Beauchamp:Adaptation

The goal of these experiments is to assess the effect on the LFP response to a stimulus when that stimulus is immediately preceded by an identical or similar stimulus.

Multiple-Repetitions Adaptation
Two stimulus categories: 20 selective stimuli (represented below by letters other than X) and 20 nonselective stimuli (represented by letter X) Randomly inserted in each de-adapting block is the stop-sign stimulus. The patient's task is to press a button every time the stop-sign appears. Design: 1) X X X X X X X X  -   de-adapting block 2) A A A A A A A A -  Multiple-repetition adaptation 3) X X X X X X X X  -   de-adapting block 4) B C D E F G H I-  Cross adaptation (8 different selective stimuli displayed in a row) Repeat 20 times. Stimuli are randomized for each block. Notes: --Stimuli are shown at 2 Hz for 125 ms. -- We expect the LFP to adapt most from the first to the second presentation. Optional variants: A B A B A B A B - Alternating Adaptation (2 different selective stimuli alternated back and forth) A X A X A X A X - Time course of adaptation (Repetitions of a selective stimulus interleaved with nonselective (de-adapting) stimuli. By varying the number of interleaved nonselective stimuli, we can assess how long it takes for the adaptive effect to disappear.

Identical-Stimulus
Stimuli: Two sets 1)	adapting stimulus (A) – a high-response stimulus which we expect to demonstrate LFP adaptation 2)	Intervening stimuli (X)– 15 unresponsive stimuli which de-adapt neurons Design: Six-block modules 1)	X X X X X X X – De-adaptation block 2)	A A X X X X X– a direct repeat of A, and 5 intervening stimuli 3)	X X X X X X X – De-adaptation block 4)	A X X X X – Single-presentation of A serves as a control condition 5)	X X X X X X X – De-adaptation block 6) A X X X X X A - A, five intervening stimuli, and another A Miscellani •	2 Hz stimulus presentation time – 500 ms ISI •	One run = 30 modules = 180 blocks •	1 block = ~10 second; 1 run = 18 minutes •    One of the X stimuli is a stop-sign, and the patient is told to press a button every time a stop-sign appears

Within-Category
Stimuli: Two sets 1)	adapting stimuli (A and B) – Two high-response stimulus in the selective category 2)	Intervening stimuli (X)– 15 unresponsive stimuli which de-adapt neurons Design: Twelve-block modules 1)	X X X X X X X – De-adaptation block 2)	A B X X X X X– A -> B, Quantifies adaptation effect of A on B 3)	X X X X X X X – De-adaptation block 4)	A X X X X X – Single-presentation of A serves as a control condition 5)	X X X X X X X – De-adaptation block 6)   A X X X X X B - Quantifies adaptation effect of A on B with 5 intervening trials 7)	X X X X X X X – De-adaptation block 8)	B A X X X X X– B -> A, Quantifies adaptation effect of B on A 9)	X X X X X X X – De-adaptation block 10)	B X X X X X – Single-presentation of B serves as a control condition 11)	X X X X X X X – De-adaptation block 12)   B X X X X X A - Quantifies adaptation effect of B on A with 5 intervening trials

Miscellani •	1.3 Hz stimulus presentation time – 750 ms ISI •	One run = 30 modules = 360 blocks •	1 block = ~10 seconds; 1 module = 2 minutes; 1 run = 60 minutes

Cross-modality
Display near-identical stimuli next to each other and calculate adaptation. Hypothesis: Adaptation willl occur if the stimulus feature which this area of cortex is encoding is the same for both stimuli. Vary stimulus A along different axes: for example, A' is a negative of A Stimuli: Two sets 1)	adapting stimuli (A and A') – High-response stimulus and a somehow similar stimulus 2)	Intervening stimuli (X) – 15 unresponsive stimuli which de-adapt neurons Design: Four-block modules 1)	X X X X X X X – De-adaptation block 2)	A A' X X X X X– A adjacent to A'. Quantifies adaptation effect of A' on A 3)	X X X X X X X – De-adaptation block 4)	A X X X X X X – Single-presentation of A serves as a control condition 5)   A' A X X X X X - A' adjacent to A. Quantifies adaptation effect of A' on A  [Back to Electrophysiology Protocol]