Conditioned lick behavior and evoked responses using whisker twitches in head restrained rats

Abstract

To examine whisker barrel evoked response potentials in chronically implanted rats during behavioral learning with very fast response times, rats must be calm while immobilized with their head restrained. We quantified their behaviors during training with an ethogram and measured each individual animals' progress over the training period. Once calm under restraint, rats were conditioned to differentiate between a reward and control whisker twitch, then provide a lick response when presented with the correct stimulus, rewarded by a drop of water. Rats produced the correct licking response (after reward whisker twitch), and learned not to lick after a control whisker was twitched. By implementing a high density 64 channel electrocorticogram (ECoG) electrode array, we mapped the barrel field of the somatosensory cortex with high spatial and temporal resolution during conditioned lick behaviors. In agreement with previous reports, we observe a larger evoked response after training, probably related to mechanisms of cortical plasticity.

Rat psychomotor vigilance task with fast response times using a conditioned lick behavior

“…The rigid restraint chamber has restricted space so movement by the animal can cause unwanted tension on the head stage by twisting of the recording cables if the head is not fixed. Our studies previously tested different methods of restraint and found the wrap to be the most comfortable method, exhibiting fewer bad behaviors [56]. Head fixation has many advantages including the ability to perform precisely timed whisker stimulation that is time-locked to an event such as licking and recording the neuronal activity related to this behavior.…”

“…Food and/or fluid deprivation is a common laboratory procedure used to increase motivation for obtaining a reward [8, 12, 13, 19, 24, 56]. However, dietary restriction has several physiological and neurobehavioral effects.…”

“…Chronic food restriction in rats augments the rewarding and motor-activating effects of many drugs of abuse [6, 9–11]. Our studies have previously employed a fluid restriction model to increase motivation for water reward but responses were not consistent [56]. Restriction-based training regimens are problematic because performance drops significantly in the second half of the session suggesting that they may have reached satiation and therefore water may not have been reinforcing enough to maintain operant behavior for the duration of the session.…”

Towards real-time detection of seizures in awake rats with GPU-accelerated diffuse optical tomography

“…Unlike other methods that tend to introduce stressful conditions that result in discomfort over long periods of time, the restraining mechanism using a hammock and jacket allows the rats to make slight adjustments in body position if necessary for comfort while providing adequate restraint still. Many studies 21 involving awake, nonanethetized, and head-restrained rats have applied this approach and proved that the rats remained calm and exhibited fewer bad behaviors during the prolonged experiment.…”

“…We implemented a restraining mechanism that allowed for the highest level of comfort possible 21 , since the rat stayed awake during the relatively long time recording in the seizure experiment. For restraint, we used both hammocks and straight-jacket type wraps to better fit our needs.…”