Anatomical pathways for auditory memory II: information from rostral superior temporal gyrus to dorsolateral temporal pole and medial temporal cortex

Auditory recognition memory in non-human primates differs from recognition memory in other sensory systems. Monkeys learn the rule for visual and tactile delayed matching-to-sample within a few sessions, and then show one-trial recognition memory lasting 10–20 min. In contrast, monkeys require hundreds of sessions to master the rule for auditory recognition, and then show retention lasting no longer than 30–40 s. Moreover, unlike the severe effects of rhinal lesions on visual memory, such lesions have no effect on the monkeys' auditory memory performance. The anatomical pathways for auditory memory may differ from those in vision. Long-term visual recognition memory requires anatomical connections from the visual association area TE with areas 35 and 36 of the perirhinal cortex (PRC). We examined whether there is a similar anatomical route for auditory processing, or that poor auditory recognition memory may reflect the lack of such a pathway. Our hypothesis is that an auditory pathway for recognition memory originates in the higher order processing areas of the rostral superior temporal gyrus (rSTG), and then connects via the dorsolateral temporal pole to access the rhinal cortex of the medial temporal lobe. To test this, we placed retrograde (3% FB and 2% DY) and anterograde (10% BDA 10,000 mW) tracer injections in rSTG and the dorsolateral area 38DL of the temporal pole. Results showed that area 38DL receives dense projections from auditory association areas Ts1, TAa, TPO of the rSTG, from the rostral parabelt and, to a lesser extent, from areas Ts2-3 and PGa. In turn, area 38DL projects densely to area 35 of PRC, entorhinal cortex (EC), and to areas TH/TF of the posterior parahippocampal cortex. Significantly, this projection avoids most of area 36r/c of PRC. This anatomical arrangement may contribute to our understanding of the poor auditory memory of rhesus monkeys

The influence of semantic and phonological factors on syntactic decisions: An event-related brain potential study

During language production and comprehension, information about a word's syntactic properties is sometimes needed. While the decision about the grammatical gender of a word requires access to syntactic knowledge, it has also been hypothesized that semantic (i.e., biological gender) or phonological information (i.e., sound regularities) may influence this decision. Event-related potentials (ERPs) were measured while native speakers of German processed written words that were or were not semantically and/or phonologically marked for gender. Behavioral and ERP results showed that participants were faster in making a gender decision when words were semantically and/or phonologically gender marked than when this was not the case, although the phonological effects were less clear. In conclusion, our data provide evidence that even though participants performed a grammatical gender decision, this task can be influenced by semantic and phonological factors

The Human Parahippocampal Region: I. Temporal Pole Cytoarchitectonic and MRI Correlation

The temporal pole (TP) is the rostralmost portion of the human temporal lobe. Characteristically, it is only present in human and nonhuman primates. TP has been implicated in different cognitive functions such as emotion, attention, behavior, and memory, based on functional studies performed in healthy controls and patients with neurodegenerative diseases through its anatomical connections (amygdala, pulvinar, orbitofrontal cortex). TP was originally described as a single uniform area by Brodmann area 38, and von Economo (area TG of von Economo and Koskinas), and little information on its cytoarchitectonics is known in humans. We hypothesize that 1) TP is not a homogenous area and we aim first at fixating the precise extent and limits of temporopolar cortex (TPC) with adjacent fields and 2) its structure can be correlated with structural magnetic resonance images. We describe here the macroscopic characteristics and cytoarchitecture as two subfields, a medial and a lateral area, that constitute TPC also noticeable in 2D and 3D reconstructions. Our findings suggest that the human TP is a heterogeneous region formed exclusively by TPC for about 7 mm of the temporal tip, and that becomes progressively restricted to the medial and ventral sides of the TP. This cortical area presents topographical and structural features in common with nonhuman primates, which suggests an evolutionary development in human species

Remodeling of cholinergic input to the hippocampus after noise exposure and tinnitus induction in Guinea pigs

Here, we investigate remodeling of hippocampal cholinergic inputs after noise exposure and determine the relevance of these changes to tinnitus. To assess the effects of noise exposure on the hippocampus, guinea pigs were exposed to unilateral noise for 2 hr and 2 weeks later, immunohistochemistry was performed on hippocampal sections to examine vesicular acetylcholine transporter (VAChT) expression. To evaluate whether the changes in VAChT were relevant to tinnitus, another group of animals was exposed to the same noise band twice to induce tinnitus, which was assessed using gap‐prepulse Inhibition of the acoustic startle (GPIAS) 12 weeks after the first noise exposure, followed by immunohistochemistry. Acoustic Brainstem Response (ABR) thresholds were elevated immediately after noise exposure for all experimental animals but returned to baseline levels several days after noise exposure. ABR wave I amplitude‐intensity functions did not show any changes after 2 or 12 weeks of recovery compared to baseline levels. In animals assessed 2‐weeks following noise‐exposure, hippocampal VAChT puncta density decreased on both sides of the brain by 20–60% in exposed animals. By 12 weeks following the initial noise exposure, changes in VAChT puncta density largely recovered to baseline levels in exposed animals that did not develop tinnitus, but remained diminished in animals that developed tinnitus. These tinnitus‐specific changes were particularly prominent in hippocampal synapse‐rich layers of the dentate gyrus and areas CA3 and CA1, and VAChT density in these regions negatively correlated with tinnitus severity. The robust changes in VAChT labeling in the hippocampus 2 weeks after noise exposure suggest involvement of this circuitry in auditory processing. After chronic tinnitus induction, tinnitus‐specific changes occurred in synapse‐rich layers of the hippocampus, suggesting that synaptic processing in the hippocampus may play an important role in the pathophysiology of tinnitus.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150542/1/hipo23058.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150542/2/hipo23058_am.pd

Variability and trends in the consumption of drugs for treating attention-deficit/hyperactivity disorder in Castile-La Mancha, Spain (1992–2015)

Introduction: Attention-deficit/hyperactivity disorder (ADHD) is one of the most common behavioural disorders of childhood; its prevalence in Spain is estimated at 5%-9%. Available treatments for this condition include methylphenidate, atomoxetine, and lisdexamfetamine, whose consumption increases each year. Material and methods: The prevalence of ADHD was estimated by calculating the defined daily dose per 1000 population per day of each drug and the total doses (therapeutic group N06BA) between 1992 and 2015 in each of the provinces of Castile-La Mancha (Spain). Trends, joinpoints, and annual percentages of change were analysed using joinpoint regression models. Results: The minimum prevalence of ADHD in the population of Castile-La Mancha aged 5-19 was estimated at 13.22 cases per 1000 population per day; prevalence varied across provinces (P < .05). Overall consumption has increased from 1992 to 2015, with an annual percentage of change of 10.3% and several joinpoints (2000, 2009, and 2012). Methylphenidate represents 89.6% of total drug consumption, followed by lisdexamfetamine at 8%. Conclusions: Analysing drug consumption enables us to estimate the distribution of ADHD patients in Castile-La Mancha. Our data show an increase in the consumption of these drugs as well as differences in drug consumption between provinces, which reflect differences in ADHD management in clinical practice. Resumen: Introducción: El trastorno por déficit de atención e hiperactividad (TDAH) es uno de los trastornos conductuales más frecuentes de la infancia, se estima su prevalencia en España en un 5-9%. Existen varios fármacos para esta patología como el metilfenidato, la atomoxetina y la lisdexanfetamina cuyos consumos están creciendo anualmente. Material y métodos: Se estima la prevalencia de TDAH a través del cálculo de las dosis diarias definidas por 1.000 habitantes y día de cada fármaco y el total (grupo terapéutico N06BA), durante los años 1992-2015, para cada una de las provincias de Castilla-La Mancha (España). Se observa la tendencia, sus puntos de cambio y los porcentajes anuales de cambio mediante modelos de regresión de joinpoint. Resultados: Se estima una prevalencia mínima de TDAH de 13,22 casos por 1.000 habitantes y día para Castilla-La Mancha en la población de 5 a 19 años, existiendo una variabilidad provincial (p < 0,05). En su conjunto, el consumo se ha incrementado un porcentaje anual de cambio de 10,3% desde 1992 a 2015 con varios años o puntos de inflexión (2000, 2009 y 2012). El metilfenidato supone el 89,6% de los fármacos consumidos, seguido por la lisdexanfetamina con un 8%. Conclusiones: El consumo de fármacos permite estimar la distribución de TDAH en Castilla-La Mancha. Se observa un crecimiento en el consumo de estos fármacos, y se observa una variabilidad provincial en su consumo, lo que supone diferencias en la práctica médica frente a esta enfermedad. Keywords: Attention-deficit/hyperactivity disorder, Pharmacoepidemiology, Methylphenidate, Atomoxetine, Lisdexamfetamine, Palabras clave: Trastorno déficit de atención e hiperactividad, Farmacoepidemiología, Metilfenidato, Atomoxetina, Lisdexanfetamin

Reciprocal connections between olfactory structures and the cortex of the rostral superior temporal sulcus in the Macaca fascicularis monkey

Convergence of sensory modalities in the nonhuman primate cerebral cortex is still poorly understood. We present an anatomical tracing study in which polysensory association cortex located at the fundus and upper bank of the rostral superior temporal sulcus presents reciprocal connections with primary olfactory structures. At the same time, projections from this polysensory area reach multiple primary olfactory centres. Retrograde (Fast Blue) and anterograde (biotinylated dextran–amine and 3H-amino acids) tracers were injected into primary olfactory structures and rostral superior temporal sulcus. Retrograde tracers restricted to the anterior olfactory nucleus resulted in labelled neurons in the rostral portion of the upper bank and fundus of superior temporal sulcus. Injections of biotinylated dextran–amine at the fundus and upper bank of the superior temporal sulcus confirmed this projection by labelling axons in the dorsal and lateral portions of the anterior olfactory nucleus, as well as piriform, periamygdaloid and entorhinal cortices. Retrograde tracer injections at the rostral superior temporal sulcus resulted in neuronal labelling in the anterior olfactory nucleus, piriform, periamygdaloid and entorhinal cortices, thus providing confirmation of the reciprocity between primary olfactory structures and the cortex at the rostral superior temporal sulcus. The reciprocal connections between the rostral part of superior temporal sulcus and primary olfactory structures represent a convergence for olfactory and other sensory modalities at the cortex of the rostral temporal lobe

Postnatal development of calcium-binding proteins immunoreactivity (parvalbumin, calbindin, calretinin) in the human entorhinal cortex

The entorhinal cortex is an essential component in the organization of the human hippocampal formation related to cortical activity. It transfers, neocortical information (ultimately distributed to the dentate gyrus and hippocampus) and receives most of the hippocampal output directed to neocortex. At birth, the human entorhinal cortex presents similar layer organization as in adults, although layer II (cell islands) and upper layer III have a protracted maturation. The presence of interneurons expressing calcium-binding proteins (parvalbumin, calbindin–D28K (calbindin) and calretinin) is well documented in the adult human entorhinal cortex. In many of them the calcium binding is co-localized with GABA. Parvalbumin-immunoreactive cells and fibers were virtually absent at birth, their presence increasing gradually in deep layer III, mostly in the lateral and caudal portions of the entorhinal cortex from the 5th month onwards. Calbindin immunoreactive cells and fibers were present at birth, mainly in layers II and upper III; mostly at rostral and lateral portions of the entorhinal cortex, increasing in number and extending to deep layers from the 5th month onwards. Calretinin immunoreactivity was present at birth, homogeneously distributed over layers I, II and upper V, throughout the entorhinal cortex. A substantial increase in the number of calretinin neurons in layer V was observed at the 5th month. The postnatal development of parvalbumin, calbindin and calretinin may have an important role in the functional maturation of the entorhinal cortex through the control of hippocampal, cortical and subcortical information

Hippocampal Formation Projection To Ventral Tegmental Area: An Anatomical Study In The Non-Human Primate

The Hippocampal Formation (HF) has a critical role in episodic memory. One of the major components in episodic memory is the encoding of novel stimuli, which is associated to dopaminergic system. Lisman and Grace (2005) proposed that novelty signals in the hippocampus modulate the activity of dopaminergic neurons in the ventral tegmental area (VTA) and that, via a feedback loop, the increase of dopamine in hippocampal neurons promotes the encoding for the novel event. Retrograde tracer studies have demonstrated that the VTA projects directly to the HF in primates (Amaral and Cowan, 1980; Insausti et al., 1987) as well as in rodents. However, whether these projections are reciprocal or not is unknown. Despite this lack of evidence of a direct projection, functional studies indicate that the dopaminergic neurons of the VTA are strongly influenced by the hippocampus indirectly through either lateral septum (Luo et al. 2011) or nucleus accumbens-ventral pallidum pathways (Lisman and Grace 2005). In order to determine the existence of direct inputs from the HF to the VTA and which are the specific fields within the HF responsible of the projection, the retrograde tracers were placed in the mesencephalic ventral and dorsal tegmentum of the Macaca fascicularis monkey, including the VTA. The retrograde cell labeling was analyzed with an epifluorescence microscope coupled to a computerized charting system. Our preliminary results showed scarce labeled cells in the HF, specifically in dorsal subiculum, and deep layers of the caudomedial portion of the entorhinal cortex (subfield EO and medialmost EI). These results clarify the functional HF-VTA loop playing a role in learning and memory, and different neuropsychiatric diseases (schizophrenia, Alzheimer´s and Parkinson's disease

Brainstem Afferents To The Hippocampal Formation: Comparative Inmunohistochemical Study In The Macaca Fascicularis Monkey

The neuroanatomical connections in the nonhuman primate of the brainstem structures to the Hippocampal Formation (HF, which includes the dentate gyrus -DG-, CA3, CA2, CA1, subiculum, pre-parasubiculum and the entorhinal cortex -EC-) are still unclear. Previous tracer studies in nonhuman primates show retrogradely labeled neurons in the brainstem including the Ventral Tegmental Area (VTA), Locus Coeruleus (LC) and Raphe Nuclei (RN), after deposits in the hippocampus (Amaral and Cowan, 1980), as well as in the EC (Insausti et al., 1987). In order to characterize the neurotransmitters associated to those projections (presumably dopaminergic -DA, VTA-, noradrenergic -NA, LC-, and serotoninergic -5-HT, RN-, respectively), and the topographic and laminar differences, we studied comparatively the innervation in the HF using immunohistochemical techniques. Inmunohistochemistry for DA (Tirosine Hidroxilase, TH), NA (Dopamine Beta Hidroxilase, DBH), and 5-HT showed: a) The DG molecular layer had TH-immunoreactive fibers, while the polymorphic layer contained positive 5-HT fiber labeling, b) CA3 pyramidal layer showed denser 5-HT labeling than TH, c) CA1 had scattered TH and 5-HT fibers, d) The superficial layer of the rostral EC (I and II) had TH- and 5-HT-labelled processes, e) TH and DBH positive cells were primarily found in the lateral subdivisions of the EC (ELR/ELc). The preferential location of these positive fibers in ELR/ELc, is significant, as this portion of the EC receives abundant unimodal and polymodal sensory input and innervates the body and tail of the hippocampus, and therefore it might be a crucial link in the consolidation of memory through the monoaminergic modulation of the HF