Inhibition of the LH Surge by Restraint Stress in Cyclic Rats: Studies on the Role of GABAA and GABAB Receptors

There is evidence that stress can alter the activity in the brain of gamma-aminobutyricacid (GABA), a neurotransmitter that has been implicated in the regulation of LH secretion. In the present study the role of GABA in the restraint stress-induced inhibition of the LH surge was investigated in the intact cyclic rat. Intracerebroventricular (icv) administration of the GABAA receptor agonist muscimol (0.1, 0.5 or 1 μg) 5 min before the presumed onset of the pro-oestrous LH surge (at 0900 h) caused a dose dependent suppression of the surge. A single dose of the GABAB receptor agonist baclofen (1 μg; icv) injected at 0855 h postponed the onset of the LH surge, and repeated injections at 0855 and 1130 h suppressed the surge. These data indicate that GABA-ergic activity in the brain can inhibit the LH surge in the cyclic rat via GABAA and GABAB receptors. Pro-oestrous rats were subjected to 5 hrs of restraint starting at 0855 h. Pretreatment with the GABAA receptor antagonist bicuculine (1 μg; icv) at 0840, 0940 and 1040 h or pretreatment with the GABAB receptor antagonist phaclofen (10 μg; icv) at 0840 h were ineffective in preventing the restraint-induced inhibition of the LH surge. The results suggest that GABAA and GABAB receptors are not involved in the inhibitory effect of restraint stress on the LH surge.     

Neural substrates of the ‘low‐level’ system for speech articulation: Evidence from primary opercular syndrome

We describe a patient with progressive disorder of speech, without language impairment (opercular syndrome). Morphometric analysis confirmed asymmetric volume reduction of the precentral areas (>left). Diffusion imaging showed significant white matter changes in the left frontal lobe, with specific involvement of the left corticobulbar tract and connections between supplementary/pre‐supplementary motor areas and the frontal operculum (frontal aslant tract). We suggest that the organization of expressive language includes a ‘low level’ motor system principally distributed in the left hemisphere that shows specific susceptibility to neurodegeneration, distinct from neural systems subtending praxic, and cognitive aspects of language.     

Naming of grammatical classes in frontotemporal dementias: linguistic and non linguistic factors contribute to noun-verb dissociation

We studied noun and verb naming in three main variants of frontotemporal dementia: the frontal variant(Fv-FTD), primary progressive aphasia (PPA) and semantic dementia (SD). We further distinguished PPA in nonfluent and fluent forms and restricted diagnosis of SD to subjects with progressive semantic breakdown leading to agnosia for words and objects. Fv-FTD and nonfluent-PPA named objects better than actions, SD showed an inverse dissociation and no specific pattern emerged in fluent-PPA. In this last group, in spite of the broad definition of fluent aphasia, quite heterogeneous patterns of language disorders and word class dissociation emerged when single-subject analyses were performed. In fv-FTD correlations between executive tasks and action naming were stronger than between executive tasks and object naming. We conclude that both linguistic and non linguistic factors, in particular an executive deficit, contribute to grammatical class dissociation. We also suggest that the fluent vs. nonfluent distinction does not reflect the complexity of primary aphasia.     

Can residual lexical knowledge concern word form rather than word meaning?

We described a patient with a dramatic deficit of both word comprehension and naming but with good preservation of visual pictorial semantics. On word-picture matching, his performances were slightly better than expected based on the observed lexical semantic disorder; in addition, the patient, who maintained good preservation of his underlying phonology, showed a tendency to point to the picture phonologically related to the target. In order to interpret these data, we advanced the hypothesis that the patient, in spite of his virtually complete inability to name, would be able, in a word-picture matching task, to "covertly" (i.e., preverbally) retrieve the name from the picture and to use this name to attempt a match with the phonological form of the stimulus word. This mechanism, that we called "phonological" comprehension, would allow the identification of the correct target and would explain the choice of the phonologically related foil that was sometimes selected.     

Letter Dyslexia in a Letter-by-Letter Reader

We describe a letter-by-letter patient who produced misreading errors in both letters in isolation and in words. All errors were visual in nature. We hypothesized an access deficit to the abstract visual representation of letters that prevents letter identification. This deficit could account for the patient's letter-by-letter behavior, since each letter constituted a potential identification problem. An access deficit, moreover, could also explain the patient's letter visual errors. In access processing, in fact, the letters sharing common structural features in their abstract representations were the ones more frequently mismatched.     

Neuropsychological Consequences of Opiate Use

Approximately 3.7 million individuals have used heroin and other opiate substances in their lifetime. Despite increasing knowledge of the effects of heroin, it remains the most abused opiate and use among adults has recently increased. The empirical literature examining the neurocognitive effects of acute and chronic opioid use remains limited; however, findings to date suggest that the use of opiates has both acute and long-term effects on cognitive performance. Neuropsychological data indicate deficits in attention, concentration, recall, visuospatial skills and psychomotor speed with both acute and chronic opioid use. The long-term effects of opiate use appear to have the greatest impact on executive functions, including the ability to shift cognitive set and inhibit inappropriate response tendencies. Factors that contribute to addiction and recovery are also discussed, as it is difficult to disentangle the effects of opiate use on cognitive performance from other factors that may affect neurobehavioral measures.     

Grammatical class effects in brain-damaged patients: functional locus of noun and verb deficit

Two patients are described with grammatical class dissociation: CG, a semantic-dementia patient who presented a disproportionate impairment of nouns compared to verbs; SA, a patient with a left parietal lesion who presented impaired sentence production and a disproportionate deficit for verbs compared to nouns. The results are discussed within the current models on semantic memory and lexical access.     

Disorders of classificatory activity in aphasia

Two nonverbal tasks of classificatory activity ("class inclusion" and "class intersection") were administered to 46 aphasics, 28 normal controls, 19 nonaphasic left-brain-damaged and 17 right-hemisphere-damaged patients in order to study if aphasic patients are more impaired than nonaphasic brain-damaged patients on these two tasks of elementary logic and if a relationship exists within the aphasic patients between inability to perform the tasks of classifiactory activity and impairment of the semantic-lexical level of integration of language. Results were for the most part in line with expectations because aphasics scored worse than normal controls and nonaphasic brain-damaged patients (even if the difference reached the level of statistical significance only on the test of "class intersection") and within the aphasic patients the worst results were obtained by subjects presenting clear signs of semantic-lexical disintegration.     

Anomia with and without lexical comprehension disorders

Anomic patients are usually described as free from language comprehension disorders, but the status of lexical comprehension in anomia is still controversial. Most anomic patients are impaired on tasks of semantic-lexical discrimination, but some of them do not present clear signs of semantic-lexical deficit at the receptive level. The aim of the present research was to elucidate the nature of word-finding disturbances by contrasting results obtained by anomic patients with and without lexical comprehension disorders on a number of variables, namely severity of anomia, implicit knowledge of words that patients failed to name, presence of verbal-semantic paraphasias, and scores obtained on a test of phoneme discrimination and on the "Token Test." The results of our investigation seem to suggest that there are two types of anomia, caused by the impairment of two different sets of mechanisms. In "purely expressive anomia" the locus of defect seems to be near to the stage in which the selected lexical item is specified into the appropriate phonological form. In "anomia with lexical comprehension disturbances" the locus of defect seems to be much deeper within the lexicon, so that the semantic disorder affects both the expressive and the receptive levels in a roughly comparable manner.     

Cognitive analysis of a case of pure dysgraphia

An Italian patient with a pure dysgraphia who incorrectly spelled words and nonwords is described. The spelling errors made by the patient were not affected by lexical factors (e.g., frequency, form class) and were qualitatively the same for words and nonwords. The pattern of writing performance is discussed in relation to current models of writing and, specifically, in relation to the role of the Output Grapheme Buffer and Phoneme-Grapheme Conversion in writing.