scholarly journals Loss of Circadian Timing Disrupts Theta Episodes during Object Exploration

2020 ◽  
Vol 2 (4) ◽  
pp. 523-535
Author(s):  
Adrienne C. Loewke ◽  
Alex Garrett ◽  
Athreya Steiger ◽  
Nathan Fisher ◽  
H. Craig Heller ◽  
...  
Keyword(s):  
Fold Increase ◽  
Light Treatment ◽  
Video Tracking ◽  
Theta Oscillations ◽  
Memory Encoding ◽  
Circadian Timing ◽  
Memory Impairments ◽  
Siberian Hamsters ◽  
Exploration Behavior ◽  
Central Pacemaker

This study examined whether theta oscillations were compromised by the type of circadian disruption that impairs hippocampal-dependent memory processes. In prior studies on Siberian hamsters, we developed a one-time light treatment that eliminated circadian timing in the central pacemaker, the suprachiasmatic nucleus (SCN). These arrhythmic animals had impaired hippocampal-dependent memory whereas animals made arrhythmic with SCN lesions did not. The current study examined whether theta oscillations are compromised by the same light treatment that produced memory impairments in these animals. We found that both methods of inducing circadian-arrhythmia shortened theta episodes in the EEG by nearly 50%. SCN-lesioned animals, however, exhibited a 3-fold increase in the number of theta episodes and more than doubled the total time that theta dominated the EEG compared to SCN-intact circadian-arrhythmic animals. Video tracking showed that changes in theta were paralleled by similar changes in exploration behavior. These results suggest that the circadian-arrhythmic SCN interferes with hippocampal memory encoding by fragmenting theta oscillations. SCN-lesioned animals can, however, compensate for the shortened theta episodes by increasing their frequency. Implications for rhythm coherence and theta sequence models of memory formation are discussed.

737 Prediction of drop out in an adjunctive light treatment trial in patients with non-seasonal depression and evening chronotype

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A287-A288
Author(s):  
Joey W Chan ◽  
Y K Wing ◽  
S P Lam ◽  
Shirley Xin Li ◽  
J Zhang
Keyword(s):  
Clinical Characteristics ◽  
Red Light ◽  
Bright Light ◽  
Fold Increase ◽  
Light Therapy ◽  
Light Treatment ◽  
Drop Out ◽  
Sleep Diary ◽  
Significant Difference ◽  
Seasonal Depression

Abstract Introduction Drop out during treatment hampers therapeutic effect of interventions. The current study examines the possible predictors of drop out during the five-week light treatment in patients with unipolar non-seasonal depression and evening-chronotype. Methods Baseline characteristics including demographics, sleep diary parameters, light treatment prescribed, and early clinical outcomes changes were compared between the Drop out and Non drop out group. Logistic regression analysis was used to examine predictors for drop out. All data were analyzed in a modified intention to treat analysis with last observation carried forward approach. Results A total of 91 subjects (Female 79%, 46.3 ± 11.8 years old) were included in the analysis. There was no significant difference in the baseline demographic and clinical characteristics between the Drop out and Non drop out group. There was also no significant difference in the improvement of clinical parameters over the first week among the two groups. However, treatment non-adherence (in terms of compliance of less than 80% of prescribed duration) over the first treatment week predicts a five-fold increase in risk of drop out during light therapy. (OR: 5.85, CI: 1.414–24.205, p=0.015) after controlling for potential confounders including age, gender, treatment group, patient expectation, and treatment-emergent adverse events. Conclusion This study found that baseline clinical characteristics including depression severity and improvement of depressive symptoms in the initial week did not differ between the Drop out and Non drop out group. The drop out was also not affected by the type of light (dim red versus bright red light), indirectly supporting dim red light as a valid placebo in bright light therapy trial. Treatment adherence is the early phase of light treatment is an important predictor of drop out. Support (if any):

scholarly journals Alteraciones de memoria en daño cerebral

2012 ◽  
Vol 4 (3) ◽  
pp. 73
Author(s):  
David De Noreña ◽  
Irene De la Vega Rodríguez
Keyword(s):  
Free Recall ◽  
Frontal Cortex ◽  
Medial Temporal Lobe ◽  
Anterograde Amnesia ◽  
Memory Encoding ◽  
Specific Group ◽  
Memory Impairments ◽  
Strategic Processes ◽  
Memory Acquisition ◽  
Per Se

Frontal cortex is involved in important memory processes but its role is different from that associated with structures in the medial temporal lobe and diencephalon. While damage in the latter structures produces profound and global anterograde amnesia, damage to the frontal cortex is manifested by an specific group of memory impairments and distortions like confabulations, source amnesia, prospective memory and metamemory deficit, or impaired free recall. Frontal lobes is less involved in memory acquisition per se than it is in leading the strategic processes that support memory encoding, retrieval and monitoring.

Frontal lobe contributions to recognition and recall: Linking basic research with clinical evaluation and remediation

2006 ◽  
Vol 12 (2) ◽  
pp. 210-223 ◽  
Author(s):  
PATRICK S. R. DAVIDSON ◽  
ANGELA K. TROYER ◽  
MORRIS MOSCOVITCH
Keyword(s):  
Decision Making ◽  
Episodic Memory ◽  
Clinical Evaluation ◽  
Basic Research ◽  
Frontal Lobes ◽  
Focal Lesion ◽  
Memory Encoding ◽  
Memory Impairments ◽  
Memory Problems

The role of the human frontal lobes in episodic memory is becoming better understood, thanks mainly to focal lesion and neuroimaging studies. Here we review some recent findings from basic research on the frontal lobes in memory encoding, search, and decision-making at retrieval. For each of these processes, researchers have uncovered cases in which frontal memory impairments can be attenuated by various task manipulations. We suggest ways in which these findings may inform clinical evaluation and rehabilitation of memory problems following frontal damage. (JINS, 2006,12, 210–223.)

scholarly journals Hippocampal theta oscillations support successful associative memory formation

2020 ◽  
Author(s):  
Srinivas Kota ◽  
Michael D. Rugg ◽  
Bradley C. Lega
Keyword(s):  
Associative Memory ◽  
Memory Formation ◽  
Associative Recognition ◽  
Theta Oscillations ◽  
Memory Encoding ◽  
Phase Reset ◽  
Intracranial Eeg ◽  
Electrophysiological Evidence ◽  
Hippocampal Theta ◽  
Encoding And Retrieval

1.AbstractModels of memory formation posit that recollection as compared to familiarity-based memory depends critically on the hippocampus, which binds features of an event to its context. For this reason, the contrast between study items that are later recollected versus those that are recognized on the basis of familiarity should reveal electrophysiological patterns in the hippocampus selectively involved in associative memory encoding. Extensive data from studies in rodents support a model in which theta oscillations fulfill this role, but results in humans results have not been as clear. Here, we employed an associative recognition memory procedure to identify hippocampal correlates of successful associative memory encoding and retrieval in patients undergoing intracranial EEG monitoring. We identified a dissociation between 2– 5 Hz and 5–9 Hz theta oscillations, by which 2–5 Hz oscillations uniquely were linked with successful associative memory in both the anterior and posterior hippocampus. These oscillations exhibited a significant phase reset that also predicted successful associative encoding, distinguished recollected from familiar items at retrieval, and contributed to reinstatement of encoding-related patterns that distinguished these items. Our results provide direct electrophysiological evidence that 2–5 Hz hippocampal theta oscillations support the encoding and retrieval of memories based on recollection but not familiarity.2.Significance StatementExtensive fMRI evidence suggests that the hippocampus plays a selective role in recollection rather than familiarity, during both encoding and retrieval. However, there is little or no electrophysiological evidence that speaks to whether the hippocampus is selectively involved in recollection. Here, we used intracranial EEG from human participants engaged in an associative recognition paradigm. The findings suggest that oscillatory power and phase reset in the hippocampus are selectively associated with recollection rather than familiarity-based memory judgements. Furthermore, reinstatement of oscillatory patterns in the hippocampus was stronger for successful recollection than familiarity. Collectively, the findings support a role for hippocampal theta oscillations in human episodic memory.

scholarly journals Transcriptional regulation of the Arabidopsis thaliana chalcone synthase gene.

1988 ◽  
Vol 8 (5) ◽  
pp. 1985-1992 ◽  
Author(s):  
R L Feinbaum ◽  
F M Ausubel
Keyword(s):  
Arabidopsis Thaliana ◽  
High Intensity ◽  
Chalcone Synthase ◽  
State Level ◽  
Fold Increase ◽  
Single Copy ◽  
Light Treatment ◽  
Cross Hybridization ◽  
Chalcone Synthase Gene ◽  
High Intensity Light

We have cloned an Arabidopsis thaliana chalcone synthase (CHS) gene on the basis of cross-hybridization with a Petroselinum hortense CHS cDNA clone. The protein sequence deduced from the A. thaliana CHS DNA sequence is at least 85% homologous to the CHS sequences from P. hortense, Antirrhinum majus, and Petunia hybrida. Southern blot analysis indicated that CHS is a single-copy gene in A. thaliana. High-intensity light treatment of A. thaliana plants for 24 h caused a 50-fold increase in CHS enzyme activity and an accumulation of visibly detectable levels of anthocyanin pigments in the vegetative structures of these plants. A corresponding increase in the steady-state level of CHS mRNA was detected after high-intensity light treatment for the same period of time. The accumulation of CHS mRNA in response to high-intensity light was due, at least in part, to an increased rate of transcription of the CHS gene as demonstrated by nuclear runoff experiments.

An intact Krüppel-like factor 9 gene is required for acute liver Period 1 mRNA response to restraint stress

Endocrinology ◽  
2021 ◽  
Author(s):  
Joseph R Knoedler ◽  
Cristina Sáenz de Miera ◽  
Arasakumar Subramani ◽  
Robert J Denver
Keyword(s):  
Restraint Stress ◽  
Mrna Level ◽  
Fold Increase ◽  
Plasma Corticosterone ◽  
Central Component ◽  
Peripheral Clocks ◽  
Central Pacemaker ◽  
Acute Stressor ◽  
The Brain ◽  
Clock Protein

Abstract The clock protein period 1 (PER1) is a central component of the core transcription-translation feedback loop governing cell-autonomous circadian rhythms in animals. Transcription of Per1 is directly regulated by the glucocorticoid (GC) receptor (GR), and Per1 mRNA is induced by stressors or injection of GC. Circulating GCs may synchronize peripheral clocks with the central pacemaker located in the suprachiasmatic nucleus of the brain. Krüppel-like factor 9 (KLF9) is a zinc finger transcription factor that, like Per1, is directly regulated by liganded GR, and it associates in chromatin at clock- and clock-output genes, including at Per1. We hypothesized that KLF9 modulates stressor-dependent Per1 transcription. We exposed wild type (WT) and Klf9 null mice (Klf9  -/-) of both sexes to 1 hr restraint stress, which caused similar 2-2.5 fold increases in plasma corticosterone (B) in each genotype and sex. While WT mice of both sexes showed a 2-fold increase in liver Per1 mRNA level after restraint stress, this response was absent in Klf9  -/- mice. However, injection of B in WT and Klf9  -/- mice induced similar increases in Per1 mRNA. Our findings support that an intact Klf9 gene is required for liver Per1 mRNA responses to an acute stressor, but a possible role for GCs in this response requires further investigation.

Transcriptional regulation of the Arabidopsis thaliana chalcone synthase gene

1988 ◽  
Vol 8 (5) ◽  
pp. 1985-1992
Author(s):  
R L Feinbaum ◽  
F M Ausubel
Keyword(s):  
Arabidopsis Thaliana ◽  
High Intensity ◽  
Chalcone Synthase ◽  
State Level ◽  
Fold Increase ◽  
Single Copy ◽  
Light Treatment ◽  
Cross Hybridization ◽  
Chalcone Synthase Gene ◽  
High Intensity Light

We have cloned an Arabidopsis thaliana chalcone synthase (CHS) gene on the basis of cross-hybridization with a Petroselinum hortense CHS cDNA clone. The protein sequence deduced from the A. thaliana CHS DNA sequence is at least 85% homologous to the CHS sequences from P. hortense, Antirrhinum majus, and Petunia hybrida. Southern blot analysis indicated that CHS is a single-copy gene in A. thaliana. High-intensity light treatment of A. thaliana plants for 24 h caused a 50-fold increase in CHS enzyme activity and an accumulation of visibly detectable levels of anthocyanin pigments in the vegetative structures of these plants. A corresponding increase in the steady-state level of CHS mRNA was detected after high-intensity light treatment for the same period of time. The accumulation of CHS mRNA in response to high-intensity light was due, at least in part, to an increased rate of transcription of the CHS gene as demonstrated by nuclear runoff experiments.

Feeding Schedule Controls Circadian Timing of Daily Torpor in SCN-Ablated Siberian Hamsters

2004 ◽  
Vol 19 (3) ◽  
pp. 226-237 ◽  
Author(s):  
Matthew J. Paul ◽  
Alexander S. Kauffman ◽  
Irving Zucker
Keyword(s):  
Daily Torpor ◽  
Feeding Schedule ◽  
Circadian Timing ◽  
Siberian Hamsters

scholarly journals Transcranial alternating current stimulation at theta frequency to the parietal cortex impairs associative, but not perceptual, memory encoding

2020 ◽  
Author(s):  
Alyssa Meng ◽  
Max Kaiser ◽  
Tom de Graaf ◽  
Felix Duecker ◽  
Alexander T. Sack ◽  
...  
Keyword(s):  
Associative Memory ◽  
Parietal Cortex ◽  
Brain Stimulation ◽  
Brain Activity ◽  
Memory Performance ◽  
Alternating Current ◽  
Theta Oscillations ◽  
Memory Encoding ◽  
Transcranial Alternating Current Stimulation ◽  
Hippocampal Network

AbstractNeural oscillations in the theta range (4-6 Hz) are thought to underlie associative memory function in the hippocampal-cortical network. While there is ample evidence supporting a role of theta oscillations in animal and human memory, most evidence is correlational. Non-invasive brain stimulation (NIBS) can be employed to modulate cortical oscillatory activity to influence brain activity, and possibly modulate deeper brain regions, such as hippocampus, through strong and reliable cortico-hippocampal functional connections. We applied high-definition transcranial alternating current stimulation (HD-tACS) at 6 Hz over left parietal cortex to modulate brain activity in the putative cortico-hippocampal network to influence associative memory encoding. After encoding and brain stimulation, participants completed an associative memory and a perceptual recognition task. Results showed that theta tACS significantly decreased associative memory performance but did not affect perceptual memory performance. These results show that parietal theta tACS modulates associative processing separately from perceptual processing, and further substantiate the hypothesis that theta oscillations are implicated in the cortico-hippocampal network and associative encoding.

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