Biomedical subjects

Julius Fridriksson

Publications and source records attributed to Julius Fridriksson.

12 recordsLinked to original sources

PubMed2006

Speech apraxia without oral apraxia: can normal brain function explain the physiopathology?

Apraxia of speech, usually associated with stroke, refers to the inability to perform speech motor movements typically with an intact ability to execute non-speech oral movements. It is uncertain whether apraxia of speech results from damage affecting the insula or the inferior frontal gyrus. The controversy started because of conflicting results from studies investigating patients with disrupted brain structure, when dysfunction of both sites can coexist. We conducted a functional magnetic resonance imaging study of individuals without neurological disorders comparing speech and non-speech movements. Speech movements did not recruit the insula, but activated the left inferior frontal gyrus, suggesting that Broca's area, but not the insula, is critical for speech articulation.

Adolescent↗

PubMed2006

Neural recruitment associated with anomia treatment in aphasia.

The purpose of this study was to investigate changes in the spatial distribution of cortical activity associated with anomia treatment in three persons with aphasia. Participants underwent three fMRI sessions before and after a period of intensive language treatment focused on object naming. The results revealed bilateral hemispheric recruitment associated with improved ability to name items targeted in treatment. This is the first study to employ multiple pre- and post-treatment fMRI sessions in the study of treatment-induced recovery from aphasia and has implications for future studies of brain plasticity in stroke.

Aged↗

PubMed2006

Age-related variability in cortical activity during language processing.

PURPOSE: The present study investigated the extent of cortical activity during overt picture naming using functional magnetic resonance imaging (fMRI). METHOD: Participants comprised 20 healthy, adult participants with ages ranging from 20 to 82 years. While undergoing fMRI, participants completed a picture-naming task consisting of 60 high-frequency nouns. RESULTS: Linear regression analysis revealed a positive relationship between age and cortical activation intensity in Broca's and Wernicke's areas as well as the right-hemisphere homologue of Broca's area. In contrast, neural activity in the anterior cingulate gyrus, an area thought to be involved in attentional processing, did not increase as a function of age. CONCLUSIONS: These findings suggest age-related increases in cortical activation during simple language tasks, such as picture naming, in brain areas typically associated with language processing.

Adult↗

PubMed2006

Functional communication and executive function in aphasia.

The purpose of this exploratory study was to investigate the relationship between functional communication and executive function ability in aphasia. Twenty-five participants with aphasia underwent examination with an extensive test battery including measures of functional communication, executive function ability, and language impairment. Compared to published norms, most participants did not perform within normal limits on the executive function tests. As expected, the correlation between severity of language impairment and functional communication ratings exceeded that among the executive functioning and functional communication measures. Eight of ten correlation coefficients for the relationship between executive functioning and functional communication reached statistical significance suggesting a clear relationship between scores on the executive functioning measures and functional communication ability. Based on these results, it appears that decreased executive functioning ability may coincide with decreased functional communication ability in persons with aphasia.

Adult↗

PubMed2006

Measuring the hemodynamic response in chronic hypoperfusion.

Although structural brain scans help assess brain injury in stroke, they cannot identify regions that are functionally disabled due to disrupted perfusion. Perfusion and functional MRI have the potential for determining the functional consequences of stroke. Here we examine the effectiveness of functional MRI to measure brain function in a single patient (LB) with chronic hypoperfusion. When LB made sustained hand movements we observed a sustained decrease in the fMRI signal, while normal individuals exhibit a sustained increase in signal while conducting this task. This work has clear implications for understanding stroke using functional MRI.

Brain Injuries↗

PubMed2006

Periodicity and frequency coding in human auditory cortex.

Understanding the neural coding of pitch and frequency is fundamental to the understanding of speech comprehension, music perception and the segregation of concurrent sound sources. Neuroimaging has made important contributions to defining the pattern of frequency sensitivity in humans. However, the precise way in which pitch sensitivity relates to these frequency-dependent regions remains unclear. Single-frequency tones also cannot be used to test this hypothesis as their pitch always equals their frequency. Here, temporal pitch (periodicity) and frequency coding were dissociated using stimuli that were bandpassed in different frequency spectra (centre frequencies 800 and 4500 Hz), yet were matched in their pitch characteristics. Cortical responses to both pitch-evoking stimuli typically occurred within a region that was also responsive to low frequencies. Its location extended across both primary and nonprimary auditory cortex. An additional control experiment demonstrated that this pitch-related effect was not simply caused by the generation of combination tones. Our findings support recent neurophysiological evidence for a cortical representation of pitch at the lateral border of the primary auditory cortex, while revealing new evidence that additional auditory fields are also likely to play a role in pitch coding.

Acoustic Stimulation↗

PubMed2005

Comparing fixed- and randomized-interval spaced retrieval in anomia treatment.

UNLABELLED: Spaced retrieval (SR) has recently been modified to target anomia in persons with aphasia (PWA). It relies on a strict management of the inter-stimulus interval (ISI) where the time between stimulus presentations is doubled or halved based on response accuracy. Although SR is successful in treating anomia, it remains to be studied whether the strict ISI management is necessary. The present study compared fixed-interval spaced retrieval (FISR) to randomized-interval spaced retrieval (RISR) in anomia treatment. Using alternating treatments single subject design, three PWA were trained to name 30 target items. Although both treatments were successful, the present data did not reveal one approach as superior even though fewer FISR sessions were needed and more FISR items were maintained on the post-treatment probes. This difference was only minimal suggesting that a less stringent stimulus schedule, as used in RISR, is sufficient for successful treatment outcome. LEARNING OUTCOMES: Readers will be able to describe the spaced retrieval treatment approach using both fixed- and randomized-interval stimulus schedules, as well as applications of this technique in the treatment of anomia in aphasia.

Aged↗

PubMed2005

Spaced retrieval treatment of anomia.

BACKGROUND: Spaced Retrieval (SR) is a treatment approach developed to facilitate recall of information by individuals with dementia. Essentially an errorless learning procedure that can be used to facilitate recall of a variety of information, SR gradually increases the interval between correct recall of target items. AIMS: Given the success of using SR in dementia, the purpose of this study was to explore its usefulness in improving naming by individuals with aphasia. The rate of acquisition and retention of items was compared between SR and a more traditional treatment technique-cueing hierarchy (CH). Also, each oral naming treatment was run concurrently with a single word writing treatment. METHODS #ENTITYSTARTX00026; PROCEDURES: Three participants who had moderate or severe naming impairments and agraphia were studied. Single-subject design was applied across oral and written naming and treated and untreated items. OUTCOMES #ENTITYSTARTX00026; RESULTS: The results indicate that for these participants, SR resulted in improved naming of specific items. The data further suggest that SR compared favourably to CH with regard to both acquisition and retention of items. The participants also benefited nicely from the writing treatment. CONCLUSIONS: These findings suggest SR may be an alternative for managing naming impairment resulting from aphasia. Furthermore, the study supports providing treatments aimed at two different modalities concurrently.

Journal Article↗

PubMed2005

Brain damage and cortical compensation in foreign accent syndrome.

Foreign Accent Syndrome (FAS) is a well-known neurological deficit whose underlying cause has remained obscure despite almost a century of study. Combining structural and functional imaging, our studies suggest that FAS represents a compensatory response to impaired motor regulation of speech. We describe a patient who acquired FAS as a result of an ischemic stroke in the left basal ganglia. In addition to this case being exceptionally clean, we were able to confirm a specific lesion location as well as provide strong evidence that impaired motor speech regulation resulted in compensation by other areas of the cortical motor speech network.

Brain Injuries↗

PubMed2005

Utilization of Speech-Language Pathology and Audiology Services in Stroke Patients.

The purpose of this study was to investigate biographical and medical factors associated with utilization of speech-language pathology and audiology services provided to stroke patients in the hospital setting. Moreover, the study sought to identify possible sub-groups of stroke patients that might be under served by speech-language pathologists and audiologists. Discharge data for over 91,000 stroke patients from the years 1996 to 2000 were examined. Using a relatively new statistical approach - a novel decision tree - the analyses revealed an association between medical diagnostic complexity, hospital setting, hospital location, and increased utilization of rehabilitation services. Biographical factors such as age, race, and gender were not related to the amount of services rendered.

Journal Article↗

PubMed2002

Aphasia severity: Association with cerebral perfusion and diffusion.

BACKGROUND: Previous studies of the relationship between perfusion, diffusion, and stroke suggest that the extent of cerebral hypoperfusion may be a better indicator of neurological status than lesion size in the early phases of recovery. It is not clear how these factors are related to aphasia severity. AIMS: The purpose of this study was to investigate the relationship between cerebral perfusion, diffusion, and aphasia severity in stroke. METHODS #ENTITYSTARTX00026; PROCEDURE: Nine participants were examined within 24 hours of stroke onset and six were re-examined at 1 month post stroke. The examination included administration of an aphasia test, a face recognition task, and a neuroimaging session including T2-, perfusion-, and diffusion-weighted MRI. OUTCOMES #ENTITYSTARTX00026; RESULTS: Participants with a variety of aphasia types and severity were included in the study. Visual inspection suggested larger perfusion abnormality than the actual lesion in eight of nine subjects at day 1. The correlation between aphasia severity and hypoperfusion was significant at day 1 and at 1 month post stroke. However, this was not the case for the relationship between aphasia severity and lesion size where the correlation was not statistically significant at day 1 or at 1 month post stroke. CONCLUSIONS: These results suggest that cerebral hypoperfusion is a more accurate indicator of aphasia severity in early stroke than lesion volume.

Journal Article↗

PubMedDate not supplied

Cortical activation and language task difficulty in aphasia.

BACKGROUND: Previous research using functional MRI (fMRI) suggests changes in cortical activation as a function of increased task difficulty. This relationship has not been explored in persons with aphasia even though it may have significant implications for pre- and post-treatment interpretation of fMRI data. AIMS: The purpose of this exploratory study was to investigate the relationship between changes in language task difficulty and cortical activation in persons with aphasia. METHODS #ENTITYSTARTX00026; PROCEDURES: Four persons with chronic anomic or Broca's aphasia and four matched control participants underwent fMRI while performing a picture-word matching task. OUTCOMES #ENTITYSTARTX00026; RESULTS: Compared to the more difficult task condition, all participants performed with greater accuracy on the easier condition. Moreover, greater mean blood oxygenated level dependent (BOLD) signal intensity and area recruitment were noted during the more difficult condition for three out of four persons with aphasia as well as three of the four controls. The increase in cortical activity was mainly noted in the superior temporal and posterior inferior frontal lobes. CONCLUSIONS: The present findings mirror those found in previous studies of normal subjects in that cortical activation increased in parallel to task difficulty for most of our participants. It is unclear what mechanism accounts for this effect; this phenomenon might need to be considered in future fMRI studies of neural plasticity associated with aphasia treatment.

Journal Article↗