Time perception and temporal order memory

Enactment encoding promotes relative temporal order memory

Studies have shown that enactment improves memory; however, in daily life, our memories of motor events often exhibit a relative temporal order. Therefore, this study examined whether enactment promotes relative temporal order memory. In Experiment 1, a sequential recall task and a subject-performed task were used to explore whether enactment encoding improved relative temporal order memory. The results showed that the relative temporal order memory of the enactment-encoding group was significantly better than that of the verbal-encoding group, indicating that enactment promoted relative temporal order memory. Since temporal order memory is often affected by spatial cues, in Experiment 2, we further controlled spatial cues and used a 2 (spatial cues: consistent with temporal order, vs. no cues) × 2 (encoding type: verbal vs. enactment) design to explore whether spatial cues influence the effect of enactment encoding on temporal order memory. The results showed that compared with verbal encoding, enactment encoding significantly improved relative temporal order memory. However, no effect of spatial cues on relative temporal order memory was found. Our study confirmed that enactment encoding promotes relative temporal order memory performance independent of spatial cues.

The Enigmatic CA2: Exploring the Understudied Region of the Hippocampus and Its Involvement in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease that affects both motor and non-motor functions. Although motor impairment is a prominent clinical sign of PD, additional neurological symptoms may also occur, particularly in the preclinical and prodromal stages. Among these symptoms, social cognitive impairment is common and detrimental. This article aims to review non-motor symptoms in PD patients, focusing on social cognitive deficits. It also examines the specific characteristics of the CA2 region and its involvement in social behavior, highlighting recent advances and perspectives. Additionally, this review provides critical insights into and analysis of research conducted in rodents and humans, which may help improve the understanding of the current status of putative therapeutic strategies for social cognitive dysfunction in PD and potential avenues related to the function of the hippocampal CA2 region.

The Potential Interaction Between Time Perception and Gaming: A Narrative Review

Compromised time control is a variable of interest among disordered gamers because time spent on videogames can directly affect individuals’ lives. Although time perception appears to be closely associated with this phenomenon, previous studies have not systematically found a relationship between time perception and gaming. Therefore, the purpose of this narrative review is to explore how gaming disorder may be associated with time perception. It has been found that gamers exhibit a stronger attentional focus as well as an improved working memory compared with non-gamers. However, gamers (and especially disordered gamers) exhibit a stronger reaction to gaming cues which—coupled with an altered emotion regulation observed among disordered gamers—could directly affect their time perception. Finally, “'flow states”' direct most of the attentional resources to the ongoing activity, leading to a lack of resources allocated to the time perception. Therefore, entering a flow state will result in an altered time perception, most likely an underestimation of duration. The paper concludes that the time loss effect observed among disordered gamers can be explained via enhanced emotional reactivity (facilitated by impaired emotion regulation).

The hippocampus contributes to temporal duration memory in the context of event sequences: A cross-species perspective

Although a large body of research has implicated the hippocampus in the processing of memory for temporal duration, there is an exigent degree of inconsistency across studies that obfuscates the precise contributions of this structure. To shed light on this issue, the present review article surveys both historical and recent cross-species evidence emanating from a wide variety of experimental paradigms, identifying areas of convergence and divergence. We suggest that while factors such as time-scale (e.g. the length of durations involved) and the nature of memory processing (e.g. prospective vs. retrospective memory) are very helpful in the interpretation of existing data, an additional important consideration is the context in which the duration information is experienced and processed, with the hippocampus being preferentially involved in memory for durations that are embedded within a sequence of events. We consider the mechanisms that may underpin temporal duration memory and how the same mechanisms may contribute to memory for other aspects of event sequences such as temporal order.

Ammon's Horn 2 (CA2) of the Hippocampus: A Long-Known Region with a New Potential Role in Neurodegeneration

The hippocampus has a critical role in cognition and human memory and is one of the most studied structures in the brain. Despite more than 400 years of research, little is known about the Ammon's horn region cornu ammonis 2 (CA2) subfield in comparison to other subfield regions (CA1, CA3, and CA4). Recent findings have shown that CA2 plays a bigger role than previously thought. Here, we review understanding of hippocampus and CA2 ontogenesis, together with basic and clinical findings about the potential role of this region in neurodegenerative disease. The CA2 has widespread anatomical connectivity, unique signaling molecules, and intrinsic electrophysiological properties. Experimental studies using in vivo models found that the CA2 region has a role in cognition, especially in social memory and object recognition. In models of epilepsy and hypoxia, the CA2 exhibits higher resilience to cell death and hypoxia in comparison with neighboring regions, and while hippocampal atrophy remains poorly understood in Parkinson's disease (PD) and dementia with Lewy bodies (DLB), findings from postmortem PD brain demonstrates clear accumulation of α-synuclein pathology in CA2, and the CA2-CA3 region shows relatively more atrophy compared with other hippocampal subfields. Taken together, there is a growing body of evidence suggesting that the CA2 can be an ideal hallmark with which to differentiate different neurodegenerative stages of PD. Here, we summarize these recent data and provide new perspectives/ideas for future investigations to unravel the contribution of the CA2 to neurodegenerative diseases.

Intensity-dependent effects of transcranial pulsed current stimulation on interhemispheric connectivity: a high-resolution qEEG, sham-controlled study

Defining optimal parameters for stimulation is a critical step in the development of noninvasive neuromodulation techniques. Transcranial pulsed current stimulation (tPCS) is emerging as another option in the field of neuromodulation; however, little is known about its mechanistic effects on electrical brain activity and how it can modulate its oscillatory patterns. The aim of this study was to identify the current intensity needed to exert an effect on quantitative electroencephalogram (qEEG) measurements. Forty healthy volunteers were randomized to receive a single session of sham or active stimulation at 0.2, 1, or 2 mA current intensity with a random frequency with an oscillatory pulsed range between 1 and 5 Hz. We conducted an exploratory frequency domain analysis to detect changes in absolute power for theta, alpha, and beta frequency bands and also interhemispheric coherence for alpha, theta, and four different sub-bands. Cognitive and nonspecific adverse effects were also recorded. Our results showed that both 1 and 2 mA can modulate interhemispheric coherence at the fronto-temporal areas for the theta band as compared with sham, while 2 mA also increased the low-beta and high-beta interhemispheric coherence at the same anatomical location. There were no group differences for adverse effects and participants could not guess correctly whether they received active versus sham stimulation. On the basis of our results, we conclude that tPCS is associated with an intensity-dependent facilitatory effect on interhemispheric connectivity. These results can guide future tPCS applications and will define its role as a neuromodulatory technique in the field.