Maria Korsnes - Academia.edu (original) (raw)

Papers by Maria Korsnes

Perceptual and motor skills, 1995

Pictorial stimuli were presented in serial lists and tested for recognition. 11 men and 9 women p... more Pictorial stimuli were presented in serial lists and tested for recognition. 11 men and 9 women participated at retention intervals of 5, 15, and 25 sec. The length of retention interval interacted with primacy and recency effects as observed in earlier studies of abstract stimuli, indicating similar basic memory functions for different types of visual stimuli. A shift from recency to primacy dominance remained despite the likelihood of verbal rehearsal. At short retention intervals a recency effect predominated and with longer delays a primacy effect predominated recognition.

American journal of Alzheimer's disease and other dementias, Jan 17, 2015

Earlier detection of dementia requires increased knowledge of how to help people in the early sta... more Earlier detection of dementia requires increased knowledge of how to help people in the early stages of dementia. However, few studies have focused on how psychotherapy should be adapted to improve the outcome of therapy for people with Alzheimer's disease. The aims of the present study were to identify and to explore possible obstacles encountered during the use of manual-based psychotherapy for people with early-stage Alzheimer's disease. The study found that individual adaptations to the treatment manual were necessary, particularly the modification of memory aids in order to adapt them to patients' functional level and previous experience with modern technology. In addition, caregivers were essential for both treatment and homework completion, while reduced awareness constituted an obstacle for adherence to the manual.

Nordisk tidsskrift for helseforskning, 2015

Journal of Integrative Neuroscience, 2014

Evidence from recent studies challenge traditional memory system accounts of separate mechanisms ... more Evidence from recent studies challenge traditional memory system accounts of separate mechanisms for implicit and explicit memory. The motive behind the present study was to further investigate whether common activations can be detected during explicit and implicit memory performance when using the same procedure for both tasks. Functional magnetic resonance imaging (fMRI) showed separate neural activation to perceptual repetition priming and perceptual recognition of real and nonsense objects, both in terms of the brain regions involved and in the direction of repeated-novel activations. Repetition priming showed deactivation for repeated stimuli in regions not overlapping regions activated in conscious recognition, activation patterns in the two tasks involved largely separate networks. Common activations were observed in three areas, considered as being involved in processes such as stimulus analyses, task monitoring and attention, i.e., processes external to memory. We interpret this as indicating an almost complete dissociation between the networks involved in priming and recognition memory.

Journal of Behavioral and Brain Science, 2014

Scandinavian Journal of Psychology, 2006

Scandinavian Journal of Psychology, 1996

Scandinavian Journal of Psychology, 2007

Perceptual and Motor Skills, 1993

List memory of 6 young and 6 older human adults was tested with lists of four visual items (black... more List memory of 6 young and 6 older human adults was tested with lists of four visual items (black and white patterns and colored abstract paintings). We investigated the effects of varying the length of the recognition interval on the serial-position function for picture recognition in the two age groups. Increases in the retention interval showed a consistent modification of the shape of the serial-position function from a monotonically increasing function at the shortest interval to a monotonically decreasing function at the longest interval. The time course of these changes was faster for older adults than for young adults. Age differences in the length of the interval required for a shift in the serial-position functions from recency to primacy effects were strikingly similar to those previously found between young people and nonhuman species.

Neuropsychologia, 2008

Drawings depicting familiar objects and unreal structures were presented twice, and participants ... more Drawings depicting familiar objects and unreal structures were presented twice, and participants (N=16) determined whether line drawings were real (familiar) or unreal (unfamiliar). The second presentation (repetition) of a drawing was typically responded to faster and more accurately than the first presentation and was accompanied by reduced activation in occipitotemporal (fusiform) and lateral precuneus regions, and increased activation in medial precuneus regions. The behavioral effects and reduced activations (e.g., lateral precuneus) on the second presentation were less pronounced for unreal objects than for real objects. Activation changes in the medial precuneus - increased activation on repetition and reduced activation for novel unreal objects - was further supported by the increased activation in this area during rest and reduced activation when workload was increased (i.e., processing novel unreal objects). The results from the present study in conjunction with those from several previous studies converge on the conclusion that the occipitotemporal and lateral regions of the precuneus are primarily involved in object priming, whereas the medial portion of precuneus primarily activates and deactivates as a function of workload.

Journal of Affective Disorders, 2012

Epilepsia, 2010

The aim of the study was to investigate behavioral and brain activation in nonpsychotic hallucina... more The aim of the study was to investigate behavioral and brain activation in nonpsychotic hallucinating individuals. Auditory hallucinations are reported by patients with epilepsy, although less frequent than visual hallucinations are. If behavioral and neuronal activation patterns in hallucinating patients with epilepsy are found to be similar to what has been found in hallucinating patients with schizophrenia, this would support a unique neuronal representation for auditory hallucinations cutting across diagnostic groups. We report behavioral and functional magnetic resonance imaging (fMRI) data from six epilepsy patients experiencing auditory hallucinations compared with six healthy control subjects. The participants had to report which of two simultaneously presented simple speech sounds they perceived on each trial, using a dichotic stimulus presentation mode. The results showed that the patients failed to show an expected right ear advantage on the task, and they also showed significantly reduced activation in temporal, frontal, and cingulate cortex areas. The results are discussed in relation to a view that neuropsychological and functional neuroimaging indices of auditory hallucinations may be orthogonal to diagnostic category and not unique to patients with schizophrenia.

Cortex, 2013

Men are often believed to have a functionally more asymmetrical brain organization than women, bu... more Men are often believed to have a functionally more asymmetrical brain organization than women, but the empirical evidence for sex differences in lateralization is unclear to date. Over the years we have collected data from a vast number of participants using the same consonant-vowel dichotic listening task, a reliable marker for language lateralization. One dataset comprised behavioral data from 1782 participants (885 females, 125 non-right-handers), who were divided in four age groups (children <10 yrs, adolescents = 10-15 yrs, younger adults = 16-49 yrs, and older adults >50 yrs). In addition, we had behavioral and functional imaging (fMRI) data from another 104 younger adults (49 females, aged 18-45 yrs), who completed the same dichotic listening task in a 3T scanner. This database allowed us to comprehensively test whether there is a sex difference in functional language lateralization. Across all participants and in both datasets a right ear advantage (REA) emerged, reflecting left-hemispheric language lateralization. Accordingly, the fMRI data revealed a leftward asymmetry in superior temporal lobe language processing areas. In the N = 1782 dataset no main effect of sex but a significant sex by age interaction emerged: the REA increased with age in both sexes but as a result of an earlier onset in females the REA was stronger in female than male adolescents. In turn, male younger adults showed greater asymmetry than female younger adults (accounting for <1% of variance). There were no sex differences in children and older adults. The males in the fMRI dataset (N = 104) also had a greater REA than females (accounting for 4% of variance), but no sex difference emerged in the neuroimaging data. Handedness did not affect these findings. Taken together, our findings suggest that sex differences in language lateralization as assessed with dichotic listening exist, but they are (a) not necessarily reflected in fMRI data, (b) age-dependent and (c) relatively small.

Brain Structure and Function, 2009

Brain Structure and Function, 2010

Behavioural Neurology, 1996

Two experiments examined short-term memory for order information in six patients diagnosed with P... more Two experiments examined short-term memory for order information in six patients diagnosed with Parkinson's disease (PD) and six control subjects while event related potentials (ERPs) were recorded. The subjects were tested for recognition of abstract spatial designs and words after a 5 s retention interval. The PD patients failed to respond in 29% of all trials, but the overall accuracy was similar to that in the control group when these trials were excluded. The corresponding ERP results show serial position variations both after presentation of the probe items, and after presentation of the memory set items. The amplitudes were generally lower at all positions for the PD patients at the parietal midline electrode, and the amplitudes were similar for both groups at the frontal electrode. Also, the ERP latencies were significantly slower for the PD patients than for the control group at all conditions. Indirectly the data are consistent with an interpretation of cognitive deficit in PD stressing attention resources.

Journal of Affective Disorders, 2013

Perceptual and motor skills, 1995

Pictorial stimuli were presented in serial lists and tested for recognition. 11 men and 9 women p... more Pictorial stimuli were presented in serial lists and tested for recognition. 11 men and 9 women participated at retention intervals of 5, 15, and 25 sec. The length of retention interval interacted with primacy and recency effects as observed in earlier studies of abstract stimuli, indicating similar basic memory functions for different types of visual stimuli. A shift from recency to primacy dominance remained despite the likelihood of verbal rehearsal. At short retention intervals a recency effect predominated and with longer delays a primacy effect predominated recognition.

American journal of Alzheimer's disease and other dementias, Jan 17, 2015

Earlier detection of dementia requires increased knowledge of how to help people in the early sta... more Earlier detection of dementia requires increased knowledge of how to help people in the early stages of dementia. However, few studies have focused on how psychotherapy should be adapted to improve the outcome of therapy for people with Alzheimer's disease. The aims of the present study were to identify and to explore possible obstacles encountered during the use of manual-based psychotherapy for people with early-stage Alzheimer's disease. The study found that individual adaptations to the treatment manual were necessary, particularly the modification of memory aids in order to adapt them to patients' functional level and previous experience with modern technology. In addition, caregivers were essential for both treatment and homework completion, while reduced awareness constituted an obstacle for adherence to the manual.

Nordisk tidsskrift for helseforskning, 2015

Journal of Integrative Neuroscience, 2014

Evidence from recent studies challenge traditional memory system accounts of separate mechanisms ... more Evidence from recent studies challenge traditional memory system accounts of separate mechanisms for implicit and explicit memory. The motive behind the present study was to further investigate whether common activations can be detected during explicit and implicit memory performance when using the same procedure for both tasks. Functional magnetic resonance imaging (fMRI) showed separate neural activation to perceptual repetition priming and perceptual recognition of real and nonsense objects, both in terms of the brain regions involved and in the direction of repeated-novel activations. Repetition priming showed deactivation for repeated stimuli in regions not overlapping regions activated in conscious recognition, activation patterns in the two tasks involved largely separate networks. Common activations were observed in three areas, considered as being involved in processes such as stimulus analyses, task monitoring and attention, i.e., processes external to memory. We interpret this as indicating an almost complete dissociation between the networks involved in priming and recognition memory.

Journal of Behavioral and Brain Science, 2014

Scandinavian Journal of Psychology, 2006

Scandinavian Journal of Psychology, 1996

Scandinavian Journal of Psychology, 2007

Perceptual and Motor Skills, 1993

List memory of 6 young and 6 older human adults was tested with lists of four visual items (black... more List memory of 6 young and 6 older human adults was tested with lists of four visual items (black and white patterns and colored abstract paintings). We investigated the effects of varying the length of the recognition interval on the serial-position function for picture recognition in the two age groups. Increases in the retention interval showed a consistent modification of the shape of the serial-position function from a monotonically increasing function at the shortest interval to a monotonically decreasing function at the longest interval. The time course of these changes was faster for older adults than for young adults. Age differences in the length of the interval required for a shift in the serial-position functions from recency to primacy effects were strikingly similar to those previously found between young people and nonhuman species.

Neuropsychologia, 2008

Drawings depicting familiar objects and unreal structures were presented twice, and participants ... more Drawings depicting familiar objects and unreal structures were presented twice, and participants (N=16) determined whether line drawings were real (familiar) or unreal (unfamiliar). The second presentation (repetition) of a drawing was typically responded to faster and more accurately than the first presentation and was accompanied by reduced activation in occipitotemporal (fusiform) and lateral precuneus regions, and increased activation in medial precuneus regions. The behavioral effects and reduced activations (e.g., lateral precuneus) on the second presentation were less pronounced for unreal objects than for real objects. Activation changes in the medial precuneus - increased activation on repetition and reduced activation for novel unreal objects - was further supported by the increased activation in this area during rest and reduced activation when workload was increased (i.e., processing novel unreal objects). The results from the present study in conjunction with those from several previous studies converge on the conclusion that the occipitotemporal and lateral regions of the precuneus are primarily involved in object priming, whereas the medial portion of precuneus primarily activates and deactivates as a function of workload.

Journal of Affective Disorders, 2012

Epilepsia, 2010

The aim of the study was to investigate behavioral and brain activation in nonpsychotic hallucina... more The aim of the study was to investigate behavioral and brain activation in nonpsychotic hallucinating individuals. Auditory hallucinations are reported by patients with epilepsy, although less frequent than visual hallucinations are. If behavioral and neuronal activation patterns in hallucinating patients with epilepsy are found to be similar to what has been found in hallucinating patients with schizophrenia, this would support a unique neuronal representation for auditory hallucinations cutting across diagnostic groups. We report behavioral and functional magnetic resonance imaging (fMRI) data from six epilepsy patients experiencing auditory hallucinations compared with six healthy control subjects. The participants had to report which of two simultaneously presented simple speech sounds they perceived on each trial, using a dichotic stimulus presentation mode. The results showed that the patients failed to show an expected right ear advantage on the task, and they also showed significantly reduced activation in temporal, frontal, and cingulate cortex areas. The results are discussed in relation to a view that neuropsychological and functional neuroimaging indices of auditory hallucinations may be orthogonal to diagnostic category and not unique to patients with schizophrenia.

Cortex, 2013

Men are often believed to have a functionally more asymmetrical brain organization than women, bu... more Men are often believed to have a functionally more asymmetrical brain organization than women, but the empirical evidence for sex differences in lateralization is unclear to date. Over the years we have collected data from a vast number of participants using the same consonant-vowel dichotic listening task, a reliable marker for language lateralization. One dataset comprised behavioral data from 1782 participants (885 females, 125 non-right-handers), who were divided in four age groups (children <10 yrs, adolescents = 10-15 yrs, younger adults = 16-49 yrs, and older adults >50 yrs). In addition, we had behavioral and functional imaging (fMRI) data from another 104 younger adults (49 females, aged 18-45 yrs), who completed the same dichotic listening task in a 3T scanner. This database allowed us to comprehensively test whether there is a sex difference in functional language lateralization. Across all participants and in both datasets a right ear advantage (REA) emerged, reflecting left-hemispheric language lateralization. Accordingly, the fMRI data revealed a leftward asymmetry in superior temporal lobe language processing areas. In the N = 1782 dataset no main effect of sex but a significant sex by age interaction emerged: the REA increased with age in both sexes but as a result of an earlier onset in females the REA was stronger in female than male adolescents. In turn, male younger adults showed greater asymmetry than female younger adults (accounting for <1% of variance). There were no sex differences in children and older adults. The males in the fMRI dataset (N = 104) also had a greater REA than females (accounting for 4% of variance), but no sex difference emerged in the neuroimaging data. Handedness did not affect these findings. Taken together, our findings suggest that sex differences in language lateralization as assessed with dichotic listening exist, but they are (a) not necessarily reflected in fMRI data, (b) age-dependent and (c) relatively small.

Brain Structure and Function, 2009

Brain Structure and Function, 2010

Behavioural Neurology, 1996

Two experiments examined short-term memory for order information in six patients diagnosed with P... more Two experiments examined short-term memory for order information in six patients diagnosed with Parkinson's disease (PD) and six control subjects while event related potentials (ERPs) were recorded. The subjects were tested for recognition of abstract spatial designs and words after a 5 s retention interval. The PD patients failed to respond in 29% of all trials, but the overall accuracy was similar to that in the control group when these trials were excluded. The corresponding ERP results show serial position variations both after presentation of the probe items, and after presentation of the memory set items. The amplitudes were generally lower at all positions for the PD patients at the parietal midline electrode, and the amplitudes were similar for both groups at the frontal electrode. Also, the ERP latencies were significantly slower for the PD patients than for the control group at all conditions. Indirectly the data are consistent with an interpretation of cognitive deficit in PD stressing attention resources.

Journal of Affective Disorders, 2013