University:
Binghamton University
Course:
BIOL 313 | Cellular Neurobiology
Academic year:

2024
Views:

315

Pages:

2
Author:

CrystalMintah

Cellular Neurobiology November 20th, 2024: Sound Localization Delay Line Mechanism for Low-Frequency Sound Direction ● Coincidence Detector Neurons: 1. Neurons fire only when they receive simultaneous input from both ears. 2. Both ears contribute inputs to neurons in the circuit. ● Mechanism: 1. Right Ear Stimulus First: ● Action potential (AP) is generated and travels along neurons in the array. ● Sound takes time to travel from the right ear to the left ear. 2. Left Ear Contribution: ● AP from the left ear reaches neuron A simultaneously with the sound wave traveling to the left ear. 3. Neuronal Response: ● Neuron C responds to sound coming from straight ahead. ● Neuron E responds to sound primarily from the left ear. Amplitude and Localization of High-Frequency Sounds ● Characteristics of High-Frequency Sound: ● Lower energy compared to low frequencies. ● Attenuates more over distance and as it passes through the head. ● Localization Mechanism: ● Intensity Difference: ● Amplitude decreases across the head, creating differences in cochlear neuron activation. ● Left ear neurons receive a larger stimulus compared to the right ear. ● Synaptic Summation: ● EPSPs (excitatory postsynaptic potentials) from the left ear outweigh IPSPs (inhibitory postsynaptic potentials) from the right ear. ● Result: Neuron fires, signaling the brain that the sound originated from the left. Motor Systems and Movement Generation: Patellar Stretch Reflex: 1. Mechanism: ● Tapping the tendon below the patella causes the muscle to stretch. ● Sensory neurons detect the stretch and stimulate motor neurons. ● Result: Muscle contraction restores its original length. ● Detected by the muscle spindle organ . Its axon to the CNS is the la afferent.