Papers by Deependra Kumar
Calcium imaging of adult-born neurons in freely moving mice
STAR Protocols
Sparse Activity of Hippocampal Adult-Born Neurons during REM Sleep Is Necessary for Memory Consolidation
Neuron
Function of adult-born neurons in maturation of fear memory engram during sleep
IBRO Reports
Molecular Brain, 2016
Background: The conditions under which memory generalization occurs are not well understood. Alth... more Background: The conditions under which memory generalization occurs are not well understood. Although it is believed that fear memory generalization is gradually established after learning, it is not clear whether experiences soon after learning affect generalization. Results: Using a contextual fear conditioning paradigm in mice, we found that fear memory generalization occurred when mice were exposed to a familiar, unconditioned context soon after fear learning. Conclusions: Our results suggest that the familiarity of contexts and the timing of their exposure influences memory generalization, which increases our understanding of the mechanisms of generalization.
Changes in Thermal Preference, Sleep-Wakefulness and Body Temperature in Adult Rats with Impaired Warm Receptors
ABSTRACT Ambient temperature (Ta) is one of the important environmental parameters influencing sl... more ABSTRACT Ambient temperature (Ta) is one of the important environmental parameters influencing sleep-wakefulness (S-W), and body temperature (Tb). Central thermoreceptors in the brain and peripheral thermoreceptors in the skin convey information about the thermal status of the body and environment to the preoptic area for regulation of Tb. The preoptic area plays a major role in regulation of S-W, Tb and thermal preference(Ray et al. 2005). In the present study we investigated the effect of elevated and lower Ta on S-W, and Tb in rats with impaired warm receptors.The S-W and Tb were recorded for 24 h at 27°C and 6 h at 18, 21, 24, 27, 30, 33, and 36°C before and after destruction of warm recep- tors at 27°C. Thermal preferences of rats were studied by putting the animals into a three interconnected environmental chamber where they could choose 27, 30 and 33°C. The central and peripheral warm sensitive receptors were destroyed after control recordings by the systemic injection of capsaicin (8-Methyl-N-Vanillyl-6-Nonenamide, 375 mg/kgBW, Sigma, USA). Normal rats preferred Ta of 27°C while rats with impaired warm receptors chose Ta of 30 and 33°C. The S-W of the normal and rats after destruction of warm receptors did not differ significantly. Though the sleep aws increased at high Ta in normal rats, it had no signifficant effect after destruction of warm receptors. Lowering Ta produced reduction in sleep in both normal and lesioned rats.The rats with impaired warm receptors showed slightly higher body temperature when compared with controls at 27°C. These rats showed increase in body temperature when exposed to elevated Ta, but when exposed to lower Ta, it did not produce any significant change. Warm sensitive receptors are important for thermoregulation and increase sleep at higher Ta. Normal thermal preferenceof the animal is also dependent on the inputs from the warm receptors
Interrelationship Between Sleep and Body Temperature at Different Ambient Temperature in Rats With Impaired Warm Reception
Objective : Ambient temperature (Ta) affects both sleep-wakefulness (S-W) and body temperature (T... more Objective : Ambient temperature (Ta) affects both sleep-wakefulness (S-W) and body temperature (Tb). Peripheral and central warm receptors convey the thermal status of changing Ta to the preoptic area (POA). The POA regulates both S-W and Tb. There is reduction in total sleep time when exposed to extreme low and high Ta. In order to understand the temperature sensitive changes in sleep , S-W and Tb at wide range of Ta (18°, 21°, 24°, 27°, 30°, 33° and 36°C) were studied in rats before and after destruction ofwarm receptors by capsaicin. Materials and Methods : Under sodium pentobarbitone anesthesia (40 mg/kg BW), 12 adult male Wistar rats were chronically implanted with electroencephalogram, electro- oculogram and electromyogram electrodes for recording S-W parameters and a temperature transmitter in the peritoneum to asses Tb. After control recording of S-W and Tb for 6 h (11:00-17:00 h) animals were equally divided into local injection group (intrapreoptic, 125 µg) for selective d...
PloS one, 2015
The optogenetic manipulation of light-activated ion-channels/pumps (i.e., opsins) can reversibly ... more The optogenetic manipulation of light-activated ion-channels/pumps (i.e., opsins) can reversibly activate or suppress neuronal activity with precise temporal control. Therefore, optogenetic techniques hold great potential to establish causal relationships between specific neuronal circuits and their function in freely moving animals. Due to the critical role of the hippocampal CA1 region in memory function, we explored the possibility of targeting an inhibitory opsin, ArchT, to CA1 pyramidal neurons in mice. We established a transgenic mouse line in which tetracycline trans-activator induces ArchT expression. By crossing this line with a CaMKIIα-tTA transgenic line, the delivery of light via an implanted optrode inhibits the activity of excitatory CA1 neurons. We found that light delivery to the hippocampus inhibited the recall of a contextual fear memory. Our results demonstrate that this optogenetic mouse line can be used to investigate the neuronal circuits underlying behavior.
Warm sensitive neurons of the preoptic area regulate ambient temperature related changes in sleep in the rat
Indian journal of physiology and pharmacology
Warm sensitive neurons (WSN) play a major role not only in body temperature regulation, but also ... more Warm sensitive neurons (WSN) play a major role not only in body temperature regulation, but also in sleep regulation. The present study was undertaken to investigate the role of WSN of the preoptic area (POA) in mediating the ambient temperature (T(amb)) related changes in sleep. The effect of T(amb) changes on sleep and body temperature was studied in rats before and after destruction of WSN of the POA by local intracerebral injection of capsaicin. Though the rats preferred 27 degrees C T(amb), they slept maximum at 30 degrees C. After destruction of WSN of the POA, slow wave sleep (SWS) peak was brought down to 27 degrees C, which was the preferred T(amb) of the rats. This indicates that WSN of the POA mediate the increase in SWS, at temperatures higher than preferred T(amb). On the other hand, in WSN destroyed rats, rapid eye movement (REM) sleep was maximum at 33 degrees C. It suggests that the REM sleep generation is under inhibitory control of the WSN of the POA. The study sup...
Intragastric administration of glutamate increases REM sleep in rats
Physiology & Behavior, 2013
Monosodium glutamate, a umami taste substance is commonly used flavor enhancer. The effect of int... more Monosodium glutamate, a umami taste substance is commonly used flavor enhancer. The effect of intragastric administration of 1.5 ml of 0.12M monosodium glutamate on sleep-wake was studied in 10 adult male Wistar rats. Sleep-wake parameters were recorded through chronically implanted electroencephalogram, electrooculogram and electromyogram electrodes using a digital recording system (BIOPAC system Inc. BSL PRO 36, USA). The sleep-wake was recorded for 6h after the intragastric administration of either glutamate or saline. Sleep-wake stages were analyzed as wake, slow wave sleep and REM sleep. Compared to saline, intragastric administration of glutamate significantly increased REM sleep duration and episode frequency. REM sleep duration was increased in all the three 2h bins, 10:00-12:00 h (p=0.037), 12:00-14:00 h (p=0.037) and 14:00-16:00 h (p=0.007). The slow wave sleep and total sleep time were not affected. It is concluded that intragastric glutamate administration increases REM sleep.
Sleep, Jan 25, 2015
The CACNA1C gene encodes the alpha 1C (α1C) subunit of the Cav1.2 voltage-dependent L-type calciu... more The CACNA1C gene encodes the alpha 1C (α1C) subunit of the Cav1.2 voltage-dependent L-type calcium channel (LTCC). Some of the other voltage-dependent calcium channels, e.g., P-/Q-type, Cav2.1; N-type, Cav2.2; E-/R-type, Cav2.3; and T-type, Cav3.3 have been implicated in sleep modulation. However, the contribution of LTCCs to sleep remains largely unknown. Based on recent genome-wide association studies, CACNA1C emerged as one of potential candidate genes associated with both sleep and psychiatric disorders. Indeed, most patients with mental illnesses have sleep problems and vice versa. To investigate an impact of Cav1.2 on sleep-wake behavior and electroencephalogram (EEG) activity, polysomnography was performed in heterozygous Cacna1c (HET) knockout mice and their wild-type (WT) littermates under baseline and challenging conditions (acute sleep deprivation and restraint stress). HET mice displayed significantly lower EEG spectral power than WT mice across high frequency ranges (be...
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Papers by Deependra Kumar