fMRI - What Is It? Then: Example of fMRI in Face Processing Psychology 355: Cognitive Psychology Instructor: John Miyamoto 04/06 /2015: Lecture 02-1 This Powerpoint presentation may contain macros that were used to create the slides. The macros aren’t needed to view the slides. If necessary, you can disable the macros without any change to the presentation.

Outline Brief review of single cell recordings & ERP fMRI - What is it? Application of fMRI to face perception. Psych 355, Miyamoto, Spr '15 2 Reminder - What Are Single Cell Recordings?

Single Cell Recordings The firing rate of individual neurons is measured by means of single cell recordings. Psych 355, Miyamoto, Spr '15 3 Strengths and Weaknesses of Single Cell Recordings

Strengths and Weaknesses of Single Cell Recording Methods Strengths Excellent spatial resolution – the scientist has a very good idea where the recording is located in the brain. Excellent temporal resolution – the scientist knows when the neuron fires to a high level of precision. Drawbacks Practically difficult to record from more than a small number of cells at a given time, e.g., 15 to 20 cells simultaneously. The method is very invasive. Psych 355, Miyamoto, Spr '15 4 Strengths & Weaknesses of Event-Related Potentials (ERP’s)

Event-Related Potentials (ERP’s) Strengths and weaknesses of ERP’s as research tool. ♦ Poor spatial resolution. ♦ Excellent temporal resolution. ♦ Relatively non-invasive. ♦ Sketchy understanding of the brain processes that are producing the EEG signal. Psych 355, Miyamoto, Spr '15 5 Functional Magnetic Resonance Imaging (fMRI)

Psych 355, Miyamoto, Spr '15 6 fMRI Uses a Big Magnet This images is used with permission of the author, J. J. B. Allen at the University of Arizona. Graphic Showing BOLD Contrast

Psych 355, Miyamoto, Spr '15 7 Control Condition Test Condition Measuring Activation – A Subtraction Measure Brain Activity =Oxygen Concentration in Test Condition MINUS Oxygen Concentration in Control Condition Details of fMRI Measurement Oxygenated Blood Deoxygenated Blood

How Does fMRI Measure Brain Activity Local neuronal activity  Increased local metabolic rate  Increased blood flow  Increased oxygenated hemoglobin  Uptake of O 2 less than supply  Decreased concentrations of deoxyhemoglobin  Increased local fMRI T2* signal (electromagnetic signal) BOLD response – Blood Oxygenated Level-Dependent response (the response is dependent on the level of oxygenated blood) A.k.a. hemodynamic response (response observed in the blood over time) Psych 355, Miyamoto, Spr '15 8 Control Condition Test Condition Define "Voxel" - The Voxels are Arranged along a "Slice" of the Brain

Different Slices of the Brain fMRI creates an image of brain activity within a slice of the brain. See images at. "Voxel" - a rectangular volume within a slice of the brain. fMRI detects changes in the BOLD response within each voxel along a slice of the brain. Psych 355, Miyamoto, Spr '15 9 Strengths and Weaknesses of fMRI

Strengths and Weaknesses of fMRI Measures of Brain Activity Excellent spatial resolution ♦ Magnetic changes can be measured at a resolution of 1 - 3mm³. Temporal resolution is poor. ♦ In the 1990’s the temporal resolution was about 4 seconds. ♦ Today the temporal resolution is about 2 seconds. MRI machines impose physical limitations on the subjects. Psych 355, Miyamoto, Spr '15 10 Example of fMRI Study of Face & Place Processing

Next: fMRI Evidence for Brain Areas for Processing Faces and Places O'Craven, K., & Kanwisher, N. (2000). Mental imagery of faces and places activates corresponding stimulus- specific brain regions. Journal of Cognitive Neuroscience, 12, FFA: Fusiform face area. Specialized for faces. (“ventral occipito-temporal cortex”) PPA: Parahippocampal place area. Specialized for representing location info. (“ventromedial cortical region”) Psych 355, Miyamoto, Spr '15 11 Graphic Showing Location of FFA & PPA

Psych 355, Miyamoto, Spr '15 12 Location of the fusiform face area and parahippocampal gyrus Graphic from the article: Haynes, J-D., & Rees, G. (2006). Decoding mental states from brain activity in humans. Nature Reviews Neuroscience, 7, Decoding mental states from brain activity in humans Parahippocampal place area (PPA) Fusiform face area (FFA) Diagram of Brain Head Facing Left fMRI Results for Face & Place Recognition Graphic from /nic/htms/fmri.html

O’Craven & Kanwisher – Research Hypotheses Research Goal: To test the claim that the fusiform face area is specialized for face perception. Prediction: FFA will be activated by face stimuli but not by location stimuli. PPA will be activated by location stimuli but not by face stimuli. Psych 355, Miyamoto, Spr '15 13

Psych 355, Miyamoto, Spr '15 14 Subjects views a face or a place. FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. Perception % Signal Change Look at Just the Upper Half of this Graph fMRI Study of Face and Place Perception

Psych 355, Miyamoto, Spr '15 15 Subjects views a face or a place. Face stimulus activates FFA; place stimulus does not. fMRI Study of Face and Place Perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. Perception % Signal Change Look at Just the Lower Half of this Graph

Psych 355, Miyamoto, Spr '15 16 Subjects views a face or a place. Place stimulus activates PPA; face stimulus does not. fMRI Study of Face and Place Perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. Perception % Signal Change Point Out that There Is a Double Dissociation

Psych 355, Miyamoto, Spr '15 17 Face and place stimuli have opposite effects on FFA and PPA. Double dissociation! Supports claim that FFA serves face perception and PPA serves spatial perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. Perception % Signal Change Define Double Dissociation; Discuss Double Dissociation fMRI Study of Face and Place Perception

Psych 355, Miyamoto, Spr '15 18 Double Dissociation in Neuropsychology Suppose you are studying the function of two brain areas, A and B. Physiological results exhibit a double dissociation with respect to areas A and B if... (i)one class of stimuli activates area A and fails to activate area B; (ii)a different class of stimuli activates area B and fails to activate area A. Example: Viewing faces activates FFA but not PPA; Viewing places activates PPA but not FFA. Double dissociations are important because they provide evidence for specialization of function. Return to Slide with fMRI Results that Display a Double Dissociation

Psych 355, Miyamoto, Spr '15 19 Face and place stimuli have opposite effects on FFA and PPA. Double dissociation! Supports claim that FFA serves face perception and PPA serves spatial perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. Perception % Signal Change Mention Concept of Localization of Function fMRI Study of Face and Place Perception

Localization of Function Specific functions are served by specific areas of the brain Cognitive functioning breaks down in specific ways when areas of the brain are damaged Brain imaging can identify areas of the brain that serve specific functions. Psych 355, Miyamoto, Spr '15 20 Summary & END

Summary Physiological methods in cognitive neuropsychology ♦ Single cell recordings ♦ Event-related potentials (ERP’s) ♦ Functional magnetic resonance imaging (fMRI) Localization of function – identifying parts of the brain that are involved in processing specific types of stimuli or performing specific tasks. Double dissociation – demonstrating that the neural response is specific to particular types of stimuli or specific tasks. Psych 355, Miyamoto, Spr '15 21 END