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Biomedical subjects

Ina M Tarkka

Publications and source records attributed to Ina M Tarkka.

At least 19 recordsLinked to original sources
PubMed2005

Footprint peak time and functional ambulation profile reflect the potential for hemiparetic gait recovery.

OBJECTIVE: Gait disturbances were monitored in patients with chronic stroke with a walkway built with pressure sensors in order to assess whether detailed gait and footprint information could provide verification for the potential for gait recovery. METHODS: Gait variables (footprint peak times, temporal and spatial parameters and Functional Ambulation Profile, FAP, scores), were first recorded in 25 patients with chronic stroke at their preferred speed and 10 healthy volunteers walking from very slow to very fast. Patients and controls were divided into four groups based on the velocity performance. Secondly, the effect of rehabilitation on the footprint peak times was evaluated in another group of 20 chronic stroke patients. RESULTS AND CONCLUSIONS: The footprint peak time behaviour of different patients with chronic stroke reflected their hemiparetic gait pattern. The slower patients had prolonged footprint peak times on the non-affected side (NS) and shorter values on the lateral footprint on the affected side (AS). The increased gait velocity and the FAP scores decreased the footprint peak times on both sides, especially on the NS. The rehabilitation increased the gait velocity with 18.2%, decreased the duration of the mid-foot and forefoot peak times on the NS and the lateral mid-foot peak times on the AS. A detailed analysis of the individual gait performance allows more accurate assessment of the potential for gait recovery.

Adult↗
PubMed2005

The effectiveness of body weight-supported gait training and floor walking in patients with chronic stroke.

OBJECTIVE: To compare body weight-supported exercise on a gait trainer with walking exercise overground. DESIGN: Randomized controlled trial. SETTING: Rehabilitation hospital. PARTICIPANTS: Forty-five ambulatory patients with chronic stroke. INTERVENTIONS: Patients were randomized to 3 groups: (1) gait trainer exercise with functional electric stimulation (GTstim), (2) gait trainer exercise without stimulation (GT), and (3) walking overground (WALK). All patients practiced gait for 15 sessions during 3 weeks (each session, 20 min), and they received additional physiotherapy 55 minutes daily. MAIN OUTCOME MEASURES: Ten-meter walk test (10MWT), six-minute walk test (6MWT), lower-limb spasticity and muscle force, postural sway tests, Modified Motor Assessment Scale (MMAS), and FIM instrument scores were recorded before, during, and after the rehabilitation and at 6 months follow-up. RESULTS: The mean walking distance using the gait trainer was 6900+/-1200 m in the GTstim group and 6500+/-1700 m in GT group. In the WALK group, the distance was 4800+/-2800 m, which was less than the walking distance obtained in the GTstim group (P=.027). The body-weight support was individually reduced from 30% to 9% of the body weight over the course of the program. In the pooled 45 patients, the 10MWT (P<.001), 6MWT (P<.001), MMAS (P<.001), dynamic balance test time (P<.001), and test trip (P=.005) scores improved; however, no differences were found between the groups. CONCLUSIONS: Both the body weight-supported training and walking exercise training programs resulted in faster gait after the intensive rehabilitation program. Patients' motor performance remained improved at the follow-up.

Analysis of Variance↗
PubMed2005

Electrical brain responses evoked by human faces in acute psychosis.

Patients with schizophrenia are known to have behavioral deficits in recognizing faces and facial expressions. However, the ability to process simple visual stimuli appears to be intact in first-episode psychosis. The aim of this study was to examine complex visual processing, especially the event-related potentials (ERPs) elicited by human faces, in early psychosis. Never-medicated patients in acute psychosis (n=18) were compared with healthy controls (n=19). Photographs of human faces were presented in a classic oddball paradigm requiring a motor response to a smiling face. Cerebral sources of ERPs were analyzed of the averaged responses, using minimum norm estimates, and dipole models. Face-sensitive response at 145 ms after the face stimuli was of significantly higher amplitude in our never-medicated patients, and the activity distribution between the groups was clearly different. At the early phase of a psychotic illness, these alterations in face-related neuronal network processes represent perceptual disturbance in psychosis, possibly including state and trait, as well as potential physiological compensatory features.

Acute Disease↗
PubMed2005

Increased perfusion in motor areas after constraint-induced movement therapy in chronic stroke: a single-photon emission computerized tomography study.

Hemiparesis is the most common deficit after cerebral stroke. Constraint-induced movement therapy (CIMT) is a new neurorehabilitation method that emphasizes task-relevant repetitive training for the stroke hand. Twelve chronic stroke patients were studied with single-photon emission computerized tomography at rest before and after the two-week CIMT period. Increased perfusion was found in motor control related areas. The specific areas with an increase in perfusion in the affected hemisphere were in the precentral gyrus, premotor cortex (Brodmann's area 6 (BA6)), frontal cortex, and superior frontal gyrus (BA10). In the nonaffected hemisphere, perfusion was increased in the superior frontal gyrus (BA6) and cingulate gyrus (BA31). In the cerebellum increased perfusion was seen bilaterally. The brain areas with increased perfusion receive and integrate the information from different sensory systems and plan the movement execution. Regional cerebral perfusion decreased in the lingual gyrus (BA18) in the affected hemisphere. In the nonaffected frontal cortex, two areas with decreased perfusion were found in the middle frontal gyrus (BA8/10). Also, the fusiform gyrus (BA20) and inferior temporal gyrus (BA37) in the nonaffected hemisphere showed decreased perfusion. Intensive movement therapy appears to change local cerebral perfusion in areas known to participate in movement planning and execution. These changes might be a sign of active reorganization processes after CIMT in the chronic state of stroke.

Adult↗
PubMed2005

Paretic hand rehabilitation with constraint-induced movement therapy after stroke.

OBJECTIVE: Hemiparesis of the upper limb after stroke can be severely disabling. We studied the effectiveness of constraint-induced movement therapy in improving motor abilities in very chronic stroke subjects. We assessed whether the obtained changes, if any, would endure after the intervention program. DESIGN: Participants were 27 consecutive chronic stroke subjects (mean age, 56 +/- 13 yrs) who fulfilled specific motor criteria. The design was an uncontrolled preintervention to postintervention comparison. The subjects participated in a 2-wk-long constraint-induced movement therapy program. The motor function of the affected arm and its daily use were assessed using a structured motor performance test in a control test 2 wks before the intervention, then again immediately before and after the intervention, and at the follow-up. The intervention was undertaken in a rehabilitation hospital. RESULTS: The motor abilities of the affected arm improved significantly as measured by the structured motor performance test. The obtained improvements in the affected arm motor behavior endured for 5 mos after the therapy. CONCLUSIONS: Chronic stroke subjects, who have sufficient residual motor control for exercise, benefit from highly concentrated therapy and can still enhance their voluntary motor control of the affected arm even years after the incident.

Adult↗
PubMed2005

Gait characteristics after gait-oriented rehabilitation in chronic stroke.

PURPOSE: To assess the effects of rehabilitation in thirty-seven ambulatory patients with chronic stroke during three weeks in-patient rehabilitation period. METHODS: In the intervention group, each patient received 75 min physiotherapy daily every workday including 20 minutes in the electromechanical gait trainer with body-weight support (BWS). In the control group, each patient participated in 45 min conventional physiotherapy daily. Motor ability was assessed with the first five items of the Modified Motor Assessment Scale (MMAS1-5) and ten meters walking speed. Spatio-temporal gait characteristics were recorded with an electrical walkway. RESULTS: The MMAS1-5 (p<0.0005 and p=0.005) and ten meters walking time (p<0.0005 and p=0.006) improved in both groups. The improvements in MMAS1-5 and ten meters walking time did not differ between the groups (p=0.217 and p=0.195). Specific gait characteristics improved only in the intervention group, as seen in increased Functional Ambulation Profile score (p=0.023), velocity (p=0.023), the step lengths (affected side, p=0.011, non-affected side p=0.040), the stride lengths (p=0.018, p=0.006) and decreased step-time differential (p=0.043). Furthermore, all gait characteristics and other motor abilities remained in the discharge level at the six months in the intervention group. CONCLUSIONS: It appears that BWS training gives a long-lasting benefit in gait qualities even in chronic stroke patients.

Adult↗
PubMed2004

How much exercise does the enhanced gait-oriented physiotherapy provide for chronic stroke patients?

BACKGROUND AND PURPOSE: Physical exercise therapy in sensorimotor rehabilitation of stroke patients includes active and repetitive exercise and task-specific training. The time spent in active practice is fundamental. The purpose of this study was to analyse what was the actual amount of exercise and content of the performed exercise of the three-week gait-oriented physiotherapy program for chronic stroke patients in an in-patient setting. METHODS: Twenty ambulatory post-stroke patients participated in an in-patient rehabilitation period during which a special effort was made to enhance gait training and the amount of therapy and its contents were recorded in structured form. Baseline and postintervention gait ability assessments were made, but the analysis concentrated on participation records in different forms of therapy. RESULTS: Patients received 19 hours of instructed physiotherapy in three weeks and together with self-initiated training they practised for 28 hours. The practice time in the upright position was 62% of the total duration of the instructed physiotherapy and 35% was performed while sitting. This amount of exercise resulted in improvement of the gait tests. CONCLUSIONS: In order to improve gait in the chronic state of disease, a sufficient amount of gait rehabilitation practice can be obtained with a combination of electromechanical gait trainer exercises, physiotherapy, instructed exercise groups and self-initiated training.

Adult↗
PubMed2004

Familiar-face recognition and comparison: source analysis of scalp-recorded event-related potentials.

OBJECTIVE: We studied the event-related potentials elicited by categorical matching of faces. The purpose was to find cortical sources responsible for face recognition and comparison. METHODS: Nineteen healthy volunteers participated in the study. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Each picture was a photograph of a familiar face with a superimposed abstract dot pattern. One cue directed attention to compare faces and another to compare patterns. 128-channel electroencephalogram was recorded. Spatio-temporal multiple dipole source models were generated using Brain Electromagnetic Source Analysis 2000, for the window of 80-600 ms from S3 onset. RESULTS: The obtained model for face recognition and comparison contained 8 dipoles explaining 97% of grand average and about 90% of individual data and showing temporal and spatial separation of sources: in the frontal region, in the occipital cortex, and in the bilateral medial temporal and inferotemporal regions. Different faces elicited larger components than same person's faces around 400 ms, mainly explained by frontal dipoles. CONCLUSIONS: The sources in our models estimate the activity common for both Face task conditions (the recognition of a familiar person) and also differential activity, related to the match/mismatch item processing.

Adult↗
PubMed2004

Footprint analysis of gait using a pressure sensor system.

The purpose of this study was to investigate if the detailed pressure data of the footprints of normal gait add essential information to the spatio-temporal variables of gait. The gait of 62 healthy adult subjects was investigated using GAITRite pressure sensor system. Each footprint was divided into 12 equal trapezoids and after that the hindfoot, midfoot and forefoot analysis was developed. A typical activation pattern of the sensors with two peaks of active area and peak pressure distribution during normal walking was obtained. The first peak reflected the heel strike, and the second peak reflected push-off at the end of the stance phase. The lowest pressure values were in the midfoot, where the lateral part of the foot activated sensors more than the medial part. The footprint patterns of right and left legs were symmetrical and corresponded with the symmetry found in the spatio-temporal variables of gait. The variability for the active area and the peak pressure were more pronounced for the lateral part of the midfoot and a smaller variation was seen in areas with concentrated observations (e.g. 1st, 2nd and 5th lateral trapezoids). Increasing active area in the forefoot was associated with decreasing pressure sensor activity in the midfoot. The footprint patterns identified the symmetry between the legs and at the same time revealed the velocity performance.

Adult↗
PubMed2003

Matching of familiar faces and abstract patterns: behavioral and high-resolution ERP study.

Electrical scalp-recorded components peaking approximately 350-400 ms were reported to be sensitive to both repetition/priming effects and face familiarity. We studied the categorical matching of familiar faces and compared it to the matching of abstract patterns. Nineteen healthy volunteers participated in the study. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Each picture was a photograph of a familiar face with a superimposed abstract dot pattern. One cue directed attention to compare faces and another to compare patterns. Participants were asked to respond by pressing different buttons. A 128-channel EEG was recorded. Analysis was done for the 600-ms window from the S3 onset, for correct performance. The face comparison was better and faster than the pattern comparison. In the Face task, match/mismatch differences were local in 200-250 ms and large and widespread in 270-550 ms. In the Pattern task, differences were found in 30-270 ms, while on longer latencies they were lesser than those in the Face task. Priming was observed in the Face task as shorter reaction times and reduced N400-like components (both in prefrontal and parietal regions) for the same items as compared to the different ones. In the Pattern task, the results were more controversial.

Adult↗
PubMed2003

Altered auditory processing in acutely psychotic never-medicated first-episode patients.

UNLABELLED: Individuals with psychosis fail to differentiate external impulses and suffer from distortions of reality testing. Schizophrenia group illnesses are also associated with deficits in working memory and perception. We examined the manifestations of a very early phase of psychotic illness to automatic auditory deviance detection to clarify the basic mechanisms underlying misinterpretations of perception. METHODS: Twenty-five never-medicated patients admitted for hospital evaluation of acute psychosis were studied. Fifty-eight EEG channels were recorded during an auditory oddball paradigm. Event-related potentials (ERPs) time-locked to non-attended deviant auditory stimuli were studied in patients and compared with healthy controls. Auditory processing was examined both at the level of the measured biosignals (standard and deviant responses) and with subtraction waveforms. Topographical differences were characterized using global field power (GFP) and minimum norm estimates. RESULTS: The maximum GFP amplitudes and mean amplitudes of the 58 channels within the time windows corresponding to the previously known 'N2b', 'P3a' and 'P3b' components were clearly reduced in patients when compared to healthy controls. However, the groups did not differ during attention-independent automatic processing corresponding to the 'N1' and 'MMN' components, or with respect to the peak latencies of the GFP maxima. CONCLUSIONS: Impairment of the processing of a deviance in simple auditory input in acutely ill drug-naive first-episode psychotic patients only appears in attention-dependent processing after about 250 ms. The alterations in auditory processing differed between stimulus types, suggesting at least two mechanisms underlying the auditory discrimination impairments in acute psychosis. After 250 ms there was a linear and gradually increasing difference in magnitude between the groups in their responses to deviant stimuli, probably related to arousal. In addition, however, there was a striking difference between the groups in the processing of standard stimuli. The early processing was similar in patients and controls, but the striking difference appeared in later processing. The sensory memory deficits associated with psychosis may be explained by an abnormality in sensory model formation rather than by impaired deviant detection.

Acoustic Stimulation↗
PubMed2003

Augmentation of auditory N1 in children with fragile X syndrome.

We compared the N1 responses of the auditory event-related brain potentials (ERPs) in school-aged children with fragile X syndrome to age-matched controls in order to assess auditory processing. Event-related potentials to non-attended standard and deviant tone stimuli were recorded with EEG electrodes and here the standard tones were analysed. The amplitude of the N1 component to standard tones was significantly larger in children with fragile X syndrome than in control children. In addition, the global field power maximum of ERP corresponding to the N2 component was significantly (p<0.05) larger in fragile X children than in controls. The N2 scalp distribution in children with fragile X syndrome appeared more frontal than that in controls. Furthermore, the fragile X children exhibited no habituation of N1 and an absence of N2 sensitization for repeated tones. Increased responsiveness observed in the N1 evoked potential together with abnormal habituation of auditory responses in childhood may indicate increased sensory sensitivity for auditory stimuli in fragile X syndrome. The data, though very limited, suggest that stimulus processing in the auditory afferent pathways and/or in the corresponding cortical receiving areas is abnormal in children with fragile X syndrome.

Acoustic Stimulation↗
PubMed2003

Gait characteristics and functional ambulation profile in patients with chronic unilateral stroke.

OBJECTIVE: Recent technical progress in gait analysis has resulted in portable walkways with embedded pressure-sensitive sensors. Often claims are made in connection with new equipment of their straightforward clinical use. The purpose of the present study was to assess whether the functional ambulation profile (FAP), calculated from walkway data, is a sensitive measure in the characterization of dissimilar patients with chronic hemiparesis due to stroke. DESIGN: We investigated the relationships between FAP and the type of stroke, patients' functional disability, and spatial and temporal variables of gait obtained with the pressure sensor system walkway. Gait variables and FAP scores were compared in 25 patients with residual hemiparesis due to stroke and in 31 healthy subjects. RESULTS: A prolonged swing phase in the affected side and a prolonged stance phase in the nonaffected side were found in patients. Footprint pressure data revealed reduced peak pressure of the affected-side metatarsal area in patients, probably reflecting foot paresis. Higher Barthel Index score and lower Rankin Scale score were reflected in FAP scores. CONCLUSIONS: The FAP scores of patients reflected well their characteristic spatio-temporal gait variations; however, the FAP score seemed a reliable measure of gait normality/abnormality only in rather unhurried gait. Thus, it is useful when a single number is needed.

Adult↗
PubMed2003

Functional specialization in the human frontal cortex observed during task anticipation.

The purpose was to evaluate whether a scalp-recorded slow potential will show specificity during the anticipation of different types of visual tasks. One of the tasks required the comparison of pairs of familiar faces, and the other was the comparison of abstract dotted patterns. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Faces and patterns were superimposed, and the switching between tasks depended on the cue. The ERP analysis was done for the time window between S1 (cue) and S2 presentations. The major differences between tasks were found in the anterior scalp regions starting at 700 ms from S1 onset. During Pattern task anticipation, the proposed sources in the right frontal area were more anterior, inferior and lateral than those in Face task. The task-specific slow electric potentials may indicate the functional specialization for attentive anticipation in the human frontal lobe.

Adult↗
PubMed2002

Cerebral signs of altered adaptability in females with acute psychosis.

In psychosis, behavior is not guided by sensory cues from surroundings. Novel, meaningful behaviors require intact integrative functions such as short-term memory and motor planning, as well as an optimized level of arousal. In this study, we monitored markers of automatic auditory processing in 15 female never-medicated psychotic patients. Fifty-eight channels of EEG were recorded simultaneously with sympathetic skin responses while arousing auditory stimuli were delivered. Neuropsychological tests concentrating on frontal lobe functions were also performed. Prominent neurophysiological and behavioral signs of increased cortical activation were observed in psychotic patients. This widespread disinhibition may attempt to compensate for the impairment of neuronal processing of sensory input from surroundings in the earliest stages of a psychotic illness.

Acute Disease↗
PubMed2002

Task-specific expectation is revealed in scalp-recorded slow potentials.

The contingent negative variation (CNV) is known as an electrical manifestation of expectancy, readiness and attention. The purpose of this study was to evaluate whether slow potentials recorded from the human scalp during the expectation to perform different tasks or during the expectation of the second stimulus in the pair demonstrate specificity regarding the type of visual stimuli. Participants were nineteen healthy adults. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Each picture of this pair was a photograph of a familiar face with superimposed abstract dot pattern. One cue directed attention to compare faces and another to compare patterns. EEG was recorded with a 128-channel net. Slow potentials following S1 and S2 presentation (SP1 and SP2) are reported here for Face and Pattern tasks. The duration of each segment of the trial was 1500 ms from the stimulus onset, and here the last 1000 ms was analyzed. Statistical comparisons of amplitudes and current density mapping were performed. Within the same task, SP1-SP2 differences were complex, implying multiple dissimilarities in the processes during the two expectation periods. Slow potentials in SP1 differed between the tasks mostly in the anterior recording sites in 700-1500 ms. These latencies corresponded to the late CNV (or stimulus preceding negativity, SPN) showing task-specificity during SP1. For SP2, the differences were located centrally in 500-900 ms, the period that reflects the superimposition of processes generating the early CNV and the late positive complex. Task-specific differences appeared only in SP1.

Adult↗