The dorsal and ventral visual streams have been considered to play distinct roles in visual processing for action: the dorsal stream is assumed to support real-time actions, while the ventral stream facilitates memory-guided actions. However, recent evidence suggests a more integrated function of these streams. We investigated the neural dynamics and functional connectivity between them during memory-guided actions using intracranial EEG. We tracked neural activity in the inferior parietal lobule in the dorsal stream, and the ventral temporal cortex in the ventral stream as well as the hippocampus during a delayed action task involving object identity and location memory. We found increased alpha power in both streams during the delay, indicating their role in maintaining spatial visual information. In addition, we recorded increased alpha power in the hippocampus during the delay, but only when both object identity and location needed to be remembered. We also recorded an increase in theta band phase synchronization between the inferior parietal lobule and ventral temporal cortex and between the inferior parietal lobule and hippocampus during the encoding and delay. Granger causality analysis indicated dynamic and frequency-specific directional interactions among the inferior parietal lobule, ventral temporal cortex, and hippocampus that varied across task phases. Our study provides unique electrophysiological evidence for close interactions between dorsal and ventral streams, supporting an integrated processing model in which both streams contribute to memory-guided actions.
Humans ; Male ; Female ; Adult ; Young Adult ; Hippocampus/physiology* ; Memory/physiology* ; Parietal Lobe/physiology* ; Temporal Lobe/physiology* ; Visual Perception/physiology* ; Electrocorticography ; Visual Pathways/physiology* ; Electroencephalography

Parvalbumin interneurons belong to the major types of GABAergic interneurons. Although the distribution and pathological alterations of parvalbumin interneuron somata have been widely studied, the distribution and vulnerability of the neurites and fibers extending from parvalbumin interneurons have not been detailly interrogated. Through the Cre recombinase-reporter system, we visualized parvalbumin-positive fibers and thoroughly investigated their spatial distribution in the mouse brain. We found that parvalbumin fibers are widely distributed in the brain with specific morphological characteristics in different regions, among which the cortex and thalamus exhibited the most intense parvalbumin signals. In regions such as the striatum and optic tract, even long-range thick parvalbumin projections were detected. Furthermore, in mouse models of temporal lobe epilepsy and Parkinson's disease, parvalbumin fibers suffered both massive and subtle morphological alterations. Our study provides an overview of parvalbumin fibers in the brain and emphasizes the potential pathological implications of parvalbumin fiber alterations.
Mice ; Animals ; Epilepsy, Temporal Lobe/pathology* ; Parvalbumins/metabolism* ; Parkinson Disease/pathology* ; Neurons/metabolism* ; Interneurons/physiology* ; Disease Models, Animal ; Brain/pathology*

A deficit in spatial memory has been taken as an early predictor of Alzheimer's disease (AD) or mild cognitive impairment (MCI). The uncinate fasciculus (UF) is a long-range white-matter tract that connects the anterior temporal lobe with the orbitofrontal cortex (OFC) in primates. Previous studies have shown that the UF impairment associated with spatial memory deficits may be an important pathological change in aging and AD, but its exact role in spatial memory is not well understood. The pathway arising from the postrhinal cortex (POR) and projecting to the ventrolateral orbitofrontal cortex (vlOFC) performs most of the functions of the UF in rodents. Although the literature suggests an association between spatial memory and the regions connected by the POR-vlOFC pathway, the function of the pathway in spatial memory is relatively unknown. To further illuminate the function of the UF in spatial memory, we dissected the POR-vlOFC pathway in mice. We determined that the POR-vlOFC pathway is a glutamatergic structure, and that glutamatergic neurons in the POR regulate spatial memory retrieval. We also demonstrated that the POR-vlOFC pathway specifically transmits spatial information to participate in memory retrieval. These findings provide a deeper understanding of UF function and dysfunction related to disorders of memory, as in MCI and AD.
Animals ; Glutamic Acid ; physiology ; Male ; Mental Recall ; physiology ; Mice, Inbred C57BL ; Neural Pathways ; cytology ; physiology ; Neuroanatomical Tract-Tracing Techniques ; Neurons ; physiology ; Prefrontal Cortex ; cytology ; physiology ; Spatial Memory ; physiology ; Temporal Lobe ; cytology ; physiology

The purpose of the present paper was to review the processing mechanisms of social cues in faces. We summarized researches relative to social cues in faces and discussed the processing mechanism of these cues from the aspects of facial expression, facial attractiveness, gaze and face direction, and lipreading. First, we discussed the general neural mechanism of face information processing and summarized the functions of face areas in the fusiform gyrus, posterior superior temporal sulcus and inferior occipital gyrus. Next, the neural mechanism of emotional face perception was discussed. The processing of emotional faces consists of encodings of perceptual and emotional components. The amygdala plays an important role in the emotional processing of facial expressions. Furthermore, the neural responses to facial expressions may be influenced by multiple factors, such as the type of emotion, the dynamic presentation of the face and the consciousness of facial expressions. With respect to facial attractiveness processing, studies has shown that the reward circuitry is activated by highly attractive faces. However, the influence of facial attractiveness on neural responses remains elusive. It is proposed that the neural responses to facial attractiveness might be modulated by factors such as the task, observer's sex, expectation and other social cues in faces. Eye gaze perception and face view perception are related to visual attention, and the relevant neural circuitry has been found to include attention-related areas, such as the intraparietal sulcus. Finally, research on lipreading reveals its important role in language perception. The auditory cortex and language-related cortex have been shown to be activated by lipreading. In summary, the present evidence may support facial information processing theory. However, the theory could be further improved based on present and future findings. Furthermore, we discussed the deficits in the processing of social cues in individuals with mental disorders and proposed future research directions in this field.
Brain Mapping ; Cues ; Emotions ; Facial Expression ; Humans ; Magnetic Resonance Imaging ; Temporal Lobe ; physiology

Prepulse inhibition (PPI) refers to a decreased response to a startling stimulus when another weaker stimulus precedes it. Most PPI studies have focused on the physiological startle reflex and fewer have reported the PPI of cortical responses. We recorded local field potentials (LFPs) in four monkeys and investigated whether the PPI of auditory cortical responses (alpha, beta, and gamma oscillations and evoked potentials) can be demonstrated in the caudolateral belt of the superior temporal gyrus (STGcb). We also investigated whether the presence of a conspecific, which draws attention away from the auditory stimuli, affects the PPI of auditory cortical responses. The PPI paradigm consisted of Pulse-only and Prepulse + Pulse trials that were presented randomly while the monkey was alone (ALONE) and while another monkey was present in the same room (ACCOMP). The LFPs to the Pulse were significantly suppressed by the Prepulse thus, demonstrating PPI of cortical responses in the STGcb. The PPI-related inhibition of the N1 amplitude of the evoked responses and cortical oscillations to the Pulse were not affected by the presence of a conspecific. In contrast, gamma oscillations and the amplitude of the N1 response to Pulse-only were suppressed in the ACCOMP condition compared to the ALONE condition. These findings demonstrate PPI in the monkey STGcb and suggest that the PPI of auditory cortical responses in the monkey STGcb is a pre-attentive inhibitory process that is independent of attentional modulation.
Animals ; Auditory Cortex ; physiology ; Evoked Potentials, Auditory ; physiology ; Macaca mulatta ; Male ; Prepulse Inhibition ; physiology ; Temporal Lobe ; physiology

OBJECTIVETo investigate the changes in the expression of EphA5 and its ligand ephrinA5 in the hippocampus of rats with epilepsy and their role in the pathogenesis of temporal lobe epilepsy (TLE).

METHODSA total of 240 Sprague-Dawley rats were randomly divided into control group and TLE group, with 120 rats in each group. A rat model of lithium-pilocarpine TLE was established, and then the rats were divided into subgroups at 12 and 24 hours and 7, 15, 30, and 60 days after epilepsy was induced. In-situ hybridization was used to measure the mRNA expression of ephrinA5 in the CA3 region and the dentate gyrus of the hippocampus in 9 rats; immunohistochemistry was used to measure the protein expression of EphA5 in the CA3 region and the dentate gyrus of the hippocampus in 9 rats; Neo-Timm silver staining was used to observe mossy fiber sprouting in the CA3 region of the hippocampus in 2 rats.

RESULTSIn-situ hybridization showed mRNA expression of ephrinA5 in the CA3 region of the hippocampus, but this was not found in the dentate gyrus. Compared with the control group at the same time point, the TLE group had a significant reduction in the mRNA expression of ephrinA5 in the CA3 region of the hippocampus at 7 and 15 days after epilepsy was induced (P<0.05); at 30 and 60 days after epilepsy was induced, the TLE group had a gradual increase in the mRNA expression of ephrinA5 in the CA3 region of the hippocampus, and there was no significant difference between the TLE and control groups (P>0.05). Immunohistochemistry showed that EphA5 protein was expressed in the CA3 region and the dentate gyrus of the hippocampus and had a similar trend of change as ephrinA5 mRNA. Neo-Timm silver staining showed that the TLE group developed marked mossy fiber sprouting in the CA3 region of the hippocampus at 7 and 15 days after epilepsy was induced.

CONCLUSIONSDownregulation of ephrinA5 and EphA5 in the CA3 region of the hippocampus may participate in the mechanism of mossy fiber sprouting and is closely associated with the development and progression of epilepsy.

Animals ; Ephrin-A5 ; analysis ; genetics ; physiology ; Epilepsy, Temporal Lobe ; etiology ; metabolism ; Hippocampus ; chemistry ; Male ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Receptor, EphA5 ; analysis ; genetics ; physiology

Temporal lobe epilepsy (TLE) is a common and severe neurological disorder which is often intractable. It can not only damage the normal structure and function of hippocampus, but also affect the neurogenesis in dentate gyrus (DG). It is well documented from researches on the animal models of TLE that after a latent period of several days, prolonged seizure activity leads to a dramatic increase in mitotic activity in the hippocampal DG. However, cell proliferation returns to baseline levels within 3-4 weeks after status epilepticus (SE). Meanwhile, there are two major abnormalities of DG neurogenesis, including the formation of hilar basal dendrites and the ectopic migration of newborn granule cells into the polymorphic cell layer, which may affect epileptogenesis and seizure onset. However, the specific contribution of these abnormalities to seizures is still unknown. In other words, whether they are anti-epileptic or pro-epileptic is still under heated discussion. This article systematically reviews current knowledge on neurogenesis and epilepsy based on the results of studies in recent years and discusses the possible roles of neurogenesis in epileptogenesis and pathologic mechanisms, so as to provide information for the potential application of neurogenesis as a new clinical therapeutic target for temporal lobe epilepsy.
Animals ; Brain ; Cell Movement ; physiology ; Cell Proliferation ; physiology ; Dendrites ; pathology ; Dentate Gyrus ; growth & development ; pathology ; Epilepsy, Temporal Lobe ; etiology ; pathology ; physiopathology ; Hippocampus ; growth & development ; pathology ; Humans ; Mitosis ; physiology ; Neurogenesis ; physiology ; Neurons ; pathology ; Seizures ; etiology ; physiopathology ; Status Epilepticus ; physiopathology

To investigate the effect of crocin on the progression and generalized seizure of temporal lobe epilepsy in mice.Hippocampus rapid kindling model was established in C57BL/6J mice. The effects of crocin on seizure stage, afterdischarge duration (ADD), number of stimulation in each stage and final state, the incidence of generalized seizure (GS), average seizure stage and ADD were observed.Crocin (20 mg/kg) significantly retarded behavioral seizure stages (<0.05) and shortened cumulative ADD (<0.01) during hippocampus rapid kindling acquisition in mice compared with vehicle group. Meanwhile, number of stimulations in stage 1-2 was significantly increased (<0.05) and the incidence of fully kindled animals was significantly decreased (<0.01). However, 10 or 50 mg/kg crocin showed no significant effect on the above indexes (all>0.05). Crocin (100 or 200 mg/kg) significantly decreased the incidence of GS (all<0.01) and reduced average seizure stages (all<0.01) in fully-kindled mice compared with vehicle group; Fifty mg/kg crocin only reduced average seizure stages (<0.05).Low-dose crocin can retard the progression in hippocampus rapid kindling acquisition in mice, while high-dose crocin relieves the GS in fully-kindled mice, which suggests that crocin may be a potential anti-epileptic compound.
Animals ; Anticonvulsants ; pharmacology ; Carotenoids ; pharmacology ; therapeutic use ; Dose-Response Relationship, Drug ; Electric Stimulation ; Epilepsy, Temporal Lobe ; chemically induced ; drug therapy ; Hippocampus ; drug effects ; physiopathology ; Kindling, Neurologic ; drug effects ; physiology ; Mice ; Mice, Inbred C57BL ; Seizures ; classification ; drug therapy

OBJECTIVETo explore the influence of verbal working memory load on associative neural networks.

METHODSTwenty-one subjects were required to complete a verbal delayed matching-to-sample task under the condition of low (3 items) or high (5 items) working memory load (WML). The 19-channels event-related potentials (ERP) were analyzed with statistical parametric mapping.

RESULTSA significant difference in working memory capacity (WMC) was found between low WML and high WML groups [2.48∓0.30 vs 3.30∓0.76; t(20)=5.950, P=0.000]. Statistical parametric mapping revealed that during the encoding stage, the effects of WML appeared in succession in the right ventral attention network (rVAN), the dorsal attention network, and the language areas in the left hemisprere. During the maintenance stage, the effects WML occured in the rVAN acompanied by either DAN or left frontal-temporal regions. CONCLUSIONS;onclusions When the WML is beyond the WMC, the rVAN may participate in the prevention of interference among items and in the activation of long-term memory.

Attention ; Evoked Potentials ; Frontal Lobe ; physiology ; Humans ; Memory, Short-Term ; Spatio-Temporal Analysis

OBJECTIVETo explore the working mechanism and age-related change of the conflict processing system of the frontal cortex.

METHODSFifteen normal elderly people and 15 youth were performed a modified Eriksen flanker paradigm, while event-related potential (ERPs), which include 32 systerm electroencephalography, reaction time and correct rate were recorded.

RESULTSThe elderly group showed a distinct effect of reaction time and effect of conflict in the respond level compared with the youth group. The elderly group had a longer time window of N380 and same amplitude as the youth group. Low resolution brain electromagnetic tomography (LORETA) showed the bilateral temporal lobe and the dorsolateral prefrontal cortex (especially right) were activated in the youth group, while the left temporal lobe, the left dorsolateral prefrontal cortex and left medial frontal gyrus were activated in the elderly group.

CONCLUSIONWhen conflict stimuli existed in the response level, old people showed frontal interference control hypofunction. N380 reflected the activation of the left dorsolateral prefrontal cortex and the left temporal lobe during response selection and executive control processing in older people.

Adolescent ; Aged ; Aging ; Electroencephalography ; Evoked Potentials ; Frontal Lobe ; physiology ; Humans ; Prefrontal Cortex ; physiology ; Reaction Time ; Temporal Lobe ; physiology