Abstract Understanding the empirical rules that regulate alterations of hippocampal firing fields will enhance our understanding function. The current study sought to extend previous research in this area by examining effect substituting a new stimulus for familiar environment. Hippocampal place cells were recorded while rats chased food pellets scattered onto floor cylindrical apparatus with white cue card affixed wall. Once cell had been presence card, was replaced black same size and...

Extinction of conditioned fear to a tone paired with foot shock is thought involve the formation new memory. In support this, previous studies have shown that extinction depends on NMDA receptor-mediated plasticity. To further investigate role receptors in extinction, we examined effects antagonist d (−)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP) freezing and suppression bar pressing (conditioned emotional response). Rats extinguished normally during 90 min session presence...

The idea that the rat hippocampus stores a map of space is based on existence "place cells" show "location-specific" firing. discharge place cells confined with remarkable precision to cell-specific part environment called cell's "firing field." We demonstrate here firing not nearly as reliable in time domain positional domain. Discharge during passes through field was compared model Poisson variance location-specific determined by time-averaged rate distribution. Place characteristically...

Place cells are hippocampal neurons whose discharge is strongly related to a rat's location in its environment. The existence of place has led the proposal that they part an integrated neural system dedicated spatial navigation, idea supported by discovery strong relationships between cell activity and problem solving. To further understand such relationships, we examined recorded while rats solved navigation task. We report that, addition having widely distributed firing fields, also...

Previous work has shown that the angular position of hippocampal place cell firing fields is accurately controlled by a single white cue card attached to wall recording cylinder: when rotated, rotate equally. In this study, we asked whether similar control could be exerted three-dimensional objects placed directly in arena. each several conditions, locations relative other and their distances from cylinder were fixed. Experiment 1, all near center cylinder. condition, could, general, not...

Hippocampus place cell discharge is an important model system for understanding cognition, but evidence missing that the code under kind of dynamic attentional control characterized in primates as selective activation one neural representation and suppression another, competing representation. We investigated apparent noise (“overdispersion”) CA1 code, hypothesizing overdispersion results from fluctuations spatial attention alternates between distal cues local/self-motion cues. The...

In the hippocampus, synaptic strength between pyramidal cells is modifiable by NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) and depression (LTD), both of which require coincident presynaptic postsynaptic activity. vivo , many exhibit location-specific activity patterns are known as “place cells.” The combination these factors suggests that plasticity will be induced at synapses connecting place with overlapping firing fields, because such fire coincidentally when rat in a...

Differences in the behavior of phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) thin lipid membranes treated with monazomycin are shown to be due negative surface charge on PG membranes. We demonstrate that shifts conductance-voltage (g-V) characteristic films produced by changes univalent or divalent cation concentrations result from membrane potential one both sides. In particular, if cations added aqueous phase not containing monazomycin, resulting asymmetry potentials results...

To further elucidate the links among synaptic plasticity, hippocampal place cells, and spatial memory, cells were recorded from wild-type mice transgenic "R(AB)" with reduced forebrain protein kinase A (PKA) activity after introduction into a novel environment. Place in both strains similar during first exposure equally stable for recording sessions separated by 1 hr. cell stability was unchanged 24 hr but R(AB) over longer interval. This pattern parallels late-phase long-term potentiation...

When present in micromolar amounts on one side of phospholipid bilayer membranes, monazomycin (a positively charged, polyene-like antibiotic) induces dramatic voltage-dependent conductance effects. Voltage clamp records are very similar shape to those obtained from the potassium system squid axon. The steady-state is proportional 5th power concentration and increases exponentially with positive voltage (monazomycin positive); there an e-fold change per 4–6 mv. major current-carrying ions...

Though it has been known for over half a century that interference with the normal activity of septohippocampal neurons can abolish hippocampal theta rhythmicity, definitive answer to question its function remained elusive. To clarify role septal circuits and in location-specific place cells spatial behavior, three drugs were delivered medial septum rats: Tetracaine, local anesthetic; muscimol, GABA-A agonist; gabazine, antagonist. All disrupted oscillatory hippocampus. However, tetracaine...

To better understand how hippocampal place cell activity is controlled by sensory stimuli, and to further elucidate the nature of environmental representation provided cells, we have made recordings in presence two distinct visual stimuli under standard conditions after several manipulations these stimuli. In line with a great deal earlier work, find that constant when repeated are which centers black card white card, separated 135° on wall cylindrical recording chamber. Rotating 45° causes...

This study examined the performance of spatial problems by rats when purely behavioral manipulations disturb relationship between place cell representation and cues used to solve problems. Place cells were recorded while performed a task in which they had locate goal gray cylinder. In “far” task, unmarked was displaced large fixed distance from white card on cylinder wall. “near” directly front card. Finally, “cue” marked black disk floor. Relationships visible stimuli activity manipulated...

Single cells in the rat anterior thalamic nucleus (ATN) and postsubiculum (PoS) discharge as a function of rat's directional heading horizontal plane, independent its location. A previous study that compared cell firing during clockwise counterclockwise head turns concluded ATN 'head direction' (HD) anticipates future heading, while PoS HD is register with current (Blair Sharp [1995] J Neurosci 15:6260–6270). In we extend these findings by using different method analysis. were first...

A key feature of perception is that the interpretation a single, continuously available stimulus can change from time to time. This aspect well illustrated by use ambiguous figures be seen in two different ways. When people view such they almost universally describe what are seeing as jumping between states. If it agreed this perceptual phenomenon causally linked activity nerve cells, state jumps would have occur conjunction with changes neural somewhere nervous system. Our experiments...

The firing of rat hippocampal pyramidal cells is determined both by the animal9s location and state EEG. Because cholinergic transmission plays a role in EEG activity, we expected that its modification would alter place cell activity. We therefore investigated effects on activity blocking muscarinic with intracerebroventricular injections scopolamine. Scopolamine reduced rate discharge inside fields spatial coherence fields; outside also showed small increases. After injections, were shifted...

Changes in the spatial arrangement or identity of objects inside a familiar environment induce reexploration. The present study looks at modifications place cell activity during such renewed exploration. Hungry rats foraged for food cylinder with salient cue card attached to wall and two distinct fixed positions on floor relative each other card. Once set CA1 cells was recorded this standard configuration, additional sessions were done after kinds manipulation. In first, rotated as rigid 90...

Earlier work on freely moving rats classified neurons in Ammon's horn as pyramidal cells (including place cells) or interneurons (previously called "theta cells") based temporal discharge correlates and waveform configurations, but the anatomical biochemical diversity of suggests they may have other distinguishing characteristics. To explore this possibility, we made extracellular recordings foraged for food an open space, used accepted criteria to identify interneurons, found two additional...