Intrahippocampal gamma and theta rhythm generation in a network model of inhibitory interneurons

2001 ◽  
Vol 38-40 ◽  
pp. 713-719 ◽  
Author(s):  
Tamás Kiss ◽  
Gergő Orbán ◽  
Máté Lengyel ◽  
Péter Érdi
1998 ◽  
Vol 10 (4) ◽  
pp. 869-882 ◽  
Author(s):  
Vikaas S. Sohal ◽  
Michael E. Hasselmo

Changes in GABAB modulation may underlie experimentally observed changes in the strength of synaptic transmission at different phases of the theta rhythm (Wyble, Linster, & Hasselmo, 1997). Analysis demonstrates that these changes improve sequence disambiguation by a neural network model of CA3. We show that in the framework of Hopfield and Tank (1985), changes in GABAB suppression correspond to changes in the effective temperature and the relative energy of data terms and constraints of an analog network. These results suggest that phasic changes in the activity of inhibitory interneurons during a theta cycle may produce dynamics that resemble annealing. These dynamics may underlie a role for the theta cycle in improving sequence retrieval for spatial navigation.


2006 ◽  
Vol 23 (10) ◽  
pp. 2731-2738 ◽  
Author(s):  
A. Nuñez ◽  
A. Cervera-Ferri ◽  
F. Olucha-Bordonau ◽  
A. Ruiz-Torner ◽  
V. Teruel

2006 ◽  
Vol 95 (6) ◽  
pp. 3645-3653 ◽  
Author(s):  
Luis V. Colom ◽  
Antonio García-Hernández ◽  
Maria T. Castañeda ◽  
Miriam G. Perez-Cordova ◽  
Emilio R. Garrido-Sanabria

A series of experiments was carried out testing the hypothesis that the septal region decreases the hippocampal susceptibility to hyperexcitability states through theta rhythm generation. Medial septal neurons were simultaneously recorded with hippocampal field potentials to investigate the septo-hippocampal function in the pilocarpine model of chronic epilepsy. The theta rhythm from chronically epileptic rats had lower amplitude (20% less) and higher frequency than controls (from 3.38 to 4.25 Hz), suggesting that both generator and pacemaker structures are affected during the epileptic process. At the cellular level, the group of rhythmically bursting firing medial septal neurons, in the epileptic animals, significantly and chronically increased their firing rates in relation to controls (from 13.86 to 29.14 spikes/s). Peristimulus histograms performed around hippocampal sharp waves showed that all high-frequency firing neurons, including rhythmically bursting neurons and most slow firing neurons, decreased firing rates immediately after hippocampal epileptic discharges. Thus inhibitory hippocampo-septal influences prevail during hippocampal epileptic discharges. The occurrence of epileptic discharges was reduced 86–97% of the number observed during spontaneous theta and theta induced by sensory (tail pinch) or chemical stimulation (carbachol), suggesting that the presence of the theta state regardless of how it was produced was responsible for the reduction in epileptic discharge frequency. The understanding of the theta rhythm “anti-epileptic” effect at the cellular and molecular levels may result in novel therapeutic approaches dedicated to protect the brain against abnormal excitability states.


2021 ◽  
Author(s):  
Loreen Hertäg ◽  
Claudia Clopath

AbstractPredictable sensory stimuli do not evoke significant responses in a subset of cortical excitatory neurons. Some of those neurons, however, change their activity upon mismatches between actual and predicted stimuli. Different variants of these prediction-error neurons exist and they differ in their responses to unexpected sensory stimuli. However, it is unclear how these variants can develop and co-exist in the same recurrent network, and how they are simultaneously shaped by the astonishing diversity of inhibitory interneurons. Here, we study these questions in a computational network model with three types of inhibitory interneurons. We find that balancing excitation and inhibition in multiple pathways gives rise to heterogeneous prediction-error circuits. Dependent on the network’s initial connectivity and distribution of actual and predicted sensory inputs, these circuits can form different variants of prediction-error neurons that are robust to network perturbations and generalize to stimuli not seen during learning. These variants can be learned simultaneously via homeostatic inhibitory plasticity with low baseline firing rates. Finally, we demonstrate that prediction-error neurons can support biased perception, we illustrate a number of functional implications, and we discuss testable predictions.


Sign in / Sign up

Export Citation Format

Share Document