Neural Control of Behavior

Stimulus-Response A male bee copulating with a female of his species, and attempting to copulate with the author’s thumb. Object of correct size and general shape elicits landing, touch receptors send message to centers (brain) that trigger a mating program of coordinated muscle activity.

Stimulus-Response The study of how neurons sense the environment and convey a coordinated response to conditions—behavior—began with Niko Tinbergen. Stimulus: parent’s beak Response: pecking the beak. Reward: food regurgitated. Similar: goose egg retrieval (continues even after the egg is removed)

Neural Processes Use sensory systems to detect the stimulus Visual, auditory, tactile… Central computation or representation Access memory, risk-reward, etc. Motor decision and response Approach, avoid, mate, beg, hide, run… Muscle contraction and movement Outcome of response: Learning Contrast to instincts

Some terms Instinct: a behavior pattern that appears in a fully functional form the first time it is executed Chick pecks parent beak Innate Releasing Mechanism Detect sign stimulus the “releaser” Parent beak Initiate fixed action pattern (FAP) Pecking at the beak

Example of Innate releasing mechanism

Discussion Question Males of various beetle species will try to copulate with everything from beer bottles to large yellow signs.

Discussion question Use ethological terms to identify the releaser, the fixed action pattern, and the innate releasing mechanism. Develop an ultimate hypothesis for why this occurs, even though the beetles often die rather than leave the inanimate object upon which they sit.

Code Breaking One species “learns” to mimic another so as to exploit it Flowers attract bees to aid in pollination Butterfly larvae secrete chemical cues identical to ants, get the ants to take care of them until they can undergo morphogenesis Called a deceptive signaler Such predictable behavior patterns can be taken advantage of if their rules can be deciphered by another animal/species

Alcon blue butterfly larvae are deceptive signalers CUE RECEPTOR SIGNAL SYNAPSES RESPONSE

Neural command centers Behavioral choices Prioritization of drives How is the nervous system organized so that conflicts don’t occur? Multiple command centers with ability to detect releasers and activate responses. Hierarchical relationship with other centers

Behaviors: search for mates sunbathe copulate fly dive away from bats catch food Lying motionless until visual system detects the presence of prey, the the mantis makes fast and accurate grasping response with the front legs to get the prey and bring it to the mouth. Muscle control is the property of each ganglion. Severing the ganglion abolished responses when the NS was active elsewhere, but electrical stimulation of the neurons in the severed ganglion elicited normal movements for that segment.

Role of the brain? The protocerebrum is inhibitory to the ganglia --Disconnecting the protocerebrum from the rest of the NS resulted in mantis’ that attempted to walk and grasp at the same time Not good Subesophogeal ganglion is the primary target of PC inhibition because when it and the PC are severed, mantis’ do not move at all A stimulus would lead to activation of part of the subesophogeal ganglion leading to selective disinhibition of certain command centers and an appropriate response

Neural circuit of mantis Stimulus receptor PC SEG ganglia However, mating is not abolished in this headless male who still coordinates a twisting copulatory attempt on the back of this intact female mantis.

Discussion Question Inhibitory neural messages play a key role in organizing animal behavior. Mature female crickets approach calling males. About 1 hour after mating, during which the male deposits a spermatophore on his partner, the female stops responding to males. If you found that removing the spermatophore reinstated the female approach response, speculate on how the nervous system controls this behavior. How might inhibitory signals be involved? What is the adaptive significance of this behavior?

Feedback inhibition in the blowfly Stretch receptors in the foregut of this fly send signals to the brain to inhibit drinking when the gut is full. If one severs the recurrent nerve (gut to brain), the fly does not stop drinking and eventually blows up.