Learned helplessness is a behavior associated with and influenced by depression in humans. Active avoidance occurs when animals attempt to move away from a risk, whereas in passive avoidance, animals try to maintain a safe distance from such a threat 12, 20, 21, in response to cues predicting an escapable risk after associative learning has occurred. This leads to generalized helpless behavior (learned helplessness) that persists even when the environment/contingencies change so that the aversive stimuli are no longer unavoidable. recorded using ANY-maze behavioral software. After several presentations under these circumstances, a mouse has difficulty learning to avoid or escape the footshock even when able to do so. After the unavoidable presentation of aversive stimuli (footshocks), a mouse learns that it has no control over these presentations (or its environment). on behavioral parameters from the Y maze or shuttle-box task and central oxidative stress status, in.
lever box (Azrin, 1956), and in the shuttle box. The mouse then receives a footshock and cannot escape it. I shall point out that there is a rich store of knowledge of active avoidance learning. Using a shuttlebox, a mouse is placed in one compartment with the door to the opposite compartment closed. Learned helplessness occurs when a mouse has been exposed to an inescapable aversive event or stimulus. It is a classic example of negative reinforcement. move to) the opposite compartment after receiving a footshock in their current compartment.
In a shuttlebox, this occurs when a mouse learns to escape (i.e. This measure is correlated with memory.Įscape conditioning occurs when an animal learns to perform an operant behavior to terminate an aversive event or stimulus. As such, the latency to enter the dark compartment (if the mouse does at all) is measured. Passive avoidance is evaluated as the suppression of the (innate) behavior of moving into the dark compartment. During the test phase, the mouse is again placed in the light compartment and monitored. The mouse should, therefore, learn that moving to the dark compartment has negative consequences. During acquisition, this innate behavior results in the connecting door shutting and an aversive shock being delivered to the mouse in the dark compartment. A shuttlebox is arranged so that one compartment is "dark" (through the use of opaque walls or an external cover) and one is "light." Mice have an innate tendency to prefer dark areas over light ones, so their natural instinct will be to move, through a connecting door, from the light compartment they are placed in to the dark compartment. Passive avoidance paradigms require the mouse to suppress a (innate) behavior to avoid an aversive stimulus (a shock). Learning a two-way avoidance task in a shuttle box involves a passive avoidance/active avoidance conflict during the initial stages of acquisition (i.e., a tendency to freezereceiving the electric shock- runs against a tendency to actively cross to the opposite compartment -avoiding the insult-) which is mediated by anxiety (e.g., Wilcock and Fulker, 1973 Gray, 1982 Gray and.
0 kommentar(er)
