Depletion of Perineuronal Nets Enhances Recognition Memory and Long-Term Depression in the Perirhinal Cortex.

Depletion of Perineuronal Nets Enhances Recognition Memory and Long-Term Depression in the Perirhinal Cortex.

J Neurosci. 2013 Apr 17; 33(16): 7057-7065
Romberg C, Yang S, Melani R, Andrews MR, Horner AE, Spillantini MG, Bussey TJ, Fawcett JW, Pizzorusso T, Saksida LM

Perineuronal nets (PNNs) are extracellular matrix structures surrounding cortical neuronal cell bodies and proximal dendrites and are involved in the control of brain plasticity and the closure of critical periods. Expression of the link protein Crtl1/Hapln1 in neurons has recently been identified as the key event triggering the formation of PNNs. Here we show that the genetic attenuation of PNNs in adult brain Crtl1 knock-out mice enhances long-term object recognition memory and facilitates long-term depression in the perirhinal cortex, a neural correlate of object recognition memory. Identical prolongation of memory follows localized digestion of PNNs with chondroitinase ABC, an enzyme that degrades the chondroitin sulfate proteoglycan components of PNNs. The memory-enhancing effect of chondroitinase ABC treatment attenuated over time, suggesting that the regeneration of PNNs gradually restored control plasticity levels. Our findings indicate that PNNs regulate both memory and experience-driven synaptic plasticity in adulthood. HubMed – depression

The Postsubiculum and Spatial Learning: The Role of Postsubicular Synaptic Activity and Synaptic Plasticity in Hippocampal Place Cell, Object, and Object-Location Memory.

J Neurosci. 2013 Apr 17; 33(16): 6928-6943
Bett D, Stevenson CH, Shires KL, Smith MT, Martin SJ, Dudchenko PA, Wood ER

Visual landmarks exert stimulus control over spatial behavior and the spatially tuned firing of place, head-direction, and grid cells in the rodent. However, the neural site of convergence for representations of landmarks and representations of space has yet to be identified. A potential site of plasticity underlying associations with landmarks is the postsubiculum. To test this, we blocked glutamatergic transmission in the rat postsubiculum with CNQX, or NMDA receptor-dependent plasticity with d-AP5. These infusions were sufficient to block evoked potentials from the lateral dorsal thalamus and long-term depression following tetanization of this input to the postsubiculum, respectively. In a second experiment, CNQX disrupted the stability of rat hippocampal place cell fields in a familiar environment. In a novel environment, blockade of plasticity with d-AP5 in the postsubiculum did not block the formation of a stable place field map following a 6 h delay. In a final behavioral experiment, postsubicular infusions of both compounds blocked object-location memory in the rat, but did not affect object recognition memory. These results suggest that the postsubiculum is necessary for the recognition of familiar environments, and that NMDA receptor-dependent plasticity in the postsubiculum is required for the formation of new object-place associations that support recognition memory. However, plasticity in the postsubiculum is not necessary for the formation of new spatial maps. HubMed – depression

The relationship between schizoaffective, schizophrenic and mood disorders in patients admitted at Mathari Psychiatric Hospital, Nairobi, Kenya.

Afr J Psychiatry (Johannesbg). 2013 Mar; 16(2): 110-117
Ndetei DM, Khasakhala L, Meneghini L, Aillon JL

OBJECTIVE: The prevalence of schizoaffective disorder (SAD) and the relationship between schizophrenia (SCZ), SAD and mood disorders (MD) in non-Western countries is unknown. To determine the prevalence of SAD and the relationship between SCZ, SAD and MD in relation to socio-demographic, clinical and therapeutic variables in 691 patients admitted at Mathari Psychiatric Hospital, Kenya. METHOD: A cross-sectional comparative study using both clinician and SCID-1 for DSM-IV diagnoses. RESULTS: Approximately twenty three percent (n=160) met DSM-IV criteria for SAD using SCID-1. There were significant differences between SCZ, SAD and MD regarding: affective and core symptoms of schizophrenia (with the exception of core symptoms of schizophrenia between SCZ and SAD); presence of past trauma; a past suicide attempt; and comorbidity with alcohol and drug abuse disorders. SAD and MD patients took significantly more mood stabilizers than SCZ patients. There were no significant differences between the three groups regarding socio-demographic variables, brief psychiatric rating scale scores, cognitive performance, anxiety and depressive symptoms, presence of obsessions, and usage of both antipsychotics and antidepressants. CONCLUSION: There is no distinct demarcation between the three disorders. This lends support to recent evidence suggesting that SAD might constitute a heterogeneous group composed of both SCZ and MD patients or a middle point of a continuum between SCZ and MD. HubMed – depression

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