Proposal for project determining

Neurological proof of context in primacy of affective/non-affective processing

Contention of paper presented:

When people see a spider, their brains process both non-affective information (a spider is an animal) and affective information (the spider is dangerous). Affective information refers to the emotional aspect and non-affective side refers to the semantic aspect of any phenomenon. The paper discussed earlier had proposed that the relative speed with which affective/non-affective processing occurs in response to stimuli is context-dependent. As a small example, they had pointed out that, for a person hiking in a tropical jungle, the affective information gets priority as he is constantly reminded of the possibly dangerous animals lurking around him. However, for a person classifying animals as part of a timed biology test, the non affective details (various physical features of animals) are far more important than if some of them are dangerous or not.

My aim:

In my project, I wish to establish a neurological support for the model proposed by the authors of this paper. I wish to conduct similar experiments as described in the paper, while imaging the brains of the subject by functional magnetic resonance imaging - fMRI, thus showing effective neurological proof of context being the determinant of the processing pathway for the affective and non-affective aspects of stimuli.

Previous work:

Earlier experiments¹ using fMRI data has shown that when exposed to emotional stimuli, a neural system is activated that learns the affective value of the stimuli. The explanation given was that this system is present to provide for a shortcut that by-passes the neural system responsible for identification of objects and people and is capable of producing a fast reaction to stimuli that are potentially life-threatening.

Past experiments² have generally always focused on the affective processing of emotionally loaded words being shown to subjects. Variations had been done with the degree of valence (unpleasant/pleasant) and arousal (intensity of emotion) of the presented stimuli. This was mapped to distinct parts of the brain for assessing valence and arousal respectively, by rating the stimuli. fMRI data showed that various ratings correlated with various areas in the brain (around the amygdala).

My design:

Here is how I would like to progress in my project:

1. I would first select the nature of stimuli to be used, as target and filler trials. As depicted in the paper discussed, picture stimuli seems to bias the subject. So, two modes, out of written words, pictures, and auditory cues (words dictated), can be selected.

2. Then, I would select a group of people and ask them to rate the valence (positive/negative) and the arousal (intensity of emotion) components of a large number of stimuli selected. After that, only the stimuli of similar arousal levels are to be selected and grouped into filler trials (for context) and target trials (for response).

3. As per the assumptions of Task-Set-Inertia paradigm, each subject is to be subjected to filler trials and target trials one by one. This is to be done in 2 groups for each modality: affective context group and non-affective context group.

4. Each subject is to make a judgment of the stimulus presented. The signal for the judgment will be practiced in a short pre-test. As the judgment is being made, the brain of the subject will be imaged by fMRI, with amygdala being the focus for affective processing centre, and the hippocampus and its surrounding regions for non-affective processing centre. The details of these brain areas are to be decided after consulting a psychologist.

5. The same experiment is to be repeated with another set of subjects, only with a different modality, that is, by exchanging the filler and target trials.

6. The scans obtained are to be analyzed with appropriate software.

Requirements:

1. A set of subjects for rating the stimuli. This needs to be a large group of people of similar age, who are reasonably well versed in simple English.

2. A set of subjects to do the fMRI scans on. This would be good if there are 3-4 people in each subgroup for the testing (modality 1-affective context, modality 1-non-affective context, modality 2-affective context, modality 2-non-affective context). So overall, 12-16 people will be a good choice. These people all need to be again, of the same age group, and reasonably well versed in simple English.

3. Access and arrangements to using the fMRI resources in SGPGI, Lucknow.

Hypothesis:

The authors of the earlier paper rather support the framework of Ad Hoc Cognition which advocates that the context in which the stimuli are present plays a very important role in determining the details of processing affective and non-affective aspects of a stimulus. This experiment could show that with affective context, the affective processing centers of the brain show higher/primal activity, whereas with non-affective context, the non-affective processing centers of the brain show higher/primal activity.

References:

1. Whalen, P.J., et al. Masked presentations of emotional facial expressions modulate amygdala activity without explicit knowledge. J Neurosci 18, 411-418 (1998).

2. Posner, J., et al. The neurophysiological bases of emotion: An fMRI study of the affective circumplex using emotion-denoting words. Hum Brain Mapp 30, 883-895 (2009).