The executive control of face memory

Abstract. Patients with frontal lobe damage and cognitively normal elderly individuals demonstrate increased susceptibility to false facial recognition. In this paper we review neuropsychological evidence consistent with the notion that the common functional impairment underlying face memory distortions in both subject populations is a context recollection/source monitoring deficit, coupled with excessive reliance on relatively preserved facial familiarity signals in recognition decisions. In particular, we suggest that due to the breakdown of strategic memory retrieval, monitoring, and decision operations, individuals with frontal lobe impairment caused by focal damage or age-related functional decline do not have a reliable mechanism for attributing the experience of familiarity to the correct context or source. Memory illusions are mostly apparent under conditions of uncertainty when the face cue does not directly elicit relevant identity-specific contextual information, leaving the source of familiarity unspecified or ambiguous. Based on these findings, we propose that remembering faces is a constructive process that requires dynamic interactions between temporal lobe memory systems that operate in an automatic or bottom-up fashion and frontal executive systems that provide strategic top-down control of recollection. Executive memory control functions implemented by prefrontal cortex play a critical role in suppressing false facial recognition and related source memory misattributions

Lexical Retrieval Treatment for Primary Progressive Aphasia

Similar to aphasia due to stroke, lexical retrieval difficulties are pervasive in primary progressive aphasia (PPA).  In fact, increasing word retrieval difficulties typically herald the onset of PPA, regardless of the underlying etiology or PPA subtype.  For that reason, behavioral interventions to improve or sustain word retrieval abilities have considerable potential to enhance language performance in PPA.  We report here on positive responses to lexical retrieval treatment in two individuals with fluent progressive aphasia profiles.  The treatment approach extends work accomplished in stroke-related aphasia that promotes strategic engagement of residual language abilities to promote self-cueing to resolve lexical retrieval difficulties

Phonological processing in primary progressive aphasia

Primary progressive aphasia (PPA) is a debilitating condition wherein speech and language deteriorate as a result of neurodegenerative disease. Three variants of PPA are now recognized, each of which shows a unique constellation of speech-language deficits and pattern of underlying atrophy in the brain (Gorno-Tempini et al., 2011). The variants include a nonfluent/agrammatic type (nfvPPA), characterized by syntactic and motor speech deficits and fronto-insular atrophy in the left hemisphere. The semantic variant (svPPA) shows degradation of semantic knowledge in the context of anterior and inferior temporal lobe atrophy (left hemisphere greater than right). Finally, the more recently characterized logopenic variant (lvPPA) shows impairments in naming and repetition that are thought to be phonological in nature. This variant, associated with atrophy of temporoparietal regions in the left hemisphere, has also been referred to as the “phonological” variant of PPA due to observed deficits on tasks that require phonological storage (i.e., the “phonological loop”) and to the presence of phonological paraphasias in connected speech (Gorno-Tempini et al., 2008). Impaired phonological processing has been considered a unique feature of the logopenic variant of PPA, however, phonological skills have not been thoroughly characterized across the three variants. Recent models of the functional neuroanatomy of language propose two pathways by which speech is processed in the brain (Hickok & Poeppel, 2007). A dorsal pathway involving temporoparietal and posterior frontal structures is thought to be involved in mapping phonological representations onto articulatory representations. A ventral pathway located in the middle and inferior temporal lobes is considered crucial for mapping phonological representations onto lexical-semantic representations. Both the dorsal and ventral streams emanate from a common cortical region in posterior, superior temporal cortex/sulcus that appears critical to the mental representation of phonology. We investigated phonological processing in PPA, with the goal of identifying whether patterns of performance in the different variants support this functional-anatomical framework. Based on our knowledge of the locus of anatomical damage in the subtypes of PPA, we hypothesized that patients with damage to dorsal route structures (nonfluent and logopenic variants) would show greater impairment on phonological processing tasks, whereas patients with damage to ventral route structures (semantic variant) would show relative preservation of phonological abilities

Verbal Learning with the Right Hemisphere

TB

Efficient visual object and word recognition relies on high spatial frequency coding in the left posterior fusiform gyrus: Evidence from a case-series of patients with ventral occipito-temporal cortex damage

Recent visual neuroscience investigations suggest that ventral occipito-temporal cortex is retinotopically organized, with high acuity foveal input projecting primarily to the posterior fusiform gyrus (pFG), making this region crucial for coding high spatial frequency information. Because high spatial frequencies are critical for fine-grained visual discrimination, we hypothesized that damage to the left pFG should have an adverse effect not only on efficient reading, as observed in pure alexia, but also on the processing of complex non-orthographic visual stimuli. Consistent with this hypothesis, we obtained evidence that a large case series (n = 20) of patients with lesions centered on left pFG: 1) Exhibited reduced sensitivity to high spatial frequencies; 2) demonstrated prolonged response latencies both in reading (pure alexia) and object naming; and 3) were especially sensitive to visual complexity and similarity when discriminating between novel visual patterns. These results suggest that the patients' dual reading and non-orthographic recognition impairments have a common underlying mechanism and reflect the loss of high spatial frequency visual information normally coded in the left pFG

Functional neuroanatomy of reading in Czech: Evidence of a dual-route processing architecture in a shallow orthography

IntroductionAccording to the strong version of the orthographic depth hypothesis, in languages with transparent letter-sound mappings (shallow orthographies) the reading of both familiar words and unfamiliar nonwords may be accomplished by a sublexical pathway that relies on serial grapheme-to-phoneme conversion. However, in languages such as English characterized by inconsistent letter-sound relationships (deep orthographies), word reading is mediated by a lexical-semantic pathway that relies on mappings between word-specific orthographic, semantic, and phonological representations, whereas the sublexical pathway is used primarily to read nonwords.MethodsIn this study, we used functional magnetic resonance imaging to elucidate neural substrates of reading in Czech, a language characterized by a shallo worthography. Specifically, we contrasted patterns of brain activation and connectivity during word and nonword reading to determine whether similar or different neural mechanisms are involved. Neural correlates were measured as differences in simple whole-brain voxel-wise activation, and differences in visual word form area (VWFA) task-related connectivity were computed on the group level from data of 24 young subject. Trial-to-trial reading reaction times were used as a measure of task difficulty, and these effects were subtracted from the activation and connectivity effects in order to eliminate difference in cognitive effort which is naturally higher for nonwords and may mask the true lexicality effects.ResultsWe observed pattern of activity well described in the literature mostly derived from data of English speakers – nonword reading (as compared to word reading) activated the sublexical pathway to a greater extent whereas word reading was associated with greater activation of semantic networks. VWFA connectivity analysis also revealed stronger connectivity to a component of the sublexical pathway - left inferior frontal gyrus (IFG), for nonword compared to word reading.DiscussionThese converging results suggest that the brain mechanism of skilled reading in shallow orthography languages are similar to those engaged when reading in languages with a deep orthography and are supported by a universal dual-pathway neural architecture

Efficient Visual Object and Word Recognition Relies on High Spatial Frequency Coding in the Left Posterior Fusiform Gyrus: Evidence from a Case-Series of Patients with Ventral Occipito-Temporal Cortex Damage

Seeing a face in motion can improve face recognition in the general population, and studies of face matching indicate that people with face recognition difficulties (developmental prosopagnosia; DP) may be able to use movement cues as a supplementary strategy to help them process faces. However, the use of facial movement cues in DP has not been examined in the context of familiar face recognition. This study examined whether people with DP were better at recognizing famous faces presented in motion, compared to static. Methods: Nine participants with DP and 14 age-matched controls completed a famous face recognition task. Each face was presented twice across 2 blocks: once in motion and once as a still image. Discriminability (A) was calculated for each block. Results: Participants with DP showed a significant movement advantage overall. This was driven by a movement advantage in the first block, but not in the second block. Participants with DP were significantly worse than controls at identifying faces from static images, but there was no difference between those with DP and controls for moving images. Conclusions: Seeing a familiar face in motion can improve face recognition in people with DP, at least in some circumstances. The mechanisms behind this effect are unclear, but these results suggest that some people with DP are able to learn and recognize patterns of facial motion, and movement can act as a useful cue when face recognition is impaired

Exploring the Neural Substrates of Phonological Recovery <br />for Symposium: Neural Correlates of Recovery and Rehabilitation

Background Phonological alexia and agraphia are written language disorders characterized by disproportionate difficulty processing nonwords compared to real words, giving rise to an exaggerated lexicality effect in reading and spelling1-5. Lesion-deficit studies demonstrate that phonological alexia/agraphia are associated with left perisylvian damage resulting in a central phonological deficit that disrupts sublexical processing of sounds and associated graphemes. The writing impairment is typically more severe and persistent than the reading deficit due to increased task demands6. Some individuals with phonological impairment have concomitant lexical-semantic deficits resulting in global agraphia manifested by poor spelling of both real or nonwords. Behavioral treatment can strengthen phonological skills and improve written language7, but response to treatment varies. Here we examined treatment outcomes in a large cohort of patients to explore the relationship between phonological recovery and lesion location. Method Forty-one individuals with left hemisphere damage were evaluated and provided treatment to improve written spelling: 23 presented with global agraphia; another 18 had phonological agraphia. High-resolution brain scans were acquired and precise 3D lesion maps were generated following procedures outlined in Andersen, Rapcsak, & Beeson (2010) 8. Three treatment protocols were implemented as indicated by initial performance, and whenever possible, participants advanced to the next treatment in the sequence. Lexical spelling treatment strengthens item-specific orthographic representations for words. Individuals with global agraphia begin with this treatment, and trained items are used as “key words” to assist in retrieval of sound-letter correspondences during phonological treatment. Phonological treatment strengthens sound-letter correspondences and phonological manipulation skills for individuals with phonological agraphia and those with global agraphia who advance from lexical treatment. Interactive treatment follows phonological treatment. A problem-solving approach is trained to promote use of residual or retrained lexical and phonological knowledge to improve spelling. Results All individuals with global agraphia successfully completed lexical treatment and proceeded to phonological treatment. They mastered retraining of sound-letter and letter-sound conversions for consonants, but 10 of 25 were not able to meet criterion on all stages of phonological treatment and did not advance to interactive treatment. Thirteen individuals with global agraphia and 18 with phonological agraphia progressed through all components of phonological and interactive treatment. Figure 1 illustrates lesion overlays by outcome groups (low global, high global, phonological), with relevant pre-post treatment performances. Groups completing phonological and interactive treatment made significant improvements on phonological transcoding and manipulation tasks, and generalized improvement reading and spelling words and nonwords. Such improvements were not significant for the low global group. Analysis of brain damage relative to treatment gains on nonword spelling revealed that whereas frontal damage was common, the low global group had greater concomitant damage to superior temporal gyrus and sulcus (see Figure). Conclusions All participants improved written language abilities in response to treatment, but one subgroup was limited in their ability to regain phonological skills. Both anterior and posterior components of the perisylvian phonological network were damaged in that group. These findings are consistent with fMRI activation when healthy adults write nonwords, and provide insight regarding neural support necessary for phonological rehabilitation