Biomedical subjects
Publications and source records attributed to D L Rosene.
The subicular cortices of the primate hippocampal formation form a physical and connectional link between the cortex of the temporal lobe and the hippocampus. Their direct connections with all classes of cortex in the temporal lobe except primary sensory cortex underscore the pivotal role of these areas in the potential interplay between the hippocampal formation and the association cortices.
The anterior cingulate cortex receives thalamic afferents mainly from the midline and intralaminar nuclei rather than the anterior thalamic nuclei. In contrast, the posterior cingulate cortex receives afferents primarily from the anterior thalamic nuclei and from extensive cortical areas in the frontal, parietal, and temporal lobes. These contrasting afferents may provide a structural basis for pain-related functions of the anterior cingulate cortex.
Nine currently available methods for HRP neurohistochemistry have been compared with each other on matching tissue sections from four rats and four rhesus monkeys. The nine methods investigated in this report are the diaminobenzidine (DAB) procedures of LaVail JH and LaVail MM (J Comp Neurol 157:303, 1974), of Adams JC (Neuroscience 2:141, 1977) and of Streit P and Reubi JC (Brain Res 126:530, 1977); the benzidine dihydrochloride (BDHC) procedures of Mesulam M-M (J Histochem Cytochem 24:1273, 1976) and of De Olmos J and Heimer L (Neurosci Lett 6:107, 1977); the o-dianisidine (O-D) procedure of De Olmos J (Exp Brain Res 29:541, 1977); the p-phenylenediamine dihydrochloride and pyrocatechol (PPD-PC) procedure of Hanker JS et al., (Histochem J 9:789, 1977) and the tetramethyl benzidine (TMB) procedures of Mesulam M-M (J Histochem Cytochem 26:106, 1978) and of De Olmos J et al. (J Comp Neurol 181:213, 1978). Quantitative comparisons were based on counts of retrogradely labeled perikarya. The extent of anterograde transport and the size of the injection site were also compared at a more qualitative level. The results indicate that one TMB procedure (Mesulam M-M, J Histochem Cytochem 26:106, 1978) is distinctly superior to each of the other eight procedures in the number of labeled perikarya that it can demonstrate. Furthermore, these differences are statistically significant at better than the 0.05 level of confidence. Differences in sensitivity are most evident when the perikarya contain small quantities of transported HRP. The same TMB method also demonstrates more anterograde transport and a larger injection site than all the other procedures. If less sensitive procedures are employed, afferent or efferent connections that are clearly demonstrated by this TMB procedure are either underestimated or completely overlooked. It is suggested that sensitivity in HRP neurohistochemistry is determined by multiple factors which include the method of fixation, post-fixation storage, the choice of chromogen, the incubation parameters, the type of HRP enzyme that is administered, and the postreaction treatment.
Cells of origin of the corpus callosum (callosal efferent neurons) in prelunate gyrus (area OA) of the rhesus monkey were studied using electrophysiological techniques. Monkeys were chronically prepared and callosal efferent neurons were identified by their antidromic activation following electrical stimulation of the contralateral prelunate gyrus and/or the splenium of the corpus callosum. Interhemispheric antidromic latencies ranged from 2.6--18.0 ms (median = 7.0 ms) while the conduction velocity along the length of the axon ranged from 2.8 to 22.5 M/s (median = 7.4 M/s) while the conduction velocity along the length of the axon ranged from 2.8 to 22.5 M/s (median = 7.4 M/s. Following the relative refractory period of a single prior impulse, all but one of 61 callosal efferent neurons studied showed a supernormal period of increased axonal conduction velocity and excitability. Following several prior impulses, the supernormal period was followed by a subnormal period of decreased axonal conduction velocity and excitability, which, depending on the number of prior impulses, lasted from several hundred ms to nearly 2 min.
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In a series of neurohistochemical experiments the effect of aldehyde fixation upon the detection of horseradish peroxidase (HRP) was examined. These experiments demonstrated that: a) Increments in fixation of as little as 1 hr significantly decreased the number of labeled neurons; 12-hr fixation abolished HRP activity in many neuronal populations and significantly reduced the apparent size of the injection site. b) This negative fixation effect was greatest where the HRP concentration was low (e.g. in small, lightly labeled neurons) but was still evident in areas of high concentration (e.g. large, heavily labeled neurons). c) This effect was also most prominent when a less sensitive diaminobenzidine histochemical procedure was employed but was still apparent with a more sensitive benzidine dihydrochloride procedure. d) Immersion of the brain in fixative after perfusion produced a greater attenuation of HRP activity in more superficial areas. e) Immersion of the brain in buffer to terminate fixation produced a prolonged and unpredictable gradient of fixation. f) Excess, unbound fixative inhibited the histochemical reaction per se and had to be removed from the tissue but prolonged washing did not resurrect enzyme activity which was lost by fixation. To obviate these problems and optimize HRP enzyme activity a new perfusion-fixation procedure was developed. It entails 30 min fixation by perfusion which is terminated by a subsequent 30 min perfusion with cold sucrose-fuller to wash out unbound fixative. This allows the tissue to be processed immediately, produces a uniform and morphologically adequate fixation, and minimizes the negative effects of fixation on HRP enzyme activity.
Local blood flow was measured in the caudate nuclei and, in some cases, other areas of rat and monkey brain by the hydrogen clearance technique. Resting values for caudate blood flow in the rat were similar to those reported elsewhere, i.e., 69 +/- 4 ml/min/100 g in the caudate. Administering D-amphetamine sulfate (0.5 mg/kg, i.p.) to rats reduced caudate flow by a maximum of about 33% after 30 min; this effect could be blocked by pretreatment with haloperidol (5.0 mg/kg, i.p.), a drug that blocks dopamine receptors. D-Amphetamine sulfate (1.5 mg/kg) also reduced caudate but not cortical blood flow in unanesthetized monkeys. Electrical stimulation of the pars compacta of the substantia nigra reduced ipsilateral caudate flow by about 25% without affecting flow in the contralateral caudate. This effect varied with the frequency and intensity of stimulation. These studies suggest that the intraparenchymal release of brain dopamine may modify intraparenchymal (local) blood flow.
The subiculum of the primate hippocampal formation stands at the end of a polarized sequence of intrinsic hippocampal efferents and is the source of efferents to the medial frontal cortex, the caudal cingulate gyrus, and the parahippocampal area and amygdala in the temporal lobe. In addition, the subiculum sends subcortical efferents to the septum and diencephalon.
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