(What) can patients with semantic dementia learn?

Semantic Dementia (SD) is a neurodegenerative disease characterised by progressive deterioration of semantic knowledge, resulting in diminished understanding of concepts, whether encountered in verbal or non-verbal form. Over the past three decades, a number of studies employing a range of treatment techniques and learning methods have examined whether patients with SD can relearn previously known concepts or learn and retain new information. In this article, we review this research, addressing two main questions: a) Can aspects of semantic knowledge that are 'lost' due to degeneration be re-acquired? b) How much do other memory systems (working and episodic memory) interact with and depend on semantic memory? Several studies demonstrate successful relearning of previously known words and concepts in SD, particularly after regular, prolonged practice; but this success tends to diminish once practice ceases, and furthermore often fails to generalise to other instances of the same object/concept. This pattern suggests that, with impaired semantic knowledge, learning relies to an abnormal extent on perceptual factors, making it difficult to abstract away from the specific visual or other perceptual format in which a given concept has been trained. Furthermore, the impact of semantic 'status' of a word or object on both working and episodic memory indicates pervasive interaction of these other memory systems with conceptual knowledge.

The Lived Experience of Parent Caregivers of Adolescents with Mental Illness: A Phenomenological Study.

Background: The challenges faced by parents of adolescents with mental disorders are profound and multifaceted. Therefore, this study aimed to explore the lived experiences and concerns of parents of adolescents with mental disorders in Oman. Methods: Interpretative phenomenological analysis was employed in this study. In-depth interviews were done with twenty caregivers from June 2021 to the end of December 2022. Data collection continued until saturation was reached, ensuring a thorough understanding of the phenomena under investigation, and thematic analysis was applied to identify and examine the recurring patterns within the data. Results: Three primary themes emerged from the data analysis including Emotional Burden and Guilt, Treatment Concerns, and Fear of the Future. Parents' experiences during their adolescents' diagnosis revealed a profound emotional struggle, encompassing anxiety, frustration, and occasional confusion as they grappled with understanding their children's illness and navigating unpredictable behaviors. The exploration of seeking treatment highlighted the complexity of their experiences. However, a persistent sense of uncertainty regarding their children's future was a consistent thread irrespective of the chosen treatment path. Conclusion: This study aimed to investigate the complex challenges faced by caregivers of adolescents suffering from mental disorders, underscoring the vital need for tailored interventions and robust support systems to address these intricate issues. The findings highlight the importance of heightened awareness, improved access to psychotherapeutic resources, and comprehensive caregiver support.

The lived experience of Omani adolescents and young adults with mental illness: A qualitative study.

There is currently limited knowledge about the firsthand experiences of adolescents and young adults with mental health problems and the meanings they ascribe to these experiences, particularly within Arab countries. This study, therefore, aimed to explore the lived experience of Omani adolescents and young adults with a mental health problem. A sample of 15 participants aged 13-22 diagnosed with a range of mental health problems took part in the study. A qualitative interview guide consisting of open-ended questions was used to allow participants to speak in-depth about their experiences. Using the thematic analysis approach to uncover patterns in the data, three major themes emerged: "living in darkness", "perilous journey" and "uncertain future". Results show that the progress of adolescents and young adults with mental health problems is characterized by several challenges; the most significant of which is having insufficient knowledge about their illness, leading to unnecessary delays in their treatment. These findings shed light on the breadth and depth of the experience of adolescents and young adults with mental health problems and lay the groundwork for further examinations. Implications lie in the development of approaches for preventing or mitigating difficulties faced by adolescents and young adults with mental health problems.

Brain correlates of action word memory revealed by fMRI.

Understanding language semantically related to actions activates the motor cortex. This activation is sensitive to semantic information such as the body part used to perform the action (e.g. arm-/leg-related action words). Additionally, motor movements of the hands/feet can have a causal effect on memory maintenance of action words, suggesting that the involvement of motor systems extends to working memory. This study examined brain correlates of verbal memory load for action-related words using event-related fMRI. Seventeen participants saw either four identical or four different words from the same category (arm-/leg-related action words) then performed a nonmatching-to-sample task. Results show that verbal memory maintenance in the high-load condition produced greater activation in left premotor and supplementary motor cortex, along with posterior-parietal areas, indicating that verbal memory circuits for action-related words include the cortical action system. Somatotopic memory load effects of arm- and leg-related words were observed, but only at more anterior cortical regions than was found in earlier studies employing passive reading tasks. These findings support a neurocomputational model of distributed action-perception circuits (APCs), according to which language understanding is manifest as full ignition of APCs, whereas working memory is realized as reverberant activity receding to multimodal prefrontal and lateral temporal areas.

What's "up"? Impaired Spatial Preposition Processing in Posterior Cortical Atrophy.

This study seeks to confirm whether lesions in posterior regions of the brain involved in visuo-spatial processing are of functional relevance to the processing of words with spatial meaning. We investigated whether patients with Posterior Cortical Atrophy (PCA), an atypical form of Alzheimer's Disease which predominantly affects parieto-occipital brain regions, is associated with deficits in working memory for spatial prepositions. Case series of patients with PCA and matched healthy controls performed tests of immediate and delayed serial recall on words from three lexico-semantic word categories: number words (twelve), spatial prepositions (behind) and function words (e.g., shall). The three word categories were closely matched for a number of psycholinguistic and semantic variables including length, bi-/tri-gram frequency, word frequency, valence and arousal. Relative to controls, memory performance of PCA patients on short word lists was significantly impaired on spatial prepositions in the delayed serial recall task. These results suggest that lesions in posterior parieto-occipital regions specifically impair the processing of spatial prepositions. Our findings point to a pertinent role of posterior cortical regions in the semantic processing of words with spatial meaning and provide strong support for modality-specific semantic theories that recognize the necessary contributions of sensorimotor regions to conceptual semantic processing.

Flexibility in Language Action Interaction: The Influence of Movement Type.

Recent neuropsychological studies in neurological patients and healthy subjects suggest a close functional relationship between the brain systems for language and action. Facilitation and inhibition effects of motor system activity on language processing have been demonstrated as well as causal effects in the reverse direction, from language processes on motor excitability or performance. However, as the documented effects between motor and language systems were sometimes facilitatory and sometimes inhibitory, the "sign" of these effects still remains to be explained. In a previous study, we reported a word-category-specific differential impairment of verbal working memory for concordant arm- and leg-related action words brought about by complex sequential movements of the hands and feet. In this article, we seek to determine whether the sign of the functional interaction between language and action systems of the human brain can be changed in a predictable manner by changing movement type. We here report that the sign of the effect of motor movement on action word memory can be reversed from interference to facilitation if, instead of complex movement sequences, simple repetitive movements are performed. Specifically, when engaged in finger tapping, subjects were able to remember relatively more arm-related action words (as compared to control conditions), thus documenting an enhancement of working memory brought about by simple hand movements. In contrast, when performing complex sequences of finger movements, an effector-specific degradation of action word memory was found. By manipulating the sign of the effect in accord with theory-driven predictions, these findings provide support for shared neural bases for motor movement and verbal working memory for action-related words and strengthen the argument that motor systems play a causal and functionally relevant role in language processing semantically related to action.

Semantic word category processing in semantic dementia and posterior cortical atrophy.

There is general agreement that perisylvian language cortex plays a major role in lexical and semantic processing; but the contribution of additional, more widespread, brain areas in the processing of different semantic word categories remains controversial. We investigated word processing in two groups of patients whose neurodegenerative diseases preferentially affect specific parts of the brain, to determine whether their performance would vary as a function of semantic categories proposed to recruit those brain regions. Cohorts with (i) Semantic Dementia (SD), who have anterior temporal-lobe atrophy, and (ii) Posterior Cortical Atrophy (PCA), who have predominantly parieto-occipital atrophy, performed a lexical decision test on words from five different lexico-semantic categories: colour (e.g., yellow), form (oval), number (seven), spatial prepositions (under) and function words (also). Sets of pseudo-word foils matched the target words in length and bi-/tri-gram frequency. Word-frequency was matched between the two visual word categories (colour and form) and across the three other categories (number, prepositions, and function words). Age-matched healthy individuals served as controls. Although broad word processing deficits were apparent in both patient groups, the deficit was strongest for colour words in SD and for spatial prepositions in PCA. The patterns of performance on the lexical decision task demonstrate (a) general lexicosemantic processing deficits in both groups, though more prominent in SD than in PCA, and (b) differential involvement of anterior-temporal and posterior-parietal cortex in the processing of specific semantic categories of words.

Motor cognition-motor semantics: action perception theory of cognition and communication.

A new perspective on cognition views cortical cell assemblies linking together knowledge about actions and perceptions not only as the vehicles of integrated action and perception processing but, furthermore, as a brain basis for a wide range of higher cortical functions, including attention, meaning and concepts, sequences, goals and intentions, and even communicative social interaction. This article explains mechanisms relevant to mechanistic action perception theory, points to concrete neuronal circuits in brains along with artificial neuronal network simulations, and summarizes recent brain imaging and other experimental data documenting the role of action perception circuits in cognition, language and communication.

Moving the hands and feet specifically impairs working memory for arm- and leg-related action words.

Language and action systems of the human brain are functionally interwoven. Speaking about actions and understanding action-related speech sparks the motor system of the human brain and, conversely, motor system activation has an influence on the comprehension of action words and sentences. Although previous research has shown that motor systems become active when we understand language, a major question still remains whether these motor system activations are necessary for processing action words. We here report that rhythmic movements of either the hands or the feet lead to a differential impairment of working memory for concordant arm- and leg-related action words, with hand/arm movements predominantly impairing working memory for words used to speak about arm actions and foot/leg movements primarily impairing leg-related word memory. The resulting cross-over double dissociation demonstrates that body part specific and meaning-related processing resources in specific cortical motor systems are shared between overt movements and working memory for action-related words, thus documenting a genuine motor locus of semantic meaning.