Brain and behavior

What are the two main components of the human nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

What cells make up the nervous system?

Neurons and glial (support) cells.

What are the main types of neurons?

Sensory neurons, motor neurons, and connector (interneurons).

What is cephalisation?

The development of a head region with a central nervous system (CNS).

Which phyla have nerve nets instead of brains?

Cnidarians (e.g., jellyfish, Hydra).

What does the fossil Alalcomenaeus tell us?

It had an early CNS ~520 million years ago, showing advanced neural structures.

What is the fundamental unit of the nervous system?

The synapse

What precedes the formation of synapses evolutionarily?

Synaptic proteins were present in single-cell organisms for cell communication.

What is behaviour?

An internally generated response to internal or external stimuli.

Can behaviour evolve?

Yes, it can evolve through natural selection as it is heritable, variable, and fitness-related.

What are Tinbergen's 4 questions?

• How does it work?

• How does it develop?

• How did it evolve?

• What is its adaptive value?

What field uses Tinbergen’s questions to study behaviour?

Behavioural ecology

How is birdsong learned?

Through early exposure to an adult “tutor”.

What is the adaptive value of birdsong?

Attracting mates, repelling rivals, and marking territory.

What defines sleep behaviourally?

• Quiescent state with reduced responsiveness.

• Rapid reversibility.

• Sleep rebound if deprived (homeostasis).

Do all animals sleep?

Sleep-like states are observed in all studied animals, including jellyfish and fruit flies.

What regulates sleep?

Fatigue (homeostatic sleep pressure), circadian rhythms, light, and genetics.

When is sleep duration highest

During early development.

What types of sleep are seen across development?

NREM and REM sleep, both present in humans and other species.

What does sleep across species suggest?

Sleep is ancient, conserved, and functionally critical.

What systems are required for sleep behaviour?

Nerve cells are required, but not necessarily a brain or CNS.

What are the core functions of sleep?

• Metabolic coordination and restoration

• Energy conservation

• Synaptic plasticity and memory

• Immune function and waste clearance

Why is sleep considered essential?

Its persistence despite vulnerability suggests vital evolutionary importance.

Quote:
"If sleep doesn't serve a vital function, it's the biggest mistake evolution ever made."
— Allan Rechtschaffen

What does the heritability of tameness in foxes demonstrate?

Behavioural traits like tameness can evolve through selective breeding.