On the delay-dependent involvement of the hippocampus in object recognition memory

The role of the hippocampus in object recognition memory processes is unclear in the current literature. Conflicting results have been found in lesion studies of both primates and rodents. Procedural differences between studies, such as retention interval, may explain these discrepancies. In the present study, acute lidocaine administration was used to temporarily inactivate the hippocampus prior to training in the spontaneous object recognition task. Male C57BL/6J mice were administered bilateral lidocaine (4%, 0.5 microl/side) or aCSF (0.5 microl/side) directly into the CA1 region of the dorsal hippocampus 5 min prior to sample object training, and object recognition memory was tested after a short ( 5 min) or long (24 h) retention interval. There was no effect of intra-hippocampal lidocaine on the time needed for mice to accumulate sample object exploration, suggesting that inactivation of the hippocampus did not affect sample session activity or the motivation to explore objects. Lidocaine-treated mice exhibited impaired object recognition memory, measured as reduced novel object preference, after a 24 h but not a 5 min retention interval. These data support a delay-dependent role for the hippocampus in object recognition memory, an effect consistent with the results of hippocampal lesion studies conducted in rats. However, these data are also consistent with the view that the hippocampus is involved in object recognition memory regardless of retention interval, and that object recognition processes of parahippocampal structures (e.g., perirhinal cortex) are sufficient to support object recognition memory over short retention intervals.     

Chlordiazepoxide-induced working memory impairments: site specificity and reversal by flumazenil (RO15-1788).

The following studies examined the dose and time dependence, site specificity, and reversibility of chlordiazepoxide (CDP)-induced working memory impairments in adult male Sprague-Dawley rats. The rats were tested in a delayed non-match-to-sample radial-arm maze task in which a 1-h delay was imposed between the first four (predelay) and all subsequent (postdelay) arm choices. Intraperitoneal (ip) injection of 2.5 or 5.0 but not 1.25 mg/kg CDP immediately following the predelay session impaired performance in the task. CDP increased the number of errors and decreased the number of correct choices during the postdelay session. The observed working memory impairments also appeared to be site specific since injection of CDP into the medial septum, but not into the anterior amygdala nuclei, immediately following the predelay session also impaired working memory in a dose-related manner. Furthermore, there was a time window for CDP-induced working memory impairments since intraseptal injection of the drug immediately but not 15 min following the predelay session disrupted memory. This observation suggests that the performance deficits reflect disrupted working memory and not proactive effects on performance or the induction of state-dependent learning. In the final experiment, rats were injected ip with either saline or an amnestic dose of CDP (5.0 mg/kg) following the predelay session and then were immediately infused with 10 nmol flumazenil (RO15-1788), a benzodiazepine receptor antagonist or vehicle, into either the medial septum or anterior nuclei of the amygdala. Intraseptal injection of flumazenil prevented the working memory impairments produced by ip injection of CDP. In contrast, intra-amygdala injection of flumazenil did not attenuate, enhance, or modify the CDP-induced working memory impairment. These observations suggest that CDP disrupts working memory by interacting with benzodiazepine receptors in the medial septum.     

Intraseptal Flumazenil Enhances, while Diazepam Binding Inhibitor Impairs, Performance in a Working Memory Task

GABA_A/benzodiazepine receptors in the medial septum modulate the activity of cholinergic neurons that innervate the hippocampus. Injection of benzodiazepine (BDZ) agonists into the medial septum impairs working memory performance and decreases high-affinity choline transport (HAChT) in the hippocampus. In contrast, intraseptal injection of the BDZ antagonist flumazenil increases HAChT and prevents the memory deficits induced by systemic BDZs. The present studies attempted to further characterize the behavioral effects of medial septal injections of flumazenil to an endogenous negative modulator of the GABA_A/BDZ receptor complex, diazepam binding inhibitor (DBI). Male Sprague–Dawley rats were cannulated to study the effects of intraseptal injections of these BDZ ligands on spatial working memory, anxiety-related behaviors in the elevated plus maze, and on general locomotor activity. Intraseptal flumazenil (10 nmol/0.5 μl) produced a delay-dependent enhancement of DNMTS performance after an 8-h, but not a 4-h, delay interval. This promnestic dose of flumazenil had no effect on locomotor activity and did not produce changes in measures of anxiety on the plus maze. Intraseptal injection of DBI had no effect (8 nmol/0.5 μl) or slightly impaired (4 nmol/0.5 μl) DNMTS radial maze performance following an 8-h delay, without producing changes in locomotion or plus maze behavior. These data demonstrate that flumazenil has a unique profile of activity in enhancing working memory following intraseptal injection.     

Contextual memory deficits observed in mice overexpressing small conductance Ca2+-activated K+ type 2 (KCa2.2, SK2) channels are caused by an encoding deficit

Hippocampal-dependent synaptic plasticity and memory are modulated by apamin-sensitive small conductance Ca2+-activated K+ (SK) channels. Transgenic mice overexpressing SK2 channels (SK2+/T mice) exhibit marked deficits in hippocampal memory and synaptic plasticity, as previously reported. Here, we examined whether SK2 overexpression affects the encoding or retention of contextual memory. Compared with wild-type littermates, SK2+/T mice exhibited significantly less context-dependent freezing 10 min and 24 h after conditioning. Interestingly, this contextual memory impairment was eliminated if SK2+/T mice were permitted longer pre-exposure to the conditioning chamber. These data support converging evidence that SK2 channels restrict the encoding of hippocampal memory.     

Emergence of a Social Inquiry Group: A Story of Fractals and Networks

This article relates the emergence of a group of faculty researchers utilizing complexity science approaches. The narrative emerges from three projects combining research into complexity, communities, and technologies. Details of how the research was initiated, and the nature and quality of the conversational method, are provided. In addition, theoretical concepts that were consciously applied and others that arose through insights from the data as it was collected are discussed. Although this is like most real narratives, a never-ending story, it concludes with a presentation of some of the ideas that separate complexity-informed research from other paradigms.     

Training analysis in the dutch society for psychoanalytic psychotherapy: A survey of attitudes and feasibility

SUMMARY

As is the case in many training courses in psychoanalytic psychotherapy, one of the training requirements of the Dutch Society for Psychoanalytical Psychotherapy (NVPP) is a training analysis, currently a minimum duration of 700 hours. During the last few years, this requirement has become somewhat controversial. Because the NVPP does not have information about the current interest in NVPP membership, the Board of the NVPP decided to do a survey. Of 995 psychiatrists, clinical psychologists and psychotherapists, who had recently completed their training, or were still in training, 623 filled in a questionnaire. Of those who are interested in the NVPP training, 39 per cent judged the training analysis as not feasible in terms of time, and 61 per cent in terms of money. Forms of personal treatment thought desirable for anyone who wishes to become a psychoanalytic psychotherapist at a specialist level are, in descending order, psychoanalytic psychotherapy (63%), psychoanalysis (39%), psychoanalytic group psychotherapy (25%), and psychoanalytic marital or family therapy (6%). Respondents who judge personal analysis as not feasible, also tend to judge psychoanalysis to be equivalent to other forms of psychoanalytic psychotherapy, whereas those who judge personal analysis as feasible, tend to think that personal analysis is essential for a psychoanalytic psychotherapist at the specialist level.     

Intraseptal administration of muscimol produces dose-dependent memory impairments in the rat

The present study examined the effects of intraseptal administration of the GABAergic agonist muscimol on performance of a radial-arm maze (RAM) task. Male Long-Evans rats were trained to perform a RAM task in which a 1-h delay was imposed between the sample and the test session. In this task rats have access to four out of eight maze arms during a predelay session. Following a 1-h delay, rats are returned to the maze and allowed to freely choose among all eight arms. Arms not blocked during the predelay session are baited, and entry into an arm chosen during the predelay session or a repeated entry into a postdelay chosen arm constitutes an error. Following acquisition, animals were implanted with a single cannula aimed at the medial septum. A within-subjects design was utilized to examine the effects of intraseptal administration of muscimol (0.0, 0.75, 1.5 or 3.0 nmol) on performance in this task. All drugs or artificial cerebrospinal fluid were administered immediately following the predelay session. Muscimol, a GABA-A agonist, produced a dose-dependent impairment in maze performance as evidenced by fewer correct choices in the first four postdelay choices and an increase in the number of errors. Intraseptal administration of muscimol did not significantly alter latency per choice on the RAM task nor did it affect locomotor activity levels. Muscimol-induced impairments were also observed when a 4-h delay was imposed between the fourth and the fifth maze selection, suggesting that the behavioral deficit represents an inability to store or retain spatial working memories rather than a general performance deficit. These data indicated that pharmacological manipulation of GABA-A receptors within the medial septum modifies working memory processes. The potential interaction of GABAergic and cholinergic mechanisms in the modulation of working memory processes is discussed.