Memory Repression: Brain Mechanisms underlying Dissociative Amnesia

2010 ◽  
Vol 22 (3) ◽  
pp. 602-613 ◽  
Author(s):  
Hirokazu Kikuchi ◽  
Toshikatsu Fujii ◽  
Nobuhito Abe ◽  
Maki Suzuki ◽  
Masahito Takagi ◽  
...  
Keyword(s):  
Neural Activity ◽  
Memory Retrieval ◽  
Direct Evidence ◽  
Neural Mechanisms ◽  
Stressful Event ◽  
Memory Impairments ◽  
Dissociative Amnesia ◽  
And Control ◽  
Increased Activity ◽  
With Memory

Dissociative amnesia usually follows a stressful event and cannot be attributable to explicit brain damage. It is thought to reflect a reversible deficit in memory retrieval probably due to memory repression. However, the neural mechanisms underlying this condition are not clear. We used fMRI to investigate neural activity associated with memory retrieval in two patients with dissociative amnesia. For each patient, three categories of face photographs and three categories of people's names corresponding to the photographs were prepared: those of “recognizable” high school friends who were acquainted with and recognizable to the patients, those of “unrecognizable” colleagues who were actually acquainted with but unrecognizable to the patients due to their memory impairments, and “control” distracters who were unacquainted with the patients. During fMRI, the patients were visually presented with these stimuli and asked to indicate whether they were personally acquainted with them. In the comparison of the unrecognizable condition with the recognizable condition, we found increased activity in the pFC and decreased activity in the hippocampus in both patients. After treatment for retrograde amnesia, the altered pattern of brain activation disappeared in one patient whose retrograde memories were recovered, whereas it remained unchanged in the other patient whose retrograde memories were not recovered. Our findings provide direct evidence that memory repression in dissociative amnesia is associated with an altered pattern of neural activity, and they suggest the possibility that the pFC has an important role in inhibiting the activity of the hippocampus in memory repression.

scholarly journals Neural correlates of beauty retouching to enhance attractiveness of self-depictions in women

2020 ◽  
Author(s):  
Chisa Ota ◽  
Tamami Nakano
Keyword(s):  
Magnetic Resonance Imaging ◽  
Social Media ◽  
Neural Activity ◽  
Facial Attractiveness ◽  
Neural Correlates ◽  
Neural Mechanisms ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Amygdala Activity ◽  
Increased Activity

AbstractBeauty filters, while often employed for retouching photos to appear more attractive on social media, when used in excess cause images to give a distorted impression. The neural mechanisms underlying this change in facial attractiveness according to beauty retouching level remain unknown. The present study used functional magnetic resonance imaging in women as they viewed photos of their own face or unknown faces that had been retouched at three levels: no, mild, and extreme. The activity in the nucleus accumbens (NA) exhibited a positive correlation with facial attractiveness, whereas amygdala activity showed a negative correlation with attractiveness. Even though the participants rated others’ faces as more attractive than their own, the NA showed increased activity only for their mildly retouched own face and the amygdala exhibited greater activation in the others’ faces condition than the own face condition. Moreover, amygdala activity was greater for extremely retouched faces than for unretouched or mildly retouched faces for both conditions. Frontotemporal and cortical midline areas showed greater activation for one’s own than others’ faces, but such self-related activation was absent when extremely retouched. These results suggest that neural activity dynamically switches between the NA and amygdala according to perceived attractiveness of one’s face.

scholarly journals Neural Activity in Human Primary Motor Cortex Areas 4a and 4p Is Modulated Differentially by Attention to Action

2002 ◽  
Vol 88 (1) ◽  
pp. 514-519 ◽  
Author(s):  
F. Binkofski ◽  
G. R. Fink ◽  
S. Geyer ◽  
G. Buccino ◽  
O. Gruber ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Motor Cortex ◽  
Functional Magnetic Resonance Imaging ◽  
Neural Activity ◽  
Primary Motor Cortex ◽  
Direct Evidence ◽  
Neural Mechanisms ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging

The mechanisms underlying attention to action are poorly understood. Although distracted by something else, we often maintain the accuracy of a movement, which suggests that differential neural mechanisms for the control of attended and nonattended action exist. Using functional magnetic resonance imaging (fMRI) in normal volunteers and probabilistic cytoarchitectonic maps, we observed that neural activity in subarea 4p (posterior) within the primary motor cortex was modulated by attention to action, while neural activity in subarea 4a (anterior) was not. The data provide the direct evidence for differential neural mechanisms during attended and unattended action in human primary motor cortex.

scholarly journals Neural Correlates of Metamemory: A Comparison of Feeling-of-Knowing and Retrospective Confidence Judgments

2009 ◽  
Vol 21 (9) ◽  
pp. 1751-1765 ◽  
Author(s):  
Elizabeth F. Chua ◽  
Daniel L. Schacter ◽  
Reisa A. Sperling
Keyword(s):  
Neural Activity ◽  
Visual Processing ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Neural Correlates ◽  
Neural Mechanisms ◽  
Multiple Forms ◽  
Functional Roles ◽  
Feeling Of Knowing ◽  
Metamemory Monitoring

Metamemory refers to knowledge and monitoring of one's own memory. Metamemory monitoring can be done prospectively with respect to subsequent memory retrieval or retrospectively with respect to previous memory retrieval. In this study, we used fMRI to compare neural activity during prospective feeling-of-knowing and retrospective confidence tasks in order to examine common and distinct mechanisms supporting multiple forms of metamemory monitoring. Both metamemory tasks, compared to non-metamemory tasks, were associated with greater activity in medial prefrontal, medial parietal, and lateral parietal regions, which have previously been implicated in internally directed cognition. Furthermore, compared to non-metamemory tasks, metamemory tasks were associated with less activity in occipital regions, and in lateral inferior frontal and dorsal medial prefrontal regions, which have previously shown involvement in visual processing and stimulus-oriented attention, respectively. Thus, neural activity related to metamemory is characterized by both a shift toward internally directed cognition and away from externally directed cognition. Several regions demonstrated differences in neural activity between feeling-of-knowing and confidence tasks, including fusiform, medial temporal lobe, and medial parietal regions; furthermore, these regions also showed interaction effects between task and the subjective metamemory rating, suggesting that they are sensitive to the information monitored in each particular task. These findings demonstrate both common and distinct neural mechanisms supporting metamemory processes and also serve to elucidate the functional roles of previously characterized brain networks.

scholarly journals Neural Mechanisms Underlying the Processing of Complex Sentences: An fMRI Study

2020 ◽  
Vol 1 (2) ◽  
pp. 226-248
Author(s):  
Margreet Vogelzang ◽  
Christiane M. Thiel ◽  
Stephanie Rosemann ◽  
Jochem W. Rieger ◽  
Esther Ruigendijk
Keyword(s):  
Cognitive Load ◽  
Sentence Processing ◽  
Neural Activity ◽  
Neural Mechanisms ◽  
Complex Object ◽  
Syntactic Complexity ◽  
Activation Patterns ◽  
Complex Sentences ◽  
Fmri Study ◽  
Increased Activity

Previous research has shown effects of syntactic complexity on sentence processing. In linguistics, syntactic complexity (caused by different word orders) is traditionally explained by distinct linguistic operations. This study investigates whether different complex word orders indeed result in distinct patterns of neural activity, as would be expected when distinct linguistic operations are applied. Twenty-two older adults performed an auditory sentence processing paradigm in German with and without increased cognitive load. The results show that without increased cognitive load, complex sentences show distinct activation patterns compared with less complex, canonical sentences: complex object-initial sentences show increased activity in the left inferior frontal and temporal regions, whereas complex adjunct-initial sentences show increased activity in occipital and right superior frontal regions. Increased cognitive load seems to affect the processing of different sentence structures differently, increasing neural activity for canonical sentences, but leaving complex sentences relatively unaffected. We discuss these results in the context of the idea that linguistic operations required for processing sentence structures with higher levels of complexity involve distinct brain operations.

Autobiographical Memory Impairments as a Transdiagnostic Feature of Mental Illness: A meta-analysis of autobiographical memory specificity and overgenerality amongst people with psychiatric diagnoses

2020 ◽  
Author(s):  
Tom Joseph Barry ◽  
David John Hallford ◽  
Keisuke Takano
Keyword(s):  
Autobiographical Memory ◽  
Memory Retrieval ◽  
Keyword Search ◽  
Meta Analysis ◽  
Future Research ◽  
Psychiatric Diagnoses ◽  
Schizophrenia Spectrum Disorders ◽  
Memory Impairments ◽  
Memory Specificity ◽  
Causal Mechanisms

Decades of research has examined the difficulty that people with psychiatric diagnoses, such as Major Depressive Disorder, Schizophrenia Spectrum Disorders, and Posttraumatic Stress Disorder, have in recalling specific autobiographical memories from events that lasted less than a day. Instead, they seem to retrieve general events that have occurred many times or which occurred over longer periods of time, termed overgeneral memory. We present the first transdiagnostic meta-analysis of memory specificity/overgenerality, and the first meta-regression of proposed causal mechanisms. A keyword search of Embase, PsycARTICLES and PsycINFO databases yielded 74 studies that compared people with and without psychiatric diagnoses on the retrieval of specific (k = 85) or general memories (k = 56). Multi-level meta-analysis confirmed that people with psychiatric diagnoses typically recall fewer specific (g = -0.864, 95% CI[-1.030, -0.698]) and more general (g = .712, 95% CI[0.524, 0.900]) memories than diagnoses-free people. The size of these effects did not differ between diagnostic groups. There were no consistent moderators; effect sizes were not explained by methodological factors such as cue valence, or demographic variables such as participants’ age. There was also no support for the contribution of underlying processes that are thought to be involved in specific/general memory retrieval (e.g., rumination). Our findings confirm that deficits in autobiographical memory retrieval are a transdiagnostic factor associated with a broad range of psychiatric problems, but future research should explore novel causal mechanisms such as encoding deficits and the social processes involved in memory sharing and rehearsal.

scholarly journals Episodic Memory Encoding and Retrieval in Face-Name Paired Paradigm: An fNIRS Study

2021 ◽  
Vol 11 (7) ◽  
pp. 951
Author(s):  
Qian Yu ◽  
Boris Cheval ◽  
Benjamin Becker ◽  
Fabian Herold ◽  
Chetwyn C. H. Chan ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Neural Activity ◽  
Near Infrared ◽  
Clinical Settings ◽  
Functional Near Infrared Spectroscopy ◽  
Associate Learning ◽  
Brodmann Areas ◽  
Parietal Cortices ◽  
Increased Activity ◽  
Encoding And Retrieval

Background: Episodic memory (EM) is particularly sensitive to pathological conditions and aging. In a neurocognitive context, the paired-associate learning (PAL) paradigm, which requires participants to learn and recall associations between stimuli, has been used to measure EM. The present study aimed to explore whether functional near-infrared spectroscopy (fNIRS) can be employed to determine cortical activity underlying encoding and retrieval. Moreover, we examined whether and how different aspects of task (i.e., novelty, difficulty) affects those cortical activities. Methods: Twenty-two male college students (age: M = 20.55, SD = 1.62) underwent a face-name PAL paradigm under 40-channel fNIRS covering fronto-parietal and middle occipital regions. Results: A decreased activity during encoding in a broad network encompassing the bilateral frontal cortex (Brodmann areas 9, 11, 45, and 46) was observed during the encoding, while an increased activity in the left orbitofrontal cortex (Brodmann area 11) was observed during the retrieval. Increased HbO concentration in the superior parietal cortices and decreased HbO concentration in the inferior parietal cortices were observed during encoding while dominant activation of left PFC was found during retrieval only. Higher task difficulty was associated with greater neural activity in the bilateral prefrontal cortex and higher task novelty was associated with greater activation in occipital regions. Conclusion: Combining the PAL paradigm with fNIRS provided the means to differentiate neural activity characterising encoding and retrieval. Therefore, the fNIRS may have the potential to complete EM assessments in clinical settings.

scholarly journals Four Weeks of Aerobic Training Affects Cardiac Tissue Matrix Metalloproteinase, Lactate Dehydrogenase and Malate Dehydrogenase Enzymes Activities, and Hepatorenal Biomarkers in Experimental Hyperhomocysteinemia in Rats

2021 ◽  
Vol 22 (13) ◽  
pp. 6792
Author(s):  
Dusan Todorovic ◽  
Marija Stojanovic ◽  
Ana Medic ◽  
Kristina Gopcevic ◽  
Slavica Mutavdzin ◽  
...  
Keyword(s):  
Physical Activity ◽  
Lactate Dehydrogenase ◽  
Malate Dehydrogenase ◽  
Subcutaneous Injection ◽  
Cardiac Tissue ◽  
Albino Rats ◽  
Wistar Albino Rats ◽  
And Control ◽  
Tissue Matrix ◽  
Increased Activity

The aim of this study was to investigate the effect of the application of homocysteine as well as its effect under the condition of aerobic physical activity on the activities of matrix metalloproteinases (MMP), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) in cardiac tissue and on hepato-renal biochemical parameters in sera of rats. Male Wistar albino rats were divided into four groups (n = 10, per group): C: 0.9% NaCl 0.2 mL/day subcutaneous injection (s.c.); H: homocysteine 0.45 µmol/g b.w./day s.c.; CPA saline (0.9% NaCl 0.2 mL/day s.c.) and a program of physical activity on a treadmill; and HPA homocysteine (0.45 µmol/g b.w./day s.c.) and a program of physical activity on a treadmill. Subcutaneous injection of substances was applied 2 times a day at intervals of 8 h during the first two weeks of experimental protocol. Hcy level in serum was significantly higher in the HPA group compared to the CPA group (p < 0.05). Levels of glucose, proteins, albumin, and hepatorenal biomarkers were higher in active groups compared with the sedentary group. It was demonstrated that the increased activities of LDH (mainly caused by higher activity of isoform LDH2) and mMDH were found under the condition of homocysteine-treated rats plus aerobic physical activity. Independent application of homocysteine did not lead to these changes. Physical activity leads to activation of MMP-2 isoform and to increased activity of MMP-9 isoform in both homocysteine-treated and control rats.

The Origins of Domestic Sheep and Goats: a Reconsideration in the Light of the Fossil Evidence

1969 ◽  
Vol 34 ◽  
pp. 368-384 ◽  
Author(s):  
Sebastian Payne
Keyword(s):  
Direct Evidence ◽  
Present Situation ◽  
Wild Relatives ◽  
The Other ◽  
Domestic Sheep ◽  
Sheep And Goats ◽  
Animal Domestication ◽  
The Past ◽  
The One ◽  
And Control

In recent discussions of the origins and process of animal domestication (Reed, 1961, Zeuner, 1963), both authors rely on two kinds of evidence: on the one hand, the present distributions and characteristics of the different breeds of whatever animal is being discussed, together with its feral and wild relatives, and, on the other hand, the past record, given by literary and pictorial sources and the bones from archaeological and geological sites. Increased recognition of the limitations of the past record, whether in the accuracy of the information it appears to give (as in the case of pictorial sources), or in the certainty of the deductions we are at present capable of drawing from it (this applies especially to the osteological record), has led these authors to argue mainly from the present situation, using the past record to confirm or amplify the existing picture.Arguing from the present, many hypotheses about the origins and process of domestication are available. The only test we have, when attempting to choose between these, lies in the direct evidence of the past record. The past record, it is freely admitted, is very fragmentary: the information provided by the present situation is more exact, ranges over a much wider field, and is more open to test and control. Nevertheless, the past record, however imperfect it is, is the only direct evidence we have about the process of domestication.

scholarly journals Loss of haem in rat liver caused by the porphyrogenic agent 2-allyl-2-isopropylacetamide

1971 ◽  
Vol 124 (4) ◽  
pp. 767-777 ◽  
Author(s):  
F. De Matteis
Keyword(s):  
Rat Liver ◽  
Microsomal Fraction ◽  
Direct Evidence ◽  
Gradual Increase ◽  
Rapid Loss ◽  
Metabolizing Enzymes ◽  
Liver Microsomal Fraction ◽  
Green Pigments ◽  
Cytochrome P 450 ◽  
Increased Activity

1. The effect of a single dose of 2-allyl-2-isopropylacetamide on the cytochrome P-450 concentration in rat liver microsomal fraction was studied. The drug caused a rapid loss of cytochrome P-450 followed by a gradual increase to above the normal concentration. 2. The loss of cytochrome P-450 was accompanied by a loss of microsomal haem and by a brown–green discoloration of the microsomal fraction suggesting that a change in the chemical constitution of the lost haem had taken place. Direct evidence for this was obtained by prelabelling the liver haems with radioactive 5-aminolaevulate: the drug caused a loss of radioactivity from the haem with an increase of radioactivity in a fraction containing certain un-identified green pigments. 3. Evidence was obtained by a dual-isotopic procedure that rapidly turning-over haem(s) may be preferentially affected. 4. The loss of cytochrome P-450 as well as the loss of microsomal haem and the discoloration of the microsomal fraction were more intense in animals pretreated with phenobarbitone and were much less evident when compound SKF 525-A (2-diethylaminoethyl 3,3-diphenylpropylacetate) was given before 2-allyl-2-isopropylacetamide, suggesting that the activity of the drug-metabolizing enzymes may be involved in these effects. 5. The relevance of the destruction of liver haem to the increased activity of 5-aminolaevulate synthetase caused by 2-allyl-2-isopropylacetamide is discussed.

scholarly journals Loss of potassium from embryonic chick hearts in potassium-free media with and without calcium

1938 ◽  
Vol 124 (837) ◽  
pp. 446-450
Keyword(s):  
Phosphate Buffer ◽  
Direct Evidence ◽  
Watch Glass ◽  
Chick Embryos ◽  
Embryonic Chick ◽  
Intercellular Spaces ◽  
Experimental Solution ◽  
Free Media ◽  
And Control ◽  
Day By Day

Experiments already described (Murray 1938) led to the inference that the cells of the chick embryonic heart lose potassium in potassium-free media. The experiments here described provide direct evidence of this. The hearts were dissected out of 2 ½-3 day chick embryos and placed in the solution PC (Table I) until they had started to beat. They were then thoroughly washed, and were allowed to lie for 5 min. (2 min. in Exp. 1) in the last wash. This last wash is called control A. The solutions used for washing were from the same flasks as the experimental solution. After their passage through control A the hearts were transferred to 2 c.c. of the experimental solution in a Jena watch-glass. After various times in this the hearts were discarded and both the experimental solution and control A were collected. If the experiment extended over more than 1 day the experimental solution and control A were used over again day by day until all the hearts in the experiment had passed through them. The use of control A was necessary for two reasons: ( a ) to show that potassium was not still being washed out of the intercellular spaces at the end of washing ( b ) in experiments lasting over several days the washing solution was fresh each day, but the experimental solution was of course not changed. Hence any small amount of potassium being carried over from the last wash would accumulate in the experimental solution because of the daily increment and might seriously affect the result; but by leaving the hearts for several minutes in the last wash (control A) and by not changing it for fresh on successive days, any such increase would be detected in that solution. In addition to control A, a daily sample (control B) was taken from the same flasks as the solutions used for washing. Details of the solutions are given in Table I ; a phosphate buffer was always used.

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