International Journal of Mental Health & PsychiatryISSN: 2471-4372

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Research Article, Int J Ment Health Psychiatry Vol: 2 Issue: 4

Deficient Integration of Short and Long Term Memory in Individuals with Schizophrenia

Victor Marinho1,2*, Kaline Rocha1, Francisco Magalhaes1, Jessica Ribeiro1, Thomaz de Oliveira1,2, Pedro Ribeiro1,3, Fernanda Sousa4, Monara Nunes4, Valécia Carvalho4, Victor Hugo Bastos4, Bruna Velasques3 and Silmar Teixeira1
1Brain Mapping and Plasticity Laboratory, Federal University of Piauí (UFPI), Parnaíba, Brazil
2Genetics and Molecular Biology Laboratory, Federal University of Piauí, Parnaíba, Brazil
3Brain Mapping and Sensory Motor Integration, Institute of Psychiatry of Federal University of Rio de Janeiro (IPUB/UFRJ), Brazil
4Brain Mapping and Functionality Laboratory, Federal University of Piauí (LAMCEF) (UFPI), Parnaíba, Brazil
Corresponding author : Francisco Victor Costa Marinho
Brain Mapping and Plasticity Laboratory- Av. Sao Sebastiao no 2819 – Nossa Sra. de Fatima –Parnaiba, PI, CEP: 64202-020, Brazil
Tel: +55 86 988374232
E-mail:
[email protected]
Received: August 16, 2016 Accepted: September 09, 2016 Published: September 12, 2016
Citation: Marinho V, Rocha K, Magalhaes F, Ribeiro J, de Oliveira T, et al. (2016) Deficient Integration of Short and Long Term Memory in Individuals with Schizophrenia. Int J Ment Health Psychiatry 2:4. doi:10.4172/2471-4372.1000134

Abstract

A deficiency in processing, retaining and consolidating information in the short and long term memory is observed in schizophrenics. Dopaminergic levels and synchronism of neural inputs in coding of events interpreted by the central nervous system appear to be related to this deficiency. However, there is limited understanding on the specific memory functions through a specialized network and focused on areas of the brain. Therefore, we conducted a literature search in the databases PubMed, Scielo, Lilacs and Bireme to demonstrate the disintegration in the processing of information attributed to failures in connectivity between hippocampal neural circuits with the various encephalic areas in schizophrenic patients. The literature reports that schizophrenics, among other causes, have deficiencies in cortico-hippocampal connections that participating in separation of time pattern, processing and consolidation of memory.

Keywords: Schizophrenia; Working memory; Short-term memory; Long-term memory; Hippocampus

Keywords

Schizophrenia; Working memory; Short-term memory; Long-term memory; Hippocampus

Context

Schizophrenia is a multifactorial disorder in which there is a disintegration in information processing [1] attributed to failures in connectivity between neural circuits [2]. The neuropathological basis is a reflection of an ineffective recruitment of dopamine in the mesolimbic pathway and cortical areas [3,4], which promotes deficiency in consolidation process of informations and performance in executive functions [5-7]. In addition to this machinery of neural integration and homeostasis of the dopaminergic system, hippocampal structures are relevant to the initial storage and the ability to acquire, retain and evoke information [5,8-12].
The commitment of connection between the dorsolateral prefrontal cortex and hippocampus (Figure 1) triggers problems during the information processing, interfering in consolidation, particularly working memory [5,13-15], a dynamic system with limited efficiency that demonstrates the individual's ability to use information from short-term memory, in order to allow the storage of information in cognitive activities [14,16]. The distorted visual perception that promotes process failures of various automatic and controlled mechanisms of the neural circuitry brings in a difficult formation of internal representations [17]. Fortunately, this ability to retain information, including the temporal information, may have their neurochemical bases modified before the pharmacological treatment with better generation of antipsychotics [5,18].
Figure 1: Schematization of functional anatomy of the central nervous system, specifying the hippocampus and its neural projections to the cortical areas and subcortical structures, in order to perform cognitive activities related to the formation of the short and long-term memory.
Research suggests that deficits in working memory can be a characteristic that compose the endophenotype of the disorder, when showing that both schizophrenics and his brothers have prolonged reaction time and deficits in working memory during the execution of a sustained attention task. However, when analyzing the performance measures of the brothers is observed superiority over schizophrenics [14,19]. The pathophysiology of memory retention deficiency canal so be justified by electrophysiological findings in synchronization of the activity of beta and gamma bands which are altered in patients with schizophrenia [20]. Since the temporal sequence of successful encodings between events to be selected and then stored depends on the emotional charge based on the importance that the event represents to the individual and in the frequency at which the event occurs [16,21].
The long-term memory and the predictive memory that are closely linked to the perception of states, which allows to access past experiences bringing a degree of ease and automatism to interpret and understand an event are also committed in schizophrenics [17,22-26]. This deficit is observed in both non-medicated patients who are in first stage of the disease and in previously treated patients. The dysfunction in the ability of evoking past memory in these patients may be related to the occurrence of hallucinations and delusions consequent disease. In this context, schizophrenia patients are unable to interpret complete images and temporal aspects related to events [25].
Disorders of episodic memory have been reported and appear to be the result of injuries that fall within the association circuit between the hippocampus, prefrontal cortex and medial temporal, structures important for consolidation and retrieval of memory [27]. The episodic memory associated with long-term memory allows to select appropriate options of social behavior to environmental adaptation contexts. Failures of this process lead to deficits in the action planning and sequence of events, which reverberate at a slower speed in the generation of action, deficiency in planning and problem solving, a classic behavioral phenotype of Schizophrenia [28]. In addition to this, changes in the short-term memory evidenced by [26], that when using a list of words to evaluate the short-term memory demonstrated inferiority in the processing and retention of information by schizophrenics compared to normal subjects. In contrast, implicit memory appears to be intact in the sepatients [10].
The commitment of some structures such as the prefrontal cortex, striatal-frontal and temporal, appear to be related to them nemonic failures in schizophrenics [5,29], in the same way that the deficiency of dorsolateral prefrontal cortex interferes in the ability to maintain active targets in working memory [16]. Neuroimaging studies indicate a change in the activation of the secircuits and similarities in deficits mechanisms in memory between patients with schizophrenia and Alzheimer's disease, with possible involvement of similar areas in both pathologies [5,27].
Abnormal activation patterns of CNS areas (i.e., prefrontal cortex and hippocampus) occur in processes to evoke the information in the hippocampus (Figure 1). In particular, the interactions between these regions of the brain in processing and evocation of memories are proposed based on transformation of time scales and stimuli sequences in a set of codes that are able to be consolidated. This fact is evidenced through the adaptive learning models, which exhibits a different spectrum of hippocampal cells in synchronization and modulation on learning of daily or conditional events [30], as well as analysis of behavioral phenotypes in neurological disorders (i.e., Schizophrenia, Alzheimer's) with timing methodologies and organization of events highlighted by tasks that require learning [31-33]. In this sense, it is evident a critical role of the hippocampus in association with cortical and subcortical areas in the temporal organization and evocation of consolidated memories [34]. Furthermore, studies demonstrate that schizophrenics have deficits in cortico-hippocampal connections, since have participation in separation of time pattern, processing, and consolidation of memory [24,35].

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