Sensory memory consolidation observed: Increased specificity of detail over days

Memories are usually multidimensional, including contents such as sensory details, motivational state and emotional overtones. Memory contents generally change over time, most often reported as a loss in the specificity of detail. To study the temporal changes in the sensory contents of associative memory without motivational and emotional contents, we induced memory for acoustic frequency by pairing a tone with stimulation of the cholinergic nucleus basalis. Adult male rats were first tested for behavioral responses (disruption of ongoing respiration) to tones (1–15 kHz), yielding pre-training behavioral frequency generalization gradients (BFGG). They next received three days of training consisting of a conditioned stimulus (CS) tone (8.00 kHz, 70 dB, 2 s) either Paired (n = 5) or Unpaired (n = 5) with weak electrical stimulation (～48 μA) of the nucleus basalis (100 Hz, 0.2 s, co-terminating with CS offset). Testing for behavioral memory was performed by obtaining post-training BFGGs at two intervals, 24 and 96 h after training. At 24 h post-training, the Paired group exhibited associative behavioral memory manifested by significantly larger responses to tone than the Unpaired group. However, they exhibited no specificity in memory for the frequency of the tonal CS, as indexed by a flat BFGG. In contrast, after 96 h post-training the Paired group did exhibit specificity of memory as revealed by tuned BFGGs with a peak at the CS-band of frequencies. This increased detail of memory developed due to a loss of response to lower and higher frequency side-bands, without any change in the absolute magnitude of response to CS-band frequencies. These findings indicate that the sensory contents of associative memory can be revealed to become more specific, through temporal consolidation in the absence of non-sensory factors such as motivation and emotion.     

Behavioral memory induced by stimulation of the nucleus basalis: Effects of contingency reversal

Specific behavioral associative memory induced by stimulation of the cortically-projecting cholinergic nucleus basalis (NB) is dependent on intrinsic acetylcholine and shares with natural memory such features as associativity, specificity, rapid formation, consolidation and long-term retention. Herein, we examined extinction and the effects of stimulus pre-exposure. Two groups of adult male rats (n = 4 each) were first tested for behavioral responses (disruption of ongoing respiration) to tones (1–15 kHz), constituting a pre-training behavioral frequency generalization gradient (BFGG). They next received a first session of training, 200 trials of a tone (8.00 kHz, 70 dB, 2 s) either paired with electrical stimulation of the NB (100 Hz, 0.2 s, ～67 μA, NBstm) (group IP) or unpaired (group IU). Twenty-four hours later, they were tested for behavioral memory by obtaining post-training BFGGs. Then the contingencies were reversed yet another 24 h later; the IP group received tone and NBstm unpaired and the IU group received them paired. A final set of generalization gradients was obtained the next day. All stimuli were presented with subjects under state control indexed by regular respiration. Tested 24 h post-initial training, the IP group developed specific associative behavioral memory indicated by increased responses only to CS-band frequencies, while the IU group did not. After subsequent training with unpaired stimuli, the IP group exhibited experimental extinction. Furthermore, after initial exposure to the CS and NBstm unpaired, the IU group exhibited a tendency toward reduced conditioning to CS/NBstm pairing and a significant increase in latency of conditioned responses. The present findings provide additional support for the hypothesis that engagement of the NB is sufficient to induce natural associative memory and suggest that activation of the NB may be a normal component in the formation of natural associative memory.     

How Can Experts See the Invisible? Reply to Bilalić and Gobet

Experts in all fields are able to see what is invisible to others. Experts are also able to see what is visible to all—and this is explored by Bilalić and Gobet. We question the method of normalizing all subjects in an experimental condition, and asking experts to behave as if they were novices. We claim that method leads Bilalić and Gobet to a nonsequitur .     

A twenty-five year follow-up study of ten exceptionally creative adolescent girls

A 25-yr. follow-up of 10 women identified as highly creative during adolescence indicated that most believed they had actualized their creative potential to a moderately high degree. However, only one woman stated that creative expression was a dominant life theme and primary commitment. Factors that facilitate and inhibit creativity over a lifetime are discussed.     

The case against coronary artery surgery

Coronary by-pass surgery has been performed in hundreds of thousands of patients in the last 15 years with a high standard of technical and surgical perfection. The indications for this kind of surgery, however, are still controversial because in spite of many retrospective and several prospective studies it cannot be proven convincingly that in a given patient this surgical procedure will prolong life or prevent myocardial infarction. The present attempt to analyze the causes for this controversy shows that the main reasons for this uncertainty lie: (a) in the enigma of the underlying (ischemic heart) disease itself, which is supposed to lend itself to surgical therapy; (b) in the inadequate methods available up until now for characterizing the state of the disease, its probable course, and its pathogenesis; and (c) in the professional group interests which have a momentum of their own.     

Vitamins E and C pretreatment prevents ovariectomy-induced memory deficits in water maze

We investigated whether the pretreatment with vitamins E (alpha-tocopherol) and C (ascorbic acid) would act on ovariectomy-induced memory deficits in Morris water maze tasks. Adult female Wistar rats were divided into three groups: (1) naive (control), (2) sham (submitted to surgery without removal of ovaries) and (3) ovariectomized. Thirty days after surgery, they were trained in the Morris water maze in order to verify ovariectomy effects both on reference and working memory tasks. Results show that ovariectomized rats presented impairment in spatial navigation in the acquisition phase, as well as in the time spent in target quadrant and in the latency to cross over the location of the platform in test session, when compared to naive and sham groups (controls), in the reference memory task. Ovariectomy did not affect performance in the working memory task. Confirming our hypothesis, ovariectomized rats pretreated for 30 days with vitamins E and C had those impairments prevented. We conclude that ovariectomy significantly impairs spatial reference learning/memory and that pretreatment with vitamins E and C prevents such effect. Assuming this experimental memory impairment might mimic, at least in part, the cognitive deficit sometimes present in the human condition of lack of reproductive hormones, our findings lend support to a novel therapeutic strategy, based on vitamins E and C, to cognitive impairments in post-menopausal women.     

The role of enactment in prospective remembering

This study investigated, in a laboratory setting, whether prospective memory (remembering to perform intended actions in the future) would be improved by self-enactment of the to-be-remembered tasks. The subjects, 45 university students, were asked to remember later to perform five tasks that they initially enacted themselves, watched the experimenter perform, or had described to them. These tasks were to be performed, ostensibly in preparation for the next subject, at the end of 30 min of filler activity, which was presented as the experimental task. Surprisingly, self-enactment produced the poorest prospective remembering. Speculative explanations are offered in terms of both metacognitive expectations about memory and output-monitoring deficiencies.