scholarly journals Refinement of the primate corticospinal pathway during prenatal development

2019 ◽  
Author(s):  
Ana Rita Ribeiro Gomes ◽  
Etienne Olivier ◽  
Herbert P. Killackey ◽  
Pascale Giroud ◽  
Michel Berland ◽  
...  
Keyword(s):  
Occipital Cortex ◽  
Prenatal Development ◽  
Zona Incerta ◽  
Central Nucleus ◽  
Projection Neurons ◽  
Subcortical Structures ◽  
Corticospinal Pathway ◽  
Contralateral Projection ◽  
Order Of Magnitude ◽  
Ipsilateral Projection

AbstractPerturbation of the developmental refinement of the corticospinal pathway leads to motor disorders. In non-primates developmental refinement is well documented, however in primates invasive investigations of the developing corticospinal pathway have been confined to neonatal and postnatal stages when refinement is relatively modest.Here, we investigated the developmental changes in the distribution of corticospinal projection neurons in cynomolgus monkey. Injections of retrograde tracer at the cervical levels of the spinal cord at embryonic day (E) 95 and E105 show that (i) areal distribution of back-labeled neurons is more extensive than in the neonate and dense labeling is found in prefrontal, limbic, temporal and occipital cortex; (ii) distributions of contra- and ipsilateral projecting corticospinal neurons are comparable in terms of location and numbers of labeled neurons, in contrast to the adult where the contralateral projection is an order of magnitude higher than the ipsilateral projection. Findings from one largely restricted injection suggest a hitherto unsuspected early innervation of the gray matter.In the fetus there was in addition dense labeling in the central nucleus of the amygdala, the hypothalamus, the subthalamic nucleus and the adjacent region of the zona incerta, subcortical structures with only minor projections in the adult control.

scholarly journals Refinement of the Primate Corticospinal Pathway During Prenatal Development

2019 ◽  
Author(s):  
Ana Rita Ribeiro Gomes ◽  
Etienne Olivier ◽  
Herbert P Killackey ◽  
Pascale Giroud ◽  
Michel Berland ◽  
...  
Keyword(s):  
Macaca Fascicularis ◽  
Occipital Cortex ◽  
Prenatal Development ◽  
Zona Incerta ◽  
Central Nucleus ◽  
Projection Neurons ◽  
Subcortical Structures ◽  
Contralateral Projection ◽  
Order Of Magnitude ◽  
Ipsilateral Projection

Abstract Perturbation of the developmental refinement of the corticospinal (CS) pathway leads to motor disorders. While non-primate developmental refinement is well documented, in primates invasive investigations of the developing CS pathway have been confined to neonatal and postnatal stages when refinement is relatively modest. Here, we investigated the developmental changes in the distribution of CS projection neurons in cynomolgus monkey (Macaca fascicularis). Injections of retrograde tracer at cervical levels of the spinal cord at embryonic day (E) 95 and E105 show that: (i) areal distribution of back-labeled neurons is more extensive than in the neonate and dense labeling is found in prefrontal, limbic, temporal, and occipital cortex; (ii) distributions of contralateral and ipsilateral projecting CS neurons are comparable in terms of location and numbers of labeled neurons, in contrast to the adult where the contralateral projection is an order of magnitude higher than the ipsilateral projection. Findings from one largely restricted injection suggest a hitherto unsuspected early innervation of the gray matter. In the fetus there was in addition dense labeling in the central nucleus of the amygdala, the hypothalamus, the subthalamic nucleus, and the adjacent region of the zona incerta, subcortical structures with only minor projections in the adult control.

scholarly journals Understanding Emotions: Origins and Roles of the Amygdala

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 823
Author(s):  
Goran Šimić ◽  
Mladenka Tkalčić ◽  
Vana Vukić ◽  
Damir Mulc ◽  
Ena Španić ◽  
...  
Keyword(s):  
Sensory Information ◽  
Anterior Cingulate ◽  
Central Nucleus ◽  
Subcortical Structures ◽  
Neuronal Populations ◽  
Efferent Projections ◽  
Short And Long Term ◽  
Understanding Emotions ◽  
Fight Or Flight Response ◽  
And Behavior

Emotions arise from activations of specialized neuronal populations in several parts of the cerebral cortex, notably the anterior cingulate, insula, ventromedial prefrontal, and subcortical structures, such as the amygdala, ventral striatum, putamen, caudate nucleus, and ventral tegmental area. Feelings are conscious, emotional experiences of these activations that contribute to neuronal networks mediating thoughts, language, and behavior, thus enhancing the ability to predict, learn, and reappraise stimuli and situations in the environment based on previous experiences. Contemporary theories of emotion converge around the key role of the amygdala as the central subcortical emotional brain structure that constantly evaluates and integrates a variety of sensory information from the surroundings and assigns them appropriate values of emotional dimensions, such as valence, intensity, and approachability. The amygdala participates in the regulation of autonomic and endocrine functions, decision-making and adaptations of instinctive and motivational behaviors to changes in the environment through implicit associative learning, changes in short- and long-term synaptic plasticity, and activation of the fight-or-flight response via efferent projections from its central nucleus to cortical and subcortical structures.

Lingual Mechanoreceptive Information II

1982 ◽  
Vol 25 (3) ◽  
pp. 357-363
Author(s):  
James P. Bowman
Keyword(s):  
Trigeminal Nerve ◽  
Somatosensory System ◽  
Single Pulse ◽  
Lingual Nerve ◽  
Medial Lemniscus ◽  
Trigeminal Nuclei ◽  
Sensorimotor Activity ◽  
Contralateral Projection ◽  
Sensory Nucleus ◽  
Ipsilateral Projection

The extent to which the known trigeminothalamic projections are related to afferents from specific peripheral branches of the trigeminal nerve is not clearly revealed by degeneration studies involving lesions of the various trigeminal nuclei. This study examines the ascending projections related to the lingual branch of the trigeminal nerve using the evoked-potential technique in pentobarbital anesthetized rhesus monkeys. The distribution of potentials within the medulla, pons, and midbrain was determined by recording with macroelectrodes following single-pulse stimulation of the lingual nerve. Results show that two pathways from the main sensory nucleus convey lingual nerve information to the thalamic ventral posteromedial nucleus: an ipsilateral projection which in position corresponds to the dorsal trigeminal tract, and a larger contralateral projection which in position corresponds to the crossed ventral trigeminal tract, or trigeminal lemniscus. Additionally, the spinal trigeminal nucleus contributes fibers of lingual nerve origin to the contralateral medial lemniscus. The role of low-threshold mechanoreceptive information in lingual sensorimotor activity is discussed in relation to current concepts of somatosensory system function.

scholarly journals Target-specific M1 inputs to infragranular S1 pyramidal neurons

2016 ◽  
Vol 116 (3) ◽  
pp. 1261-1274 ◽  
Author(s):  
Amanda K. Kinnischtzke ◽  
Erika E. Fanselow ◽  
Daniel J. Simons
Keyword(s):  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
Projection Neurons ◽  
Cell Type ◽  
Intrinsic Properties ◽  
Subcortical Structures ◽  
Medial Nucleus ◽  
Cell Type Specific ◽  
Posterior Medial Nucleus

The functional role of input from the primary motor cortex (M1) to primary somatosensory cortex (S1) is unclear; one key to understanding this pathway may lie in elucidating the cell-type specific microcircuits that connect S1 and M1. Recently, we discovered that a subset of pyramidal neurons in the infragranular layers of S1 receive especially strong input from M1 (Kinnischtzke AK, Simons DJ, Fanselow EE. Cereb Cortex 24: 2237–2248, 2014), suggesting that M1 may affect specific classes of pyramidal neurons differently. Here, using combined optogenetic and retrograde labeling approaches in the mouse, we examined the strengths of M1 inputs to five classes of infragranular S1 neurons categorized by their projections to particular cortical and subcortical targets. We found that the magnitude of M1 synaptic input to S1 pyramidal neurons varies greatly depending on the projection target of the postsynaptic neuron. Of the populations examined, M1-projecting corticocortical neurons in L6 received the strongest M1 inputs, whereas ventral posterior medial nucleus-projecting corticothalamic neurons, also located in L6, received the weakest. Each population also possessed distinct intrinsic properties. The results suggest that M1 differentially engages specific classes of S1 projection neurons, thereby regulating the motor-related influence S1 exerts over subcortical structures.

scholarly journals A specialized reciprocal connectivity suggests a link between the mechanisms by which the superior colliculus and parabigeminal nucleus produce defensive behaviors in rodents

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Alfonso Deichler ◽  
Denisse Carrasco ◽  
Luciana Lopez-Jury ◽  
Tomas Vega-Zuniga ◽  
Natalia Márquez ◽  
...  
Keyword(s):  
Superior Colliculus ◽  
Central Nucleus ◽  
Binocular Field ◽  
Defensive Behaviors ◽  
Contralateral Projection ◽  
Parabigeminal Nucleus ◽  
Mammalian Homologue ◽  
Avoidance Reactions ◽  
Stimulation Of

Abstract The parabigeminal nucleus (PBG) is the mammalian homologue to the isthmic complex of other vertebrates. Optogenetic stimulation of the PBG induces freezing and escape in mice, a result thought to be caused by a PBG projection to the central nucleus of the amygdala. However, the isthmic complex, including the PBG, has been classically considered satellite nuclei of the Superior Colliculus (SC), which upon stimulation of its medial part also triggers fear and avoidance reactions. As the PBG-SC connectivity is not well characterized, we investigated whether the topology of the PBG projection to the SC could be related to the behavioral consequences of PBG stimulation. To that end, we performed immunohistochemistry, in situ hybridization and neural tracer injections in the SC and PBG in a diurnal rodent, the Octodon degus. We found that all PBG neurons expressed both glutamatergic and cholinergic markers and were distributed in clearly defined anterior (aPBG) and posterior (pPBG) subdivisions. The pPBG is connected reciprocally and topographically to the ipsilateral SC, whereas the aPBG receives afferent axons from the ipsilateral SC and projected exclusively to the contralateral SC. This contralateral projection forms a dense field of terminals that is restricted to the medial SC, in correspondence with the SC representation of the aerial binocular field which, we also found, in O. degus prompted escape reactions upon looming stimulation. Therefore, this specialized topography allows binocular interactions in the SC region controlling responses to aerial predators, suggesting a link between the mechanisms by which the SC and PBG produce defensive behaviors.

scholarly journals Increased Callosal Connectivity in Reeler Mice Revealed by Brain-Wide Input Mapping of VIP Neurons in Barrel Cortex

2020 ◽  
Author(s):  
Georg Hafner ◽  
Julien Guy ◽  
Mirko Witte ◽  
Pavel Truschow ◽  
Alina Rüppel ◽  
...  
Keyword(s):  
Long Range ◽  
Cortical Neurons ◽  
Barrel Cortex ◽  
Projection Neurons ◽  
Subcortical Structures ◽  
Virus Tracing ◽  
Cortical Inputs ◽  
Callosal Projection ◽  
To Receive ◽  
The Brain

Abstract The neocortex is composed of layers. Whether layers constitute an essential framework for the formation of functional circuits is not well understood. We investigated the brain-wide input connectivity of vasoactive intestinal polypeptide (VIP) expressing neurons in the reeler mouse. This mutant is characterized by a migration deficit of cortical neurons so that no layers are formed. Still, neurons retain their properties and reeler mice show little cognitive impairment. We focused on VIP neurons because they are known to receive strong long-range inputs and have a typical laminar bias toward upper layers. In reeler, these neurons are more dispersed across the cortex. We mapped the brain-wide inputs of VIP neurons in barrel cortex of wild-type and reeler mice with rabies virus tracing. Innervation by subcortical inputs was not altered in reeler, in contrast to the cortical circuitry. Numbers of long-range ipsilateral cortical inputs were reduced in reeler, while contralateral inputs were strongly increased. Reeler mice had more callosal projection neurons. Hence, the corpus callosum was larger in reeler as shown by structural imaging. We argue that, in the absence of cortical layers, circuits with subcortical structures are maintained but cortical neurons establish a different network that largely preserves cognitive functions.

New Vistas on Amygdala Networks in Conditioned Fear

2004 ◽  
Vol 92 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Denis Paré ◽  
Gregory J. Quirk ◽  
Joseph E. Ledoux
Keyword(s):  
Brain Stem ◽  
Conditioned Fear ◽  
Current Model ◽  
Central Nucleus ◽  
Projection Neurons ◽  
Conditioned Freezing ◽  
Fear Potentiated Startle ◽  
Classically Conditioned ◽  
The Brain ◽  
Critical Site

It is currently believed that the acquisition of classically conditioned fear involves potentiation of conditioned thalamic inputs in the lateral amygdala (LA). In turn, LA cells would excite more neurons in the central nucleus (CE) that, via their projections to the brain stem and hypothalamus, evoke fear responses. However, LA neurons do not directly contact brain stem-projecting CE neurons. This is problematic because CE projections to the periaqueductal gray and pontine reticular formation are believed to generate conditioned freezing and fear-potentiated startle, respectively. Moreover, like LA, CE may receive direct thalamic inputs communicating information about the conditioned and unconditioned stimuli. Finally, recent evidence suggests that the CE itself may be a critical site of plasticity. This review attempts to reconcile the current model with these observations. We suggest that potentiated LA outputs disinhibit CE projection neurons via GABAergic intercalated neurons, thereby permitting associative plasticity in CE. Thus plasticity in both LA and CE would be necessary for acquisition of conditioned fear. This revised model also accounts for inhibition of conditioned fear after extinction.

scholarly journals Projection neurons from the central nucleus of the amygdala to the nucleus pontis oralis

2010 ◽  
Vol 89 (3) ◽  
pp. 429-436 ◽  
Author(s):  
Simon J. Fung ◽  
MingChu Xi ◽  
JianHua Zhang ◽  
Pablo Torterolo ◽  
Sharon Sampogna ◽  
...  
Keyword(s):  
Central Nucleus ◽  
Projection Neurons

Current source density analysis of contra- and ipsilateral isthmotectal connections of the frog

2006 ◽  
Vol 23 (5) ◽  
pp. 713-719 ◽  
Author(s):  
NORIAKI HOSHINO ◽  
KAZUYA TSURUDOME ◽  
HIDEKI NAKAGAWA ◽  
NOBUYOSHI MATSUMOTO
Keyword(s):  
Current Source ◽  
Current Source Density ◽  
Source Density ◽  
Intracellular Study ◽  
Contralateral Projection ◽  
Ipsilateral Projection ◽  
Density Analysis ◽  
Output Neurons ◽  
Threat Avoidance ◽  
Electrophysiological Examination

The nucleus isthmi (NI) of the frog receives input from the ipsilateral optic tectum and projects back to both optic tecta. After ablation of NI, frogs display no visually elicited prey-catching or threat avoidance behavior. Neural mechanisms that underlie the loss of such important behavior have not been solved. Electrophysiological examination of the contralateral isthmotectal projection has proved that it contributes to binocular vision. On the other hand, there are very few physiological investigations of the ipsilateral isthmotectal projection. In this study, current source density (CSD) analysis was applied to contra- and ipsilateral isthmotectal projections. The contralateral projection produced monosynaptic sinks in superficial layers and in layer 8. The results confirmed former findings obtained by single unit recordings. The ipsilateral projection elicited a prominent monosynaptic sink in layer 8. Recipient neurons were located in layers 6–7. These results, combined with those from the former intracellular study, led to the following neuronal circuit. Afferents from the ipsilateral NI inhibit non-efferent pear shaped neurons in the superficial layers, and strongly excite large ganglionic neurons projecting to the descending motor regions. Thus feedback to the output neurons strengthens the visually elicited responses.

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