Alsophis rufiventris

Number of Pages: 4Integrative BiologyGeological Science

Kainate induced theta-frequency oscillatory network activity in the medial septum/diagonal band complex

The medial septum/diagonal band complex (MS/DB) forms part of the septo-hippocampal feedback loop and is thought to have a major functional role in the generation and/or maintenance of the hippocampal theta rhythm in vivo (4 * 15 Hz). Several different mechanistic scenarios may underlie the generation of a theta-frequency EEG pattern, amongst them (1) an external pacemaker-type input (2) theta activity being an emergent property of the septo-hippocampal feedback loop and (3) theta arising in the synaptic network of the MS/DB itself. This investigation tested the latter scenario by using an in vitro slice preparation of the (deafferented) MS/DB. Longitudinal slices (0.45 mm) from 21 day old rats were maintained at 32 deg C in an interface recording chamber perfused with oxygenated ACSF. Following the bath application of the AMPA/kainate receptor agonist kainate (25 *100 nM), extracellular recordings, using ACSF-filled micropipettes, showed rhythmic population activity with a mean peak frequency of ~6 Hz which was most prominent along the midline of the MS/DB. The higher concentrations of kainate were accompanied by corresponding increases in spectral power (amplitude). Subsequently, intracellular recordings were obtained with QX-314 containing electrodes to prevent spiking-activity, and thus allowing IPSPs to be recorded at depolarised membrane potentials. These recordings revealed the presence of rhythmic IPSPs (~6 Hz) in the class of fast-firing cells of oscillating MS/DB slices, presumably arising in the mutually connected interneuronal network of the MS/DB and pacing the oscillation. Moreover, these findings clearly demonstrate that the intrinsic circuitry of the isolated MS/DB complex is sufficient to generate rhythmic theta frequency activity

Kainate induced theta-frequency oscillatory network activity in the medial septum/diagonal band complex

The medial septum/diagonal band complex (MS/DB) forms part of the septo-hippocampal feedback loop and is thought to have a major functional role in the generation and/or maintenance of the hippocampal theta rhythm in vivo (4 * 15 Hz). Several different mechanistic scenarios may underlie the generation of a theta-frequency EEG pattern, amongst them (1) an external pacemaker-type input (2) theta activity being an emergent property of the septo-hippocampal feedback loop and (3) theta arising in the synaptic network of the MS/DB itself. This investigation tested the latter scenario by using an in vitro slice preparation of the (deafferented) MS/DB. Longitudinal slices (0.45 mm) from 21 day old rats were maintained at 32 deg C in an interface recording chamber perfused with oxygenated ACSF. Following the bath application of the AMPA/kainate receptor agonist kainate (25 *100 nM), extracellular recordings, using ACSF-filled micropipettes, showed rhythmic population activity with a mean peak frequency of ~6 Hz which was most prominent along the midline of the MS/DB. The higher concentrations of kainate were accompanied by corresponding increases in spectral power (amplitude). Subsequently, intracellular recordings were obtained with QX-314 containing electrodes to prevent spiking-activity, and thus allowing IPSPs to be recorded at depolarised membrane potentials. These recordings revealed the presence of rhythmic IPSPs (~6 Hz) in the class of fast-firing cells of oscillating MS/DB slices, presumably arising in the mutually connected interneuronal network of the MS/DB and pacing the oscillation. Moreover, these findings clearly demonstrate that the intrinsic circuitry of the isolated MS/DB complex is sufficient to generate rhythmic theta frequency activity

Theta oscillations in the rat MS/DB complex in vitro: a locally generated, inhibition-based brain rhythm

The medial septum/diagonal band (MS/DB) complex, which forms part of the septohippocampal feedback loop, is thought to be critical for the generation and/or maintenance of the hippocampal theta rhythm (4-15 Hz) in vivo. Previously we demonstrated the presence of theta frequency rhythmic activity, within an in vitro slice preparation of the MS/DB, following application of the AMPA/kainate receptor agonist kainate (25–100 nM). Here we further investigate this rhythmic activity, in particular the effects of GABAA receptor mediated inhibition, on kainate induced theta activity in the MS/DB, using bath application of bicuculline. Longitudinal slices of the MS/DB (450 μm), from 21 day old rats, were maintained at 32°C in an interface recording chamber perfused with oxygenated ACSF. Following the bath application of kainate at 100 nM to the MS/DB, extracellular recordings of neuronal population activity, using ACSF-filled micropipettes, revealed rhythmic theta frequency activity. Bicuculline was then applied to the recording chamber and subsequent changes to the kainate induced activity were recorded at 30 and 60 minutes there after. Application of 10 µM bicuculline produced a significant reduction (P< 0.05, Student's T test) in the activity recorded at theta frequency (spectral integral in 4-15 Hz range) and in peak amplitude within 60 minutes of application (n=6). These results indicate a pivotal role for inhibitory transmission in pacing and maintaining the rhythmic activity that is observed in the MS/DB slice preparation following kainate induced theta frequency oscillations. SPONSOR: British Neuroscience Association

Measuring compulsive buying behaviour: Psychometric validity of three different scales and prevalence in the general population and in shopping centres

Due to the problems of measurement and the lack of nationally representative data, the extent of compulsive buying behaviour (CBB) is relatively unknown. Methods: The validity of three different instruments was tested: Edwards Compulsive Buying Scale (ECBS; Edwards, 1993), Questionnaire About Buying Behavior (QABB; Lejoyeux & Adès, 1994) and Richmond Compulsive Buying Scale (RCBS; Ridgway, et. al., 2008) using two independent samples. One was nationally representative of the Hungarian population (N=2710) while the other comprised shopping mall customers (N=1447). Results: A new, four-factor solution for the ECBS was developed (ECBS-R), and confirmed the other two measures. Additionally, cut-off scores were defined for all measures. Results showed that the prevalence of CBB is 1.85% (with QABB) in the general population but significantly higher in shopping mall customers (8.7% with ECBS-R, 13.3% with QABB and 2.5% with RCBS-R). Conclusions: Due to the diversity of content, each measure identifies a somewhat different CBB group

Involvement of electrical signalling in theta frequency oscillations generated in the medial septum/diagonal band of Broca in vitro

Theta frequency (4 – 15 Hz) extracellular field activity can be reliably and repeatedly evoked in the medial septum/diagonal band of Broca (MS/DB) in vitro by the application of kainate. We have previously demonstrated a critical role for inhibitory neurotransmission in the maintenance of this activity and presented data that indicates parvalbumin GABAergic neurons are responsible for pacing rhythmic theta activity in the MS/DB. Evidence of functional electrical coupling between GABAergic interneurons has been reported in the hippocampus and neocortex and it has recently become clear that gap junctions may have a significant function in the generation of neuronal population activity. Here we demonstrate that application of the gap-junction uncoupling agent carbenoxolone causes a significant reduction (P< 0.05, Paired T test) in the kainate induced activity recorded at theta frequency (spectral integral in 4-15 Hz range) in the MS/DB slice in vitro. MS/DB slices were prepared from male Wistar rats (21 days), which were terminally anaesthetised with pentobarbitone sodium (120 mg.kg-1, i.p.). The animals were transcardially perfused with ~ 25ml of modified ACSF and rapidly decapitated. Longitudinal slices (450 µm) were placed in an interface recording chamber and maintained at 32°C. Persistent theta oscillations were induced by bath application of 100 nM kainate. Carbenoxolone was bath applied to stabilized kainate induced activity at a concentration of 100 μM for 60 minutes. At 60 minutes there was a significant reduction in the theta frequency activity recorded (56.6% ± 2.3) and in peak amplitude (n = 6). These results indicate a pivotal role for electrical signalling in the theta frequency rhythmic activity induced in the MS/DB upon application of kainate

Involvement of electrical signalling in theta frequency oscillations generated in the medial septum/diagonal band of Broca in vitro

Theta frequency (4 – 15 Hz) extracellular field activity can be reliably and repeatedly evoked in the medial septum/diagonal band of Broca (MS/DB) in vitro by the application of kainate. We have previously demonstrated a critical role for inhibitory neurotransmission in the maintenance of this activity and presented data that indicates parvalbumin GABAergic neurons are responsible for pacing rhythmic theta activity in the MS/DB. Evidence of functional electrical coupling between GABAergic interneurons has been reported in the hippocampus and neocortex and it has recently become clear that gap junctions may have a significant function in the generation of neuronal population activity. Here we demonstrate that application of the gap-junction uncoupling agent carbenoxolone causes a significant reduction (P< 0.05, Paired T test) in the kainate induced activity recorded at theta frequency (spectral integral in 4-15 Hz range) in the MS/DB slice in vitro. MS/DB slices were prepared from male Wistar rats (21 days), which were terminally anaesthetised with pentobarbitone sodium (120 mg.kg-1, i.p.). The animals were transcardially perfused with ~ 25ml of modified ACSF and rapidly decapitated. Longitudinal slices (450 µm) were placed in an interface recording chamber and maintained at 32°C. Persistent theta oscillations were induced by bath application of 100 nM kainate. Carbenoxolone was bath applied to stabilized kainate induced activity at a concentration of 100 μM for 60 minutes. At 60 minutes there was a significant reduction in the theta frequency activity recorded (56.6% ± 2.3) and in peak amplitude (n = 6). These results indicate a pivotal role for electrical signalling in the theta frequency rhythmic activity induced in the MS/DB upon application of kainate

Soft-walled monothalamid foraminifera from the intertidal zones of the Lorn area, north-west Scotland

Recent advances in molecular phylogeny and increasing numbers of studies carried out worldwide in subtidal and deep-water marine sites have confirmed that monothalamid foraminifera represent a significant component of the marine benthos. Fewer studies have been carried out on monothalamids in littoral zones, and here I describe more than 13 novel morphotypes of soft-walled monothalamids found at several intertidal sites in the Lorn area of north-west Scotland. Samples of sediment were collected from these areas and monothalamid tests were removed from the mud by direct manipulation with brushes, by coverslip-capture, by capture with a magnet for those with magnetic particles or by extraction from mud balls. Attached forms of tests from the same sites were isolated from collected seaweed blades, pebbles and decaying shells. Monothalamids were observed live and photographed in their natural colours, followed by examination after preservation in alcohol and embedding in glycerol. The greatest diversity of species was found to be at estuaries near to the mouths of the sea lochs, and the abundance of some of the species varied with the time of the year, being different for each species. The observed taxa included a Vellaria sp. and Psammophaga sp., two allogromiids, three saccamminids and six undetermined species; each assemblage of specimens may have contained more than one species not readily discernible by morphological characteristics alone. Taxonomic parallels between the described specimens and those in reports for other parts of the world and in deeper waters in western Scotland are discussed

Acute Marjolin Ulcer From A Dog Bite

Marjolin ulcers are cancers, usually of squamous cell carcinoma pathology, that occur in scars or wounds. They are classically described in burn victims but can occur with other types of trauma and are rarely seen in association with bite wounds. Marjolin ulcers typically have a latent period of many years post-injury until the development of malignancy, but there are a few case reports of an exceedingly rare acute form. We present a case of a 78-year-old female who developed a Marjolin ulcer one month after sustaining a dog bite to the left index finger