Physiologic and anatomic investigation of a visual cortical area situated in the ventral bank of the anterior ectosylvian sulcus of the cat

Summary In this paper a cortical area is described that covers approximately the posterior two-thirds of the ventral bank of the anterior ectosylvian sulcus of the cat and is called anterior ectosylvian visual area (AEV).In cats anesthetized with a combination of N₂O and barbiturate we explored this area by recording extracellularly the responses of AEV neurons to visual and electric stimulation as well as by injecting HRP into physiologically verified points. AEV neurons were found to be highly sensitive to small light stimuli moving rapidly in a particular direction through their large receptive fields. The properties of 74 neurons were quantitatively analyzed. Increasing the length of the stimulus within the receptive field to more than 2 deg strongly inhibited the responses, whereas increasing the speed of the stimulus movement up to 72–120 deg/s enhanced the neuronal responsiveness. Although the majority of neurons responded to a wide range of possible directions, one clearly preferred direction could usually be found for each neuron. There was a predominance of preferred directions toward the contralateral hemifield. Anatomic and electrophysiologic connectivity studies showed that AEV receives its main afferent inputs from the lateral suprasylvian visual area (LS) and from the tecto-recipient zone of the nucleus lateralis posterior (LP)-pulvinar complex.Although these studies suggested some topographical organization within the projection from LS to AEV, the large receptive fields in AEV, the great majority of which included the central area, did not reveal a clear retinotopic order. It is concluded that AEV is a specific visual area and that functionally the extrageniculate inputs predominate.Abbreviations AEs anterior ectosylvian sulcus - ALLS anterolateral lateral suprasylvian area - AMLS anteromedial lateral suprasylvian area; - Cl Claustrum - DLS dorsal lateral suprasylvian area - LGNd dorsal nucleus of lateral geniculate body - LGNv ventral nucleus of lateral geniculate body - LM nucleus lateralis medialis - LP1a nucleus lateralis posterior, pars lateralis - LPm nucleus lateralis posterior, pars medialis - Ls lateral sulcus - MGmc magnocellular division of medial geniculate body - MGpc parvocellular division of medial geniculate body - MSs middle suprasylvian sulcus - NP nucleus posterior of Rioch - PLLS postero-lateral lateral suprasylvian area - PLs posterolateral sulcus - PMLS posteromedial lateral suprasylvian area - Pu putamen - Pul pulvinar - Sg suprageniculate nucleus - VLS ventral lateral suprasylvian area Sponsored by Max-Planck-Gesellschaft and IBRODept. of Anatomy, School of Medicine, Iwate Medical University, Morioka 020, JapanSponsored by Alexander von Humboldt-FoundationDept. of Physiology, University Medical School, Szeged, Hungary     

Interconnections of the auditory cortical fields of the cat with the cingulate and parahippocampal cortices

Summary The interconnections of the auditory cortex with the parahippocampal and cingulate cortices were studied in the cat. Injections of the anterograde and retrograde tracer WGA-HRP were performed, in different cats (n = 9), in electrophysiologically identified auditory cortical fields. Injections in the posterior zone of the auditory cortex (PAF or at the PAF/AI border) labeled neurons and axonal terminal fields in the cingulate gyrus, mainly in the ventral bank of the splenial sulcus (a region that can be considered as an extension of the cytoarchitectonic area Cg), and posteriorly in the retrosplenial area. Labeling was also present in area 35 of the perirhinal cortex, but it was sparser than in the cingulate gyrus. Following WGA-HRP injection in All, no labeling was found in the cingulate gyrus, but a few neurons and terminals were labeled in area 35. In contrast, no or very sparse labeling was observed in the cingulate and perirhinal cortices after WGA-HRP injections in the anterior zone of the auditory cortex (AI or AAF). A WGA-HRP injection in the cingulate gyrus labeled neurons in the posterior zone of the auditory cortex, between the posterior ectosylvian and the posterior suprasylvian sulci, but none was found more anteriorly in regions corresponding to AI, AAF and AII. The present data indicate the existence of preferential interconnections between the posterior auditory cortex and the limbic system (cingulate and parahippocampal cortices). This specialization of posterior auditory cortical areas can be related to previous observations indicating that the anterior and posterior regions of the auditory cortex differ from each other by their response properties to sounds and their pattern of connectivity with the auditory thalamus and the claustrum.Abbreviations AAF anterior auditory cortical field - aes anterior ectosylvian sulcus - AI primary auditory cortical field - AII secondary auditory cortical field - ALLS anterior-lateral lateral suprasylvian visual area - BF best frequency - C cerebral cortex - CC corpus callosum - CIN cingulate cortex - CL claustrum - DLS dorsal lateral suprasylvian visual area - DP dorsoposterior auditory area - E entorhinal cortex - IC inferior colliculus - LGN lateral geniculate nucleus - LV pars lateralis of the ventral division of the MGB - LVe lateral ventricule - MGB medial geniculate body - OT optic tract - OV pars ovoidea of the ventral division of the MGB - PAF posterior auditory cortical field - pes posterior ectosylvian sulcus - PLLS posterior-lateral lateral suprasylvian visual area - PS posterior suprasylvian visual area - PU putamen - RE reticular complex of thalamus - rs rhinal sulcus - SC superior colliculus - SS suprasylvian sulcus - T temporal auditory cortical field - TMB tetramethylbenzidine - VBX ventrobasal complex of thalamus, external nucleus - VL pars ventrolateralis of the ventral division of the MGB - VLS ventrolateral suprasylvian visual area - VPAF ventroposterior auditory cortical field - WGA-HRP wheat germ agglutinin labeled with horseradish peroxidase - wm white matter     

Topographical organization of the cortical afferent connections to the cortex of the anterior ectosylvian sulcus in the cat

Summary The cortical afferents to the cortex of the anterior ectosylvian sulcus (SEsA) were studied in the cat, using the retrograde axonal transport of horseradish peroxidase technique. Following injections of the enzyme in the cortex of both banks, fundus and both ends (postero-dorsal and anteroventral) of the anterior ectosylvian sulcus, retrograde labeling was found in: the primary, secondary, and tertiary somatosensory areas (SI, SII and SIII); the motor and premotor cortices; the primary, secondary, anterior and suprasylvian fringe auditory areas; the lateral suprasylvian (LS) area, area 20 and posterior suprasylvian visual area; the insular cortex and cortex of posterior half of the sulcus sylvius; in area 36 of the perirhinal cortex; and in the medial bank of the presylvian sulcus in the prefrontal cortex. Moreover, these connections are topographically organized. Considering the topographical distribution of the cortical afferents, three sectors may be distinguished in the cortex of the SEsA. 1) The cortex of the rostral two-thirds of the dorsal bank. This sector receives cortical projections from areas SI, SII and SIII, and from the motor cortex. It also receives projections from the anterolateral subdivision of LS, and area 36. 2) The cortex of the posterior third of the dorsal bank and of the posterodorsal end. It receives cortical afferents principally from the primary, secondary and anterior auditory areas, from SI, SII and fourth somatosensory area, from the anterolateral subdivision of LS, vestibular cortex and area 36. 3) The cortex of the ventral bank and fundus. This sulcal sector receives abundant connections from visual areas (LS, 20, posterior suprasylvian, 21 and 19), principally from the lateral posterior and dorsal subdivisions of LS. It also receives abundant connections from the granular insular cortex, caudal part of the cortex of the sylvian sulcus and suprasylvian fringe. Less abundant cortical afferents were found to arise in area 36, second auditory area and prefrontal cortex. The abundant sensory input of different modalities which appears to converge in the cortex of the anterior ectosylvian sulcus, and the consistent projection from this cortex to the deep layers of the superior colliculus, make this cortical region well suited to play a role in the control of the orientation movements of the eyes and head toward different sensory stimuli.Supported by FISSS grants 521/81 and 1250/84     

Thalamic projections to the posterior sylvian and posterior ectosylvian gyri of the sheep brain, revealed with the retrograde transport of horseradish peroxidase

Summary The auditory area of the sheep cerebral cortex was studied on the basis of its afferents from the medial geniculate nucleus, traced with the horseradish peroxidase retrograde transport method. The results show that the medial geniculate nucleus projects only to the anterior parts of the posterior ectosylvian gyrus and the posterior sylvian gyrus. A small area of the posterior ectosylvian gyrus receives afferents exclusively from the ventral part of the medial geniculate nucleus, while the anterior part of the posterior sylvian gyrus receives also afferents from the posterior nucleus of the thalamus and the pulvinar. In addition, it was found that the medial part of the medial geniculate nucleus projects in a sparse way to the auditory cortex. The middle part of the posterior ectosylvian gyrus receives afferents from the posterior nucleus of the thalamus, the suprageniculate nucleus and the pulvinar, while the posterior part of the posterior ectosylvian gyrus together with the posteriormost part of the posterior sylvian gyrus receive afferents from the pulvinar. Finally, the area located between the anterior and the posteriormost part of the posterior sylvian gyrus receives afferents from both the posterior nucleus of the thalamus and the pulvinar.Abbreviations Ad nucleus anterior dorsalis - Am nucleus anterior medialis - Av nucleus anterior ventralis - BCI nucleus of the brachium colliculi inferioris - bci brachium colliculi inferioris - Cg substantia grisea centralis - ci capsula interna - Cm nucleus centralis medialis - EC sulcus ectomarginalis - EN sulcus entomarginalis - Ep epiphysis - ES sulcus ectosylvius - fd columna fornicis descendens - FS fissura sylvia - Hl nucleus habenularis lateralis - Hm nucleus habenularis medialis - Iv nucleus interventralis - Ld nucleus lateralis dorsalis - LGN nucleus geniculatus lateralis - LGNd nucleus geniculatus lateralis, pars dorsalis - LGNv nucleus geniculatus lateralis, pars ventralis - lme lamina medullaris thalami externa - Lp nucleus lateralis posterior - Lt nucleus lateralis thalami - MA sulcus marginalis - Md nucleus medialis dorsalis - MGN nucleus geniculatus medialis - MGNd nucleus geniculatus medialis, pars dorsalis - MGNm nucleus geniculatus medialis, pars magnocellularis - MGNv nucleus geniculatus medialis, pars ventralis - MIN medial interlaminar nucleus - mt fasciculus mamillothalamicus - ml lemniscus medialis - Mv nucleus medialis ventralis - ot tractus opticus - p putamen - pc pedunculus cerebri - Pl nucleus paralemniscalis - Po nucleus posterior - Pp nucleus paraventricularis posterior - Pta nucleus praetectalis anterior - Ptp nucleus praetectalis posterior - Pul pulvinar - R nucleus ruber - rf fasciculus retroflexus - Rh nucleus rhomboidalis - RH sulcus rhinalis lateralis - Rt nucleus reticularis thalami - Sg nucleus suprageniculatus - SN substantia nigra - SP sulcus cinguli - SS sulcus suprasylvius - Sth nucleus subthalamicus - Va nucleus ventralis anterior - Vl ventrolateral nuclear complex - Vll pars lateralis of the ventrolateral nuclear complex - Vm nucleus ventralis medialis - Vp nucleus ventralis posterior - Vpl nucleus ventralis posterior, pars lateralis - Vpm nucleus ventralis posterior, pars medialis - W Wernicke's field     

Corticothalamic connections of the superior temporal sulcus in rhesus monkeys

Summary The corticothalamic connections of the superior temporal sulcus (STS) were studied by means of the autoradiographic technique. The results indicate that corticothalamic connections of the STS in general reciprocate thalamocortical connections. The cortex of the upper bank of the STS-multimodal areas TPO and PGa-projects to four major thalamic targets: the pulvinar complex, the mediodorsal nucleus, the limitanssuprageniculate nucleus, as well as intralaminar nuclei. Within the pulvinar complex, the main projections of the upper bank of the STS are directed to the medial pulvinar (PM) nucleus. Rostral upper bank regions tend to project caudally and medially within the PM nucleus, caudal upper bank regions, more laterally and ventrally. The mid-portion of the upper bank tends to occupy the central sector of the PM nucleus. There are also relatively minor projections from upper bank regions to the lateral pulvinar (PL) and oral pulvinar (PO) nuclei. In contrast to the upper bank, the projections from the lower bank are directed primarily to the pulvinar complex, with only minor projections to intralaminar nuclei. The rostral portion of the lower bank projects mainly to caudal and medial regions of the PM nucleus, whereas the caudal lower bank projects predominantly to the lateral PM nucleus, and also to the PL, PO, and inferior pulvinar (PI) nuclei. The mid-portion of the lower bank projects mainly to central and lateral portions of the PM nucleus, and also to the PI and PL nuclei. The rostral depth of the STS projects mainly to the PM nucleus, with only minor connections to the PO, PI, and PL nuclei. The midportion of multimodal area TPO of the upper bank, areas TPO₂ and TPO₃, projects preferentially to the central sector of the PM nucleus. It is possible that this STS-thalamic connectivity has a role in behavior that is dependent upon more than one sensory modality.Abbreviations AM anterior medial nucleus - AS arcuate sulcus - AV anterior ventral nucleus - BSC brachium of the superior colliculus - Cd caudate nucleus - Cif nucleus centralis inferior - Cim nucleus centralis intermedialis - CL central lateral nucleus - CM centromedian nucleus - CM-Pf centromedian-parafascicular nucleus - Cs nucleus centralis superior - CS central sulcus - CSL nucleus centralis lateralis superior - GLd dorsal lateral geniculate nucleus - GM medial geniculate nucleus - Hb habenula - IOS inferior occipital sulcus - IPS intraparietal sulcus - LD lateral dorsal nucleus - LF lateral fissure - Li limitans nucleus - LP lateral posterior nucleus - LS lunate sulcus - MD mediodorsal nucleus - Pa paraventricular nucleus - Pen paracentral nucleus - Pf parafascicular nucleus - PI inferior pulvinar nucleus - PL lateral pulvinar nucleus - PM medial pulvinar nucleus - PO oral pulvinar nucleus - PS principal sulcus - Pt parataenial nucleus - R reticular nucleus - Re reuniens nucleus - SG suprageniculate nucleus - STN subthalamic nucleus - STS superior temporal sulcus - THI habenulo-interpeduncular tract - VLc nucleus ventralis lateralis, pars caudalis - VLm nucleus ventralis lateralis, pars medialis - VLo nucleus ventralis lateralis, pars oralis - VLps nucleus ventralis lateralis, pars postrema - VPI ventroposteroinferior nucleus - VPLc nucleus ventralis posterior lateralis, pars caudalis - VPLo nucleus ventralis posterior lateralis, pars oralis - VPM ventroposteromedial nucleus - VPMpc ventroposteromedial nucleus, parvocellular portion - X nucleus X     

The association connexions of the suprasylvian fringe (SF) and other areas of the cat auditory cortex

The association connexions of the peri-auditory (SF, Ea and INS) and auditory (AI, AII and Ep) areas of the cat cortex were studied in silver impregnated material of 32 experiments with cortical lesions. The cortex of the lateral bank of the rostral part of the middle suprasylvian sulcus (SF) sends many fibres to AI and to the insular cortex (INS), and has scanty projections upon AII and Ep. In addition, it sends fibres to the visual area 17 as well as to the ventral bank of the medial part of the cruciate sulcus. It receives fibres from the three auditory areas AI, AII and Ep, as well as from Ea and INS. The dorsal part of the anterior ectosylvian gyrus (Ea) projects upon SF, AI, and AII. Ea sends few fibres to Ep, and receives relatively dense projections from AI and AII. The anterior sylvian gyrus (INS) projects heavily upon AII as well as upon the superficial part of SF. It sends a few fibres also to Ep. INS receives heavy projections from AII and relatively lighter connections from SF, AI and Ep. The three auditory areas AI, AII and Ep are strongly mutually interconnected. AI and Ep have scanty projections upon the visual area 19, and AI also to the lateral suprasylvian visual area, as well as upon the ventral bank of the medial cruciate sulcus. Correlations of the association connexions with the functions of each area are discussed.     

Branching cortical neurons in cat which project to the colliculi and to the pons: a retrograde fluorescent double-labeling study

Summary The fluorescent double-labeling technique has been used to determine whether the corticopontine and the corticotectal fibers in the cat are derived from two different sets of neurons or whether they are derived from branching neurons which distribute collaterals to the pontine grey and the colliculi. After unilateral DY.2HCl injections in the pontine grey and FB injections in the ipsilateral colliculi, large numbers of FB-DY.2HCl double-labeled neurons were present in the cortex of the ipsilateral hemisphere. However, the labeled neurons in its rostral part may have represented pyramidal tract neurons which were labeled retrogradely because their fibers descended through the DY.2HCl injection area. Therefore, also DY.2HCl injections were made in the pyramid (i.e. caudal to the pons) and the cortical pyramidal tract area, containing the retrograde DY.2HCl-labeled neurons, was delineated. In the rest of the experiments only the DY.2HCl-labeled neurons in the caudal two thirds of the hemisphere (outside the pyramidal tract area) were taken into account because only these neurons could, with confidence, be regarded as corticopontine neurons. In some anterograde HRP transport experiments the trajectories of the corticotectal and the corticopontine fibers were visualized. On the basis of the findings the DY.2HCl injections in the pontine grey were placed such that they could not involve any of the corticotectal fibers passing from the cerebral peduncle to the colliculi. Thus artifactual doublelabeling of cortical neurons was avoided. However, also under these circumstances many double-labeled neurons were present in the caudal two thirds of the hemisphere. This led to the conclusion that in the cat a large proportion of the corticopontine neurons in the caudal two thirds of the hemisphere represent branching neurons which also distribute collaterals to the colliculi. The parietal (anterior part of the lateral gyrus, middle and posterior suprasylvian gyri) and the cingulate areas together contained three quarters of all labeled corticopontine neurons outside the pyramidal tract area. In the parietal areas roughly 25% of them were double-labeled and in the cingulate area 14%. However, in the visual areas 18 and 19 a much larger percentage (30–60%) was doublelabeled. In a recent study from our laboratory it was found that in the cat the pyramidal tract fibers distribute an abundance of collaterals to the pontine grey. Therefore, a large proportion of all corticopontine connections in this species appear to be established by branching neurons which also distribute fibers to other cell groups in the brain stem and the spinal cord.Abbreviations A.E. anterior ectosylvian sulcus - a.e.s. anterior ectosylvian sulcus - BC brachium conjunctivum - BCI brachium colliculus inferior - BP brachium pontis - cor. sulc. coronal sulcus - CP cerebral peduncle - CR. cruciate sulcus - CUN cuneiform nucleus - DBC decussation brachium conjunctivum - DLP dorsolateral pontine nucleus - IC inferior colliculus - inf. coll. inferior colliculus - INS. insula cortex - IO inferior olive - IP interpeduncular nucleus - LAT. lateral sulcus - l.s. lateral sulcus - MG medial geniculate body - LL lateral lemniscus - ML medial lemniscus - MLF medial longitudinal fascicle - NdG dorsal nucleus of Gudden - NLL nucleus lateral lemniscus - NRTP reticular tegmental pontine nucleus - ORB. orbital sulcus - P pyramid - PAG periaqueductal grey - P.E. posterior ectosylvian sulcus - RF reticular formation - PG pontine grey - RB restiform body - RN red nucleus - S. sylvian sulcus - SC superior colliculus - SN substantia nigra - SO superior olive - SPV spinal trigeminal complex - S.S. suprasylvian sulcus - s.syl.s. suprasylvian sulcus - S.SPL. suprasplenial sulcus - SPL. splenial sulcus - spl.s. splenial sulcus - sup. coll. superior colliculus - syl.s. sylvian sulcus - TB trapezoid body - VC vestibular complex - Vm trigeminal motor nucleus - Vs trigeminal principle nucleus - III oculomotor nucleus - IV trochlear nucleus - VI abducens nucleus - VII facial nerve - VIII vestibulo-trochlear nerve Supported in part by grant 13-46-91 of FUNGO/ZWO (Dutch Organization for Fundamental Research in Medicine)     

Quantitative analyses of principal and secondary compound parieto-occipital feedback pathways in cat

The purpose of our study was to quantify the magnitude of principal and secondary pathways emanating from the middle suprasylvian (MS) region of visuoparietal cortex and terminating in area 18 of primary visual cortex. These pathways transmit feedback signals from visuoparietal cortex to primary visual cortex. (1) WGA-HRP was injected into area 18 to identify inputs from visual structures. In terms of numbers of neurons, feedback projections to area 18 from MS sulcal cortex (areas PMLS, AMLS and PLLS) comprise 26% of inputs from all visual structures. Of these neurons, between 21% and 34.9% are located in upper layers 2–4 and the dominant numbers are located in deep layers 5 and 6. Areas 17 (11.8%) and 19 (11.2%) provide more modest cortical inputs, and another eight areas provide a combined total of 4.3% of inputs. The sum of neurons in all subcompartments of the lateral geniculate nucleus (LGN) accounts for another 34.8% of the input to area 18, whereas inputs from the lateral division of the lateral-posterior nucleus (LPl) account for the final 11.9%. (2) Injection of tritiated-(³H)-amino acids into MS sulcal cortex revealed substantial direct projections from MS cortex that terminated in all layers of area 18, but with a markedly lower density in layer 4. Projections from MS cortex to both areas 17 and 19 are of similar density and characteristics, whereas those to other cortical targets have very low densities. Quantification also revealed minor-to-modest axon projections to all components of LGN and a massive projection throughout the LP-Pul complex. (3) Superposition of the labeled terminal and cell fields identified secondary, compound feedback pathways from MS cortex to area 18. The largest secondary pathway is massive and it includes the LPl nucleus. Much more modest secondary pathways include areas 17 and 19, and LGN. The relative magnitudes of the secondary pathways suggest that the one through LPl exerts a major influence on area 18, whereas the others exert more modest or minor influences. MS cortex in the contralateral hemisphere also innervates area 18 directly. These data are important for interpreting the impact of deactivating feedback projections from visuoparietal cortex on occipital cortex.Abbreviations A layer A of LGN - A1 layer A1 of LGN - ALLS anterolateral visual area of the lateral suprasylvian sulcus (Palmer et al. 1978) - AMLS anteromedial visual area of the lateral suprasylvian sulcus (Palmer et al. 1978) - Aud auditory cortex of the middle ectosylvian gyrus - CC corpus callosum - Cg cingulate gyrus - Cm magnocellular layers of LGN - Cp parvocellular layers of LGN - LGN dorsal lateral geniculate nucleus - LP lateral posterior nucleus - LPl lateral division of the lateral posterior nucleus - LPm medial division of the lateral posterior nucleus (Graybiel and Berson 1980, Berson and Graybiel 1978; Raczkowski and Rosenquist 1983) - MIN medial interlaminar nucleus subdivision of LGN - MS cortex bounding the middle suprasylvian sulcus (areas AMLS, ALLS, PMLS, and PLLS) - OR optic radiation - PE posterior ectosylvian visual cortex - PLLS posterolateral visual area of the lateral suprasylvian sulcus (Palmer et al. 1978) - PMLS posteromedial visual area of the lateral suprasylvian sulcus (Palmer et al. 1978) - Pul pulvinar nucleus - SVA splenial visual area - V1 primary visual cortex - V2 secondary visual cortex - V3 third visual area - V5/MT fifth visual area/middle temporal area - WGA-HRP wheat germ agglutinin conjugated to horseradish peroxidase - Wing wing of LGN - 7 area 7 - 17 area 17 - 18 area 18 - 19 area 19     

An autoradiographic study of cortical projections from motor thalamic nuclei in the macaque monkey.

The special areal and laminar distributions of cortical afferent connections from various thalamic nuclei in the monkey (Macaca fuscata) were studied by using the anterograde axonal transport technique of autoradiography. The following findings were obtained. The superficial thalamocortical (T-C) projections, terminating in the (superficial half of) cortical layer I, arise mainly from the nucleus ventralis anterior, pars principalis (VApc) and nucleus ventralis lateralis, pars oralis (VLo), and possibly from the nucleus ventralis lateralis, pars medialis (VLm) and nucleus ventralis anterior, pars magnocellularis (VAmc). The VApc gives rise to the superficial T-C and deep T-C projections onto the postarcuate premotor area around the arcuate genu and spur, and onto the dorsomedial part of the caudal premotor area as well as the supplementary motor area (SMA). The VApc also gives rise to only deep T-C projections onto the remaining premotor area and onto the rostral bank of the arcuate sulcus as well as the ventral bank of the cingulate sulcus at the level of the premotor area. The VLo gives rise to the superficial T-C projections onto the ventrolateral part of the motor area (mainly to the forelimb motor area) and onto the dorsomedial part to the mesial cortex at the rostral level of the motor area. The VAmc gives rise to the superficial T-C projections onto the banks of the arcuate genu and adjacent region of area 8. Area X, the nucleus ventralis posterolateralis, pars oralis (VPLo), nucleus ventralis posterolateralis, pars caudalis (VPLc), nucleus ventralis posteromedialis (VPM) and possibly the nucleus ventralis lateralis, pars caudalis (VLc) send only deep T-C projections. The dorsal and medial parts of the VLc project onto the premotor area, the rostral part of the motor area and the SMA, and also the ventral bank of the cingulate sulcus. Area X projects onto the premotor area, the SMA, and the caudal part of area 8. The thalamic relay nuclei projecting onto the frontal association cortex were found to be the VAmc, medial VLc and area X.     

Connections of the medial posterior parietal cortex (area 7m) in the monkey

The afferent and efferent cortical and subcortical connections of the medial posterior parietal cortex (area 7m) were studied in cebus (Cebus apella) and macaque (Macaca fascicularis) monkeys using the retrograde and anterograde capabilities of the horseradish peroxidase (HRP) technique. The principal intraparietal corticocortical connections of area 7m in both cebus and macaque cases were with the ipsilateral medial bank of the intraparietal sulcus (MIP) and adjacent superior parietal lobule (area 5), inferior parietal lobule (area 7a), lateral bank of the IPS (area 7ip), caudal parietal operculum (PGop), dorsal bank of the caudal superior temporal sulcus (visual area MST), and medial prestriate cortex (including visual area PO and caudal medial lobule). Its principal frontal corticocortical connections were with the prefrontal cortex in the shoulder above the principal sulcus and the cortex in the shoulder above the superior ramus of the arcuate sulcus (SAS), the area purported to contain the smooth eye movement-related frontal eye field (FEFsem) in the cebus monkey by other investigators. There were moderate connections with the cortex in the rostral bank of the arcuate sulcus (purported to contain the saccade-related frontal eye field; FEFsac), supplementary eye field (SEF), and rostral dorsal premotor area (PMDr). Area 7m also had major connections with the cingulate cortex (area 23), particularly the ventral bank of the cingulate sulcus. The principal subcortical connections of area 7m were with the dorsal portion of the ventrolateral thalamic (VLc) nucleus, lateral posterior thalamic nucleus, lateral pulvinar, caudal mediodorsal thalamic nucleus and medial pulvinar, central lateral, central superior lateral, and central inferior intralaminar thalamic nuclei, dorsolateral caudate nucleus and putamen, middle region of the claustrum, nucleus of the diagonal band, zona incerta, pregeniculate nucleus, anterior and posterior pretectal nuclei, intermediate layer of the superior colliculus, nucleus of Darkschewitsch and dorsomedial parvicellular red nucleus (macaque cases only), dorsal, dorsolateral and lateral basilar pontine nuclei, nucleus reticularis tegmenti pontis, locus ceruleus, and superior central nucleus. The findings are discussed in terms of the possibility that area 7m contains a "medial parietal eye field" and belongs to a neural network of oculomotor-related structures that plays a role in the control of eye movement.     

The laminar distribution of cortical connections with the tecto- and cortico-recipient zones in the cat's lateral posterior nucleus

The anterograde and retrograde transport of wheat germ agglutinin congugated to horseradish peroxidase was used to examine the laminar organization of cortical connections with the two visual zones that comprise the cat's lateral posterior nucleus. Microelectrophoretic deposits of the tracer into the principal tecto-recipient zone in the medial division of the lateral posterior nucleus revealed reciprocal connections with the following cortical fields: areas 19 and 21a, the medial and lateral banks of the middle suprasylvian sulcus, and the dorsal and ventral banks of the lateral suprasylvian sulcus, which correspond to the dorsal lateral suprasylvian and ventral lateral suprasylvian visual areas of Palmer et al. [(1978) Brain Res. 177, 237-256] and an area in the fundus of the posterior suprasylvian sulcus. In each of these cortical areas two distinct populations of cells were labeled, small pyramidal neurons in layer VI and large pyramidal cells in layer V. Overlying these backfilled cells were two bands of anterograde label, a narrow strip in layer I and a wide band centered in layer IV. Deposits of wheat germ agglutinin conjugated to horseradish peroxidase confined to the striate-recipient zone in the lateral portion of the lateral posterior nucleus resulted in cortical label in areas 17, 18, 19, 20a and b, 21a, the medial and lateral banks of the middle suprasylvian sulcus, the posterior suprasylvian sulcus and in the fundus of the splenial sulcus. In all cortical areas other than 17 and 18, the laminar distribution of label was the same as that found after deposits of the tracer into the medial division of the lateral posterior nucleus. In contrast, areas 17 and 18 contained backfilled cells that were confined to layer V and anterograde label that was restricted to layer I. These findings indicate that the cortical areas that receive a direct projection from the A laminae of the dorsal lateral geniculate nucleus maintain a distinct laminar organization of reciprocal connections with the extrageniculate visual thalamus. Conversely, all other visual areas of the cortex share a common pattern of reciprocal connections with both the tecto- and striate-recipient zones of the lateral posterior nucleus.     

Topographic organization of the auditory thalamocortical system in the albino rat

Summary The organization of the auditory thalamocortical connections was studied in rats. Retrograde transport of horseradish peroxidase conjugated to wheat germ agglutinin following injections into parietal, occipital and temporal cortex was used. The medial geniculate body, the suprageniculate, the lateral part of the nucleus posterior thalami, the posterior part of the nucleus lateralis thalami, and the nucleus ventroposterior project to the investigated part of the neocortex. Corresponding to different patterns of labeling, five areas of auditory neocortex were distinguished: 1. The rostral area is innervated by neurons of the nucleus ventroposterior, the lateral part of the nucleus posterior thalami, and the medial division of the medial geniculate body. 2. The dorsal area is innervated by neurons of the suprageniculate, the posterior part of the nucleus lateralis thalami and the rostral region of the dorsal division of the medial geniculate body. 3. The caudal area is innervated by neurons of the posterior part of the nucleus lateralis thalami, the suprageniculate, the medial division, the caudal region of the dorsal division and the ventrolateral nucleus of the medial geniculate body. 4. The ventral area is innervated by neurons of the suprageniculate, the medial division, the caudal region of the dorsal division, and the ventrolateral nucleus of the medial geniculate body. 5. The core area of the temporal cortex is exclusively connected to the caudal region of the medial division and the ventral division of the medial geniculate body.The findings of the present study indicate topographic organizations of the ventral division of the medial geniculate body and of the corea area. Four segments (a-d) of the ventral division each show a different set of topographic axes. They correspond to sets of topographic axes in the core area of the auditory cortex. These topographies characterize the segments which are each exclusively connected to one of the four fields of the core area.Abbreviations AC Auditory Cortex - c Caudal - d Dorsal - FR Fissura rhinalis, Rhinal Fissure - l Lateral - LTP Nucleus lateralis thalami, pars posterior - m Medial - MGB Medial geniculate body - MGBd Medial geniculate body, dorsal division - MGBm Medial geniculate body, medial division - MGBmc Medial geniculate body, caudal third of MGBm - MGBv Medial geniculate body, ventral division - MGBvl Medial geniculate body, ventrolateral nucleus - NPT Nucleus posterior thalami, pars lateralis - r Rostral - SG Suprageniculatum - VP Nucleus ventroposterior     

Cortical control of sound localization in the cat: unilateral cooling deactivation of 19 cerebral areas

We examined the ability of mature cats to accurately orient to, and approach, an acoustic stimulus during unilateral reversible cooling deactivation of primary auditory cortex (AI) or 1 of 18 other cerebral loci. After attending to a central visual stimulus, the cats learned to orient to a 100-ms broad-band, white-noise stimulus emitted from a central speaker or 1 of 12 peripheral sites (at 15 degrees intervals) positioned along the horizontal plane. Twenty-eight cats had two to six cryoloops implanted over multiple cerebral loci. Within auditory cortex, unilateral deactivation of AI, the posterior auditory field (PAF) or the anterior ectosylvian sulcus (AES) resulted in orienting deficits throughout the contralateral field. However, unilateral deactivation of the anterior auditory field, the second auditory cortex, or the ventroposterior auditory field resulted in no deficits on the orienting task. In multisensory cortex, unilateral deactivation of neither ventral or dorsal posterior ectosylvian cortices nor anterior or posterior area 7 resulted in any deficits. No deficits were identified during unilateral cooling of the five visual regions flanking auditory or multisensory cortices: posterior or anterior ii suprasylvian sulcus, posterior suprasylvian sulcus or dorsal or ventral posterior suprasylvian gyrus. In motor cortex, we identified contralateral orienting deficits during unilateral cooling of lateral area 5 (5L) or medial area 6 (6m) but not medial area 5 or lateral area 6. In a control visual-orienting task, areas 5L and 6m also yielded deficits to visual stimuli presented in the contralateral field. Thus the sound-localization deficits identified during unilateral deactivation of area 5L or 6m were not unimodal and are most likely the result of motor rather than perceptual impairments. Overall, three regions in auditory cortex (AI, PAF, AES) are critical for accurate sound localization as assessed by orienting.     

Postnatal development of thalamocortical projections upon striate and extrastriate visual cortical areas in the cat

The development of visual thalamocortical projections was analyzed quantitatively by comparing, in cresyl violet-stained brain sections of early postnatal (10-17 days) and adult cats, the cell body dimensions and total cell packing density (CPD) of neuronal populations in different laminae (A, A1 and C) of the dorsal lateral geniculate (dLGN), medial interlaminar nucleus (MIN), and in lateral (LPl), intermediate (LPi) and medial (LPm) subdivisions of the lateral posterior complex. Following injections of different fluorescent tracers (FB, NY, EB, RITC) into cortical visual areas 17/18, posterior medial (PMLS) and posterior lateral (PLLS) lateral suprasylvian and anterior ectosylvian (AEV), the thalamic distribution and densities of retrogradely labeled neurons were analyzed. Projection CPDs and ratios of projection/total CPDs were determined and compared within the different thalamic components in the kitten and adult cat. A significant decrease in total cell packing density was observed in the various thalamic components of the adult cat, varying between 43% and 65%, and a marked increase in mean cell body diameter in the A, A1 and C laminae and MIN from kitten to adult (8.4+/-1.8 and 11.8+/-2.8 microm respectively) compared to the LP subnuclei (9.0+/-1.3 and 9.1+/-1.5 microm). The ratios of projection/total CPDs decreased significantly for projections upon areas 17/18 stemming from layers A and A1 (20 and 25%, respectively) and from LPi upon both PMLS (34%) and AEV (16%). Thalamocortical projections observed in the kitten from LPi upon areas 17/18 and from the A-laminae upon PMLS were absent in the adult cat. The data indicate that, in comparison to the lateral posterior nucleus, the maturation of neurons within the dLGN and MIN is incomplete with respect to cell body size during the early postnatal period. In addition, the developmental changes observed involve both reductions in the total number of thalamic neurons and a differential loss of cortical projections. The selective elimination of early cortical connections stemming from dorsal lateral geniculate laminae A and A1 and from the intermediate division of the lateral posterior nucleus may occur through a process of axon collateral withdrawal from the expanded cortical sites, thereby giving rise to the adult pattern.     

Auditory corticocortical interconnections in the cat: evidence for parallel and hierarchical arrangement of the auditory cortical areas

Summary The origin and laminar arrangement of the homolateral and callosal projections to the anterior (AAF), primary (AI), posterior (PAF) and secondary (AII) auditory cortical areas were studied in the cat by means of electrophysiological recording and WGA-HRP tracing techniques. The transcallosal projections to AAF, AI, PAF and AII were principally homotypic since the major source of input was their corresponding area in the contralateral cortex. Heterotypic transcallosal projections to AAF and AI were seen, originating from the contralateral AI and AAF, respectively. PAF received heterotypic commissural projections from the opposite ventroposterior auditory cortical field (VPAF). Heterotypic callosal inputs to AII were rare, originating from AAF and AI. The neurons of origin of the transcallosal connections were located mainly in layers II and III (70–92%), and less frequently in deep layers (V and VI, 8–30%). Single unit recordings provided evidence that both homotypic and heterotypic transcallosal projections connect corresponding frequency regions of the two hemispheres. The regional distribution of the anterogradely labeled terminals indicated that the homotypic and heterotypic auditory transcallosal projections are reciprocal. The present data suggest that the transcallosal auditory interconnections are segregated in 3 major parallel components (AAF-AI, PAF-VPAF and AII), maintaining a segregation between parallel functional channels already established for the thalamocortical auditory interconnections. For the intrahemispheric connections, the analysis of the retrograde tracing data revealed that AAF and AI receive projections from the homolateral cortical areas PAF, VPAF and AII, whose neurons of origin were located mainly in their deep (V and VI) cortical layers. The reciprocal interconnections between the homolateral AAF and AI did not show a preferential laminar arrangement since the neurons of origin were distributed almost evenly in both superficial (II and III) and deep (V and VI) cortical layers. On the contrary, PAF received inputs from the homolateral cortical fields AAF, AI, AII and VPAF, originating predominantly from their superficial (II and III) layers. The homolateral projections reaching AII originated mainly from the superficial layers of AAF and AI, but from the deep layers of VPAF and PAF. The laminar distribution of anterogradely labeled terminal fields, when they were dense enough for a confident identification, was systematically related to the laminar arrangement of neurons of origin of the reciprocal projection: a projection originating from deep layers was associated with a reciprocal projection terminating mainly in layer IV, whereas a projection originating from superficial layers was associated with a reciprocal projection terminating predominantly outside layer IV. This laminar distribution indicates that the homolateral auditory cortical interconnections have a feed-forward/feed-back organization, corresponding to a hierarchical arrangement of the auditory cortical areas, according to criteria previously established in the visual system of primates. The principal auditory cortical areas could be ranked into 4 distinct hierarchical levels. The tonotopically organized areas AAF and AI represent the lowest level. The second level corresponds to the non-tonotopically organized area AII. Higher, the tonotopically organized areas VPAF and PAF occupy the third and fourth hierarchical levels, respectively.Abbreviations AAF anterior auditory cortical area - AI primary auditory cortical area - AII secondary auditory cortical area - BF best frequency - C cerebral cortex - CA caudate nucleus - CL claustrum - D dorsal nucleus of the dorsal division of the MGB - ea anterior ectosylvian sulcus - ep posterior ectosylviansulcus - IC internal capsule - LGN lateral geniculate nucleus - LV pars lateralis of the ventral division of the MGB - LVe lateral ventricule - M pars magnocellularis of the medial division of the MGB - MGB medial geniculate body - MGBv ventral division of the MGB - OT optic tract - OV pars ovoidea of the ventral division of the MGB - PAF posterior auditory cortical area - PH parahippocampal cortex - PO lateral part of the posterior group of thalamic nuclei - PU putamen - RE reticular complex of thalamus - rs rhinal sulcus - SG suprageniculate nucleus of the dorsal division of the MGB - ss suprasylvian sulcus - TMB tetrametylbenzidine - VBX ventrobasal complex - VLa ventrolateral complex - VL ventro-lateral nucleus of the ventral division of the MGB - WGA-HRP wheat germ agglutinin conjugated to horse-radish peroxidase - WM white matter - VPAF ventro-posterior auditory cortical area     

Postnatal development of thalamocortical projections upon striate and extrastriate visual cortical areas in the cat

The development of visual thalamocortical projections was analyzed quantitatively by comparing, in cresyl violet-stained brain sections of early postnatal (10–17 days) and adult cats, the cell body dimensions and total cell packing density (CPD) of neuronal populations in different laminae (A, A1 and C) of the dorsal lateral geniculate (dLGN), medial interlaminar nucleus (MIN), and in lateral (LPl), intermediate (LPi) and medial (LPm) subdivisions of the lateral posterior complex. Following injections of different fluorescent tracers (FB, NY, EB, RITC) into cortical visual areas 17/18, posterior medial (PMLS) and posterior lateral (PLLS) lateral suprasylvian and anterior ectosylvian (AEV), the thalamic distribution and densities of retrogradely labeled neurons were analyzed. Projection CPDs and ratios of projection/total CPDs were determined and compared within the different thalamic components in the kitten and adult cat. A significant decrease in total cell packing density was observed in the various thalamic components of the adult cat, varying between 43% and 65%, and a marked increase in mean cell body diameter in the A, A1 and C laminae and MIN from kitten to adult (8.4±1.8 and 11.8±2.8 μm respectively) compared to the LP subnuclei (9.0±1.3 and 9.1±1.5 μm). The ratios of projection/total CPDs decreased significantly for projections upon areas 17/18 stemming from layers A and A1 (20 and 25%, respectively) and from LPi upon both PMLS (34%) and AEV (16%). Thalamocortical projections observed in the kitten from LPi upon areas 17/18 and from the A-laminae upon PMLS were absent in the adult cat. The data indicate that, in comparison to the lateral posterior nucleus, the maturation of neurons within the dLGN and MIN is incomplete with respect to cell body size during the early postnatal period. In addition, the developmental changes observed involve both reductions in the total number of thalamic neurons and a differential loss of cortical projections. The selective elimination of early cortical connections stemming from dorsal lateral geniculate laminae A and A1 and from the intermediate division of the lateral posterior nucleus may occur through a process of axon collateral withdrawal from the expanded cortical sites, thereby giving rise to the adult pattern. Accepted: 15 June 2000     

Pupillary constriction evoked from the posterior medial lateral suprasylvian (PMLS) area in cats

Pupillary constriction was evoked by systematic stimulation using a microelectrode in the upper medial bank of the middle suprasylvian sulcus in the parieto-occipital cortex of the cat. The pupillo-constrictor area corresponded to the rostral and middle parts of the posterior medial lateral suprasylvian (PMLS) area. This pupillo-constrictor area extended by 2-3 mm along the middle suprasylvian sulcus. It is suggested that this pupillo-constrictor area overlaps or lies in close proximity of a part of the region in PMLS area related to lens accommodation, in which unit activity temporally related to lens accommodation was recorded and from which lens accommodation was evoked by electric stimulation.     

Projections of the bed nucleus of the stria terminalis to the mesencephalon,pons, and medulla oblongata in the cat

Summary Injections of HRP in the nucleus raphe magnus and adjoining medial reticular formation in the cat resulted in many labeled neurons in the lateral part of the bed nucleus of the stria terminalis (BNST) but not in the medial part of this nucleus. HRP injections in the nucleus raphe pallidus and in the C2 segment of the spinal cord did not result in labeled neurons in the BNST. Injections of ³H-leucine in the BNST resulted in many labeled fibers in the brain stem. Labeled fiber bundles descended by way of the medial forebrain bundle and the central tegmental field to the lateral tegmental field of pons and medulla. Dense BNST projections could be observed to the substantia nigra pars compacta, the ventral tegmental area, the nucleus of the posterior commissure, the PAG (except its dorsolateral part), the cuneiform nucleus, the nucleus raphe dorsalis, the locus coeruleus, the nucleus subcoeruleus, the medial and lateral parabrachial nuclei, the lateral tegmental field of caudal pons and medulla and the nucleus raphe magnus and adjoining medial reticular formation. Furthermore many labeled fibers were present in the solitary nucleus, and in especially the peripheral parts of the dorsal vagal nucleus. Finally some fibers could be traced in the marginal layer of the rostral part of the caudal spinal trigeminal nucleus. These projections appear to be virtually identical to the ones derived from the medial part of the central nucleus of the amygdala (Hopkins and Holstege 1978). The possibility that the BNST and the medial and central amygdaloid nuclei must be considered as one anatomical entity is discussed.Abbreviations AA anterior amygdaloid nucleus - AC anterior commissure - ACN nucleus of the anterior commissure - ACO cortical amygdaloid nucleus - AL lateral amygdaloid nucleus - AM medial amygdaloid nucleus - APN anterior paraventricular thalamic nucleus - AQ cerebral aqueduct - BC brachium conjunctivum - BIC brachium of the inferior colliculus - BL basolateral amygdaloid nucleus - BNSTL lateral part of the bed nucleus of the stria terminalis - BNSTM medial part of the bed nucleus of the stria terminalis - BP brachium pontis - CA central nucleus of the amygdala - Cd caudate nucleus - CI inferior colliculus - CL claustrum - CN cochlear nucleus - CP posterior commissure - CR corpus restiforme - CSN superior central nucleus - CTF central tegmental field - CU cuneate nucleus - D nucleus of Darkschewitsch - EC external cuneate nucleus - F fornix - G gracile nucleus - GP globus pallidus - HL lateral habenular nucleus - IC interstitial nucleus of Cajal - ICA internal capsule - IO inferior olive - IP interpeduncular nucleus - LC locus coeruleus - LGN lateral geniculate nucleus - LP lateral posterior complex - LRN lateral reticular nucleus - MGN medial geniculate nucleus - MLF medial longitudinal fascicle - NAdg dorsal group of nucleus ambiguus - NPC nucleus of the posterior commissure - nV trigeminal nerve - nVII facial nerve - OC optic chiasm - OR optic radiation - OT optic tract - P pyramidal tract - PAG periaqueductal grey - PC cerebral peduncle - PO posterior complex of the thalamus - POA preoptic area - prV principal trigeminal nucleus - PTA pretectal area - Pu putamen - PUL pulvinar nucleus - R red nucleus - RF reticular formation - RM nucleus raphe magnus - RP nucleus raphe pallidus - RST rubrospinal tract - S solitary nucleus - SC suprachiasmatic nucleus - SCN nucleus subcoeruleus - SI substantia innominata - SM stria medullaris - SN substantia nigra - SO superior olive - SOL solitary nucleus - SON supraoptic nucleus - spV spinal trigeminal nucleus - spVcd spinal trigeminal nucleus pars caudalis - ST stria terminalis - TRF retroflex tract - VC vestibular complex - VTA ventral tegmental area of Tsai - III oculomotor nucleus - Vm motor trigeminal nucleus - VI abducens nucleus - VII facial nucleus - Xd dorsal vagal nucleus - XII hypoglossal nucleus     

Projections from the medial agranular cortex to brain stem visuomotor centers in rats

Summary Projections from medial agranular cortex to brain stem in rat were determined by use of the anterograde tracers Phaseolus vulgaris leucoagglutinin, or wheat germ agglutinin conjugated horseradish peroxidase. Axonal trajectories were also followed by means of the Wiitanen modification of the Fink-Heimer degeneration technique. AGm was identified on the basis of its cytoarchitectonics. AGm projected to the anterior pretectal nucleus, the rostral interstitial nucleus of the medial longitudinal fasciculus, the medial accessory oculomotor nucleus of Bechterew, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, the nucleus cuneiformis and subcuneiformis, intermediate and deep superior collicular layers, the paramedian pontine reticular formation (reticularis pontis oralis and caudalis, and reticularis gigantocellularis), and raphe centralis superior. Differences in connections between rostral and caudal injections were observed: pontine and medullary projections were lighter from the rostral portion of AGm than from the more caudal portions of AGm. The heaviest projections to the anterior pretectal nucleus were from the caudal portion of AGm. The subcortical projections were very similar to those described for the frontal eye field in monkeys, and the majority of them targeted areas thought to be involved in coordination of gaze with head and neck movements. Thus AGm in rats may contain the homologue of the primate frontal eye fields.Abbreviations 3 main oculomotor nucleus - 7 facial motor nucleus; - I, II–IV, V, and VI cortical layers - III third ventricle - 7n facial nerve - AC Anterior commissure - AGm medial agranular cortex - Bec Nucleus of Bechterew - cc corpus callosum - Dark Nucleus of Darkschewitsch - Dc dorsal cochlear nucleus - DLG dorsal lateral geniculate nucleus - F fornix - fr fasciculus retroflexus - ic inferior colliculus - Me5 mesencephalic trigeminal nucleus - ml medial lemniscus - mlf medial longitudinal fasciculus - Mo5 trigeminal motor nucleus - nV trigeminal nerve - pc posterior commissure - pn pons - Po posterior thalamic nucleus - PPo pedunculo-pontine nucleus - PPRF paramedian pontine reticular formation - py pyramidal tract - R red nucleus - RaCs raphe centralis superior - RaD dorsal raphe nucleus - RCf reticularis cuneiformis - RiMLF rostral interstitial nucleus of the medial longitudinal fasciculus - RMc reticularis magnocellularis - RPc reticularis parvocellularis - RPoCa reticularis pontis caudalis pars alpha - RPoCb reticularis pontis caudalis pars beta - RPoO reticularis pontis oralis - RPoOm reticularis pontis oralis pars medialis - RScf reticularis subcuneiformis - sc superior colliculus - SCP superior cerebellar peduncle - so superior olive - Sp5 spinal trigeminal nucleus - Tz trapezoid nucleus - WGA-HRP wheat germ agglutinin- horseradish peroxidase     

Projections from eye movement-evoking cerebral cortices to the striatum and claustrum in the cat

Projection fields in the striatum and claustrum from eye movement-evoking cerebral cortices (EMECs) in the cat were investigated using the WGA-HRP tracing method under electrophysiological guidance to place WGA-HRP in the appropriate sites. The EMECs in the frontal cortex, which are located in the medial wall under the cruciate sulcus (CRUo), the medial and lateral banks of the presylvian sulcus the the knee portion of the coronal sulcus (CORo), projected to the rostral part of the striatum. The EMEC in the temporal cortex, which is located in the ventral bank of the anterior ectosylvian sulcus, projected to the middle part of the striatum. Concerning the EMECs in the frontal cortex, the medially situated CRUo projected to the dorsomedial portion of the striatum, and the laterally situated CORo projected to the ventrolateral portion of the striatum. The dorsal half of the claustrum had reciprocal connections with all of the EMECs.