Activity-Dependent β-Adrenergic Modulation of Low Frequency Stimulation Induced LTP in the Hippocampal CA1 Region

Abstractβ-Adrenergic receptor activation has a central role in the enhancement of memory formation that occurs during heightened states of emotional arousal. Although β-adrenergic receptor activation may enhance memory formation by modulating long-term potentiation (LTP), a candidate synaptic mechanism involved in memory formation, the cellular basis of this modulation is not fully understood. Here, we report that, in the CA1 region of the hippocampus, β-adrenergic receptor activation selectively enables the induction of LTP during long trains of 5 Hz synaptic stimulation. Protein phosphatase inhibitors mimic the effects of β-adrenergic receptor activation on 5 Hz stimulation–induced LTP, suggesting that activation of noradrenergic systems during emotional arousal may enhance memory formation by inhibiting protein phosphatases that normally oppose the induction of LTP

Improving language mapping in clinical fMRI through assessment of grammar.

IntroductionBrain surgery in the language dominant hemisphere remains challenging due to unintended post-surgical language deficits, despite using pre-surgical functional magnetic resonance (fMRI) and intraoperative cortical stimulation. Moreover, patients are often recommended not to undergo surgery if the accompanying risk to language appears to be too high. While standard fMRI language mapping protocols may have relatively good predictive value at the group level, they remain sub-optimal on an individual level. The standard tests used typically assess lexico-semantic aspects of language, and they do not accurately reflect the complexity of language either in comprehension or production at the sentence level. Among patients who had left hemisphere language dominance we assessed which tests are best at activating language areas in the brain.MethodWe compared grammar tests (items testing word order in actives and passives, wh-subject and object questions, relativized subject and object clauses and past tense marking) with standard tests (object naming, auditory and visual responsive naming), using pre-operative fMRI. Twenty-five surgical candidates (13 females) participated in this study. Sixteen patients presented with a brain tumor, and nine with epilepsy. All participants underwent two pre-operative fMRI protocols: one including CYCLE-N grammar tests (items testing word order in actives and passives, wh-subject and object questions, relativized subject and object clauses and past tense marking); and a second one with standard fMRI tests (object naming, auditory and visual responsive naming). fMRI activations during performance in both protocols were compared at the group level, as well as in individual candidates.ResultsThe grammar tests generated more volume of activation in the left hemisphere (left/right angular gyrus, right anterior/posterior superior temporal gyrus) and identified additional language regions not shown by the standard tests (e.g., left anterior/posterior supramarginal gyrus). The standard tests produced more activation in left BA 47. Ten participants had more robust activations in the left hemisphere in the grammar tests and two in the standard tests. The grammar tests also elicited substantial activations in the right hemisphere and thus turned out to be superior at identifying both right and left hemisphere contribution to language processing.ConclusionThe grammar tests may be an important addition to the standard pre-operative fMRI testing

The significance of the riparian zone in forest land management: A project presented in partial fulfilment of the requirements of a Diploma in Natural Resources from Lincoln College

The mechanisms governing the production of storm runoff have been a controversial topic since Horton first published his classical theory of overland flow (Horton, 1933). In response to the deficiencies in this theory, another concept was put forward (Hewlett, 1961; Betson, 1964) stating that storm runoff originates only from certain areas within the catchment. The most important of these is the land in the riparian zone, immediately adjacent to the stream channel. The recognition of an active zone and a passive zone in a catchment has implications that go beyond the explanation, prediction and man­ipulation of flood flows. Kunkle (1974) suggested the concept may be useful in the prediction and prevention of water pollution resulting from the spraying of pesticides and fertilisers. Similarly Engman (1974) discussed the potential of applying the concept to the manipulation of water yield. The practice of leaving unlogged buffer strips along streams is widely, although not universally, accepted as an integral part of production forestry management in the U.S.A. and in Canada, and is written into forest management procedures in both countries. (Stoddard, 1978; Ontario Ministry of Natural Resources 1973). Emphasis is placed on preventing the entry of sediments into streams, and protecting fresh­water fish habitats during logging. This is a practical application of an active-passive zone concept that preceded formal development of the partial contributing area concept. Differential, rather than blanket management of catchments may well be a viable proposition for water resource management as well as production forestry. This paper reviews the literature relating to the management of small forested catchments, comparing the New Zealand and overseas experience. It attempts to identify situations in which manipulation of the vegetation in the riparian zones may have a significant effect on the system's response, when manipulating the hydrologic response of the catchment and in the management of production forests where artificial stresses have been imposed on the system. Some general findings, indicating situations when selective management of riparian zones may be effective, are presented

Intrinsic network connectivity and own body perception in gender dysphoria.

Gender dysphoria (GD) is characterized by incongruence between one's identity and gender assigned at birth. The biological mechanisms of GD are unclear. We investigated brain network connectivity patterns involved in own body perception in the context of self in GD. Twenty-seven female-to-male (FtM) individuals with GD, 27 male controls, and 27 female controls underwent resting state fMRI. We compared functional connections within intrinsic connectivity networks involved in self-referential processes and own body perception -default mode network (DMN) and salience network - and visual networks, using independent components analyses. Behavioral correlates of network connectivity were also tested using self-perception ratings while viewing own body images morphed to their sex assigned at birth, and to the sex of their gender identity. FtM exhibited decreased connectivity of anterior and posterior cingulate and precuneus within the DMN compared with controls. In FtM, higher "self" ratings for bodies morphed towards the sex of their gender identity were associated with greater connectivity of the anterior cingulate within the DMN, during long viewing times. In controls, higher ratings for bodies morphed towards their gender assigned at birth were associated with right insula connectivity within the salience network, during short viewing times. Within visual networks FtM showed weaker connectivity in occipital and temporal regions. Results suggest disconnectivity within networks involved in own body perception in the context of self in GD. Moreover, perception of bodies in relation to self may be reflective rather than reflexive, as a function of mesial prefrontal processes. These may represent neurobiological correlates to the subjective disconnection between perception of body and self-identification

Generalized Psychophysiological Interaction (PPI) Analysis of Memory Related Connectivity in Individuals at Genetic Risk for Alzheimer's Disease.

In neuroimaging, functional magnetic resonance imaging (fMRI) measures the blood-oxygenation-level dependent (BOLD) signal in the brain. The degree of correlation of the BOLD signal in spatially independent regions of the brain defines the functional connectivity of those regions. During a cognitive fMRI task, a psychophysiological interaction (PPI) analysis can be used to examine changes in the functional connectivity during specific contexts defined by the cognitive task. An example of such a task is one that engages the memory system, asking participants to learn pairs of unrelated words (encoding) and recall the second word in a pair when presented with the first word (retrieval). In the present study, we used this type of associative memory task and a generalized PPI (gPPI) analysis to compare changes in hippocampal connectivity in older adults who are carriers of the Alzheimer's disease (AD) genetic risk factor apolipoprotein-E epsilon-4 (APOEε4). Specifically, we show that the functional connectivity of subregions of the hippocampus changes during encoding and retrieval, the two active phases of the associative memory task. Context-dependent changes in functional connectivity of the hippocampus were significantly different in carriers of APOEε4 compared to non-carriers. PPI analyses make it possible to examine changes in functional connectivity, distinct from univariate main effects, and to compare these changes across groups. Thus, a PPI analysis may reveal complex task effects in specific cohorts that traditional univariate methods do not capture. PPI analyses cannot, however, determine directionality or causality between functionally connected regions. Nevertheless, PPI analyses provide powerful means for generating specific hypotheses regarding functional relationships, which can be tested using causal models. As the brain is increasingly described in terms of connectivity and networks, PPI is an important method for analyzing fMRI task data that is in line with the current conception of the human brain

Sex differences in own and other body perception.

Own body perception, and differentiating and comparing one's body to another person's body, are common cognitive functions that have relevance for self-identity and social interactions. In several psychiatric conditions, including anorexia nervosa, body dysmorphic disorder, gender dysphoria, and autism spectrum disorder, self and own body perception, as well as aspects of social communication are disturbed. Despite most of these conditions having skewed prevalence sex ratios, little is known about whether the neural basis of own body perception differs between the sexes. We addressed this question by investigating brain activation using functional magnetic resonance imaging during a Body Perception task in 15 male and 15 female healthy participants. Participants viewed their own body, bodies of same-sex, or opposite-sex other people, and rated the degree that they appeared like themselves. We found that men and women did not differ in the pattern of brain activation during own body perception compared to a scrambled control image. However, when viewing images of other bodies of same-sex or opposite-sex, men showed significantly stronger activations in attention-related and reward-related brain regions, whereas women engaged stronger activations in striatal, medial-prefrontal, and insular cortices, when viewing the own body compared to other images of the opposite sex. It is possible that other body images, particularly of the opposite sex, may be of greater salience for men, whereas images of own bodies may be more salient for women. These observations provide tentative neurobiological correlates to why women may be more vulnerable than men to conditions involving own body perception