Neuronal NT-3 Is not Required For Synaptic Transmission or Long-Term Potentiation in Area CA1 of the Adult Rat Hippocampus

Neurotrophic factors, including BDNF and NT-3, have been implicated in the regulation of synaptic transmission and plasticity. Previous attempts to analyze synaptic transmission and plasticity in mice lacking the NT-3 gene have been hampered by the early death of the NT-3 homozygous knockout animals. We have bypassed this problem by examining synaptic transmission in mice in which the NT-3 gene is deleted in neurons later in development, by crossing animals expressing the CRE recombinase driven by the synapsin I promoter to animals in which the NT-3 gene is floxed. We conducted blind field potential recordings at the Schaffer collateral–CA1 synapse in hippocampal slices from homozygous knockout and wild-type mice. We examined the following indices of synaptic transmission: (1) input-output relationship; (2) paired-pulse facilitation; (3) post-tetanic potentiation; and (4) long-term potentiation: induced by two different protocols: (a) two trains of 100-Hz stimulation and (b) theta burst stimulation. We found no difference between the knockout and wild-type mice in any of the above measurements. These results suggest that neuronal NT-3 does not play an essential role in normal synaptic transmission and some forms of plasticity in the mouse hippocampus.     

Interaction of depression and bereavement on mental health in the elderly

Three hundred ninety-three elderly adults aged 55 and older were divided into 1 of 9 subgroups in a 3 (bereavement group: survivors of spouses who died by natural death or by suicide and nonbereaved control Ss) x 3 (depression group: none, mild, and moderate-severe) design over 4 times of measurement--1 month, 6 months, 1 year, and 2.5 years after death of spouse. Significant Bereavement x Depression Group effects were obtained on Brief Symptom Inventory scores. The moderate-severe depression/suicide subgroup had the greatest psychiatric complications with bereavement. Results indicated that elderly persons with significant clinical depression at the time of a spouse's death were at significant risk for psychological complications during the bereavement process, and survivors of spouses who had committed suicide were even more at risk within the greatest depression group.     

Development and validation of the Physical Appearance Related Teasing Scale

The development and preliminary validation of the Physical Appearance Related Testing Scale (PARTS) is reported. The 18-item scale has good psychometric qualities (high internal consistency and test-retest reliabilities) and consists of two factors: Weight/Size Testing (W/ST) and General Appearance Teasing (GAT). The W/ST converges well with measures of eating disturbance, body image dissatisfaction, social comparison, depression, and self-esteem, whereas the GAT scale shows little relationship to these variables. The role of teasing history as an etiological component of body image and eating disturbance is discussed; the need for further validation work on the PARTS is addressed.     

Integration of features in comparing multifeature stimuli

For a series of trials, the subject indicated whether or not two face-like stimuli were identical with respect to the features they contained (a positive or negative response, respectively); reaction time (RT) was recorded. The stimuli were separated by .5 or 4.0 sec, and each contained either two or three features. On some trials, the features of the first stimulus were represented within a single head outline; on others, they were distributed over several spatially separated outlines (components). Positive-response RT increased with the number of stimulus features and with the number of first-stimulus components (c); these two factors were additive. Negative-response RT increased with c, decreased with the number of differing features, and these two factors interacted. These effects did not vary with interstimulus interval. The results indicate that the subject did not integrate the first-stimulus components, but instead compared the second stimulus to each component, holistically (for positive responses) or analytically (for negative responses).     

An automated odor test for rats

The odor-testing apparatus described consists of a circular open-field area opening into four glass tubes, each with an odor source at the far end. When a rat is introduced, each tube is blocked by a grid; when the rat has touched each grid (sampled each odor), the tubes automatically open and recording of preference behavior starts. Two measures of preference are recorded by a photocell outside each tube, the number of visits and the time spent near the odor source. A uniformity test with food odor in all tubes showed that the apparatus did not promote position bias. In two separate sensitivity tests, one with food odor and one with estrous female urine odor, male rats significantly preferred an attractive odor in one tube to odorless controls. The apparatus yields relatively sensitive and reliable odor preference determinations by ensuring sampling of each odor before data are recorded and by eliminating visual, auditory and gustatory cues.     

CONTINGENCY SPACES AND MEASURES IN CLASSICAL AND INSTRUMENTAL CONDITIONING1

The contingency between conditional and unconditional stimuli in classical conditioning paradigms, and between responses and consequences in instrumental conditioning paradigms, is analyzed. The results are represented in two- and three-dimensional spaces in which points correspond to procedures, or procedures and outcomes. Traditional statistical and psychological measures of association are applied to data in classical conditioning. Root mean square contingency, ø, is proposed as a measure of contingency characterizing classical conditioning effects at asymptote. In instrumental training procedures, traditional measures of association are inappropriate, since one degree of freedom—response probability—is yielded to the subject. Further analysis of instrumental contingencies yields a surprising result. The well established “Matching Law” in free-operant concurrent schedules subsumes the “Probability Matching” finding of mathematical learning theory, and both are equivalent to zero contingency between responses and consequences.     

An automated sound-localization chamber

A completely automated free-field sound-localization apparatus is described along with a behavioral technique that provides several advantages over previously available methods. With the apparatus, the ability to localize the source of a sound has been tested in a wide variety of mammals including cats, rats, squirrel monkeys, hedgehogs, and tree shews.