Visual memory, mainly composed of visual long-term memory (VLTM) and visual working memory (VWM), is an important mechanism of human information storage. Since Baddeley proposed the multicomponent working memory model, the idea that VWM is independent of the VLTM system has been widely accepted. However, the new theoretical evidence suggested a close connection between VLTM and VWM. For instance, the three embedded components model describes the VLTM and VWM in the same framework, which suggests that VWM is only a distinct state of VLTM. On the one hand, the operating function of VWM is supported by the persistence of VLTM. On the other hand, the evidence from neuroimaging studies shows that VWM and VLTM tasks activate some same brain areas. In addition, the whole visual memory system shows a trend of processing from early visual cortex to prefrontal cortex. The present article not only reviews the current studies about the relationship between VLTM and VWM but also gives some forecasts for future studies.
Brain ; physiology ; Humans ; Memory, Long-Term ; Memory, Short-Term ; Visual Cortex ; physiology ; Visual Perception

Astrocytes are increasingly recognized to play an active role in learning and memory, but whether neural inputs can trigger event-specific astrocytic Ca²⁺ dynamics in real time to participate in working memory remains unclear due to the difficulties in directly monitoring astrocytic Ca²⁺ dynamics in animals performing tasks. Here, using fiber photometry, we showed that population astrocytic Ca²⁺ dynamics in the hippocampus were gated by sensory inputs (centered at the turning point of the T-maze) and modified by the reward delivery during the encoding and retrieval phases. Notably, there was a strong inter-locked and antagonistic relationship between the astrocytic and neuronal Ca²⁺ dynamics with a 3-s phase difference. Furthermore, there was a robust synchronization of astrocytic Ca²⁺ at the population level among the hippocampus, medial prefrontal cortex, and striatum. The inter-locked, bidirectional communication between astrocytes and neurons at the population level may contribute to the modulation of information processing in working memory.
Animals ; Astrocytes ; Hippocampus/physiology* ; Humans ; Memory, Short-Term/physiology* ; Mice ; Neurons/physiology* ; Population Dynamics

Working memory (WM) refers to the process of temporally maintaining and manipulating input information. WM is the global workspace of cognitive functions, however, with severely restricted capacity and precision. Previous cognitive and computational models discussed the methods of calculating capacity and precision of WM and the reason why they are so limited. It still remains debated which model is the best across all datasets, and whether there exists upper limits of items. Besides, sensory cortices and the frontal-parietal loop are suggested to represent WM memorandum. Yet recently, the sensory recruitment hypothesis that posits an important role of sensory cortices in WM is strongly argued. Meanwhile, whether the prefrontal cortex shows sustained activity or bursting γ oscillations is intensely debated as well. In the future, disentangling the contribution to WM of feedforward γ vs feedback α/β oscillations, and/or dopamine vs serotonin systems, is critical for understanding the neural mechanisms underlying WM. It will further do help to recognize the basis for the psychiatric (e.g. schizophrenia) or neurological (e.g. Alzheimer's disease) disorders, and potentially to develop effective training and intervening methods.
Cognition ; Humans ; Memory, Short-Term ; Models, Neurological ; Parietal Lobe ; physiology ; Prefrontal Cortex ; physiology

OBJECTIVETo explore the influence of verbal working memory load on associative neural networks.

METHODSTwenty-one subjects were required to complete a verbal delayed matching-to-sample task under the condition of low (3 items) or high (5 items) working memory load (WML). The 19-channels event-related potentials (ERP) were analyzed with statistical parametric mapping.

RESULTSA significant difference in working memory capacity (WMC) was found between low WML and high WML groups [2.48∓0.30 vs 3.30∓0.76; t(20)=5.950, P=0.000]. Statistical parametric mapping revealed that during the encoding stage, the effects of WML appeared in succession in the right ventral attention network (rVAN), the dorsal attention network, and the language areas in the left hemisprere. During the maintenance stage, the effects WML occured in the rVAN acompanied by either DAN or left frontal-temporal regions. CONCLUSIONS;onclusions When the WML is beyond the WMC, the rVAN may participate in the prevention of interference among items and in the activation of long-term memory.

Attention ; Evoked Potentials ; Frontal Lobe ; physiology ; Humans ; Memory, Short-Term ; Spatio-Temporal Analysis

Working memory is an important foundation for advanced cognitive function. The paper combines the spatiotemporal advantages of electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) to explore the neurovascular coupling mechanism of working memory. In the data analysis, the convolution matrix of time series of different trials in EEG data and hemodynamic response function (HRF) and the blood oxygen change matrix of fNIRS are extracted as the coupling characteristics. Then, canonical correlation analysis (CCA) is used to calculate the cross correlation between the two modal features. The results show that CCA algorithm can extract the similar change trend of related components between trials, and fNIRS activation of frontal pole region and dorsolateral prefrontal lobe are correlated with the delta, theta, and alpha rhythms of EEG data. This study reveals the mechanism of neurovascular coupling of working memory, and provides a new method for fusion of EEG data and fNIRS data.
Electroencephalography/methods* ; Memory, Short-Term ; Neurovascular Coupling/physiology* ; Prefrontal Cortex ; Spectroscopy, Near-Infrared/methods*

With the widespread use of electrical equipment, cognitive functions such as working memory (WM) could be severely affected when people are exposed to 50 Hz electromagnetic fields (EMF) for long term. However, the effects of EMF exposure on WM and its neural mechanism remain unclear. In the present paper, 15 rats were randomly assigned to three groups, and exposed to an EMF environment at 50 Hz and 2 mT for a different duration: 0 days (control group), 24 days (experimental group I), and 48 days (experimental group II). Then, their WM function was assessed by the T-maze task. Besides, their local field potential (LFP) in the media prefrontal cortex (mPFC) was recorded by the in vivo multichannel electrophysiological recording system to study the power spectral density (PSD) of θ and γ oscillations and the phase-amplitude coupling (PAC) intensity of θ-γ oscillations during the T-maze task. The results showed that the PSD of θ and γ oscillations decreased in experimental groups I and II, and the PAC intensity between θ and high-frequency γ (hγ) decreased significantly compared to the control group. The number of days needed to meet the task criterion was more in experimental groups I and II than that of control group. The results indicate that long-term exposure to EMF could impair WM function. The possible reason may be the impaired communication between different rhythmic oscillations caused by a decrease in θ-hγ PAC intensity. This paper demonstrates the negative effects of EMF on WM and reveals the potential neural mechanisms from the changes of PAC intensity, which provides important support for further investigation of the biological effects of EMF and its mechanisms.
Humans ; Rats ; Animals ; Memory, Short-Term/physiology* ; Electromagnetic Fields/adverse effects* ; Prefrontal Cortex ; Cognition

Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment, with the predominant clinical diagnosis of spatial working memory (SWM) deficiency, which seriously affects the physical and mental health of patients. However, the current pharmacological therapies have unsatisfactory cure rates and other problems, so non-pharmacological physical therapies have gradually received widespread attention. Recently, a novel treatment using 40 Hz light flicker stimulation (40 Hz-LFS) to rescue the cognitive function of model animals with AD has made initial progress, but the neurophysiological mechanism remains unclear. Therefore, this paper will explore the potential neural mechanisms underlying the modulation of SWM by 40 Hz-LFS based on cross-frequency coupling (CFC). Ten adult Wistar rats were first subjected to acute LFS at frequencies of 20, 40, and 60 Hz. The entrainment effect of LFS with different frequency on neural oscillations in the hippocampus (HPC) and medial prefrontal cortex (mPFC) was analyzed. The results showed that acute 40 Hz-LFS was able to develop strong entrainment and significantly modulate the oscillation power of the low-frequency gamma (lγ) rhythms. The rats were then randomly divided into experimental and control groups of 5 rats each for a long-term 40 Hz-LFS (7 d). Their SWM function was assessed by a T-maze task, and the CFC changes in the HPC-mPFC circuit were analyzed by phase-amplitude coupling (PAC). The results showed that the behavioral performance of the experimental group was improved and the PAC of θ-lγ rhythm was enhanced, and the difference was statistically significant. The results of this paper suggested that the long-term 40 Hz-LFS effectively improved SWM function in rats, which may be attributed to its enhanced communication of different rhythmic oscillations in the relevant neural circuits. It is expected that the study in this paper will build a foundation for further research on the mechanism of 40 Hz-LFS to improve cognitive function and promote its clinical application in the future.
Humans ; Adult ; Rats ; Animals ; Memory, Short-Term/physiology* ; Rats, Wistar ; Neurodegenerative Diseases ; Hippocampus ; Prefrontal Cortex

Event-Related Potentials, P300 ; physiology ; Humans ; Individuality ; Male ; Memory, Short-Term ; physiology ; Neuropsychological Tests ; standards ; Young Adult

Transcranial magneto-acoustic-electrical stimulation is a new non-invasive neuromodulation technology, in which the induced electric field generated by the coupling effect of ultrasound and static magnetic field are used to regulate the neural rhythm oscillation activity in the corresponding brain region. The purpose of this paper is to investigate the effects of transcranial magneto-acoustic-electrical stimulation on the information transfer and communication in neuronal clusters during memory. In the experiment, twenty healthy adult Wistar rats were randomly divided into a control group (five rats) and stimulation groups (fifteen rats). Transcranial magneto-acoustic-electrical stimulation of 0.05~0.15 T and 2.66~13.33 W/cm ² was applied to the rats in stimulation groups, and no stimulation was applied to the rats in the control group. The local field potentials signals in the prefrontal cortex of rats during the T-maze working memory tasks were acquired. Then the coupling differences between delta rhythm phase, theta rhythm phase and gamma rhythm amplitude of rats in different parameter stimulation groups and control group were compared. The experimental results showed that the coupling intensity of delta and gamma rhythm in stimulation groups was significantly lower than that in the control group ( P<0.05), while the coupling intensity of theta and gamma rhythm was significantly higher than that in the control group ( P<0.05). With the increase of stimulation parameters, the degree of coupling between delta and gamma rhythm showed a decreasing trend, while the degree of coupling between theta and gamma rhythm tended to increase. The preliminary results of this paper indicated that transcranial magneto-acoustic-electrical stimulation inhibited delta rhythmic neuronal activity and enhanced the oscillation of theta and gamma rhythm in the prefrontal cortex, thus promoted the exchange and transmission of information between neuronal clusters in different spatial scales. This lays the foundation for further exploring the mechanism of transcranial magneto-acoustic-electrical stimulation in regulating brain memory function.
Acoustics ; Animals ; Electric Stimulation ; Memory, Short-Term/physiology* ; Rats ; Rats, Wistar ; Theta Rhythm/physiology* ; Transcranial Direct Current Stimulation

OBJECTIVETo explore the neuropsychological characteristics of children with attention deficit hyperactivity disorder (ADHD).

METHODSNeuropsychological tests, including visual working memory, Stroop test, digits inverse reciting, vocabulary fluency, Wisconsin card sort test (WCST), and Temporal discounting were used to evaluate the capacity of response inhibition, phonological working memory, visual working memory executive function and delayed satisfying capacity of subjects.

RESULTS1. The ADHD children spent longer time [ADHD-I (84(20), ADHD-C: 98 (31), normal: 70 (28)] to accomplish color naming and made more errors [ADHD-I: 3 (3), ADHD-C: 6 (19), normal: 2 (5)] than the normal control when the color was inconsistent with the word meaning in Stroop test (P < 0.01). 2. The scores of digits reciting [ADHD-I: 3 (3), ADHD-C: 3 (4), normal 4 (4)] inverse was lower in ADHD than in normal control (P < 0.01). 3. The representation of ADHD was poorer than normal control in visual working memory [ADHD-I: 21 (3), ADHD-C: 20 (5), Normal: 20 (3)], and in delayed visual memory [ADHD-I: 19 (5), ADHD-C: 19 (5), Normal: 20 (5)] (P < 0.01). 4. The scores of vocabulary fluency [ADHD-I: 1 (1), ADHD-C: 2 (1), normal: 0 (0)] was lower in ADHD than in normal control (P < 0.01). 5. In WCST, the ADHD children made more errors [ADHD-I :15 (17), ADHD-C: 15 (15), normal: 13 (13)] and less classification [ADHD-I: 5 (4), ADHD-C: 5 (4), normal: 5 (3)] than normal control (P < 0.01). 6. In Temporal discounting, the ADHD children showed significantly more impairments than normal control did (P < 0.01). 7. There was significant difference between the two subtype groups on some tests (P < 0.01).

CONCLUSIONSObvious cognitive impairments were found in children with ADHD, involving poor response inhibition, impaired working memory, dysfunction of planning and set-shifting, and there was no significant difference between the two subtype groups.

Attention Deficit Disorder with Hyperactivity ; classification ; immunology ; physiopathology ; psychology ; Child ; Cognition Disorders ; physiopathology ; psychology ; Humans ; Memory ; Memory Disorders ; immunology ; psychology ; Memory, Short-Term ; physiology ; Neuropsychological Tests