|
Vinogradova OS (2001) Hippocampus as comparator: role of the two input and two output Systems of the hippocampus in selection and registration of information. Hippocampus 11:578–598.
ABSTRACT: Processing of multimodal sensory information by the morphological
subdivisions of the hippocampus and its input and output
structures was investigated in unanesthetized rabbits by extracellular
recording of neuronal activity. Analysis shows principal differences between
CA3 neurons with uniform multimodal, mainly inhibitory, rapidly
habituating sensory responses, and CA1-subicular neurons, substantial
parts of which have phasic reactions and patterned on-responses, depending
on the characteristics of the stimuli. These differences result from the
organization of the afferent inputs to CA1 and CA3. Analysis of neuronal
responses in sources of hippocampal inputs, their electrical stimulation,
and chronic disconnection show the greater functional significance of the
brain-stem reticular input for tonic responses characteristic of CA3. This
input signal before entering the hippocampus is additionally preprocessed
at the MS-DB relay, where it becomes more uniform and frequencymodulated
in the range of theta-rhythm. It is shown that the new sensory
stimuli produce inhibitory reset, after which synchronized theta-modulation
is triggered. Other stimuli, appearing at the background of the
ongoing theta, do not evoke any responses of the hippocampal neurons.
Thus, theta-modulation can be regarded as a mechanism of attention,
which prolongs response to a selected stimulus and simultaneously protects
its processing against interference.
|