Conference Paper

Single trial hemodynamic response estimation in a block anagram solution study using fNIR spectroscopy

Sch. of Biomed. Eng., Sci. & Health Syst., Drexel Univ., Philadelphia, PA, USA
DOI: 10.1109/ICASSP.2005.1416383 Conference: Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on, Volume: 5
Source: IEEE Xplore

ABSTRACT Near infrared spectroscopy (NIRs) has shown great potential in examining functional brain activity during cognitive tasks by enabling the measurement of changes in the concentration of deoxygenated and oxygenated hemoglobin. It has attracted great interest due to its portability, low cost, safety and non-invasiveness. We present a novel single trial hemodynamic response estimation algorithm in an anagram solution study using functional NIRs (fNIRs). The temporal profile of the hemodynamic response to each single trial stimulus is estimated by minimizing the error between the oxygenation data measured by fNIRs and a linear model. No prior assumption on the amplitude, latency, or variance of the hemodynamic response is required other than its shape to be a γ function. Once the estimates of single trial hemodynamic responses gathered from the dorsolateral prefrontal cortex are obtained, features, such as maximum amplitude, rise time, etc., are extracted and compared for different difficulty levels of the test.

0 Bookmarks
 · 
76 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Fear could be acquired indirectly via social observation. However, it remains unclear which cortical substrate activities are involved in vicarious fear transmission. The present study was to examine empathy-related processes during fear learning by-proxy and to examine the activation of prefrontal cortex by using functional near-infrared spectroscopy. We simultaneously measured participants' hemodynamic responses and skin conductance responses when they were exposed to a movie. In this movie, a demonstrator (i.e., another human being) was receiving a classical fear conditioning. A neutral colored square paired with shocks (CSshock) and another colored square paired with no shocks (CSno-shock) were randomly presented in front of the demonstrator. Results showed that increased concentration of oxygenated hemoglobin in left prefrontal cortex was observed when participants watched a demonstrator seeing CSshock compared with that exposed to CSno-shock. In addition, enhanced skin conductance responses showing a demonstrator's aversive experience during learning object-fear association were observed. The present study suggests that left prefrontal cortex, which may reflect speculation of others' mental state, is associated with social fear transmission.
    The Scientific World Journal 01/2013; 2013:652542. · 1.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Data indicated that dyslexic individuals exhibited difficulties on tasks involving Working Memory (WM). Previous studies have suggested that these deficits stem from impaired processing in the Phonological Loop (PL). The PL impairment was connected to poor phonological processing. However, recent data has pointed to the Central Executive (CE) system as another source of WM deficit in dyslexic readers. This opened a debate whether the WM deficit stems solely from PL or can also be seen as an outcome of poor CE processing. In an attempt to verify this question, the current study compared adult skilled and compensated dyslexic readers with no impairment of phonological skills. The participants' PL and CE processing were tested by using the fNIR device attached to the frontal lobe and measured the changes in brain oxygen values when performing N-back task. As it was previously suggested, the N = 0 represented PL and N = 1 to 3 represent CE processing. It was hypothesized that dyslexic readers who show non-impaired phonological skills will exhibit deficits mainly in the CE subsystem and to a lesser extent in the PL. Results indicated that the two reading level groups did not differ in their accuracy and reaction times in any of the N-Back conditions. However, the dyslexic readers demonstrated significant lower maximum oxyHb values in the upper left frontal lobe, mainly caused due to a significant lower activity under the N = 1 condition. Significant task effects were found in the medial left hemisphere, and the high medial right hemisphere. In addition, significant correlations between fNIR-features, reading performance and speed of processing were found. The higher oxyHb values, the better reading and speed of processing performance obtained. The results of the current study support the hypothesis that at least for the group of dyslexics with non-impaired PL, WM deficit stems from poor CE activity.
    PLoS ONE 01/2012; 7(11):e46527. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The process of reading activates a large-scale neural network which includes different cortical brain regions. This network is thought to be age-dependent and changes throughout the process of reading acquisition. The frontal lobe is considered to be related to higher, executive, functions. We conducted a functional Near InfraRed Spectroscopy (fNIR) study in order to compare frontal lobe performance during a Lexical Decision Task (LDT) among two different age-groups: children and adults. Data indicated significant differences with age in LDT behavioral performance, and brain activity in the upper left frontal lobe. The young group exhibited slower reaction times and lower accuracy in addition to differences both in the level of blood oxygenation as well in the blood oxygenation timeline. The current study’s results suggest 1) the involvement of the frontal lobe during the process of reading and that 2) frontal lobe activity is modified with the age of maturity.
    Foundations of Augmented Cognition. Directing the Future of Adaptive Systems - 6th International Conference, FAC 2011, Held as Part of HCI International 2011, Orlando, FL, USA, July 9-14, 2011. Proceedings; 01/2011

Full-text

Download
0 Downloads
Available from