Neuroscience
-
Object recognition requires differentiation across different objects and generalization across views of the same object. We previously demonstrated that discrimination of object images at several views without any possibility of association was enough to achieve object recognition within a certain range of viewing angles and confirmed the response tolerance of monkey inferotemporal cells within a similar range of viewing angles. However, neither behavioral object recognition nor electrophysiological response tolerance was complete across views. ⋯ When monkeys were trained to discriminate objects at several views, we found that they could discriminate the trained objects regardless of the eventual change in viewing angle, and confirmed a response tolerance at the population level over a large viewing angle range covering all the viewpoints experienced. At the cell population level, such overtraining leads to significantly higher neural response similarity for views of the same objects than for views of different objects regardless of the extent of viewing angle separation. These results suggest a possible method of view-invariant object recognition development.
-
This study aims to investigate the value of diffusion kurtosis imaging (DKI) in assessing microstructural changes associated with cognitive impairment in chronic traumatic brain injury (TBI). At 7 months, six TBI rats and six control rats underwent Morris water maze (MWM) tests, followed by DKI examinations. DKI parameters were measured in bilateral cortex, hippocampus, and callosum. ⋯ Further correlational study showed a positive relationship between MK and NeuN, MD and MBP in ipsilateral cortex, and a negative relationship between MK and Iba-1, MBP in ipsilateral cortex and hippocampus (P < 0.05). The MK in ipsilateral cortex and hippocampus were also correlated with MWM test results (P < 0.05). Our study suggests that DKI could be used to assess the microstructural changes associated with cognitive impairment in chronic TBI.
-
Using data from time-resolved cortical stimulation, intracranial neural recordings, and focal surgical resections, Lee et al. (2018) demonstrate that a small area within left posterior superior temporal gyrus (pSTG) supports the ability to produce functional morphemes but not other basic aspects of language production or comprehension. These findings are intriguing because they raise important questions about the functional architecture of language processing, including critically, the relationship between production and comprehension. Here, we highlight some of the puzzles that remain and that we hope will guide future empirical explorations of the cognitive and neural mechanisms that support our capacity for language.
-
Chronic cocaine exposure produces enduring neuroadaptations in the brain's reward system. Persistence of early cocaine-evoked neuroadaptations in the ventral tegmental area (VTA) is necessary for later synaptic alterations in the nucleus accumbens (NAc), suggesting a temporal sequence of neuroplastic changes between these two areas. However, the molecular nature of the signal that mediates this sequential event is unknown. ⋯ Results showed that intra-VTA ZIP microinfusion successfully blocked cocaine-evoked synaptic enhancement in the VTA and the expected AMPA/NMDA ratio decrease in the NAc following cocaine sensitization. ZIP microinfusions also blocked the expected AMPA/NMDA ratio increase in the NAc following cocaine withdrawal. These results suggest that a persistent increase in AMPA/NMDA ratio, mediated by aPKCs, could be the molecular signal that enables the VTA to elicit synaptic alterations in the NAc following cocaine administration.
-
Neonatal hypoxic-ischemic brain damage (HIBD) is a cerebral hypoxic-ischemic disease caused by a variety of insults during the perinatal period, leading to varying degrees of cognitive dysfunction. Mesenchymal stem cells play an important role in functional recovery, but the mechanism is not yet clear. It has been reported that HIF-1
and PTEN are involved in the process of hypoxia-ischemia, but the specific roles that these proteins play remains to be understood. ⋯ Apoptosis was increased when HIF-1 was inhibited, but neurons remained protected when PTEN was suppressed. We further established that HIF-1 was enriched at the PTEN promoter both in BMSCs and hippocampal neurons, with increased enrichment under hypoxic conditions, leading to reduced transcription of PTEN. Our findings support the conclusion that CoCl2 preconditioning of BMSCs can simulate hypoxic conditions and can protect OGD neurons, an effect that is mediated through activation of the HIF-1 system and repression of PTEN transcription.