Overview: Rolls and
colleagues discovered spatial view neurons, object-and-spatial view
neurons, reward-and-spatial view neurons, and whole body motion neurons
(termed 'speed cells' in rodents) in the hippocampus, and head
direction cells in the presubiculum, of primates. These neurons provide
a foundation for understanding how the hippocampal system operates in episodic memory, and navigation to
landmarks, in primates including humans. The neurophysiological
discoveries are complemented by a theory of how neuronal networks in
the hippocampal system operate using pattern separation and pattern
completion, and what remains the only quantitative theory of how
information is recalled from the hippocampus to the neocortex. Key
summary descriptions are in 633, 584, B15, 594, 539, 550 and 186.
spatial view neurons that provide an allocentric representation of
locations being viewed, and that are updated by self-motion (129, 152, 202, 237, 244,
267, 594, B15, 633).
spatial view neurons that combine information about spatial view and
objects (130, 131, 380)
or rewards (387), and are
involved in recall (399), providing
a basis for implementing episodic memory (539,
B12, 594, B15).
A theory for how hippocampal spatial view cells are involved in memory (584, 594, 539,
B12, B15) and navigation (594, B15, 633).
Hippocampal neurons in primates that respond
to a combination of spatial view and place, or to place (202).
motion neurons in the hippocampus (184), more recently termed 'speed
cells'. These are relevant to hippocampal
spatial representation update by self-motion, i.e. idiothetic update (633).
neurons that respond to a combination of spatial view and whole body
motion (184, 202).
direction cells in the primate presubiculum (271).
representation of long-term familiarity memory in the perirhinal cortex
theory and model of hippocampal operation and episodic memory,
including pattern separation and pattern completion (111, 125,
453, 479, 504, 507, 521, 527,
550, 571, 584,
Extensive cortical connectivity of the human hippocampal memory system shown by diffusion tractography (635), functional connectiivty, and effective connectivity.
A theory and model
of the generation of time in the hippocampal memory system. Entorhinal
cortex time ramping cells produce through a competitive network
hippocampal time cells, providing neuronal mechanisms to encode the
order of events (605). The theory shows how cells could be generated that show 'replay' and 'reverse replay' (605).
A theory and model
of coordinate transforms in the dorsal visual system using a
combination of gain modulation and slow or trace rule competitive
learning. The theory starts with retinal position inputs gain modulated
by eye position to produce a head centred representation, followed by
gain modulation by head direction, followed by gain modulation by
place, to produce an allocentric representation in spatial view
coordinates useful for the idiothetic update of hippocampal spatial
view cells (612). This is important in the theory of navigation using spatial view cells when the view details are obscured (B15, 633).
A theory of navigation in
humans and other primates that utilizes hippocampal spatial view cells
to navigate from landmark to landmark (B15, 633).
This is an alternative to navigation involving place cells, and does not require a spatial cognitive Euclidean map. Idiothetic
update by head direction and whole body motion cells is part of the
theory (633). Allocentric bearing to a landmark cells may also be involved in a related type of navigation (633).
A theory of how spatial view cells and hippocampal attractor networks are involved in the art of memory (the method of loci) (571, 595).
Hypertension and impaired memory: even moderate hypertension is associated with reduced hippocampal functional connectivity and impaired memory (625).
storage capacity of autoassociation and pattern association networks
sparse representations and diluted connectivity (150,
228, 515, 545,
forebrain, probably cholinergic neurons, that project to the cortex and
to forebrain-decoded reward, aversive, and novel stimuli (144, 145,
146, 177, B7, B11).
These are thought to play a role in
keeping the cerebral cortex alert to
potentially important stimuli, and reducing the adaptation of cortical
Reduction in the performance of this system may contribute to some of
cognitive changes during aging (B8, B9,
involving synaptic facilitation that enable several items to be held
simultaneously in short-term memory (523)
and that may be useful in the syntax for language (537).
can be retrieved from biologically plausible attractor neuronal
rapidly (in less than 2 time constants of the synapses) (with A.Treves
makes cortical computation with attractor networks