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1

Repeated intrinsic signal optical imaging (ISOI) from the mice primary somatosensory cortex

100%
Posluszny A., Zakrzewska R., Kossut M.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
INTRODUCTION: A noninvasive method of mapping cortical activation in the same animal before and after behavioral training for assessing experience-dependent cortical plasticity is of great value. Previously, we mapped changes in cortical representation of vibrissae involved in behavioral training with 2-deoxyglucose (2-DG). We wanted to replicate the 2-DG results with ISOI. AIM(S): The aim of the experiments was to find a protocol of vibrissae stimulation for the ISOI from the barrel cortex, which could provide constant signal in temporally separated recordings and enable visualization of plastic changes. METHOD(S): Two subsequent ISOI were performed with 6 days interval. Conditioning consisted of 3 daily sessions of 40 trials of manual stimulation of row B vibrissae on one side of the snout coupled with a mild tail shock. 24 hours after the last conditioning session the second ISOI was performed. Two protocols of vibrissae stimulation during ISOI were tested. In the first protocol 5-ms deflections of B1 vibrissa were applied for 1 s with frequency of 5 Hz (this protocol was used in earlier studies of experience-dependent cortical plasticity seen after whisker deprivation). In the second protocol 5-ms deflections of B1 vibrissa were applied for 6 s with frequency of 10 Hz. Additionally, after second ISOI a 2-DG mapping was performed in order to confirm plasticity in the somatosensory cortex. Using 2-DG method a comparison was performed between left (involved during conditioning) and right (not involved) vibrissae representation. RESULTS: The paired ISOI using the first protocol (1 s/5 Hz) of vibrissae stimulation revealed no change of the B1 vibrissa representation after conditioning, a result that is inconsistent with 2-DG maps. ISOI in which the second vibrissae stimulation protocol (6 s/10 Hz) was applied showed expansion of cortical representation of vibrissa stimulated during conditioning. CONCLUSIONS: Different protocols are suitable for different types of experience-dependent cortical plasticity. FINANCIAL SUPPORT: Project supported by National Science Centre, Poland (DEC-2012/05/D/NZ3/00994).
2

Orientation tuning in mouse primary visual cortex – Intrinsic signal optical imaging study

100%
Raciborska I., Kordecka K., Posluszny A., Waleszczyk W. J.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
INTRODUCTION: Accumulating body of research has shown a cardinal bias for preference of spatially oriented targets in different species including humans, indicating greater neuronal responses in the primary visual cortex for horizontal or vertical contours in opposite to oblique ones. AIM(S): We used intrinsic signal optical imaging, a popular tool to map cortical function in rodents to verify the hypothesis whether a cardinal bias is present also in mouse primary visual cortex. METHOD(S): The experiments were performed on 7 week old wild mice under isoflurane anaesthesia. Intrinsic signals were recorded using CCD camera set above the visual cortex. Visual stimuli, square-wave black-and-white gratings (spatial frequency 0.05 cycle/degree, and temporal frequency 2 Hz, four orientations: 0, 45, 90, 135 degree) drifting in two directions, back and forth, were presented in random order with uniform grey images in 16 trials. Imaging was performed under the control of Imager 3001 system. Data were collected with 10 Hz resolution from 1 s before stimulus onset, during 7 s of visual stimulation and to 1 s after stimulus offset with 7 s interval between recordings. RESULTS: Using the described protocol of visual stimulation and data collection we could successfully map cortical responses to visual stimuli of different orientations. Collected images showed the strongest responses for horizontally and vertically oriented gratings. CONCLUSIONS: Our results support the hypothesis of the bias toward cardinal orientation preference in mouse visual cortex. FINANCIAL SUPPORT: Supported by the Polish National Science Center grant Symfonia 1 (2013/08/W/ NZ4/00691).
3

Theta generators in combined transected hippocampal formation slices

88%
Golebiewski H., Kowalczyk T., Bocian R., Posluszny A., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
Rhythmic slow activity (RSA, theta) is commonly associated with the hippocampal formation (HPC). It is generally agreed that HPC theta rhythm is dependent on an intact septal area that act as a pacemaker for the RSA. However, hippocampal neurons cannot be considered as passive followers of rhythmic septal inputs. The local hippocampal networks may also contribute to the RSA – application of the cholinergic agonist, carbachol produce theta rhythm in HPC slices in vitro. The evaluation of theta amplitude and phase profi le indicates the existence of two theta generators located in CA1 and DG areas. Moreover, model of slice preparation demonstrated that in the CA3c HPC region the third RSA generator is localized. In our previous experiments we hypothesized that completely isolated DG area is not capable of theta rhythm generation. In the present study we attempted to verify this hypothesis, using model of combined transected HPC slices. We analyzed theta activity in two different transected slices: DG slices containing CA1 area and DG slices containing CA3c region. We demonstrated that both CA1 and CA3c regions are capable of independent generation high amplitude RSA, whereas theta recorded in DG was characterized by signifi cantly lower theta amplitude. Our in vitro obtained fi ndings are consistent with earlier reports suggesting that HPC theta generators are localized in CA1 and CA3c but not in DG region. Supported by grant MNiSzW NN 303 091 834.
4

The gap junction mediation of hippocampal theta rhythm in anasthetized rats

88%
Bocian R., Posluszny A., Kowalczyk T., Golebiewski H., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 3
5

GAP junction in the hippocampal formation network: interaction between GAP junction bloker and opener

88%
Bocian R., Posluszny A., Kowalczyk T., Golebiewski H., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
Gap junction (GJ) channels provide an aqueous pathway for the passage ions current and small molecules between cell cytoplasms. It has been demonstrated that various physiological stimuli, experimental treatments and chemical agents can modulate activity of those structures. In our previous studies we showed that intrahippocampal injection of carbenoxolone (GJ blocker) abolished local recorded theta rhythm in anesthetized rats. However, intrahippocampal formation (HPC) administration of trimethylamine (GJ opener) evoked an opposite effect i.e. well synchronized theta activity. The similar fi ndings were also obtained in many experiments carried out on awake animals and in studies conducted in in vitro conditions. In the present studies, performed on anesthetized rats, the interaction between GJ blocker and opener, separately injected into HPC on locally registered theta rhythm, were established. When diminishing effect of HPC injection of carbenoxolone (100 μg/1 μl) on theta rhythm amplitude and power was observed, trimethylamine (30 μg/1 μl) was locally administered. Trimethylamine was found to alleviate blocking effect on spontaneous HPC theta rhythm. In the next experiment, all rats pretreated with trimethylamine were injected with carbenoxolone. GJ blocker was found to prevent facilitating effect of trimethylamine on theta rhythm. The mechanism underlying GJ involvement in theta rhythm generation in vivo is discussed. These studies were supported by grant MNiSzW NN 401 2811 33.
6

Is the dental gyrus an independent generator of in vitro theta rhythm?

88%
Kowalczyk T., Golebiewski H., Bocian R., Posluszny A., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 3
7

Discharge patterns of theta-related cells in transected hippocampal formations slices

88%
Kowalczyk T., Golebiewski H., Bocian R., Posluszny A., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
Hippocampal formation (HPC) theta rhythm is approximately sinusoidal, most prominent and well-documented EEG pattern recorded from the mammalian brain. Following the discovery of cholinergically induced theta rhythm recorded in slice preparations of HPC, central mechanisms underlying theta generation have been successfully studied in the in vitro conditions. In our previous work we have attempted to record an EEG activity of three types of transected hippocampal slices (CA1 trans-slice, CA3c trans-slice, and DG trans-slice) examining activity of separated intrahippocampal theta generators. Data obtained in those studies revealed that dentate gyrus isolated from generators located in CA1 and CA3c fi elds respectively, is not able to generate theta rhythm in the in vitro conditions. The purpose of the present study was to extend our previous in vitro studies concerning the activity patterns of theta related cells. This time theta cells were recorded in transacted hippocampal slices i.e. CA1 trans-slice, CA3c trans-slice, and DG trans-slice. Sixty cells were isolated and recorded from transected slices, including thirty cells from CA3c (20 theta-on cells, 6 theta-off cells, and 4 gating cells), and thirty cells from CA1 (15 theta-on cells, 13 thetaoff cells, and 2 gating cells). None of DG transected slices tested generated any synchronous fi eld potentials and accompanying cell activity. Supported by MNiSW grant No. N N 303 091 834.
8

The effect of carbachol on hippocampal theta in carbenoxolone pretreated rats

88%
Posluszny A., Bocian R., Kowalczyk T., Golebiewski H., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
Among the number of the mechanisms of signal transmission evolved in biological systems, a distinctive feature of gap-junction coupling is ability of direct high-speed information spreading over the space of coupled cells. It is performed on cytoplasmic tracks provided by the channel structure of gap junction assemblies (electrical synapses). In the nervous system this high-speed pathway is considered as a promoter of neuronal synchrony, and so – an underground for oscillatory events. On the other hand, it is well known that to produce oscillations, the brain tissue needs qualitatively and quantitatively balanced neurotransmitter input feeding the oscillation-generating networks. The question arise what is the real contribution of the two signalling systems: electrical and chemical to oscillatory activity. Hippocampal formation (HPC) theta rhythm is one of the best synchronized brain oscillations. Our earlier experiments demonstrted that the cessation of gap junction coupling had a spectacular effect on HPC spontaneous theta rhythm. HPC administrations of carbenoxolone (CBX), a gap junction blocker, produced progressive impairment of theta oscillations up to their abolition. In order to estimate if high-level enhancement of chemical transmission is capable of counteracting the gap junction blockage, in the present work carbachol, a cholinergic agonist, was injected into CBX pretreated hippocampus. Under CBX-blockage no effect of carbachol was noticed. Grant MNiSzW NN 401 2811 33.
9

Cholinergic/GABAergic interaction in hippocampal theta production in freely moving cats

76%
Golebiewski H., Eckersdorf B., Kowalczyk T., Bocian R., Posluszny A., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 3
10

NMDA - induced electrophysiological activity in hippocampal formation slices - attempts to induce rhythmic oscillations

76%
Kazmierska P., Bocian R., Kowalczyk T., Golebiewski H., Posluszny A., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2011
|
tom 71
|
nr S
Theta rhythm is a model example of oscillation and synchrony in neural networks of the central nervous system. Cholinergic and GABAergic nature of the in vitro and in vivo induced theta rhythm has been earlier established. However, according to the recent report by Bland and colleagues (2007) it is suggested that glutamatergic septohippocampal projection represents a third, independent pathway capable of generating hippocampal field and cellular synchrony. With regard to above data, the aim of the study was to investigate whether the stimulation of NMDA receptors is able to induce rhythmic activity in the hippocampal formation maintained in complete de-afferentation. In the present work field potential and intracellular recordings were made from the CA1 and CA3 fields of hippocampal formation during the bath perfusion of the following concentration of NMDA: 1 µM, 3 µM, 10 µM, 30 µM, 50 µM and 80 µM. Application of all but 1 µM NMDA resulted in epileptic activity in aproximate range 0,1 - 1 Hz. The attempts of synchronization were observed in 23% and 31% of all active slices treated with 20 µM and 50 µM NMDA. Since an “effective dose” of NMDA which administration resulted in the highest probability to induce the attempts of synchronization was 50 µM NMDA, the influence of following mixtures on hippocampal EEG activity has been examined: 50 µM NMDA was tested with 10 µM 2-hydroxy-saclofen and 50 µM NMDA was tested with 10 µM bicuculine. Short attempts of synchronization of EEG activity were noticeable in 15% of active slices treated with the first mixture and in 21% of active slices treated with the other. The effect of NMDA was completely blocked after preincubation with 50 µM selective NMDA receptor antagonist D-AP5. I the light of above results it seems that stimulation of NMDA receptor itself is not sufficient to induce theta oscillations in completely deafferented hippocampal formation. Project supported by the European Union under European Social Fund (HUMAN - BEST INVESTMENT)
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