Biomedical subjects

Daniela Montaldi

Publications and source records attributed to Daniela Montaldi.

5 recordsLinked to original sources

PubMed2006

Are mild head injuries as mild as we think? Neurobehavioral concomitants of chronic post-concussion syndrome.

BACKGROUND: Mild traumatic brain injury (MTBI) can sometimes lead to persistent postconcussion symptoms. One well accepted hypothesis claims that chronic PCS has a neural origin, and is related to neurobehavioral deficits. But the evidence is not conclusive. In the attempt to characterise chronic MTBI consequences, the present experiment used a group comparison design, which contrasted persons (a) with MTBI and PCS, (b) MTBI without PCS, and (c) matched controls. We predicted that participants who have experienced MTBI but show no signs of PCS would perform similar to controls. At the same time, a subgroup of MTBI participants would show PCS symptoms and only these volunteers would have poorer cognitive performance. Thereby, the performance deficits should be most noticeable in participants with highest PCS severity. METHOD: 38 patients with a single MTBI that had occurred at least 12 month prior to testing, and 38 matched controls, participated in the experiment. A combination of questionnaires and neuropsychological test batteries were used to assess the extent of PCS and related deficits in neurobehavioral performance. RESULTS: 11 out of 38 MTBI participants (29%) were found to suffer from PCS. This subgroup of MTBI patients performed poorly on neuropsychological test batteries. Thereby, a correlation was found between PCS symptom severity and test performance suggesting that participants with more pronounced PCS symptoms performed worse in cognitive tasks. In contrast, MTBI patients with no PCS showed performed similar to matched control. We further found that loss of consciousness, a key criterion for PCS diagnosis, was not predictive of sustained PCS. CONCLUSION: The results support the idea that MTBI can have sustained consequences, and that the subjectively experienced symptoms and difficulties in everyday situations are related to objectively measurable parameters in neurocognitive function.

Adult↗

PubMed2006

The neural system that mediates familiarity memory.

In recognition memory tests, feelings of familiarity for stimuli vary in strength. Increasing levels of felt familiarity should modulate activity in brain structures that mediate familiarity memory. We used this expectation to identify the neural system that underlies scene familiarity memory. Normal subjects studied pictures of scenes and 2 days later while undergoing event-related functional magnetic resonance imaging (fMRI) rated old and new pictures as novel, slightly familiar, moderately familiar, very familiar, or recollected, although they were specifically instructed not to try and recollect. Familiarity strength was, therefore, judged as absent (misses) or present at three levels of increasing strength. A parametric analysis showed that, as perceived strength of familiarity increased activity in the perirhinal cortex, insula and left superior temporal cortex declined linearly whereas activity in the left dorsomedial thalamus, left ventrolateral and anteromedial frontal cortex, posterior cingulate cortex, and left parietal neocortex increased linearly. Hippocampal activity was not modulated linearly or quadratically by changes in familiarity strength. Recollection activated the hippocampus, and left anterior and inferolateral frontal and parietal cortices more than strong familiarity. In contrast, no brain region that was unaffected by recollection (relative to misses and correct rejections) was modulated by variations in familiarity strength. The implications of these findings for the functional and neural bases of familiarity and recollection are considered.

Adult↗

PubMed2004

Induced gamma band responses: an early marker of memory encoding and retrieval.

Although mnemonic processes have been widely studied using event-related potentials (ERPs), memory-related oscillatory changes in the EEG have been relatively neglected. The aim of this study was to investigate memory encoding- and retrieval-related changes in the frequency domain. In particular, we focused on induced gamma band responses (GBRs), which are a candidate for the establishment and activation of widespread cell assemblies. At encoding, results revealed increased GBRs for subsequently recognised relative to subsequently forgotten items. At retrieval, recognised old stimuli were associated with higher GBRs compared to new stimuli. During encoding and retrieval GBR modulation preceded that of ERPs. Thus, GBRs might be a correlate of processes that onset earlier to those responsible for memory encoding and retrieval ERP effects.

Adolescent↗

PubMed2004

Recalling spatial information as a component of recently and remotely acquired episodic or semantic memories: an fMRI study.

Activations produced by the recall of episodic and semantic memories differing in spatial content and age were examined. Recall of recent episodic memories with differing spatial content activated the medial temporal lobes and the retrosplenial-posterior cingulate cortex-precuneus complex more than recall of recent semantic memories with similarly differing spatial content. Some of these differences related to the amount of spatial information recalled because spatially richer recent memories, regardless of whether they were episodic or semantic, activated the right posterior parahippocampal cortex, precuneus, and posterior parietal cortex more. This spatial effect was found to be independent of memory age for semantic memories, although some episodic-semantic memory differences, including one in the left hippocampus, were not age independent. Episodic-semantic memory recall activation differences are therefore probably a function of the amount recalled, memory age, and what is recalled, particularly with respect to spatial information.

Adult↗

PubMed2004

Dissociation between recall and recognition memory performance in an amnesic patient with hippocampal damage following carbon monoxide poisoning.

Some patients with relatively selective hippocampal damage have shown proportionate recall and recognition deficits. Moreover, familiarity as well as recollection have been found to be impaired in some of these patients. In contrast, other patients with apparently similar damage presented with relatively preserved recognition despite having severely impaired recall, and some of these patients have been shown to have preserved familiarity. We report here the case of an amnesic patient who suffered bilateral hippocampal damage and temporoparietal atrophy after carbon monoxide poisoning. On tests matched for difficulty, his recall performance was more severely impaired than his recognition memory, for verbal as well as for visual materials. Moreover, he performed within the range of healthy matched subjects on nine recognition tests out of ten. In a task using the process dissociation procedure, the patient's familiarity was preserved although his recollection was impaired. These findings indicate that recall and recognition memory can be dissociated in amnesic patients with hippocampal lesions even when temporoparietal cortical atrophy is also present.

Aged↗