Prospective Memory as a Specific Form of Task Switching. Intention and Executive Control

Transcription

1 Prospective Memory as a Specific Form of Task Switching Intention and Executive Control

2 Yehene E, Meiran N, Soroker N Taskalternationcostwithoutask alternation:measuringintentionality. A behavioral dissociation between intention and action was demonstrated by patient AF who sustained damage to the left-hemisphere including basal ganglia. Althoughnotaskswitchingtokplace,AF continued to demonstrate behaviorally her intentiontoswitchtasks. She knew she had to task switch, the intention was there, but she was unable to execute the task.

3 Task Switching - A Two Part Model 1) The intention to switch Realizing that a task switch is necessary and forming an intention to execute it 2) The execution of the intention to switch Executing the task switch To carry out a task switch you need intention and cognitive ability (executive control). If either function is impaired task switching should be limited.

4 Prospective Memory as a Specific Case of Task Switching To carry out a PM task you have to stop what you are doing and switch to this particular task (sounds a lot like task switching except the task switch in PM is triggered by an event stimulus) Therefore, intention and executive control should also be necessary for PM If either function is impaired, task switching and PM should be affected.

5 A Two Part Study Study A: Analyzing the need for proper functioning of the basal ganglia (involved in executive control) for task switching and PM Study B: Analyzing the need for proper functioning of the hippocampus (related to LTM and monitoring, and forming an intention) for task switching and PM

6 Basal Ganglia The Basal Ganglia includes the caudate nucleus, the putamen, and the globus pallidus (in the telencephalon under the cerebral cortex), as well as the substantia nigra (buried deep within the midbrain)

7 Basal Ganglia A behavioral dissociation between intention and action was demonstrated by patient AF who sustained damage to the left-hemisphere including basal ganglia. Action = the ability to execute the task Action is impaired when basal ganglia are damaged. You may have the intention to execute the task switch (or the switch to the PM task) but because youdon thavethenecesaryexecutivecontrolyou do not perform the action.

8 Basal Ganglia Basal ganglia are especially important in the performance of movement influenced by memories (Biological Psychology, 339) Basal ganglia play a role in determining the amplitude and direction of movement (executive function) DamagetobasalgangliainParkinson slows movement

9 Study A Executive Control Experiment 1: Hypothesis: Patients with damage to the basal ganglia(patientswithparkinson s disease) will be impaired in task switching.

10 Experiment 1 Method: 1. Patients with damage to the basal ganglia (patients withparkinson sdisease)wilbetestedfortheir ability to task switch using a standardized task switching paradigm. 2. Their performance will be compared with the performance of a control group of normal subjects. 3. If the findings of the first part of the experiment are in line with our hypothesis we will proceed with Experiment 2.

11 Experiment 2: Hypothesis: Patients with damage to the basal ganglia(patientswithparkinson s disease) who were impaired in executing task switches will also be impaired in executing Prospective Memory tasks.

12 Experiment 2 Method: 1. Patients with damage to the basal ganglia (patientswithparkinson sdisease)wilbe tested for their ability to perform a PM task using a standardized PM paradigm. 2. Their performance will be compared with the performance of a control group of normal subjects.

13 Controls Each subject will serve as his or her own control between Experiments 1 and 2. Subjects in the experimental and control groups will be selected according to specific criteria to minimize variability. The overall scores of the experimental group will be compared to those of the control group to test for a main effect of basal ganglia dysfunction.