Language-Activated Cerebral Blood Oxygenation and Hemodynamic Changes of the Left Prefrontal Cortex in Poststroke Aphasic Patients

Abstract

Background and Purpose-In normal subjects, regional cerebral blood flow (rCBF) is greatly increased by neuronal activity, whereas the cerebral metabolic rate for O 2 is increased only slightly. However, it is not clear what kinds of cerebral blood oxygenation and hemodynamic changes can be induced by language activities in language-relevant areas of poststroke aphasics. In the present study, we investigated the difference in the changes of cerebral blood oxygenation and hemodynamics in the left prefrontal cortex induced by language activities between normal subjects, poststroke nonaphasic patients, and nonfluent aphasic patients using near-infrared spectroscopy (NIRS). Methods-Twenty-nine participants performed speech tasks, such as confrontational naming, to evaluate changes among poststroke nonfluent (Broca's) aphasia patients (10 cases; meanϮSEM, 56.9Ϯ2.2 years), age-matched normal subjects (13 cases; 50.7Ϯ2.2 years) and poststroke nonaphasic patients (6 cases; 52.5Ϯ3.9 years). The optodes of NIRS were placed over the left prefrontal cortex. We analyzed the NIRS parameter (oxyhemoglobin [oxy-Hb], deoxyhemoglobin [deoxy-Hb], and total hemoglobin [total-Hb]) changes by qualitative pattern analysis of the parameter changes and quantitative analysis of the parameter values among the groups. Results-The most common NIRS parameter change was an increase in oxy-Hb and total-Hb, with a slight decrease or no change in deoxy-Hb in the normal subjects (5 of 13 cases, 38.5%) and the nonaphasic cerebrovascular disease (CVD) patients (3 of 6 cases, 50.0%). In contrast, the most common pattern in the aphasic patients was an increase of deoxy-Hb, with an increase of oxy-Hb and total-Hb (5 of 10 cases, 50%). However, this pattern was observed in only 3 of 13 cases (23.1%) in the normal subjects and 1 of 6 cases (16.7%) in the nonaphasic CVD patients. The mean (ϮSEM) changes of deoxy-Hb of the aphasic patients, the normal subjects, and the nonaphasic CVD patients were 0.78Ϯ0.29, 0.06Ϯ0.16, and -0.18Ϯ0.22, respectively. The statistical analysis demonstrated a significant effect for deoxy-Hb (PϽ0.05), with the aphasic patients differing significantly from the normal subjects and the nonaphasic CVD patients, while the 2 nonaphasic groups did not differ from each other. Conclusions-The present results demonstrate a multiplicity of language-activated cerebral blood oxygenation and hemodynamic changes in the left prefrontal cortex in the nonaphasic and aphasic groups. The increase of deoxy-Hb with increases of oxy-Hb and total-Hb in the aphasics during language tasks suggests that the left prefrontal cortex of the aphasics utilizes more oxygen than the nonaphasics during language tasks. Finally, functional MRI, which images the activation area in the brain by detecting the reduced concentration of deoxy-Hb during neuronal activation, should be performed on the patients with cerebral dysfunction, giving special consideration to the possible multiplicity of the rCBF and cerebral oxygen metabolism responses to functional tasks. (Stroke...

Task-Related Signal Decrease on Functional Magnetic Resonance Imaging.

“…Most patients with poststroke aphasia showed an increase in deoxy-Hb with an increase in oxy-Hb and total Hb on NIRS during a speech task. 30) Similar increases in deoxy-Hb levels were also detected in normal subjects, but were far more frequent in aphasic patients. Possibly, the brain of aphasic patients utilizes more oxygen than that of nonaphasic subjects to perform the same speech task.…”

Funtional Near Infrared Spectroscopy Study of Language, Joint Attention and Motor Skills

“…Some of the many applications (sample references listed) of NIRS to neuroimaging include: (i) cerebral response to visual Meek et al, 1995;Ruben et al, 1997), auditory (Sakatani et al, 1998) and somatosensory stimuli (Franceschini et al, 2003); (ii) cerebral response to motor system (Colier et al, 1999;Hirth et al, 1996;Schwartz et al, 2005) and language (Sato et al, 1999); and (iii) prevention and treatment of seizures (Adelson et al, 1999;Sokol et al, 2000;Steinhoff et al, 2005;Watanabe et al, 2000) and psychiatric concerns such as depression (Eschweiler et al, 2000;Matsuo et al, 2000;Okada et al, 1996), Alzheimer disease (Fallgatter et al, 1997;Hanlon et al, 1999;Hock et al, 1996) and schizophrenia Okada et al, 2004), as well as stroke rehabilitation (Chen et al, 2000;Nemoto et al, 2000;Saitou et al, 2000;Vernieri et al, 1999); (iv) detection of brain ischemia (Kuebler et al, 1998;Patel et al, 1998), necrosis, and hemorrhage (Yodh et al, 2003). During my doctoral work, NIRS was implemented to investigate the neural basis of language, joint attention and planning and execution of motor skills in healthy adults, as described below in section 2.4.…”

“…The studies were focused primarily in understanding the differences in the hemodynamic responses in different (typically frontal and temporal) regions of the brain in response to language-based stimuli (Herrmann et al, 2003;Hermann et al, 2006;Jayakar et al, 2005;Kubota et al, 2005;Kuwabara et al, 2006;Quaresima et al, 2002;Sakatani et al, 1998). In addition, a few researchers have analyzed the cortical lateralization and dominance features of the brain in different populations, based on their application focus (e.g.…”

“…schizophrenia, epilepsy) (Gallagher et al, 2008;Hermann et al, 2003;Kennan et al, 2002;Kubota et al, 2005;Noguchi et al, 2002;Watanabe et al, 2000;Watson et al, 2004) . All the language studies carried out so far using NIRS (Gallagher et al, 2008;Herrmann et al, 2003, Jayakar et al, 2005Kennan et al, 2002;Kubota et al, 2005;Kuwabara et al, 2006;Noguchi et al, 2002;Qaresima et al, 2002;Sakatani et al, 1998;Watanabe et al, 1998;Watson et al, 2004) have focused on the brain activity differences and/or cortical dominance. To the best of our knowledge none of these studies have investigated the functional and effective connectivity and/or lateralization in the language regions of brain simultaneously.…”

“…In the area of language development and brain activation/functionality using NIRS, researchers have performed studies using various experimental paradigms in normal adults and pediatric populations (Bortfeld et al, 2009;Herrmann et al, 2003;Hermann et al, 2006;Kuwabara et al, 2006;Sakatani et al, 1998). The studies were focused primarily in understanding the differences in the hemodynamic responses in different (typically frontal and temporal) regions of the brain in response to languagebased stimuli (Herrmann et al, 2003;Hermann et al, 2006;Jayakar et al, 2005;Kubota et al, 2005;Kuwabara et al, 2006;Quaresima et al, 2002;Sakatani et al, 1998). In addition, a few researchers have analyzed the cortical lateralization and dominance features of the brain in different populations, based on their application focus (e.g.…”