Information flows from the environment, through animals, and back to the environment:

Environment - Organism - Behavioral output - Environment

 **INFO TRANSFER TEXT**

**NEURON TEXT**

Information flow WITHIN the animal's body is controlled almost entirely by special cells called neurons.

Nearly all behavioral actions are directed by neurons.

**GENERAL NEURON STRUCTURE**

**DIVERSITY OF NEURON STRUCTURE **

Neurons function by transmitting a simple electrical signal that moves in one direction. The signal is called an Action Potential.

Cannot modify direction or strength of signal. Can modify timing of signals.

Neurons communicate with each other across synapses: There is a diversity of neurotransmitters and electrical (gap junction) connections. Synaptic signals can be excitatory or inhibitory.

**SYNAPTIC STRUCTURE**

**MULTIPLE SYNAPSES TO ONE CELL AND DIVERSITY OF SYNAPSE TYPES**

How to study neuronal function: Can record electrical impulses from one neuron and correlate neuronal firing with behavior.

**EXCITATORY/INHIBITORY PSP AND SPIKES**

 It is possible to experimentally manipulate neurons in several ways.

-Stimulate: Electrically or Chemically

-Cut

-Anesthetize

**ELECTROANTENNAGRAM SETUP**

Nervous system architecture

Sense organs- Sensory neurons -Interneurons- Motor neurons - Effectors (muscles, glands)

**VERTEBRATE NERVOUS SYSTEM LAYOUT**

**INVERTEBRATE NERVOUS SYSTEM LAYOUT**

The brain does not organize all behavior:

-Reflex arc

-Mantis copulation; Headless fly learning

**INSECT CEPHALIZATION**

**MANTIS COPULATION**

Higher levels of nervous system complexity:

Specific nerves (groups of axons) convey particular information to/from CNS. Specific regions of CNS (especially in the brain) regulate specific aspects of behavior.

**NEUROANATOMY TEXT**

One set of approaches to studying the function of larger neural structures is to use histology- visualization, usually through staining, of neuroanatomy. The relative size or development of structures is often an important measure.

Neural structures can be compared among species with different behavioral capabilities, or among individuals from different behavioral classes.

Examples: Seed caching and spatial memory and relationships with the size of the hippocampus in birds; sex differences in hippocampus size related to nest visiting; task associated differences in social insect brain structure; seasonal changes in bird song nuclei.

**HIPPOCAMPAL VOLUME/SEED STORING**

**COWBIRD SEX DIFFS. IN HIPPOCAMPUS**

**POLYBIA BRAINS**

**POLYBIA BRAIN VOLUME**

**SONG NUCLEI DIAGRAM**

**SONG NUCLEI CHANGE DATA**

A more direct method of locating neural function in space and time is to use functional imaging. Nervous system activity is correlated with behavioral output.

**MRI MAGNET**

**MRI DATA PHOTOS**

**BEE BRAIN FUNCTIONAL IMAGE**

**GENETICS TEXT**

Genetics: Transfer of information across generations. Using modern techniques we can test for genetic effects on behavioral variation among individuals (classical approach to behavioral genetics), and we can examine patterns of gene expression within and among individuals (developmental genetics).

One approach to studying genetic effects on behavior is to correlate the possession of certain genes with the expression of behavioral traits.

**HUNTINGTON'S PEDIGREE**

We can also try to identify differences in gene expression that are associated with behavioral differences.

**MICROARRAY METHODS**

**MICROARRAY DATA PLOT**

**GENE PRODUCTS STAINING**

**SENSE ORGANS TEXT**

A final consideration: Limits imposed by design of sense organs. Every species (perhaps every individual) lives in its own sensory world.

***BARN OWL EARS***

**FLY COMPOUND EYES***

**JUMPING SPIDER EYES** 

**NIGHT MONKEY EYES**

**BAT EARS**

**LANTERN FISH LIGHT**

**ELECTRIC FISH**