Hippocampus as comparator: Role of the two input and two output systems of the hippocampus in selection and registration of information.

摘要: Processing of multimodal sensory information by the morphological subdivisions hippocampus and its input output structures was investigated in unanesthetized rabbits extracellular recording neuronal activity. Analysis shows principal differences between CA3 neurons with uniform multimodal, mainly inhibitory, rapidly habituating responses, CA1-subicular neurons, substantial parts which have phasic reactions patterned on-responses, depending on characteristics stimuli. These result from organization afferent inputs to CA1 CA3. responses sources hippocampal inputs, their electrical stimulation, chronic disconnection show greater functional significance brain-stem reticular for tonic characteristic This signal before entering is additionally preprocessed at MS-DB relay, where it becomes more frequency-modulated range theta-rhythm. It shown that new stimuli produce inhibitory reset, after synchronized theta-modulation triggered. Other stimuli, appearing background ongoing theta, do not evoke any neurons. Thus, can be regarded as a mechanism attention, prolongs response selected stimulus simultaneously protects processing against interference. The cortical introduces highly differentiated analyzed highest levels neocortex through intermediary entorhinal cortex presubiculum. However, only CA1-subiculum receives this directly; entrance into CA3, FD secondary simplification signals occurs. As result, two (MS-DB FD) messages just about presence level each them, performs relatively simple functions determination match/mismatch weights. For comparator system, reticulo-septal equivalent quality novelty. appears some delay, analysis shaping prehippocampal structures; besides, gradually increased due LTP-like incremental changes PP mossy fiber synapses. potentiated synapses respond stimuli; is, efficacy "familiarity" signal, terminating reactive state integrity both necessary gradual habituation hippocampus. following precommissural fornix relay-LS nucleus strong regulatory influence brain activity (arousal), an important condition registration information. primary targets are raphe nuclei, suppress ascending excitatory RF. In state, keeps RF under control. Inhibition majority pyramidal during novel action decreases volume releases inhibition (increase forebrain, arousal). When habituate, initial high reinstated, well suppression second (by Schaffer's collaterals CA1) pathway block access upon local system or shunting propagation apical dendrites. act filter controlling transmission CA1; such given moment allowed those receive SC responding Disconnection fibers results disappearance all target (raphe, RF, CA1). follows postcommissural chain main limbic circuit: mammillary bodies (medial nucleus), anterior thalamic nuclei (mainly antero-ventral cingulate posterior area). these links, processed. Habituation nearly absent instead, st