Construction of complex memories via parallel distributed cortical–subcortical iterative integration

Normative mammillary body volumes: From the neonatal period to young adult

“…The mammillary bodies (MBs) may be small, but they form a key part of an extended memory network and are particularly important for encoding complex memories ( McNaughton and Vann, 2022 ). In adults, damage to the MBs often occurs due to thiamine deficiency resulting in Korsakoff syndrome ( Kopelman, 1995 ).…”

Theta dominates cross-frequency coupling in hippocampal-medial entorhinal circuit during awake-behavior in rats

“…Should the proponents of “routing information by gamma in the hippocampus” be unable to account for these anomalies alternative theories should be considered. Fortunately, other ideas exist in terms of the energy cascade model in which theta reflects the coordination of post-synaptic volleys across regions ( Buzsaki and Draguhn, 2004 ; McNaughton and Vann, 2022 ; Sheremet et al., 2018a , 2018c , 2018c ; Vertes et al., 2001 ).…”

“…The amplitude of the oscillation is indicative of the number of neurons engaged, whereas the frequency provides insights into the size of the recurrent loop as well as axonal conduction velocity and synaptic delays. Propagating activity in a ring-attractor-like manner offers a mechanism of maintaining theta timescale coordinated activity across regions while also maintaining a degree of independence ( Maurer and Nadel, 2021 ; McNaughton and Vann, 2022 ; Skaggs, 1995 ; Vertes et al., 2001 ). Small, local anatomical loops support higher frequency oscillations, such as gamma.…”

“…Theta has long been associated with awake behavior and REM sleep, generated by the coordinated action of propagating activity across multiple brain regions (for examples, see Buzsaki, 2002 ; Buzsáki, 2005 ; Jouvet, 1969 ; McNaughton and Vann, 2022 ; Vertes et al., 2001 ). The gamma oscillation, modulated by the theta rhythm (e.g., Bragin et al., 1995 ; Chrobak and Buzsaki, 1998 ), has been proposed to reflect the average duration of inhibition, clocked by the GABAa receptor time constant ( Lytton and Sejnowski, 1991 ; Wang and Buzsáki, 1996 ) and facilitated by gap junctions ( Hormuzdi et al., 2001 ; Traub et al., 2002 ).…”

Engram Stability and Maturation During Systems Consolidation Underlies Remote Memory

“…While investigating the connectivity-based properties of the CA1 engram, we found alterations to its input-output connections. The bi-directional circuit between the CA1 and the MB is essential for memory ( 60 ), but based on our findings, the size of input from CA1 engram cells to the MB and from the MB to CA1 engram cells is constant. The CA1-ACC circuitry, however, changes as the memory ages.…”