What is an advantage of block design in fMRI?

* Block designs allow for considerable experimental flexibility, allowing parametric designs and multi-factorial designs to be employed. * Block design can be especially advantageous and a good starting point for newcomers to the field of FMRI research.

What is a block design fMRI?

There are two major types of experimental designs for fMRI studies: blocked and event-related designs. In a blocked design, a condition is presented continuously for an extended time interval (block) to maintain cognitive engagement, and different task conditions are usually alternating in time.

What is jitter in fMRI?

Jitter. Another feature of many fMRI experiments is “Jitter”, or variable duration between trials. Adding jitter to experiments with conditions that are relatively close to each other (e.g., less than 10-15 seconds apart) allows the independent estimation of the hemodynamic response to each condition.

What do you need to know about fMRI?

2 Introduction to fMRI: experimental design and data analysis 2.1 Introduction to fMRI Functional Magnetic Resonance Imaging (functional MRI or fMRI) is a non- invasive neuroimaging technique that can be used for studying human brain function in vivo .

When does the BOLD signal respond in fMRI?

One complication in fMRI is that the BOLD signal responds slowly and is temporally extended Peak response is 4-6 seconds after stimulus presentation Simply putting 1’s in the design matrix rows corresponding to stimulus presentation can miss considerable amounts of variance in the signal 0 1 1 0 0 1 1 0 Simple “boxcar” stimulus function

How to use a contrast vector in fMRI?

A contrast vector defines how to weight each column of the design matrix E.g. to find areas more active in condition 1 than condition 2, use the contrast [1 -1 0] If c is a row vector of contrast weights, and β is a row vector of beta values, Contrast = cβ’ 3.5 0.6 4.2 4.2 0.6 3.5 1 -1 0 β =ββ ==β = c === 1 -1 0*= 4.2 – 0.6 = 3.6 Contrasts

Which is memory paradigm is blocked by fMRI?

“Blocked” fMRI: Memory Paradigm STI PRE HORSE 0 8 74 118 140 184 206 250 GRE STI PRE LOVE STR STI PRE HUMOR TIME (SEC) 52 STR STI PRE CHAIR [Wagner et al., OHBM, 1998]