Anterograde versus Retrograde Effects of Damage to Identified Learning and Memory Systems during Acquisition, Retention, and Re-Acquisition of an Instrumental Visual Discrimination Task: Dorsal Striatum, Perirhinal Cortex, and Hippocampus.

Background: The goal of these experiments was to determine which learning and memory system(s) were necessary for the retention of visual discriminations and subsequent acquisition of a second problem. The dorsal striatum should be involved in the acquisition and expression of this task based on previous work implicating this region in instrumental learning and memory processes. The perirhinal cortex has been implicated in learning and memory processes associated with visual information like objects, and pictures and may also play a role in the acquisition and/or retention of visual discriminations.

Tracheoesophageal Voice Therapy in Postlaryngectomy Rehabilitation: A Systematic Review.

Background: Following total laryngectomy, surgical voice restoration is considered the optimal modality for re-establishing communication via tracheoesophageal voice. Yet beyond the insertion of a voice prosthesis to elicit voice production, there is suboptimal clinical knowledge of how to rehabilitate the perceptual quality of tracheoesophageal voice. This systematic review will identify and critically evaluate the quality and effectiveness of therapeutic interventions for tracheoesophageal voice.

Approaches to tracheoesophageal voice rehabilitation: a survey of the UK and Irish speech and language therapists' current practice and beliefs.

Background: After total laryngectomy, surgical voice restoration is used to establish communication via tracheoesophageal voice prosthesis. Once voice is established, there is a paucity of information on what speech and language therapists (SLTs) should do to improve tracheoesophageal voice quality to ensure functional communication. No existing surveys or studies investigate this specific question.

Cannabinoid regulation of neurons in the dentate gyrus during epileptogenesis: Role of CB1R-associated proteins and downstream pathways.

The hippocampal formation plays a central role in the development of temporal lobe epilepsy (TLE), a disease characterized by recurrent, unprovoked epileptic discharges. TLE is a neurologic disorder characterized by acute long-lasting seizures (i.e.

Exploring research impact; why it matters?

Purpose Of Review: Making research impactful is becoming a vital part of research proposal development. Funding bodies now require evidence of clear dissemination strategies that demonstrate achievable broad impact from proposed studies. This review addresses what impact means in practice and how to achieve it.

Reorganization of CA1 dendritic dynamics by hippocampal sharp-wave ripples during learning.

The hippocampus plays a critical role in memory consolidation, mediated by coordinated network activity during sharp-wave ripple (SWR) events. Despite the link between SWRs and hippocampal plasticity, little is known about how network state affects information processing in dendrites, the primary sites of synaptic input integration and plasticity. Here, we monitored somatic and basal dendritic activity in CA1 pyramidal cells in behaving mice using longitudinal two-photon calcium imaging integrated with simultaneous local field potential recordings.

Local feedback inhibition tightly controls rapid formation of hippocampal place fields.

Hippocampal place cells underlie spatial navigation and memory. Remarkably, CA1 pyramidal neurons can form new place fields within a single trial by undergoing rapid plasticity. However, local feedback circuits likely restrict the rapid recruitment of individual neurons into ensemble representations.

Supramammillary regulation of locomotion and hippocampal activity.

Locomotor speed is a basic input used to calculate one’s position, but where this signal comes from is unclear. We identified neurons in the supramammillary nucleus (SuM) of the rodent hypothalamus that were highly correlated with future locomotor speed and reliably drove locomotion when activated. Robust locomotion control was specifically identified in (substance P)–expressing (SuM) neurons, the activation of which selectively controlled the activity of speed-modulated hippocampal neurons.

Reactivation predicts the consolidation of unbiased long-term cognitive maps.

Spatial memories that can last a lifetime are thought to be encoded during 'online' periods of exploration and subsequently consolidated into stable cognitive maps through their 'offline' reactivation. However, the mechanisms and computational principles by which offline reactivation stabilize long-lasting spatial representations remain poorly understood. Here, we employed simultaneous fast calcium imaging and electrophysiology to track hippocampal place cells over 2 weeks of online spatial reward learning behavior and offline resting.

Maximally selective single-cell target for circuit control in epilepsy models.

Neurological and psychiatric disorders are associated with pathological neural dynamics. The fundamental connectivity patterns of cell-cell communication networks that enable pathological dynamics to emerge remain unknown. Here, we studied epileptic circuits using a newly developed computational pipeline that leveraged single-cell calcium imaging of larval zebrafish and chronically epileptic mice, biologically constrained effective connectivity modeling, and higher-order motif-focused network analysis.

Alternating sources of perisomatic inhibition during behavior.

Interneurons expressing cholecystokinin (CCK) and parvalbumin (PV) constitute two key GABAergic controllers of hippocampal pyramidal cell output. Although the temporally precise and millisecond-scale inhibitory regulation of neuronal ensembles delivered by PV interneurons is well established, the in vivo recruitment patterns of CCK-expressing basket cell (BC) populations has remained unknown. We show in the CA1 of the mouse hippocampus that the activity of CCK BCs inversely scales with both PV and pyramidal cell activity at the behaviorally relevant timescales of seconds.

Hippocampal adult-born granule cells drive network activity in a mouse model of chronic temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is characterized by recurrent seizures driven by synchronous neuronal activity. The reorganization of the dentate gyrus (DG) in TLE may create pathological conduction pathways for synchronous discharges in the temporal lobe, though critical microcircuit-level detail is missing from this pathophysiological intuition. In particular, the relative contribution of adult-born (abGC) and mature (mGC) granule cells to epileptiform network events remains unknown.

Volumetric Ca Imaging in the Mouse Brain Using Hybrid Multiplexed Sculpted Light Microscopy.

Calcium imaging using two-photon scanning microscopy has become an essential tool in neuroscience. However, in its typical implementation, the tradeoffs between fields of view, acquisition speeds, and depth restrictions in scattering brain tissue pose severe limitations. Here, using an integrated systems-wide optimization approach combined with multiple technical innovations, we introduce a new design paradigm for optical microscopy based on maximizing biological information while maintaining the fidelity of obtained neuron signals.

Normal CA1 Place Fields but Discoordinated Network Discharge in a Fmr1-Null Mouse Model of Fragile X Syndrome.

Silence of FMR1 causes loss of fragile X mental retardation protein (FMRP) and dysregulated translation at synapses, resulting in the intellectual disability and autistic symptoms of fragile X syndrome (FXS). Synaptic dysfunction hypotheses for how intellectual disabilities like cognitive inflexibility arise in FXS predict impaired neural coding in the absence of FMRP. We tested the prediction by comparing hippocampus place cells in wild-type and FXS-model mice.

Control of recollection by slow gamma dominating mid-frequency gamma in hippocampus CA1.

Behavior is used to assess memory and cognitive deficits in animals like Fmr1-null mice that model Fragile X Syndrome, but behavior is a proxy for unknown neural events that define cognitive variables like recollection. We identified an electrophysiological signature of recollection in mouse dorsal Cornu Ammonis 1 (CA1) hippocampus. During a shocked-place avoidance task, slow gamma (SG) (30-50 Hz) dominates mid-frequency gamma (MG) (70-90 Hz) oscillations 2-3 s before successful avoidance, but not failures.

Impaired hippocampal place cell dynamics in a mouse model of the 22q11.2 deletion.

Hippocampal place cells represent the cellular substrate of episodic memory. Place cell ensembles reorganize to support learning but must also maintain stable representations to facilitate memory recall. Despite extensive research, the learning-related role of place cell dynamics in health and disease remains elusive.

Active place avoidance is no more stressful than unreinforced exploration of a familiar environment.

Training in the active place avoidance task changes hippocampus synaptic function, the dynamics of hippocampus local field potentials, place cell discharge, and active place avoidance memory is maintained by persistent PKMζ activity. The extent to which these changes reflect memory processes and/or stress responses is unknown. We designed a study to assess stress within the active place avoidance task by measuring serum corticosterone (CORT) at different stages of training.

Hippocampal CA2 activity patterns change over time to a larger extent than between spatial contexts.

The hippocampal CA2 subregion has a different anatomical connectivity pattern within the entorhino-hippocampal circuit than either the CA1 or CA3 subregion. Yet major differences in the neuronal activity patterns of CA2 compared with the other CA subregions have not been reported. We show that standard spatial and temporal firing patterns of individual hippocampal principal neurons in behaving rats, such as place fields, theta modulation, and phase precession, are also present in CA2, but that the CA2 subregion differs substantially from the other CA subregions in its population coding.

Recent memory for socially transmitted food preferences in rats does not depend on the hippocampus.

The standard model of systems consolidation holds that the hippocampus (HPC) is involved only in the initial storage and retrieval of a memory. With time hippocampal-neocortical interactions slowly strengthen the neocortical memory, ultimately enabling retrieval of the memory without the HPC. Key support for this idea comes from experiments measuring memory recall in the socially-transmitted food preference (STFP) task in rats.

What is optimized in an optimal path?

An animal confronts numerous challenges when constructing an optimal navigational route. Spatial representations used for path optimization are likely constrained by critical environmental factors that dictate which neural systems control navigation. Multiple coding schemes depend upon their ecological relevance for a particular species, particularly when dealing with the third, or vertical, dimension of space.

Neither time nor number of context-shock pairings affect long-term dependence of memory on hippocampus.

There are still basic uncertainties concerning the role of the hippocampus (HPC) in maintaining long-term context memories. All experiments examining the effects of extensive HPC damage on context memory for a single learning episode find that damage soon after learning results in robust retrograde amnesia. Some experiments find that if the learning-to-damage interval is extended, remote context memories are spared.

Interfering with post-learning hippocampal activity does not affect long-term consolidation of a context fear memory outside the hippocampus.

There are still uncertainties about the role of the hippocampus (HPC) in memory consolidation. One theory, systems consolidation, states that the HPC is required for the initial storage of certain memories that subsequently become established in non-HPC networks through a lengthy process, involving an interaction with the HPC. A similar process may underlie the ability of multiple, distributed learning episodes of contextual fear conditioning to create a HPC-independent context fear memory, in a memory task that does not undergo systems consolidation with the mere passage of time [5].

Neuronal code for extended time in the hippocampus.

The time when an event occurs can become part of autobiographical memories. In brain structures that support such memories, a neural code should exist that represents when or how long ago events occurred. Here we describe a neuronal coding mechanism in hippocampus that can be used to represent the recency of an experience over intervals of hours to days.

Suppression of neurotoxic lesion-induced seizure activity: evidence for a permanent role for the hippocampus in contextual memory.

Damage to the hippocampus (HPC) using the excitotoxin N-methyl-D-aspartate (NMDA) can cause retrograde amnesia for contextual fear memory. This amnesia is typically attributed to loss of cells in the HPC. However, NMDA is also known to cause intense neuronal discharge (seizure activity) during the hours that follow its injection.

Between-systems memory interference during retrieval.

Context memories normally depend on the hippocampus (HPC) but, in the absence of the HPC, other memory systems are capable of acquiring and supporting these memories. This suggests that the HPC can interfere with other systems during memory acquisition. Here we ask whether the HPC can also interfere with the retrieval of a context memory that was independently acquired by a non-HPC system.