The engram theory is a theory of memory that proposes that memories are stored in the brain as physical changes in the neural connections. This theory was first proposed by Richard Semon in 1904.

The holographic memory theory is a theory of memory that proposes that memories are stored in the brain as holograms. This theory was first proposed by Karl Pribram in 1969.

The distributed memory theory is a theory of memory that proposes that memories are stored in the brain as distributed patterns of activity across multiple neurons. This theory was first proposed by Donald Hebb in 1949.

The state-dependent memory theory is a theory of memory that proposes that memories are stored in the brain as changes in the state of the brain. This theory was first proposed by Robert Ornstein in 1972.

The hybrid memory theory is a theory of memory that proposes that memories are stored in the brain as a combination of physical changes in the neural connections and changes in the state of the brain. This theory was first proposed by James McGaugh in 1983.

The synaptic plasticity theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression. This theory was first proposed by Eric Kandel in 1983.

The neuromodulatory theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators. This theory was first proposed by Jaak Panksepp in 1982.

The cell assembly theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators, and that these changes are organized into cell assemblies. This theory was first proposed by Donald Hebb in 1949.

The network theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators, and that these changes are organized into cell assemblies, and that these cell assemblies are connected to each other by Hebbian synapses. This theory was first proposed by James McClelland and David Rumelhart in 1986.

The hierarchical network theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators, and that these changes are organized into cell assemblies, and that these cell assemblies are connected to each other by Hebbian synapses, and that these networks are organized into a hierarchy. This theory was first proposed by Geoffrey Hinton and David Rumelhart in 1986.

The global workspace theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators, and that these changes are organized into cell assemblies, and that these cell assemblies are connected to each other by Hebbian synapses, and that these networks are organized into a hierarchy, and that these hierarchies are organized into a global workspace. This theory was first proposed by Bernard Baars in 1988.

The conscious memory theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators, and that these changes are organized into cell assemblies, and that these cell assemblies are connected to each other by Hebbian synapses, and that these networks are organized into a hierarchy, and that these hierarchies are organized into a global workspace, and that this global workspace is accessed by consciousness. This theory was first proposed by Stanislas Dehaene in 1998.

The materialist theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators, and that these changes are organized into cell assemblies, and that these cell assemblies are connected to each other by Hebbian synapses, and that these networks are organized into a hierarchy, and that these hierarchies are organized into a global workspace, and that this global workspace is accessed by consciousness, and that this consciousness is a product of the brain's activity. This theory was first proposed by Paul Churchland in 1981.

The physicalist theory is a theory of memory that proposes that memories are stored in the brain as a combination of long-term potentiation and long-term depression, and that these changes are regulated by neuromodulators, and that these changes are organized into cell assemblies, and that these cell assemblies are connected to each other by Hebbian synapses, and that these networks are organized into a hierarchy, and that these hierarchies are organized into a global workspace, and that this global workspace is accessed by consciousness, and that this consciousness is a product of the brain's activity, and that this brain activity is governed by the laws of physics. This theory was first proposed by David Chalmers in 1996.