Section 1 summary:•Input specialization

•Domain specific transduction •Fovea

•Receptive fields •Spatial position on the sensory array encodes information•Cells also have receptive fields

•Typically center surround•Strictly speaking these don’t have to be round

•Tuning•Specificity of tuning relates to the specificity of the task

•Narrow tuning: highly specific task •Filters/amplifies sensitivity

•Maps•There is an organization of all sensory input

•Topographic integrity: the physical organization of stimuli on the sensory array is mantained in the CNS•From point to point in processing •Sensory alignment (feature analyzers)

•Abstraction •Raw sensory input is decomposed into “featural elements”

•Feature analyzers•Featural elements are reassembled into ever more complex representations (perception)

•Coincidence detection•The basis of information processing•May require delay lines

Lecture 1Lecture 2

Male cricket reproductive behaviors

3 male song types:•Calling•Courtship•Aggressive

*Females don’t sing

Intraspecific communication

Male crickets produce context specific songs:•Calling: attraction of distant females/advertisement of male potential quality•Courtship: female/s near male advertises potential quality•Aggressive: Male is attempting to establish/maintain territory in the presence of another male

Factors that negatively affect male song success (i.e. noise)•Intraspecifc competition (males against males)•Sympatric noise (closely related species)•Nonspecific noise (e.g. cars, trucks, wind)•Distance and dampening

Intraspecific communication requirements:•Sender & receiver share common coding/decoding system•Sympatric codes must be unique

Intraspecific communication

Male Stridulation: Wing anatomy

Male Stridulation: Sound production

•Sound is produced during the wing closing movement

•Produced by the scraper (or plectrum) rubbing against the file

•Each ratchet of scraper and file creates one cycle of the sound wave

•Carrier frequency produced is dependent on the physiology of scraper, file, muscle etc.

•Carrier frequency is relatively species-specific.

•One “click” or ratchet = one wave cycle•Flexing of harp amplifies signal

•Harp resonates at the “carrier” frequency

•Thus the 3 components (scrap, file and harp) have coevolved to produce an amplified species-specific “carrier frequency” signal

Male Stridulation: Sound production

Resonance frequency amplifies

Male Stridulation: “Song anatomy”

A number of variables make song species-specific:

•Carrier frequency

•Pulse width

•Chirp shape

•Chirp rate

•Inter-chirp-interval (chirp period)

•Trill length and variability

“Envelope”

tropical house cricket (Gryllodes sigillatus)

house cricket (Acheta domesticus)

sand field cricket (Gryllus firmus)

Male Stridulation: Calls are species-specific

Male Stridulation: song production physiology

•2 muscles involved in stridulation:•M90 (closer)•M99 (opener)

•Systematic delay between motor neuron AP and sound production.•Antagonistic activity between M90 and M99 produce the back and forth movement.•Movement pattern is specific to call type.•The rhythmic movements of stridulation can occur without a head.

Male Stridulation: song production neuro-physiology

Metathorasic ganglionMesothorasic ganglionProthorasic ganglion

Meso- and metathorasic cell activity during stridulation

head

tail

Single cell

Nerve bundle

Single cellNerve bundle

Brain stimulation mediates specific song patterns

Brain stimulation produces song that is consistent with normal structure

Given stimulation in the same place but at different amplitudes and frequencies you can elicit different song

Male Stridulation: stimulation and lesions and song production

Lesion experiments:•Stridulation occurs in absence of head•Song production does not•Lesioning meta TG disrupts coordination between L and R wing•Lesioning meta and meso TG results in no movement of ipsalateral wing•Lesioning meta from meso TG does not affect coordination.

Model of song production

Meso TG

Meta TG

Stimulation experiments:

•As mentioned stimulation of brain (i.e. MB) can elicit song

•Stimulation of a single descending neuron can elicit song

•Song type again dependent on stimulation frequency and amplitude

•Hyper polarization of descending neuron can stop song.