One prominent view holds that episodic memory emerged recently in humans and lacks a “(neo)Darwinian evolution” [Tulving E (2002) Annu Rev Psychol 53:1–25]. Here, we review evidence supporting the alternative perspective has long evolutionary history. We show fundamental features of capacity are present mammals birds major brain regions responsible for have anatomical functional homologs other species. propose depends on neural circuit is similar across mammalian avian species, suggesting...

Abstract Episodic memory-based decision-making requires top-down medial prefrontal cortex and hippocampal interactions. This integrated prefrontal-hippocampal memory state is thought to be organized by synchronized network oscillations mediated connectivity with the thalamic nucleus reuniens (RE). Whether how RE synchronizes networks in memory, however, remains unknown. Here, we recorded local field potentials from prefrontal-RE-hippocampal while rats engaged a nonspatial sequence task,...

The hippocampus is critical to the memory for sequences of events, a defining feature episodic memory. However, fundamental neuronal mechanisms underlying this capacity remain elusive. While considerable research indicates hippocampal neurons can represent locations, direct evidence coding sequential relationships among nonspatial events remains lacking. To address important issue, we recorded neural activity in CA1 as rats performed hippocampus-dependent sequence-memory task. Briefly, task...

ABSTRACT A critical feature of episodic memory is the ability to remember order events as they occurred in time, a capacity shared across species including humans, nonhuman primates, and rodents. Accumulating evidence suggests that this depends on network structures hippocampus prefrontal cortex, but their respective contributions remain poorly understood. As addressing important issue will require converging from complementary investigative techniques, we developed cross‐species, nonspatial...

We remember our lives as sequences of events, but it is unclear how these memories are controlled during retrieval. In rats, the medial prefrontal cortex (mPFC) positioned to influence sequence memory through extensive top-down inputs regions heavily interconnected with hippocampus, notably nucleus reuniens thalamus (RE) and perirhinal (PER). Here, we used an hM4Di synaptic-silencing approach test hypothesis that specific mPFC→RE mPFC→PER projections regulate First, found non-overlapping...

Episodic memory includes information about how long ago specific events occurred. Since most of our experiences have overlapping elements, remembering this temporal context is crucial for distinguishing individual episodes. The discovery timing signals in hippocampal neurons, including evidence “time cells” and gradual changes ensemble activity over timescales, strongly suggests that the hippocampus important capacity. However, behavioral critical elapsed time lacking. This possibly because...

Delta-frequency network activity is commonly associated with sleep or behavioral disengagement accompanied by a dearth of cortical spiking, but delta in awake behaving animals not well understood. We show that hippocampal (HC) synchronization the frequency band (1-4 Hz) related to animals' locomotor behavior using detailed analyses HC local field potential (LFP) and simultaneous head- body-tracking data. In contrast running-speed modulation theta rhythm (6-10 Hz), was most prominent when...

Pretraining lesions of rat perirhinal (PR) cortex impair fear conditioning to ultrasonic vocalizations (USVs) but have no effect on continuous tones. This study attempted deconstruct USVs into simpler stimulus features that cause be PR-dependent. Rats were conditioned one three cues: a multicall 19-kHz USV, discontinuous tone, and tone. The tone duplicated the on/off pattern individual calls in it lacked characteristic frequency modulations. Well-localized neurotoxic PR impaired training...

Pretraining lesions of rat perirhinal cortex (PR) severely impair pavlovian fear conditioning to a 22 kHz ultrasonic vocalization (USV) cue. However, PR are without significant effect when the cue is continuous tone at same or lower frequency. Here we examined fear-conditioning-produced changes in single-unit firing elicited by USV Chronic recording electrodes were introduced from lateral surface skull. Altogether, 200 well isolated units studied 28 rats. Overall, 73% recorded single (145...

Abstract Estrogens can be neuroprotective following traumatic brain injury. Immediately after trauma to the zebra finch hippocampus, estrogen‐synthetic enzyme aromatase is rapidly upregulated in astrocytes and radial glia around lesion site. Brain injury also induces high levels of cell proliferation. promote neuronal differentiation, migration, survival naturally avian brain. We suspect that are a source estrogens promoting proliferation neural To explore this hypothesis, we examined...

Abstract Estrogens influence neuronal differentiation, migration, and survival in intact brains. In injured brains, estrogens can also be neuroprotective. Experiment 1, following a unilateral penetrating injury to the hippocampus (HP), adult female zebra finches were injected once with BrdU label mitotic cells then sacrificed 2 h, 1 day, or 7 days postinjection. Cell proliferation was dramatically enhanced ipsilateral HP, as well neuroproliferative areas including subventricular zone (SVZ)...

Typical aging is associated with diminished episodic memory performance. To improve our understanding of the fundamental mechanisms underlying this age-related deficit, we previously developed an integrated, cross-species approach to link converging evidence from human and animal research. This novel focuses on ability remember sequences events, important feature memory. Unlike existing paradigms, task nonspatial, nonverbal, can be used isolate different cognitive processes that may...

Abstract The midline thalamus bidirectionally connects the medial prefrontal cortex (mPFC) and hippocampus (HC) creating a unique cortico‐thalamo‐cortical circuit fundamental to memory executive function. While anatomical connectivity of has been thoroughly investigated, little is known about its cellular organization within each nucleus. Here we used immunohistological techniques examine distributions in based on calcium binding proteins parvalbumin (PV), calretinin (CR), calbindin (CB). We...

Remembering sequences of events defines episodic memory, but retrieval can be driven by both ordinality and temporal contexts. Whether these modes operate at the same time or not remains unclear. Theoretically, medial prefrontal cortex (mPFC) confers ordinality, while hippocampus (HC) associates in gradually changing Here, we looked for evidence each with BOLD fMRI a sequence task that taxes modes. To test ordinal modes, items were transferred between retained their position (e.g., AB 3 )....

There has not been a major change in how neuroscientists approach stereotaxic methods decades. Here, we present new method that provides an alternative to traditional u-frame device and reduces costs, surgical time, aids repeatability. The RatHat brain implantation system is 3D-printable for rats fabricated prior surgery fits the shape of skull. builds are directly implanted into without need head-leveling or coordinate-mapping during surgery. can be used conjunction with device, but does...