עבוד אותות במערכת החושים סמסטר א' תש"ע Lecture 6 *Virtual

Action Potentials

Neural Activity:

Spontaneous Neural Activity (1) Stationary ……

Spontaneous Neural Activity (2) Correlation

Spontaneous Neural Activity (3)

Spontaneous Neural Activity (4) The spontaneous neural activity can be described as: A stationary, renewal process. The length of successive intervals are statistically independent. Thus The probability density function of interval length describes the process

Spontaneous Neural Activity (5)  - Interval length N(0,T) – number of spikes in the interval T

Spontaneous Rate

Post Stimulus Histogram

Neural Activity: Response to Click

Neural Activity: Response to a Tone

Single Fiber Tuning Curve  Characteristic frequency (tip)  Tail  Difference in slope between the low frequency and high frequency sides  Shaded area is the response area לנוירונים יש רגישות אופטימלית לתדירות מסוימת – תדירות אופיינית - CF

 ה - Tuning curve של נוירונים עם CF בתדר הנמוך הם יותר סימטריים משני צדי ה - CF.  ה - Tuning curve של נוירונים עם CF בתדר הגבוה הם יותר צרים מאלה של התדרים הנמוכים . ה - Tuning curve של נוירונים עם CF בתדר הגבוה יש להם שוליים רחבים כלפי התדרים הנמוכים מה -CF. וכלפי התדרים הגבוהים השוליים מאוד צרים וחדים. The shape of tuning curves of auditory nerve

Tuning Curves from Single Fibers Throughout the Length of the Basilar Membrane

Neural Response as a function of Level

This figure shows the input-output function of a single fiber. Notice that the firing rate of the neuron increases as the stimulus intensity increases within its dynamic range, and eventually plateaus. Input-Output Function of a Single Auditory Nerve Fiber

In general, the auditory nerve fibers that have higher levels of spontaneous activity (HSR), have lower thresholds and lower saturation points. The fibers that have lower levels of spontaneous acitivity (LSR), have higher thresholds and higher saturation points threshold saturation Auditory nerve rate-intensity functions

Neural Activity: Response to Speech