Integrate & analyse multiple inputs

Activate muscles etc. to create actions

Neural processing

Neural Circuitry

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August Krogh

• Krogh’s Principle: “For a large number of problems there will be some animal of choice on which it can be most conveniently studied.”

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Invertebrates

Diverse and Specialized

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Invertebrate nervous systems

• Ventral• Distributed, ganglia and connectives• Large neurons• Relatively simple circuits (“identified

neurons”)• Very robust

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Distributed, ventral CNS

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Large Neurons

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Identified Neurons

N. Hatsopoulos, F. Gabbiani and G. Laurent (1995). Elementary Computation of ObjectApproach by a Wide Field Visual Neuron, Science,270:1000-1003.

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Very robust

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• Detailed analyses• Fundamental mechanisms

– neurophysiology– neuroethology - link between behaviour and

underlying mechanism• Understanding and application...

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Fundamental MechanismsCaenorhabditis elegans

959 cells

(302 neurons)

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It’s not only invertebrates

ToadFrog

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Applications

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Topics• Hearing

– Cricket phonotaxis• Vision

– Bee navigation– Fly motion detection

• Olfaction– Locust smell processing

• Pattern generation– Neural networks

• Others?– Electroreception– Echolocation – Robotics