André Roch Lecours

Areas of brain activation in males and females during viewing of erotic film excerpts

Various lines of evidence indicate that men generally experience greater sexual arousal (SA) to erotic stimuli than women. Yet, little is known regarding the neurobiological processes underlying such a gender difference. To investigate this issue, functional magnetic resonance imaging was used to compare the neural correlates of SA in 20 male and 20 female subjects. Brain activity was measured while male and female subjects were viewing erotic film excerpts. Results showed that the level of perceived SA was significantly higher in male than in female subjects. When compared to viewing emotionally neutral film excerpts, viewing erotic film excerpts was associated, for both genders, with bilateral blood oxygen level dependant (BOLD) signal increases in the anterior cingulate, medial prefrontal, orbitofrontal, insular, and occipitotemporal cortices, as well as in the amygdala and the ventral striatum. Only for the group of male subjects was there evidence of a significant activation of the thalamus and hypothalamus, a sexually dimorphic area of the brain known to play a pivotal role in physiological arousal and sexual behavior. When directly compared between genders, hypothalamic activation was found to be significantly greater in male subjects. Furthermore, for male subjects only, the magnitude of hypothalamic activation was positively correlated with reported levels of SA. These findings reveal the existence of similarities and dissimilarities in the way the brain of both genders responds to erotic stimuli. They further suggest that the greater SA generally experienced by men, when viewing erotica, may be related to the functional gender difference found here with respect to the hypothalamus. Hum. Brain Mapping 16:1–13, 2002.

Neural correlates of lexical and sublexical processes in reading

The purpose of the present study was to compare the brain regions and systems that subserve lexical and sublexical processes in reading. In order to do so, three types of tasks were used: (i). silent reading of very high frequency regular words (lexical task); (ii). silent reading of nonwords (sublexical task); and, (iii). silent reading of very low frequency regular words (sublexical task). All three conditions were contrasted with a visual/phonological baseline condition. The lexical condition engaged primarily an area at the border of the left angular and supramarginal gyri. Activation found in this region suggests that this area may be involved in mapping orthographic-to-phonological whole word representations. Both sublexical conditions elicited significantly greater activation in the left inferior prefrontal gyrus. This region is thought to be associated with sublexical processes in reading such as grapheme-to-phoneme conversion, phoneme assembly and underlying verbal working memory processes. Activation in the left IFG was also associated with left superior and middle temporal activation. These areas are thought to be functionally correlated with the left IFG and to contribute to a phonologically based form of reading. The results as a whole demonstrate that lexical and sublexical processes in reading activate different regions within a complex network of brain structures.

Agrammatism in Sentence Production without Comprehension Deficits: Reduced Availability of Syntactic Structures and/or of Grammatical Morphemes? A Case Study

A French-speaking patient with Brocas aphasia--following a left-hemisphere lesion involving the sylvian region but sparing Brocas area--is presented. Like G. Miceli, A. Mazzuchi, L. Menn, and H. Goodglasss (1983, Brain and Language, 19, 65-97) case 2, this patient produces agrammatic speech in the absence of any comprehension deficit. Unlike Micelis patient, though, agrammatic speech can be observed in all sentence production tasks (from spontaneous speech to repetition, oral reading, and writing) whereas production of individual words--be they open class or closed class--is almost always intact. On the basis of extensive (psycho)linguistic testing, it is argued that this patients deficit is not central and not crucially syntactic (at least) at the level of knowledge but seems to disrupt specifically those (automatic?) processes responsible for both retrieval and production of free-standing grammatical morphemes whenever they have to be inserted into phrases and sentences.

The mt-86 β aphasia battery: A subset of normative data in relation to age and level of school education

Abstract The MT-86 β version of the Montreal-Toulouse Aphasia Battery has been devised for the clinical assessment of adult French speakers with language disorders. It includes 22 subtests for the appraisal of linguistic abilities in both encoding and decoding oral and written speech. The whole battery has been administered to a total of 143 neurologically healthy adults. This report deals with normative data for seven of the MT-86 β subtests, i.e. repetition, reading aloud, writing to dictation, copy, naming, verbal fluency, word and sentence picture-matching. These subtests correspond to classical tests used in aphasia batteries and are often discussed in the literature in relation to the effect of ageing of linguistic function. Mean scores, standard deviations and score ranges are reported and cut-off scores corresponding to the fifth percentile are suggested. Main effects of both age and education were found to exist in five subtests. Differences indicate better scores among younger versus older adult...

Jules Dejerine and His Interpretation of Pure Alexia

Dejerines interpretation of pure alexia is routinely mentioned in all neuropsychological textbooks, yet the details of his account and the evidence on which it is based have never been subjected to a critical analysis. We provide such an evaluation in this paper, summarizing the behavioral data that Dejerine presented in his now famous case report and the theoretical framework he adopted to explain the phenomenon of alexia without agraphia. We also provide a link between Dejerines work and current hypotheses on the nature of the syndrome.

Proportional localization system for anatomical interpretation of cerebral computed tomograms.

The existence of individual variations in size and shape of the human brain constitutes a problem for the anatomical interpretation of brain reconstructed images obtained from scanning devices; it is, for example, responsible for most of the inaccuracies in reading CT scans. One way to account for these variations is to use a proportional localization system. In the 1960s a group of neurosurgeons developed such a system based on two pivotal intracerebral structures, the anterior and the posterior commissures; they published an atlas consisting of horizontal, coronal, and sagittal brain sections interpreted in the proportional system. The atlas also included standard proportional brain schemes based on anatomical and radiological studies on large numbers of individuals. In this article we report a target localization experiment that we carried out to determine if this atlas could be used as a reference for a more accurate interpretation of CT and, eventually, of positron emission tomography (PET) and nuclear magnetic resonance (NMR) scans. Ten radiopaque small targets were inserted through the skull in the cortex of three cadavers; head CT was performed, and the atlas was used for predicting the cortical location of the targets seen on the CT images: The predictions were confirmed. These results strongly support the use of the proportional atlas for the interpretation of CT as well as of PET and NMR scans.

The contribution of the right cerebral hemisphere to the recovery from aphasia: a single longitudinal case study

We examined the role of the right cerebral hemisphere in the recovery from aphasia of HJ, a 50-year-old right-handed and unilingual man who suffered from severe aphasia caused by an extensive left hemisphere (LH) lesion. He was followed-up over 10 months at 4-month intervals, with a lateralized lexical decision task (LDT), an attentional task, and a language battery. Testing started when HJ was 2 months poststroke. In the LDT, words were presented to central vision or lateralized to the left or right visual hemifield. At each test period, we examined the effect of the degree of imageability (high vs. low), and the grammatical class (noun vs. verb) of the targets on HJs response times and error rates, with left visual field, right visual field, and central vision presentations. The results of the experiment showed that the pattern obtained with the LDT could not be accounted for by fluctuations in attention. There was an interaction of grammatical class with degree of imageability with left visual field displays only. The right hemisphere (RH) was faster with high-imageability words than with low-imageability words, regardless of their grammatical class. There was also an overall RH advantage on response times at 2 and 6 months after onset. This RH predominance coincided with a major recovery of language comprehension and the observation of semantic paralexias, while no major change in language expression was observed at that point. Ten months after onset, the pattern of lateralization changed, and response times for the LDT with either presentation site were equivalent. This LH improvement coincided with some recovery of language expression at the single-word level. The results of this study suggest that, in cases of severe aphasia caused by extensive LH lesions, the RH may play an important role in the recovery process. Furthermore, these results show that the contribution of the two cerebral hemispheres to recovery may vary overtime and affect specific aspects of language.

The role of sublexical graphemic processing in reading.

Dual-route models of reading postulate the existence of two separate mechanisms: The lexical route allows words to be recognized in their holistic form, and the sublexical route proceeds by converting the written sublexical entities of a word or a nonword into their corresponding phonological equivalents. Sublexical reading is assumed to require three stages of processing: graphemic parsing, graphophonemic conversion, and phoneme blending. This study provides evidence in favor of the existence of a graphemic parsing process which occurs prior to grapheme-phoneme conversion. A group of normal subjects read nonwords which contained multiletter graphemes significantly more slowly than graphemically simple nonwords. These results, best interpretable in the context of a recent dual-route model of reading, confirm previous data obtained in pathology which suggest the functional independence of this cognitive procedure.

Lexical reading in Spanish: Two cases of phonological dyslexia

The way spoken language is represented by orthographic structure is thought to influence the cognitive reading mechanism for a language, and therefore language breakdown patterns should reflect this. The present article focuses on two patients, both monolingual native Spanish speakers, who were able to read words but showed great difficulty in reading nonwords. This finding could be attributed to the fact that these patients were reading globally using a lexical route. This pattern of reading behavior is known as phonological dyslexia. It has been argued that lexical reading is not an option for Spanish readers since its orthography is highly regular. Our findings contradict this hypothesis and support the view that cognitive reading mechanisms are universal.

Two Different Dysgraphic Syndromes in a Regular Orthography, Spanish☆

In opaque orthographies, such as English and French, three central dysgraphic syndromes have been described: surface dysgraphia, phonological dysgraphia, and deep dysgraphia. Writing breakdown patterns reveal that spelling can proceed by phoneme-to-grapheme conversion, or by a more direct or lexical approach. Ardila et al. (1989, 1991) claim that for Spanish speakers a lexical strategy for reading and writing is not an option due to the regularity of the orthography of this language. In this study we report two clear cases of dysgraphia in Spanish, one of surface dysgraphia and another of phonological dysgraphia, where a dissociation between lexical and sublexical writing can be observed, thus contradicting Ardilas position.