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PubMed1993

Effects on visual recognition of combined and separate ablations of the entorhinal and perirhinal cortex in rhesus monkeys.

Performance on visual delayed nonmatching-to-sample was assessed in rhesus monkeys with combined and separate ablations of the perirhinal and entorhinal cortex, as well as in unoperated controls. Combined (i.e., rhinal cortex) lesions yielded a striking impairment on this task, one almost as severe as that seen after combined amygdalohippocampal removals that included some of this subjacent cortex (Mishkin, 1978; Murray and Mishkin, 1984). Ablations of the perirhinal cortex alone produced a deficit nearly as severe as that found after rhinal cortex lesions, whereas ablations of the entorhinal cortex alone produced only a mild deficit. Contrary to the conclusion from an earlier study (Murray and Mishkin, 1986), the present results demonstrate not only that damage limited to the rhinal cortex is sufficient to produce a severe loss in visual recognition, but also that such damage leads to a far greater loss than damage to any other single structure in the medial part of the temporal lobe.

Animals↗

PubMedDate not supplied

Putrescine, polyamines, and N1-acetylpolyamine levels in retina, visual cortex and cerebellum of free-running mice kept under continuous light or darkness.

Putrescine, spermidine and spermine levels were detected in the retina, visual cortex, cerebellum and parietal cortex of CD1 mice exposed to 36h continuous light or darkness. Retinal putrescine and polyamine concentrations were found to be highest in dark-adapted mice, and the stimulation of dark-adapted retina with flicker illumination was also accompanied by a significant decrease in putrescine, spermidine and spermine levels. In visual cortex as well as in cerebellum spermidine and spermine contents were higher in dark-adapted mice in comparison to light-exposed animals, while in parietal cortex no significant change was found neither in spermidine nor spermine levels. In the brain areas studied flicker illumination produced no significant decreases in putrescine and polyamine contents. The total polyamines expressed as putrescine equivalents were noticeably decreased in retina, visual cortex and cerebellum of light-adapted mice. In the retina spermine/spermidine molar ratio was significantly higher than in dark-adapted mice. The administration of N1, N2-bis-(2,3-butadienyl)-1,4-butanediamine (MDL 72527) produced a strong decrease of retinal putrescine and spermidine concentrations in both dark-adapted and light-exposed mice, and in the retina of mice exposed to continuous light a significant decrease in the spermine level was also observed. According to the influence on polyamine reutilization, after the irreversible inhibition of polyamine oxidase by MDL 72527, in the retina N1-acetylspermidine and N1-acetylspermine accumulation was highest in light-adapted mice. On the contrary in visual cortex, cerebellum and parietal cortex the MDL 72527 administration produced a more marked decrease of putrescine and spermidine contents in mice kept in continuous darkness.

Animals↗

PubMed1996

Selective alterations in gene expression for NMDA receptor subunits in prefrontal cortex of schizophrenics.

NMDA receptor antagonists can induce a schizophrenia-like psychosis, but the role of NMDA receptors in the pathophysiology of schizophrenia remains unclear. Expression patterns of mRNAs for five NMDA receptor subunits (NR1/NR2A-D) were determined by in situ hybridization in prefrontal, parieto-temporal, and cerebellar cortex of brains from schizophrenics and from neuroleptic-treated and nonmedicated controls. In the cerebral cortex of both schizophrenics and controls, mRNAs for NR1, NR2A, NR2B, and NR2D subunits were preferentially expressed in layers II/III, Va, and VIa, with much higher levels in the prefrontal than in the parieto-temporal cortex. Levels of mRNA for the NR2C subunit were very low overall. By contrast, the cerebellar cortex of both schizophrenics and controls contained very high levels of NR2C subunit mRNA, whereas levels for the other subunit mRNAs were very low, except NR1, for which levels were moderate. Significant alterations in the schizophrenic cohort were confined to the prefrontal cortex. Here there was a shift in the relative proportions of mRNAs for the NR2 subunit family, with a 53% relative increase in expression of the NR2D subunit mRNA. No comparable changes were found in neuroleptic-treated or untreated controls. These findings indicate regional heterogeneity of NMDA receptor subunit expression in human cerebral and cerebellar cortex. In schizophrenics, the alterations in expression of NR2 subunit mRNA in prefrontal cortex are potential indicators of deficits in NMDA receptor-mediated neurotransmission accompanying functional hypoactivity of the frontal lobes.

Autoradiography↗

PubMed1996

Upregulation of BDNF mRNA expression in the barrel cortex of adult mice after sensory stimulation.

Upregulation of brain-derived neurotrophic factor (BDNF) mRNA expression by neuronal activity has been reported in cultured hippocampal cells and in different in vivo excitotoxic paradigms. The aim of the present study was to determine whether sensory stimulation of the whisker-to-barrel pathway alters BDNF mRNA expression in the cortex and, if so, to evaluate the specificity of this effect. To this end, a set of mystacial whiskers was unilaterally stimulated by mechanical deflection, and the expression of BDNF mRNA was analyzed in the barrel cortex by in situ hybridization (ISH) using a 35S-labeled antisense BDNF riboprobe and emulsion autoradiography. A clear-cut and specific upregulation of the BDNF mRNA expression was found at the level of the somatosensory cortex after the increased peripheral stimulation. In the barrel cortex of control mice, BDNF mRNA was present in a few cells in layers II/III and VI, whereas it was almost undetectable in layer IV. After 6 hr of whisker stimulation, increased levels of BDNF mRNA were found in layers II to VI of the contralateral barrel cortex. In layer IV, BDNF upregulation was confined to the barrels corresponding to the stimulated follicles. ISH combined with immunocytochemistry against the three calcium-binding proteins parvalbumin, calretinin, and calbindin-D28K revealed that BDNF mRNA-expressing cells do not belong to the GABAergic cell population of the barrel cortex. The present results support a role for BDNF in activity-dependent modifications of the adult cerebral cortex.

Animals↗

PubMed1996

The effects of superior temporal cortex lesions on the processing and retention of auditory information in monkeys (Cebus apella).

Three monkeys with extensive preoperative training on visual and auditory memory tasks (delayed matching-to-sample), an auditory pattern-discrimination task, and a visual serial-order task, received bilateral lesions of the superior temporal (ST) cortex in two stages, with testing after each lesion. Unilateral ST cortex lesions resulted in only moderate auditory memory impairments, whereas bilateral ST cortex lesions resulted in severe auditory memory impairments. The bilateral ST cortex lesions also resulted in severe impairments in the ability to relearn the auditory pattern-discrimination task. In contrast to the auditory impairments, neither unilateral nor bilateral ST cortex lesions had any effect whatsoever on either visual memory or visual serial-order behavior. These findings indicate that the ST cortex plays a role in auditory processing and retention similar to that played by the inferior temporal cortex for visual processing and retention.

Acoustic Stimulation↗

PubMed1996

The calcarine sulcus as an estimate of the total volume of human striate cortex: a morphometric study of reliability and intersubject variability.

The human primary visual cortex consists of a region buried in the calcarine sulcus and a region outside this sulcus on the free surface of the occipital lobe. Since the depth of the calcarine sulcus can be easily estimated in magnetic resonance images of the living human brain, in vivo morphometry of the human primary visual cortex would be feasible for studying development, intersubject variability and interhemispheric asymmetry if the sulcal depth or a correlated measure such as the intracalcarine surface area would be a precise and reliable estimate of the total volume of the human primary visual cortex. The correlations between total volume of the striate cortex and its intra- and extra-calcarine surface areas were therefore tested in the present observations. The total volume of the striate cortex and the surface areas of its intra-and extracalcarine portions were measured in Nissl-stained serial sections through 20 adult human hemispheres. The intra- and extracalcarine portions of the striate area are not significantly correlated with each other, but correlated with the total volume of the striate cortex. The intracalcarine surface area or the depth of the calcarine sulcus are thus useful parameters for in vivo estimates of the total size of the striate cortex.

Adolescent↗

PubMed1997

Distribution of calretinin-immunoreactivity in the rat entorhinal cortex: coexistence with GABA.

Inhibitory neurons in the entorhinal cortex control information flow between the cortical areas and the hippocampus. We characterized the inhibitory circuits in the rat entorhinal cortex by analyzing the distribution of calretinin-immunoreactivity and its colocalization with glutamate decarboxylase (GAD) and gamma-aminobutyric acid (GABA). The location of calretinin-immunoreactive (IR) neurons and terminals varies between the different layers and subfields of the entorhinal cortex. The immunopositive neurons can be divided into two major morphological classes: bipolar and multipolar, which have two or more long, aspiny or sparsely spiny dendrites that extend through several layers. In addition, there are unclassified immunopositive neurons that have large lightly stained somata. They are located primarily in layer V. Colocalization analyses with GAD and GABA revealed that approximately 40% (657 out of 1,777) of all calretinin-IR cells within the entorhinal cortex contain GAD or GABA. In layers I-III, over 90% of the calretinin-IR neurons contain GAD or GABA. In layers V-VI, however, most of the calretinin-IR neurons do not colocalize with either GAD or GABA. The distribution patterns of calretinin-immunoreactivity in the entorhinal cortex is consistent with the partitioning of the rat entorhinal cortex into six subfields. Furthermore, calretinin is expressed in a morphologically heterogeneous population of cells in the rat entorhinal cortex which includes both GABAergic and non-GABAergic neurons.

Animals↗

PubMed1997

Differential regulation of D2 and D4 dopamine receptor mRNAs in the primate cerebral cortex vs. neostriatum: effects of chronic treatment with typical and atypical antipsychotic drugs.

The RNase Protection Assay was used to examine the regulation of D2 and D4 dopamine receptor mRNAs in the cerebral cortex and neostriatum of nonhuman primates after chronic treatment with a wide spectrum of antipsychotic medications (chlorpromazine, clozapine, haloperidol, molindone, olanzapine, pimozide, remoxipride and risperidone). Tiapride, a D2 antagonist that lacks antipsychotic activity, was also included. All drugs were administered orally for 6 months at doses recommended for humans. All antipsychotic drug treatments examined in this study caused a statistically significant up-regulation of both the long and short isoforms of the D2 receptor mRNAs in the prefrontal and temporal cortex. Tiapride, in contrast, significantly up-regulated only the level of D2-long mRNA in these areas. The same drug treatments produced less uniform effects in the neostriatum than in the cortex: clozapine and olanzapine failed to significantly elevate either D2-long or D2-short receptor messages in this structure unlike all other drugs, including tiapride. In both the cerebral cortex and striatum, D4 receptor mRNA was upregulated by certain typical (chlorpromazine and haloperidol) and certain atypical (clozapine, olanzapine and risperidone) antipsychotic agents as well as by tiapride. Other drugs of the typical (molindone and pimozide) and atypical (remoxipride) classes had no effect on D4 mRNA levels in either cortical or striatal tissue. The finding that up-regulation of D2 dopamine receptor mRNAs was a consistently observed effect of a wide range of antipsychotic agents in the cerebral cortex but not in the neostriatum, coupled with the fact that the D2-short isoforms in the cortex were not regulated by a nonantipsychotic D2 antagonist, tiapride, draws attention to the importance of the D2 dopamine receptor in the cerebral cortex as a potentially critical, common site of action of antipsychotic medications.

Animals↗

PubMedDate not supplied

[The mechanism of movement instrumental learning in a Hopfield environment in the feline motor cortex].

A model of the neuronal processes in the motor cortex is proposed, which provides the mechanism for instrumentalization (voluntary reproduction) of movements primarily evoked by stimulation of the parietal cortex. The main propositions of the model are as follows: the late NMDA-dependent response of the motor cortex neurons to stimulation of the parietal cortex reflects the discharges in the recurrent collaterals of the pyramidal cell axons; learning processes in the motor cortex are based on the long-term potentiation of the efficiency of the recurrent collaterals; the Hopfield's theory of neuronal nets is applied to the processes of motor learning in the cortex. The movement instrumentalization is viewed as the stable state formation in the collaterally linked neuronal structure; the voluntary reproduction of the previously learned movement in considered as the process of transition of the neuronal structure into the stable state. The data on acetylcholine and dopamine modulatory influences on the reactions of motor cortex neurons are discussed.

Animals↗

PubMed2006

Organization of the somatosensory cortex in elephant shrews (E. edwardii).

The superorder Afrotheria consists of a diverse group of mammals, including elephants, hyraxes, dugongs, sea cows, aardvarks, tenrecs, golden moles, and elephant shrews. Recent studies suggest this clade diverged from other placental mammals 100 million years ago and thus may represent the sister group to the remaining placental mammals. Despite this important taxonomic position, relatively few studies have investigated cortical organization in these species. Here we present results of an investigation of the somatosensory cortex in the Cape elephant shrew (Elephantulus edwardii). Using multiunit electrophysiological recording techniques, we identified a topographic map of the elephant shrew's body in a location and orientation consistent with the primary somatosensory cortex (S1). The elephant shrew's elongated snout, extensive facial vibrissae, and long tongue accounted for a large portion of the somatosensory representation, located in a relatively rostral area of cortex. Evidence for an additional somatosensory area, presumed to be secondary somatosensory cortex (S2), was found just lateral to S1. Visual and auditory responsive areas were also identified and the extent of visual cortex appeared to be quite large in these highly visual mammals. Despite the elephant shrew's exceptionally well-developed eyes, ears, and vibrissae, there were no anatomical correlates to sensory areas, or body part representations (e.g., barrels), that could be identified in the flatted cortex.

Animals↗

PubMed2006

Cortical connections of the auditory cortex in marmoset monkeys: core and medial belt regions.

The auditory cortex of primates contains a core region of three primary areas surrounded by a belt region of secondary areas. Recent neurophysiological studies suggest that the belt areas medial to the core have unique functional roles, including multisensory properties, but little is known about their connections. In this study and its companion, the cortical and subcortical connections of the core and medial belt regions of marmoset monkeys were compared to account for functional differences between areas and refine our working model of the primate auditory cortex. Anatomical tracer injections targeted two core areas (A1 and R) and two medial belt areas (rostromedial [RM] and caudomedial [CM]). RM and CM had topographically weighted connections with all other areas of the auditory cortex ipsilaterally, but these were less widespread contralaterally. CM was densely connected with caudal auditory fields, the retroinsular (Ri) area of the somatosensory cortex, the superior temporal sulcus (STS), and the posterior parietal and entorhinal cortex. The connections of RM favored rostral auditory areas, with no clear somatosensory inputs. RM also projected to the lateral nucleus of the amygdala and tail of the caudate nucleus. A1 and R had topographically weighted connections with medial and lateral belt regions, infragranular inputs from the parabelt, and weak connections with fields outside the auditory cortex. The results indicated that RM and CM are distinct areas of the medial belt region with direct inputs from the core. CM also has somatosensory input and may correspond to an area on the posteromedial transverse gyrus of humans and the anterior auditory field of other mammals.

Acoustic Stimulation↗

PubMed1992

Differential development of the dual serotoninergic fiber system in the cerebral cortex of the cat.

The changes in distribution and density of the serotoninergic innervation of the cerebral cortex were studied in kittens from birth (PO) to 60 days of age (P59). Three cortical areas were sampled: prefrontal, primary auditory, and primary visual areas. Two systems of serotoninergic axons were demonstrated by immunocytochemical techniques: the fine axon system characterized by small fusiform varicosities up to 1 micron in diameter, and the beaded axon system, the fibers of which have round varicosities up to 5 microns in diameter. The density of the two types of fibers across the cortical layers at different ages was measured with a semiautomatic computerized system. In all three areas, the density of fine axons increased steadily from birth, although the pattern of innervation changed from an even distribution at PO to a distinct concentration of the fibers in layers I-III by week 2 in the prefrontal cortex and by week 3 in auditory and visual cortices. By contrast, the beaded axons first appeared in the cortex at week 2 for the prefrontal cortex, at week 3 in auditory and visual areas. Initially, these fibers were distributed throughout all cortical layers and were of much lower density than the fine axons. At later ages the beaded axons became confined to layers I-III where they gradually increased in number, and from week 4, they formed pericellular arrays which were only observed in the prefrontal and auditory cortices, not in visual cortex. These findings provide further evidence for the existence of two parallel subsystems of serotoninergic axons which are different not only in their morphology and nuclear origin, but also in their development. Our finding that the two serotoninergic fiber systems arrive in the cortex in two different stages suggests that they have differential roles in development. The late formation of the pericellular arrays indicates that the formation of the specific connections made by the beaded fibers could be dependent on a certain degree of maturity of the target neurons.

Afferent Pathways↗

PubMed1995

Organization of somatosensory cortex in monotremes: in search of the prototypical plan.

The present investigation was designed to determine the number and internal organization of somatosensory fields in monotremes. Microelectrode mapping methods were used in conjunction with cytochrome oxidase and myelin staining to reveal subdivisions and topography of somatosensory cortex in the platypus and the short-billed echidna. The neocortices of both monotremes were found to contain four representations of the body surface. A large area that contained neurons predominantly responsive to cutaneous stimulation of the contralateral body surface was identified as the primary somatosensory area (SI). Although the overall organization of SI was similar in both mammals, the platypus had a relatively larger representation of the bill. Furthermore, some of the neurons in the bill representation of SI were also responsive to low amplitude electrical stimulation. These neurons were spatially segregated from neurons responsive to pure mechanosensory stimulation. Another somatosensory field (R) was identified immediately rostral to SI. The topographic organization of R was similar to that found in SI; however, neurons in R responded most often to light pressure and taps to peripheral body parts. Neurons in cortex rostral to R were responsive to manipulation of joints and hard taps to the body. We termed this field the manipulation field (M). The mediolateral sequence of representation in M was similar to that of both SI and R, but was topographically less precise. Another somatosensory field, caudal to SI, was adjacent to SI laterally at the representation of the face, but medially was separated from SI by auditory cortex. Its position relative to SI and auditory cortex, and its topographic organization led us to hypothesize that this caudal field may be homologous to the parietal ventral area (PV) as described in other mammals. The evidence for the existence of four separate representations in somatosensory cortex in the two species of monotremes indicates that cortical organization is more complex in these mammals than was previously thought. Because the two monotreme families have been separate for at least 55 million years (Richardson, B.J. [1987] Aust. Mammal. 11:71-73), the present results suggest either that the original differentiation of fields occurred very early in mammalian evolution or that the potential for differentiation of somatosensory cortex into multiple fields is highly constrained in evolution, so that both species arrived at the same solution independently.

Animals↗

PubMed1993

Retinotopy of cortical connections between the striate cortex and extrastriate visual areas in the rat.

Previous studies have determined that the striate cortex of the rat is reciprocally connected with multiple extrastriate cortical areas that are retinotopically organized. The objective of this study was to investigate the retinotopy of the striate-extrastriate connections in the rat, by placing triple or double injections of fluorescent tracers (fluorogold, fast blue, rhodamine dextran, or rhodamine-labeled microspheres) in different regions of the striate cortex (Oc1) and mapping the distribution of cells and fibers labeled with the different tracers in the lateral (Oc2L) and medial (Oc2M) extrastriate cortex. The tracer injection sites were visualized in tangential sections of the flattened cortex and correlated with the myelin layout of the striate cortex and with an electrophysiological map from previous studies. The results showed retinotopically organized Oc1 connections with ten different extrastriate cortical areas. The location of these extrastriate areas and the retinotopy of their striate connections remained mostly invariant despite changes of the injection sites in Oc1. Thus, the quadrantic retinotopy was obtained for striate connections to areas posterior, posterolateral, lateromedial, laterointermediate, laterolateral, anterolateral and rostrolateral in Oc2L; and to areas posteromedial, anteromedial, and anterior in Oc2M. The present anatomical map correlates well with electrophysiological maps of the rat extrastriate cortex from previous studies. Furthermore, they provide a definition of the retinotopy of some areas that have not been completely mapped before. These results reaffirm the existence of multiple extrastriate visual areas in the rat.

Animals↗

PubMed1999

Gaze effects in the cerebral cortex: reference frames for space coding and action.

Visual information is mapped with respect to the retina within the early stages of the visual cortex. On the other hand, the brain has to achieve a representation of object location in a coordinate system that matches the reference frame used by the motor cortex to code reaching movement in space. The mechanism of the necessary coordinate transformation between the different frames of reference from the visual to the motor system as well as its localization within the cerebral cortex is still unclear. Coordinate transformation is traditionally described as a series of elementary computations along the visuomotor cortical pathways, and the motor system is thought to receive target information in a body-centered reference frame. However, neurons along these pathways have a number of similar properties and receive common input signals, suggesting that a non-retinocentric representation of object location in space might be available for sensory and motor purposes throughout the visuomotor pathway. This paper reviews recent findings showing that elementary input signals, such as retinal and eye position signals, reach the dorsal premotor cortex. We will also compare eye position effects in the premotor cortex with those described in the posterior parietal cortex. Our main thesis is that appropriate sensory input signals are distributed across the visuomotor continuum, and could potentially allow, in parallel, the emergence of multiple and task-dependent reference frames.

Animals↗

PubMed1991

Further indication that distinct dopaminergic subsets project to the rat cerebral cortex: lack of colocalization with neurotensin in the superficial dopaminergic fields of the anterior cingulate, motor, retrosplenial and visual cortices.

The extent of neurotensin (NT) colocalization in the different dopamine (DA) terminal fields of the rat cerebral cortex has been investigated and compared to previous data obtained in man (Gaspar et al., J. Comp. Neurol., 279 (1989) 249-271). Both innervations were revealed with single- or double-labeling immunocytochemical methods. Tyrosine hydroxylase (TH) was used as a specific marker of DA fibers after lesioning the noradrenergic system either with 6-hydroxydopamine (6-OHDA) at birth or DSP4 in adulthood. Three classes of afferents were observed which had a different regional and laminar distribution. First, a dense meshwork of finely dotted NT-positive varicosities occupied restricted areas of the limbic system: the granular retrosplenial and the deep entorhinal cortices and the subicular complex. These NT projections contained no double-labeled fibers and did not correspond to a mixed NT/TH pathway. Secondly, the mixed NT/DA projections identified previously in the prefrontal cortex (Studler et al., Neuropeptides, 11 (1988) 95-100), extended in fact rostrocaudally in layer VI of the whole cerebral cortex and formed small cluster-like groupings in layers II-III of the medial and lateral entorhinal cortex. In all these areas, the mixed NT/TH projections constituted approximately half of the DA terminals. Finally, the DA projections to the superficial layers of the anterior cingulate, motor, retrosplenial and visual cortices, were not colocalized with NT. The DA innervation of layers I-III of the rat anterior cingulate cortex displays striking similarities with that observed in the cingulate, primary motor, premotor and supplementary motor cortices in man: highest regional and laminar density of DA afferents and lack of colocalization with NT. It might thus represent a valuable model for understanding the pharmacology of the DA system besides the mixed DA/NT pathway which does not seem to have a counterpart in the human cerebral cortex. By contrast, that part of the NT innervation of the limbic system which is not colocalized with DA in rat, appears to represent the major fraction of the cortical NT innervation in man.

Animals↗

PubMed1985

Involvement of the sensory cortex in adrenocortical responses following photic and acoustic stimulation in the rat.

In order to examine the possibility that the sensory cortex participates in the mediation of adrenocortical responses following sensory stimuli, the effects of photic and acoustic stimuli on plasma corticosterone were studied in rats with either visual or auditory cortex ablation. In animals with visual cortex ablation, the adrenocortical response to acoustic stimuli was intact; however, it was significantly reduced following photic stimulation. On the other hand, in animals with auditory cortex ablation, the response to acoustic stimulation was significantly reduced, but the response to photic stimulation remained intact. These data demonstrate the participation of the specific sensory cortex in adrenocortical responses following the stimulation of the corresponding sensory modality. The possible mechanisms involved may be either a tonic facilitatory effect of the specific cortex on subcortical mechanisms or the transmission of the specific stimuli in the primary sensory pathways, to achieve a full adrenocortical discharge.

Adrenal Cortex↗

PubMed1997

Transient developmental expression of CD15 in the motor and auditory cortex of the mouse.

The distribution of the glycoprotein CD15 (FAL, SSEA-1, Le(x)) in the developing cortex of the mouse has been examined by immunohistochemistry of paraffin sections. The pattern of CD15 immunoreactivity was observed to occur in 4 stages. In the first stage, the presumptive subplate region in the lateral and rostral parts of the developing isocortex was transiently labelled at E12. In the second stage, between E13 and E17, very faint label was found only in the ventricular germinal zone, possibly within radial glial fibres. The third stage began at E18, when transient labelling of several discrete cortical areas was apparent; the motor cortex (from E18 to P3), an area in the temporal lobe (presumptive primary auditory cortex; from E18 to P5.5) and the piriform and entorhinal cortices (from E18 to P3). The final stage began at P2, when a mosaic camouflage pattern of labelling started to appear throughout the developing cortex, particularly in layer I. The distribution of the transient label in the motor cortex during the perinatal period suggests that it may be associated with early events in corticospinal or other projection neuron maturation (apical dendrite growth and differentiation). The labelling in the presumptive auditory cortex (Te1) may also be involved in the differentiation of neurons in the upper cortical plate.

Aging↗