PSYC 112 MIDTERM

Neuroethology

The study of the neural basis of natural behavior; combines neuroscience, ecology, and animal behavior.

Goal of neuroethology

To understand how animals produce natural behaviors and discover general principles of brain function.

Model system

An animal with specialized adaptations used to study general principles of nervous system function.

Krogh Principle

For almost every biological problem, there is an ideal animal model to study it.

Tinbergen's Four Questions

Function, Causation, Development, Evolution.

Function (Tinbergen)

How does the behavior increase survival or reproductive success?

Causation (Tinbergen)

What stimuli trigger the behavior and what neural mechanisms produce it?

Development (Tinbergen)

How does the behavior change with age and experience?

Evolution (Tinbergen)

How did the behavior evolve compared with related species?

Command neuron

A neuron whose activation is sufficient to trigger an entire behavior.

Crayfish escape response

Rapid tail flip used to escape predators.

Tail flip behavior

Rapid (<0.2 sec) flexion of the abdomen away from the stimulus.

Lateral Giant (LG) escape

Triggered by stimulation of the tail; causes forward escape.

Medial Giant (MG) escape

Triggered by stimulation of the head; causes backward escape.

Coincidence summation

Multiple excitatory inputs arrive simultaneously and sum to reach threshold.

Why is coincidence summation important?

Prevents accidental activation of escape behavior.

Chain reflex

A sequence of linked reflexes that together produce a coordinated escape response.

Behavioral modulation of escape

Crayfish increase escape threshold while feeding to avoid interrupting feeding.

Receptive field

The region of sensory space that influences the firing of a neuron.

Visual receptive field

Region of visual space where a stimulus changes a neuron's activity.

Auditory receptive field

Range of sound frequencies that activate a neuron.

Simple cell

Receives converging input from many LGN neurons; responds to oriented edges at a specific location.

Complex cell

Receives converging input from many simple cells; responds to oriented edges regardless of exact location.

Hierarchy of visual processing

Retina → LGN → Simple cells → Complex cells.

Feature selectivity

A neuron responds best to a particular feature such as orientation, shape, color, or frequency.

Hierarchical processing

Simple information is combined into more complex representations.

Parallel processing

Multiple types of information are processed simultaneously in separate pathways.

Rate code

Information is represented by the firing rate of neurons.

Temporal code

Information is represented by the precise timing of action potentials.

Bat echolocation

Bats emit ultrasonic calls and analyze returning echoes to locate prey.

Why are ultrasonic frequencies used?

They provide high spatial resolution for detecting small prey.

A1 receptor neuron (moth)

Highly sensitive receptor that detects distant bats and triggers steering away.

A2 receptor neuron (moth)

Less sensitive receptor activated by nearby bats; triggers emergency escape.

Moth response to distant bat

Turn away from the bat.

Moth response to nearby bat

Erratic diving or last-second evasive maneuvers.

Evolutionary arms race

Continuous evolutionary adaptations between predator and prey.

Barn owl facial ruff

Collects and funnels sound toward the ears.

Barn owl asymmetrical ears

Right ear points upward; left ear points downward to improve elevation detection.

Azimuth

Horizontal position (left-right).

Elevation

Vertical position (up-down).

Barn owl localization accuracy

Approximately 1–2 degrees.

Interaural Time Difference (ITD)

Difference in arrival time of sound between the two ears.

ITD is mainly used for

Determining azimuth (left-right location).

Interaural Intensity Difference (IID)

Difference in sound intensity between the two ears.

IID is mainly used for

Determining elevation (up-down location).

Auditory map

A neural representation of sound locations in space.

How are auditory maps formed?

By combining ITD and IID information through converging neural pathways.

Experience-dependent plasticity

The nervous system changes in response to experience.

Ear plug experiment in owls

Young owls gradually relearn sound localization using vision after ear plugs shift auditory cues.

Why is vision important in ear plug experiments?

Vision recalibrates auditory localization.

Prism experiment

Prisms shift the visual field while auditory cues remain unchanged.

Effect of prisms on young owls

Young owls recalibrate sound localization to match shifted vision.

Effect of prisms on adult owls

Adults show little or no auditory plasticity.

Sensitive period

A developmental period when experience strongly influences neural development.

Critical period

A developmental period after which plasticity greatly decreases or stops.

Difference between sensitive and critical periods

Sensitive period = greatest capacity for change; Critical period = end of lasting plasticity.

Knudsen & Knudsen (1990) main finding

Vision calibrates auditory localization during development.

Young owls exposed to prisms

Showed large changes in sound localization.

Older owls exposed to prisms

Showed much smaller changes in sound localization.

Why does visual calibration occur?

Vision provides accurate spatial information that teaches the auditory system.

Fixed Action Pattern (FAP)

An innate, stereotyped sequence of behaviors triggered by a specific stimulus.

Toad prey capture sequence

Orient → Approach → Fixate → Snap.

Sign stimulus

A specific stimulus that triggers a behavioral response.

Releasing mechanism

The neural interface between a sign stimulus and a fixed action pattern.

Feature detector

A neuron or group of neurons selective for a particular stimulus feature.

Ewert's experiment

Used moving dummy stimuli to determine which visual features trigger prey-catching.

Preferred prey stimulus for toads

A long horizontal moving object ("worm").

Antiworm stimulus

A vertical moving object that rarely triggers prey capture.

Large moving object response

May be interpreted as a predator and trigger escape.

Small moving object response

Interpreted as prey and triggers feeding.

Releasing value

The effectiveness of a stimulus in eliciting behavior.

What determines prey recognition in toads?

Shape, orientation, size, and movement of the stimulus.

Excitation vs inhibition in toads

Behavior depends on the balance between excitatory and inhibitory neural pathways.

Why are barn owls excellent model systems?

They have extremely accurate sound localization and specialized auditory adaptations.

Why are crayfish excellent model systems?

They possess simple, identifiable escape circuits.

Why are bats excellent model systems?

They have specialized echolocation systems.

Why are toads excellent model systems?

They exhibit simple visually guided prey-catching behaviors.

Convergence

Multiple neurons synapse onto one neuron to create more complex responses.

Adaptive plasticity

The ability of neural circuits to change in response to experience.

Sensory map

An organized neural representation of sensory information.

Why is neuroethology important?

It reveals general principles of nervous system organization by studying specialized animal behaviors.