3 - Bats and Bisonar Flashcards
(18 cards)
What method do bats use to detect prey and avoid obstacles?
Echolocation (sonar)
Bats emit ultrasonic sound pulses and use the returning echoes to identify their surroundings.
What type of sound call does the mustache bat emit?
A call with a Constant Frequency (CF) component followed by a frequency-modulated (FM) downsweep
This combination helps in effective echolocation.
What is the primary auditory cortex (A1) specialized for in bats?
Processing sounds and their echoes
A1 has enlarged regions dedicated to different types of sound analysis.
Which acoustic features do bats detect?
- Distance to the target (FM-FM)
- Relative velocity of target (CF-CF)
- Detailed frequency analysis of target (DSCF)
Each feature is processed in distinct regions of A1.
What happens to bat calls as they approach a target?
Bats emit shorter calls at a higher rate
This adaptation enhances their ability to detect and recognize objects.
Who first recorded ultrasonic sounds emitted by bats?
Donald Griffin
He showed that the rate of pulse emission increases as bats approach objects.
What is echolocation?
The ability of bats to use emitted sounds and their echoes to avoid objects and detect prey
This behavior was discovered by Donald Griffin.
What are the two types of signals used by bats in echolocation?
- CF signals – longer pulses at a very narrow frequency
- FM sweeps – pulses that traverse a wide range of frequencies
These signals serve different purposes in detecting and analyzing prey.
What does the distance to a target depend on in echolocation?
The time between emitted pulse and returning echo
Rapid FM sweeps are effective for this measurement.
How do bats compute relative velocity of their prey?
By analyzing the Doppler shift of echo frequencies
CF signals are particularly useful for this sensitive analysis.
What does a higher frequency echo indicate to a bat?
The bat is gaining on the target
A lower frequency echo indicates the target is moving away.
What is the significance of the Doppler shift in bat echolocation?
It provides information about both the relative velocity of prey and its fine structure
This includes details such as the wingbeats of insects.
What is the ‘acoustic fovea’ in bats?
The area in A1 with the lowest threshold and the narrowest tuning curves
It is where bats are most sensitive to specific frequencies.
How do bats solve the problem of Doppler shift compensation?
By lowering the frequency of their call
This helps prevent echoes from falling outside their most sensitive range.
What is parallel processing in bat auditory cortex?
Functional specialization in A1 for different auditory tasks
Distinct regions process emitted sounds and their echoes.
What type of neurons are found in the FM-FM region of A1?
Neurons specialized to respond to particular combinations of pulse and echo
These neurons act as feature detectors.
What is hierarchical organization in bat auditory processing?
Combination-sensitive neurons are formed through a mix of serial and parallel processing
Lower brain areas project to higher areas with complex response properties.
What does the term ‘feature detectors’ refer to in bat auditory processing?
Neurons that respond to specific combinations of auditory information
They help bats interpret complex acoustic environments.
