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M Pritzel

Publications and source records attributed to M Pritzel.

At least 19 recordsLinked to original sources
PubMed1988

Callosal projections between areas 17 in the adult tree shrew (Tupaia belangeri).

In the primary visual cortex (area 17) of the tree shrew (Tupaia belangeri) neurons projecting to the contralateral area 17 via the corpus callosum were identified by horseradish peroxidase histochemistry (HRP, WGA-HRP). The distribution of homotopic and heterotopic connections was studied. We found that a narrow stripe of area 17 close to the dorsal area 17/18 border - which corresponds to the visual field along the vertical meridian - is connected via homotopic callosal projections. The adjacent dorsal part of area 17, which largely corresponds to the binocular visual field, is connected via homotopic as well as heterotopic projections. Heterotopic projections originate in the cortical stripe along the area 17/18 border and their contralateral targets are displaced medially. Callosal neurons are located mostly in supragranular but also occur in infragranular layers. The supragranular neurons in general are pyramidal cells. In addition to these findings, we confirmed earlier reports on ipsilateral projections of the primary visual area to the dLGN, the claustrum, area 18 and other visual areas.

Animals↗
PubMed1987

Single unit activity in cat prefrontal and parietal cortex during performance of a symmetrically reinforced go-no go task.

Relationships between the performance in a symmetrically reinforced go-no go task and cellular firing patterns in prefrontal and parietal association areas of the neocortex were studied in six cats. During recordings, animals lay in a box, with their heads fixed to a stereotaxic frame, and performed an auditory go-no go task by pressing a retractable lever in front of them. Units obtained were classified into eight types according to the correlation of their activity changes with aspects of the task and/or with sensory stimuli. These types were (poly-) sensory, reward related, EMG-related, EOG-related, event-related, movement-initiating, expressing expectancy or novelty, and nonspecific or task-unrelated active units. Between the two recording areas a considerable degree of similarity was obtained in unit firing patterns. It was concluded that within the cerebral cortex, and especially within its association areas, a considerable functional overlap exists, that neurons may be involved in the processing of several and rather different phenomena, and that the processing of information at this level of the brain is generally done via widespread, interwoven neuronal nets so that only the average network activity, but not that of a particular, single neuron, represents a stimulus or an event.

Animals↗
PubMed1986

Further evidence for excitatory amino acid transmission in the lateral habenular projection to the rostral raphe nuclei: lesion-induced decrease of high affinity glutamate uptake.

In previous autoradiographic studies we reported selective retrograde D-[3H]aspartate labelling of lateral habenular afferents to the nuclei raphe dorsalis (NRD) and centralis superior (RCS). This study reports biochemical support, lesion-induced decrease of high affinity glutamate uptake, for excitatory amino acid transmission in the habenulo-raphe connection. Rats received bilateral electrolytic lesions in the lateral habenular nuclei and survived 9-10 days. Brainstems were sectioned on a Vibratome, and NRD and RCS tissue microdissected. Glutamate uptake in sham-operated rats was in the NRD 23.6 +/- 2.3 nmol/g prot. (mean +/- S.E.M.) ([3H]glutamate 10(-7) M, 3 min, 25 degrees C) and in the RCS 14.6 +/- 1.0 nmol/g. Habenular lesions reduced glutamate uptake in the NRD by 20.7 +/- 2.0% (P less than 0.001) and in the RCS by 10.7 +/- 4.3% (P less than 0.05).

Amino Acids↗
PubMed1986

Afferent and efferent connections of striatal grafts implanted into the ibotenic acid lesioned neostriatum in adult rats.

The afferent and efferent connections of grafts of fetal caudate-putamen, implanted into the ibotenic acid (IA)-lesioned striatum of adult rats, have been studied with wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) as a combined retrograde and anterograde tracer, and with aldehyde fluorescence histochemistry for the visualisation of dopamine-containing nigrostriatal afferents from the host. The WGA-HRP was deposited in crystalline form (within a capillary tip) either into the depth of the graft tissue, or into the IA lesioned host striatum as a control. Labelling was only evaluated in specimens where the WGA-HRP deposit was entirely confined within the graft. Retrogradely labelled neurons were most consistently found in the ipsilateral host substantia nigra and the spared portions of the host CP, and in one case also in the midline and intralaminar thalamic nuclei normally projecting to the striatum. Some neurons, although weakly labelled, occurred in the deep layers of the frontal cortex in all grafted rats. Signs of anterograde WGA-HRP labelling in the host were found in one of the five animals in the ipsilateral globus pallidus and substantia nigra, pars reticulata. Fluorescence histochemistry revealed extensive ingrowth of dopamine-containing fibres from the host striatum into the grafted striatal tissue. The ingrowing fibres formed distinct and partly interconnected patches, most prominently in the peripheral regions of the grafts. The results provide evidence that intrastriatal grafts of fetal striatal tissue receive extensive dopaminergic afferents from the host substantia nigra, and that they may be capable of establishing connections also with thalamus, neocortex and globus pallidus of the host, as well as with the spared portions of the host caudate-putamen. The afferent connections from the thalamus and neocortex were notably more variable and sparse. However, since the control WGA-HRP deposits (into the lesioned host striatum) labelled the cortical and thalamic afferent neurons only poorly, it appears that the cortico-striatal and thalamo-striatal afferents (in contrast to the nigro-striatal ones) had undergone substantial degenerative changes (atrophy and/or cell death) in the long-term (6-11 months) IA-lesioned rats. The sparse thalamic and cortical afferent connections to the grafts may thus reflect an inability of the grafted striatal tissue to prevent the course of degenerative changes in these striatal input systems.

Animals↗
PubMed1985

The neuropathology of amnesia.

Relations between brain damage and memory disturbance are outlined with emphasis on the so-called amnesic syndrome. Following a brief introduction into forms of memory and memory failures, the basic causes of brain damaage (with relevance to amnestic failures) are described. Thereafter, the two best-known forms of brain damage-amnesia relations are reviewed: the consequences of damage to medial temporal lobe structures and to diencephalic regions. For the cases with medial temporal lobe damage, evidence is reported in greater detail for H.M., who has been examined more than any other amnesic patient for more than 30 years now, as a considerable amount of literature has accumulated on his behavior in diverse situations. Other cases with more or less circumscribed damage to medial temporal lobe structures are reviewed so as to outline criteria for or against the hypothesis that there are regions within the medial temporal lobe whose damage might be critical for the amnesic syndrome. Two cases of diencephalic amnesia are summarized in particular (cases of Mair et al., 1979) as they have received extensive neuropsychological and neuropathological investigation. Other cases with, for example, Korsakoff's disease are reviewed, as well as cases with diencephalic, or combined mesencephalic-diencephalic damage without nutritional causes. A third group of patients with massive, but still selective amnesic disturbances are then described: cases of basal forebrain damage, followed by descriptions of Alzheimer's disease which has similarities in the underlying neuropathology. This leads over to cases with more generalized intellectual deteriorations (dementia), which may have developed on the basis of primarily cortical damage or damage principally to basal ganglia structures. After reviewing cases with mainly material-specific memory failures--usually as a consequence of restricted neocortical damage--a separate section follows on patients in whom retrograde amnesia is the prominent symptom. The contribution of animal models of human amnesia is critically reviewed and discrepancies are analyzed between human and animal memory disturbances. This section emphasizes the value of investigating inter-dependencies between brain structures by pointing out that relations between memory disturbances and brain damage may be more complicated than apparent from a simple structure-function assignment. This aspect is further followed up in the conclusions.

Alcohol Amnestic Disorder↗
PubMed1984

Interhemispheric nigrothalamic projections and behavioral recovery following turning behavior induced by unilateral peripheral sensory and motor restriction.

We investigated the relationship between unilateral peripheral lesions plus partial sensory deprivation and interhemispheric nigrothalamic projections. Sensory-motor asymmetries were induced in rats by unilateral ligature of sensory and motor nerves of the forelimbs and hind limbs and partial sensory deprivation (cutting the vibrissae unilaterally and suturing one eyelid). This operation resulted in spontaneous turning which was partially compensated for within the first 5 postoperative days. Sixteen days after the surgery, animals were implanted with horseradish peroxidase in the ventrobasal thalamus of one hemisphere. Brains were processed by the tetramethylbenzidine procedure. Microscopical analysis revealed interhemispheric nigrothalamic projections from the substantia nigra situated ipsilateral but not contralateral to the denervated limbs. The results are interpreted in terms of a reorganization (sprouting) of interhemispheric nigrothalamic projections in response to unilateral peripheral lesions. The lesion-induced behavioral asymmetry and its partial compensation may be one of the determinants of the observed neuronal plasticity.

Animals↗
PubMed1983

Hypothalamic self-stimulation in rats with one hemisphere isolated anterior to the midbrain and the other hemisphere devoid of the telencephalon.

The telencephalon was removed unilaterally in rats. In addition, the forebrain of the other hemisphere was isolated from its brain stem by a precollicular transverse cut. This preparation was then tested for self-stimulation via electrodes implanted in the region of the lateral hypothalamus and medial forebrain bundle (LH-MFB) of either hemisphere. Self-stimulation was found to be intact in both hemispheres. Possible pathways connecting the LH-MFB region of one hemisphere to the contralateral diencephalon were also investigated in the bilaterally detelencephalized rat. The technique of retrograde transport of horseradish peroxidase was used for this purpose. Some fibers from the LH-MFB of one hemisphere were found to decussate to the other hemisphere by way of the thalamic commissure. The supraoptic decussation as well as diffusely organized interdiencephalic connections provide additional routes for interhemispheric LH-MFB projections.

Animals↗
PubMed1983

Effects of reducing sensory-motor feedback on the appearance of crossed nigro-thalamic projections and recovery from turning induced by unilateral substantia nigra lesions.

This experiment addressed the question of whether the increase in interhemispheric nigrothalamic projections, found after unilateral lesions of the substantia nigra (SN), is related to recovery from the lesion-induced sensory-motor asymmetry. We examined the effects of diminished information feedback about the animals' own behavior on recovery from turning induced by unilateral substantia nigra lesions, and the appearance of an increase in number of crossed nigro-thalamic projections. The animals received unilateral 6-hydroxydopamine lesions and were placed in a hammock for the next 7 days. Thus, they were prevented from engaging in turning behavior. They were then implanted with horseradish peroxidase (HRP) in the thalamus ipsilateral to the lesion. No HRP-labeled cells were found in the SN contralateral to the HRP implantation in these animals. In rats, which were allowed 7 days normal interaction with the environment subsequent to unilateral SN damage, labeled cells were found in the undamaged SN when HRP was implanted in the thalamus ipsilateral to the lesion. Animals which were kept in the hammock and subsequently allowed a week of normal interaction with the environment showed the same pattern of recovery from turning behavior as the animals which were allowed to recover normally immediately after the unilateral SN lesion. It was concluded that the relationship between the appearance of the nigro-thalamic projections and the cessation of turning behavior is not fortuitous. Also, it would appear that some form of sensory-motor learning is involved in the recovery of function after unilateral SN lesions. Thus, the results substantiate the idea that these cross-projections form part of a physical basis of recovery from unilateral lesion-induced asymmetries.

Animals↗
PubMed1983

Interhemispheric nigrostriatal projections in the rat: bifurcating nigral projections and loci of crossing in the diencephalon.

The organization of interhemispheric nigrostriatal projections in the rat was studied with (1) a double labeling technique combined with a histofluorescence method for monoamines and with (2) horseradish-peroxidase (HRP) as a tracer. Each animal received an injection of Fast Blue (FB) into the caudate nucleus (NC) of one hemisphere and an injection of Nuclear Yellow (NY) into the NC of the other hemisphere. Brains were processed according to the sucrose-potassium phosphate-glyoxylic acid (SPG) method in order to identify monoaminergic neurons. About 5% of the neurons which were labeled by either of the tracers in the substantia nigra (SN) ipsilateral to the injection site were also labeled in the contralateral SN. Most of these interhemispherically projecting SN-neurons were monoaminergic. A small number of neurons in either SN was labeled with both fluorescent tracers. This suggests that bifurcating, monoaminergic neurons in the SN project to both NC. In the second experiment, rats received a unilateral injection of HRP into NC. After a survival time of several hours the animals were perfused and the brains were processed using benzidine-dihydrochloride. Fibers crossing the hemisphere were found within the massa intermedia of the thalamus and within the inferior thalamic peduncle. The results are discussed with respect to a possible functional role of interhemispheric nigrostriatal connections.

Animals↗
PubMed1983

Afferents from limbic system-related regions to the frontal cortex in the bush baby (Galago senegalensis).

Afferents from limbic system-related structures (aside from the cingulate and retrosplenial cortex) to medial and lateral regions of the bush baby's frontal cortex were investigated by means of the somatopetal transport of horseradish peroxidase. The frontopolar region received afferents from the subicular cortex, the lateral nucleus of the amygdala, from hypothalamic nuclei, the ventral tegmental area and other brain stem nuclei. Injections of horseradish peroxidase into other frontal regions usually resulted in labeled cells in brain stem nuclei and in the hypothalamus, but not in telencephalic regions; only the large injection into the posterior part of the frontal cortex was followed by labeled amygdaloid neurons. From these results it is concluded that a small number of limbic system-related telecephalic areas projects to the frontal cortex and that a somewhat larger number of diencephalic and brain stem nuclei reaches this part of the cortex.

Afferent Pathways↗
PubMed1982

Plasticity of cortico-thalamic projections and functional recovery in the unilateral detelencephalized infant rat.

Previous results have shown that the unilateral removal of the telencephalon in adult rats leads to the appearance of crossed connections from the remaining telencephalon to the thalamus one week after the ablation. This study extends this finding to infant rats. The telencephalon structures were unilaterally removed in 7-day-old animals. As in adult rats the ablation induced behavioral asymmetries, including active turning behavior which ceased within the first days after the lesion. Either immediately after the ablation or one week thereafter the animals were injected with horseradish peroxidase (HRP) into the posterior part of the thalamus ipsilateral to the lesion. HRP-labeled cells appeared in the remaining contralateral cortex in animals that were injected one week after the lesion. Rapid functional recovery from the lesion-induced behavioral asymmetries, as indicated, for example, by the cessation of spontaneous turning behavior, may be related to the observed appearance of crossed projections between structures that are normally connected only ipsilaterally.

Animals↗
PubMed1982

Organization of cortical afferents to the prefrontal cortex in the bush baby (Galago senegalensis).

Cortical afferents to the prefrontal cortex were studied in 10 bush babies (Galago senegalensis) by means of somatopetal transport of horseradish peroxidase. The lateral injections invariably labeled neurons in the temporal cortex and in most cases also in the insular and parietal regions. In some of these brains the cingulate and retrosplenial areas contained labeled perikarya. Injections into the medial cortex, on the other hand, consistently labeled cell bodies in the cingulate cortex, but not in the insular, temporal and parietal regions. When both lateral and medial sites of the bush baby's prefrontal cortex are considered together, apparently fewer cortical areas (as defined by Brodmann's cytoarchitectonic maps) project to the prefrontal cortex in the bush baby than in the rhesus monkey. This statement holds for both ipsi- and contralateral projections.

Afferent Pathways↗
PubMed1981

Neural and behavioral plasticity: crossed nigro-thalamic projections following unilateral substantia nigra lesions.

Unilateral lesions of the substantia nigra of rats by injection of 6-hydroxydopamine or kainic acid induced ipsi- and contraversive turning behavior. Spontaneous turning was no longer exhibited one week after the lesions. This behavioral recovery was correlated in time with the development of crossed projections from the intact contralateral substantia nigra to the ventromedial thalamus of the lesioned hemisphere which, in the intact animal, receives projections only from the ipsilateral substantia nigra.

Animals↗
PubMed1981

Unilateral ablation of telencephalon induces appearance of contralateral cortical and subcortical projections to thalamic nuclei.

This study sought to investigate the afferent connections of the thalamus in the rat following massive telencephalic lesions. After unilateral removal of the telencephalon, horseradish peroxidase (HRP) was injected into the thalamic nuclei ipsilateral or, for control purposes, contralateral to the lesioned side. Injection of HRP into the ventral or posterior thalamus ipsilateral to the lesioned telencephalon led to retrograde transport and HRP-labeling of cells in unilateral projection areas in the cortex, diencephalon and mesencephalon and, in addition, unexpectedly, in their mirror-image sites in the hemisphere contralateral to the injected thalamus. HRP-positive cells in the contralateral hemisphere were found whenever HRP was injected 7 days postlesion, when the animals had ceased to exhibit spontaneous turning behavior, but not when it was injected immediately after the lesion. We favor the hypothesis that the development of contralateral afferents to the thalamic nuclei represents a morphological substrate of the behavioral reorganization necessitated by the asymmetrical removal of the telencephalon.

Afferent Pathways↗
PubMed1981

Cortico-prefrontal afferents in the guinea pig.

The prefrontal cortex of the guinea pig was investigated in a search for afferents from cortical areas outside the frontal lobe using the horseradish peroxidase retrograde tracing technique. Based on afferents from the medial, the lateral, and from both parts of the thalamic mediodorsal nucleus, three prefrontal subregions were defined, namely the sulcal (within and above the rhinal sulcus), the medial (anterior and superior to the genu of the corpus callosum), and the fronto-polar subfield. Only the fronto-polar region was found to receive afferents from insular, cingulate, retrosplenial, parietal, and temporal cortical fields. Both of the other subfields received afferents only from neighboring cortical regions: the medial subfield from cingulate and retrosplenial areas and the sulcal subfield from the insular cortex. For all three subregions, the number of labeled cells was found to be small. These results were interpreted with caution, as extent and subdivisions of the guinea pig's prefrontal cortex and its comparability with that of other species depend considerably on the criteria used.

Afferent Pathways↗