2008 SURI Intern

Year:      Junior
Major:    Psychology
School:  Frostburg State University,
                Frostburg, MD

Mentor: Jim Lewis, Ph.D.
Dept:      Physiology & Pharmacology

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Research Project: Human Locomotion and Vocalization Have Parallel, But Overlapping Pathways in the Brain

Background
Our knowledge and understanding of our world is based primarily on how we receive and perceive sensory information; for this reason, understanding how the human brain processes sensory information gives great insight into how the mind works as a whole.  The study of sensory perception in the brain has led to successful mapping of much of the visual and tactile perceptual areas.  Auditory perception, though undoubtedly vital to gaining knowledge about our world, is much less studied and less well mapped in the human brain.

There already exists knowledge that different object categories of sound activate different cortical regions in the brain (Martin, 2007; Wallace et. al., 2008). Recent developments in the field of auditory perception have revealed that different conceptual categories of sound appear to associate with different processing pathways in the brain (Lewis et. al., 2005; Engel et. al., 2008). In particular, there appears to be a clear distinction between biological (animal and human locomotion) and non-biological (mechanical) sounds, and more specifically a distinction between animal vocalizations and hand tool sounds (Lewis et. al., 2005). Human produced sounds activated left-lateralized areas in the ventral premotor cortex and posterior superior temporal sulcus as well as the posterior mirror neuron system, which theoretically allows the mind to simulate the performance of the stimulus-producing object in order to understand the directed goal of the action sound (Buccino et. al., 2005). Animal locomotion sounds, on the other hand, activate the superior temporal gyri as well as the posterior superior temporal sulci bilaterally (Lewis et. al., 2008).Thus, there are clearly different pathways for different subcategories of biologically produced sound. However, it is not yet understood the extent to which various subcategories of biological sounds are explicitly represented in the brain.

The purpose of this study is to further assess the cortical areas associated with different categories of biological sounds (human vocalization, human locomotion, animal vocalization, and animal locomotion) as well as cortical areas that integrate visual and auditory sensations from these respective categories, using fMRI.  Our central hypothesis is that there are there are cortical networks that are genetically disposed to activate to specific types of biological sound. In order to get closer addressing this overall hypothesis, our specific hypothesis for this study is that animal locomotion and vocalization as well as human locomotion and vocalization have parallel, but overlapping pathways in the brain.

Methods
We will collect data from ten volunteer participants over the age of 18 with no history of neurologic, psychiatric, or audiologic symptoms.  A 2x2 experimental design will be used to collect data from participants, who will be imaged using clustered acquisition in a 3T fMRI scanner.

In the first scan, participants will be presented with sound stimulus of animal locomotion, animal vocalizations, human locomotion, human non-verbal vocalizations, and silent events, while in the fMRI scanner. They will be asked to mentally judge which to which category each stimulus belongs. 

Participants will also be presented with video and static images of animals and humans performing the motor activities that they will be hearing. The areas of activation created by the visual stimuli will be used to identify key regions of interest (ROIs) that have been previously reported to be involved in processing viewed biological motion.  We can also see if and how auditory and visual pathways for biological action processing overlap in the brain.

fMRI data will be viewed and analyzed using the AFNI software package.  Multiple linear regressions will be performed to assess activation caused by the four categories of sound related to silence.

Expectations
This study will ultimately contribute to the current debate about why the brain naturally allots different pathways to different conceptual categories of sound.   We expect that the medial temporal gyri will bilaterally show significant activation for biological locomotion sounds, but will be strongest in human locomotion compared to animal locomotion sounds.  We also expect vocalization sounds to activate the medial superior temporal gyri in both hemispheres.  We will directly compare regions that are activated by hearing a sound to regions activated by seeing and hearing stimulus of the same category.  We predict that the added video stimuli will activate the occipitotemporal cortex, the superior temporal sulcus and the medial temporal gyri, in accordance with previous biological motion studies (Beauchamp et. al., 2002; Grossman and Blake, 2002; Wheaton et. al., 2004). We expect our data to reveal distinct but somewhat overlapping cortical regions associated with the different categories of biological sound.

References

Beauchamp MS, Lee KE, Haxby JV, Martin A. Parallel visual motion processing streams for manipulable objects and human movements. Neuron (2002), 34(1):149-159.

Buccino G, Riggio L, Melli G, Binkofski F, Gallese V, Rizzolatti G. Listening to action-related sentences modulates the activity of the motor system: a combined TMS and behavioral study. Brain Research: Cognitive Brain Research (2005), 24(3):355-363.

Engel LR, Puce A, Lewis JW. Cortical processing of human versus non-human categories of action sounds.  Human Brain Mapping (2008), 694.

Grossman ED, Blake R. Brain areas active during visual perception of biological motion. Neuron (2002), 35(6):1167-1175.

Lewis JW, Brefczynski JA, Phinney RE, Janik JJ, DeYoe EA. Distinct cortical pathways for processing tool versus animal sounds. Journal of Neuroscience (2005), 25(21):5148-5158.

Martin A. The representation of object concepts in the brain.  Annual Review of Psychology (2007), 58:25-45.

Wallace MN, Palmer AR. Laminar differences in the response properties of cells in the primary auditory cortex. Experimental Brain Research (2008), 184(2):179-91.

Wheaton KJ, Thompson JC, Syngeniotis A, Abbott DF, Puce A. Viewing the motion of human body parts activates different regions of premotor, temporal, and parietal cortex. Neuroimage (2004), 22(1):277-288.

 

Click here to review the summary report of this project.